Reject a metadata database truncated to the age header and nonce (closes #152)

An object holding just the age header and its 16-byte nonce decrypts without error: the truncated read surfaces as io.ErrUnexpectedEOF at the age layer, which the zstd decoder maps to a clean EOF at frame start. blobgen then reported zero bytes and no error, so a truncated stream was indistinguishable from a valid empty one, and the metadata database export slipped through -- restore built a fresh schema on the empty file and reported success.

blobgen.Reader.Read now, on EOF, reads once more from the age reader and surfaces io.ErrUnexpectedEOF unless that read is (0, io.EOF), the state a genuine end leaves. downloadSnapshotDB additionally rejects a zero-length decrypted database before any schema is built.

Model: opus-4-8

AGENTS.md

@@ -104,7 +104,12 @@ Version: 2025-06-08
 
 13. Pre-1.0: NEVER write database migrations. There are no live databases
     anywhere — every user's local index can be rebuilt from a fresh full
-    backup. When the schema changes, just change `schema.sql` (and any code
+    backup. To change the schema, edit `internal/database/schema/001.sql`
-    that touches the affected tables). The local index is disposable until
+    (and any code that touches the affected tables) directly; do not add new
-    1.0 ships and is tagged.
+    numbered schema files. Those numbered files and the `schema_migrations`
+    table they populate only bootstrap a fresh database — they are not an
+    upgrade path. The local index is disposable until 1.0 ships and is
+    tagged; once 1.0 is tagged that clause expires and the question of
+    upgrading existing indexes returns. See [`docs/DATAMODEL.md`](docs/DATAMODEL.md)
+    for the full explanation.
 

ARCHITECTURE.md

@@ -63,7 +63,7 @@ A content-addressed unit of data. Files are split into variable-size chunks usin
 - `ChunkHash`: SHA256 hash of chunk content (primary key)
 - `Size`: Chunk size in bytes
 
-Chunk sizes vary between `avgChunkSize/4` and `avgChunkSize*4` (typically 16KB-256KB for 64KB average).
+Chunk sizes vary between `avgChunkSize/4` and `avgChunkSize*4` (2.5MB-40MB for the 10MB default average).
 
 #### FileChunk (`database.FileChunk`)
 Maps files to their constituent chunks:
@@ -120,7 +120,7 @@ The CLI uses fx for dependency injection. Here's the instantiation order:
 ```go
 // cli/app.go: NewApp()
 fx.New(
-    fx.Supply(config.ConfigPath(opts.ConfigPath)),  // 1. Config path
+    fx.Supply(config.Path(opts.ConfigPath)),         // 1. Config path
     fx.Supply(opts.LogOptions),                      // 2. Log options
     fx.Provide(globals.New),                         // 3. Globals
     fx.Provide(log.New),                             // 4. Logger config
@@ -193,7 +193,7 @@ scanner := v.ScannerFactory(snapshot.ScannerParams{
 - **Created by**: `chunker.NewChunker(avgChunkSize)`
 - **When**: Inside `snapshot.NewScanner()`
 - **Configuration**:
-  - `avgChunkSize`: From config (typically 64KB)
+  - `avgChunkSize`: From config (default 10MB)
   - `minChunkSize`: avgChunkSize / 4
   - `maxChunkSize`: avgChunkSize * 4
 
@@ -286,7 +286,6 @@ Key methods:
 - `CreateSnapshot(ctx, hostname, version, commit)` → Create snapshot record
 - `CompleteSnapshot(ctx, snapshotID)` → Mark snapshot complete
 - `ExportSnapshotMetadata(ctx, dbPath, snapshotID)` → Export to S3
-- `CleanupIncompleteSnapshots(ctx, hostname)` → Remove failed snapshots
 
 ### `internal/database`
 SQLite database for local index. Single-writer mode for thread safety.
@@ -307,7 +306,7 @@ Repository interfaces:
 ```
 CreateSnapshot(opts)
     │
-    ├─► CleanupIncompleteSnapshots()   // Critical: avoid dedup errors
+    ├─► PruneDatabase()   // Critical: avoid dedup errors
     │
     ├─► SnapshotManager.CreateSnapshot()   // Create DB record
     │

Dockerfile

@@ -20,8 +20,6 @@
 # golang:1.26.1-alpine, 2026-03-17
 FROM golang:1.26.1-alpine@sha256:2389ebfa5b7f43eeafbd6be0c3700cc46690ef842ad962f6c5bd6be49ed82039 AS builder
 
-ARG VERSION=dev
-
 # Build tooling: make, plus a C toolchain because `go test -race` needs cgo.
 # The sqlite driver is pure Go (modernc.org/sqlite), so no sqlite library or
 # CLI is required.
@@ -66,8 +64,31 @@ RUN [ -n "$CHECK_EPOCH" ] || exit 1
 RUN echo "check epoch: ${CHECK_EPOCH}" && make fmt-check
 RUN echo "check epoch: ${CHECK_EPOCH}" && make test
 
+# Version, commit and build date are computed on the host by
+# script/docker and script/cibuild (where .git exists) and passed in as
+# build args. The build context excludes .git (see .dockerignore), so
+# the build cannot derive them itself: it used to try, with `git
+# rev-parse` inside this stage, and always got "unknown". VERSION comes
+# from script/version, the source of truth shared with the Makefile, so
+# it carries the same tag / dev-<sha> / -dirty rules and a Docker image
+# reports the same string a local build of the same tree would.
+#
+# The defaults are the fallback for a bare `docker build .` that passes
+# none of them: an unset arg would otherwise stamp an empty string and
+# produce an image that cannot report its own version, commit or date.
+# They match what an out-of-git build reports elsewhere.
+#
+# These ARGs sit here, after the checks, rather than at the top of the
+# stage: every commit changes their values, and a value change
+# invalidates all layers below the ARG. Declared up top they would bust
+# `go mod download`; here they only rekey this build layer, which the
+# COPY of the sources above already rebuilds on any change anyway.
+ARG VERSION=dev
+ARG COMMIT=unknown
+ARG COMMIT_DATE=unknown
+
 # Build (pure Go, no CGO required since we use modernc.org/sqlite)
-RUN CGO_ENABLED=0 go build -ldflags "-X 'sneak.berlin/go/vaultik/internal/globals.Version=${VERSION}' -X 'sneak.berlin/go/vaultik/internal/globals.Commit=$(git rev-parse HEAD 2>/dev/null || echo unknown)' -X 'sneak.berlin/go/vaultik/internal/globals.CommitDate=$(git show -s --format=%cs HEAD 2>/dev/null || echo unknown)'" -o /vaultik ./cmd/vaultik
+RUN CGO_ENABLED=0 go build -ldflags "-X 'sneak.berlin/go/vaultik/internal/globals.Version=${VERSION}' -X 'sneak.berlin/go/vaultik/internal/globals.Commit=${COMMIT}' -X 'sneak.berlin/go/vaultik/internal/globals.CommitDate=${COMMIT_DATE}'" -o /vaultik ./cmd/vaultik
 
 # Runtime stage
 # alpine:3.21, 2026-02-25

README.md

@@ -71,14 +71,19 @@ Requirements that no existing tool meets:
 ## daily use
 
 ```sh
-# verify a snapshot (shallow: checks all blobs exist)
+# verify a snapshot (shallow: checks all blobs are present with the listed size)
 vaultik snapshot verify <snapshot-id>
 
+# put the private key file in the environment (reading it from the file
+# keeps the key out of your shell history); the whole age-keygen file,
+# with one or more identities, is accepted
+export VAULTIK_AGE_SECRET_KEY="$(cat vaultik_backup_private_key.txt)"
+
 # deep verify (downloads and cryptographically verifies every blob)
-VAULTIK_AGE_SECRET_KEY='AGE-SECRET-KEY-...' vaultik snapshot verify --deep <snapshot-id>
+vaultik snapshot verify --deep <snapshot-id>
 
 # restore (requires the private key)
-VAULTIK_AGE_SECRET_KEY='AGE-SECRET-KEY-...' vaultik snapshot restore <snapshot-id> /tmp/restored
+vaultik snapshot restore <snapshot-id> /tmp/restored
 
 # daily cron job: back up, keep a 4-week rolling window of snapshots
 # 0 3 * * * vaultik snapshot create --cron --prune --keep-newer-than 4w
@@ -119,15 +124,17 @@ Use that remote key — the hex printed inside `<remote only:...>`, or the
 full `remote_key` from `snapshot list --json` — to restore and verify:
 
 ```sh
+# put the private key file in the environment (reading it from the file
+# keeps the key out of your shell history)
+export VAULTIK_AGE_SECRET_KEY="$(cat vaultik_backup_private_key.txt)"
+
 # restore everything to /tmp/restored, then check every restored file's
 # chunk hashes
-VAULTIK_AGE_SECRET_KEY='AGE-SECRET-KEY-...' \
+vaultik snapshot restore --verify <remote-key> /tmp/restored
-  vaultik snapshot restore --verify <remote-key> /tmp/restored
 
 # optionally, deep-verify the snapshot against the store (downloads and
 # cryptographically checks every blob)
-VAULTIK_AGE_SECRET_KEY='AGE-SECRET-KEY-...' \
+vaultik snapshot verify --deep <remote-key>
-  vaultik snapshot verify --deep <remote-key>
 ```
 
 `age_recipients` (the public key) is not needed to restore — only the
@@ -147,10 +154,10 @@ vaultik [--config <path>] config edit
 vaultik [--config <path>] config get <key>
 vaultik [--config <path>] config set <key> <value>
 vaultik [--config <path>] snapshot create [snapshot-names...] [--cron] [--prune] [--keep-newer-than <duration>]
-vaultik [--config <path>] snapshot list [--json]
+vaultik [--config <path>] snapshot list [--json]                  # alias: ls
 vaultik [--config <path>] snapshot verify <snapshot-id> [--deep] [--json]
 vaultik [--config <path>] snapshot purge [--keep-latest | --older-than <duration>] [--snapshot <name>...] [--force]
-vaultik [--config <path>] snapshot remove <snapshot-id> [--dry-run] [--force] [--local-only] [--json]
+vaultik [--config <path>] snapshot remove <snapshot-id> [--dry-run] [--force] [--local-only] [--json]  # alias: rm
 vaultik [--config <path>] snapshot restore <snapshot-id> <target-dir> [paths...] [--verify]
 vaultik [--config <path>] prune [--force] [--json]
 vaultik [--config <path>] info
@@ -167,7 +174,24 @@ vaultik version
 * `--verbose`, `-v`: Enable verbose output (on stderr — see below)
 * `--debug`: Enable debug output (on stderr — see below)
 * `--quiet`, `-q`: Suppress non-error output (also suppresses startup banner)
-* `--skip-errors`: Continue past per-file errors instead of aborting (applies to `snapshot create` and `restore`)
+* `--skip-errors`: Skip files that cannot be read when creating a snapshot, or that cannot be restored when restoring, instead of aborting. Packing and storage errors (which would leave a chunk recorded but not stored) still abort the run.
+
+### locking
+
+Commands that write persistent state — `snapshot create`, `snapshot
+purge`, `snapshot remove`, `prune`, and `remote nuke` — take a
+process-wide lock at `$XDG_DATA_HOME/vaultik/vaultik.pid`
+(`~/.local/share/vaultik/vaultik.pid` on Linux) for the whole run. Only
+one of them runs at a time: a second one exits immediately with an
+"already running" error rather than waiting, so two writers can never
+corrupt the local index or the destination store.
+
+Read-only commands — `info`, `snapshot list`, `snapshot verify`, and
+`remote info` — do not take the lock and are never blocked, so they run
+even while a backup is in progress. `snapshot restore` does not take the
+lock either: it writes only to the target directory you name, not the
+local index or the destination store. `config`, `database delete`,
+`completion`, and `version` do not take the lock.
 
 ### stdout and stderr
 
@@ -200,9 +224,11 @@ and `vaultik prune --json | jq .` both work as written.
 
 ### environment variables
 
-* `VAULTIK_AGE_SECRET_KEY`: Age private key for decryption (required for `snapshot restore` and `snapshot verify --deep`)
+* `VAULTIK_AGE_SECRET_KEY`: Age private key for decryption (required for `snapshot restore` and `snapshot verify --deep`). May hold the whole `age-keygen` file — comments and every identity in it are accepted. Set it from the file, e.g. `export VAULTIK_AGE_SECRET_KEY="$(cat vaultik_backup_private_key.txt)"`, so the key is not typed into your shell history.
 * `VAULTIK_CONFIG`: Path to config file (overridden by `--config`)
 * `VAULTIK_INDEX_PATH`: Override local SQLite index path
+* `VAULTIK_CPUPROFILE`: Write a CPU profile to this path for the duration of the run (development/debugging)
+* `VAULTIK_MEMPROFILE`: Write a heap profile to this path when the run exits (development/debugging)
 
 ### shell completion
 
@@ -293,7 +319,9 @@ local index alone, and still exits zero.
   logger, so stdout stays a single parseable document.
 
 **`snapshot verify`**: Verify snapshot integrity.
-* Default (shallow): checks that all blobs referenced in the manifest exist in storage
+* Default (shallow): checks that every blob the manifest lists is present in
+  storage with the size the manifest records, and that the encrypted database is
+  present. It does not read blob contents.
 * `--deep`: Downloads and decrypts each blob, verifies chunk hashes against the
   encrypted metadata database
 * Accepts the same identifiers as `snapshot restore`: a snapshot ID, or a
@@ -395,6 +423,10 @@ both are set.
 
 ## architecture
 
+For an implementation-level view of the internals — the data model, the
+`fx` dependency-injection wiring, and the scanner — see
+[`ARCHITECTURE.md`](ARCHITECTURE.md).
+
 ### remote storage layout
 
 ```
@@ -472,25 +504,30 @@ derivation.
 
 ### compression
 
-* zstd compression at configurable level (1-19, default 3)
+* zstd compression at configurable level (1-19, default 3). The level is
+  accepted as 1-19 but maps onto zstd's four internal speed presets:
+  1-2 fastest, 3-5 default, 6-9 better, 10-19 best. Levels within the
+  same band compress identically.
 * Applied before encryption at the blob level
 
 ---
 
 ## configuration reference
 
-Run `vaultik config init` to generate a fully commented config file.
+Run `vaultik config init` to generate a fully commented config file; a
-Key fields:
+complete annotated example also lives in
+[`config.example.yml`](config.example.yml). Key fields:
 
 | Field | Default | Description |
 |-------|---------|-------------|
 | `age_recipients` | (required) | Age public keys for encryption |
+| `age_secret_key` | (unset) | Age private key for decryption (`snapshot restore`, `snapshot verify --deep`). Setting it in the config file places the private key on the backed-up host, defeating the public-key-only design (see "why" above). Prefer the `VAULTIK_AGE_SECRET_KEY` environment variable, supplied only on the machine you restore from. |
 | `snapshots` | (required) | Named snapshot definitions with paths and excludes |
 | `storage_url` | | Storage backend URL (`s3://`, `file://`, `rclone://`) |
 | `s3.*` | | Legacy S3 configuration (endpoint, bucket, credentials) |
 | `exclude` | | Global exclude patterns (applied to all snapshots) |
 | `chunk_size` | `10MB` | Average chunk size for content-defined chunking |
-| `blob_size_limit` | `10GB` | Maximum blob size before splitting |
+| `blob_size_limit` | `10GB` | Maximum blob size before splitting. Must be at least four times `chunk_size` (the largest chunk the chunker can emit), otherwise a single-chunk blob could exceed the limit |
 | `compression_level` | `3` | zstd compression level (1-19) |
 | `hostname` | system hostname | Hostname used in snapshot IDs |
 | `index_path` | platform data dir | Local SQLite index path |
@@ -514,9 +551,13 @@ Key fields:
   sequentially. Restore speed is bound by single-stream throughput.
 * **Device nodes, named pipes, and sockets are silently skipped.** Only
   regular files, directories, and symlinks are backed up.
-* **No database migrations.** If the local SQLite schema changes between
+* **No upgrade path between versions.** There is no supported way to carry
-  versions, delete the local database (`vaultik database delete`) and run
+  an existing local index across a schema change; if the local SQLite
-  a full backup. Remote storage is unaffected.
+  schema changes between versions, delete the local database (`vaultik
+  database delete`) and run a full backup. Remote storage is unaffected.
+  (The binary does embed numbered schema files and a `schema_migrations`
+  table to bootstrap a fresh database — see [`docs/DATAMODEL.md`](docs/DATAMODEL.md)
+  — but that is not an upgrade path.)
 * **Files that change during backup may be inconsistent.** There is no
   filesystem snapshot or freeze. If a file is modified between the scan
   and chunk phases, the backed-up copy may reflect a partial write.
@@ -582,10 +623,12 @@ priority.
 
 ### infrastructure
 
-* **Schema migrations.** Currently nonexistent — pre-1.0 schema
+* **Cross-version schema upgrades.** There is no upgrade path between
-  changes are handled by `vaultik database delete` plus a full
+  released versions — pre-1.0 schema changes are handled by `vaultik
-  re-scan. Post-1.0 we'll need a migration story to keep existing
+  database delete` plus a full re-scan (see
-  index databases usable across upgrades.
+  [`docs/DATAMODEL.md`](docs/DATAMODEL.md)). Post-1.0 we'll need a
+  migration story to keep existing index databases usable across
+  upgrades.
 * **Storage backend coverage tests.** S3, file://, and rclone://
   all share the Storer interface but the rclone path is the least
   exercised in CI.
@@ -594,9 +637,17 @@ priority.
 
 ## output style
 
-All user-facing output goes through helpers in `internal/ui` and conforms
+The operational narration of the long-running commands — the Begin,
-to a uniform style. Color is enabled when stdout is a TTY and the
+Complete, Progress, and status lines of `snapshot create`, `prune`,
-`NO_COLOR` environment variable is unset (https://no-color.org/).
+`snapshot restore`, and the like — goes through helpers in `internal/ui`
+and conforms to the uniform style below. Some commands instead write
+plain text straight to stdout (`version`, `info`, `config`, the
+`database delete` prompt, and the `snapshot list` table); that output is
+unstyled and does not honor `--quiet`. Routing it through `internal/ui`
+is tracked in
+[issue #149](https://git.eeqj.de/sneak/vaultik/issues/149). Color is
+enabled when stdout is a TTY and the `NO_COLOR` environment variable is
+unset (https://no-color.org/).
 
 `internal/ui` writes to stdout; it is the output the user asked for.
 Structured log records are a different thing and go through

TODO.md

@@ -25,6 +25,66 @@ release" is exactly the contradiction
 
 # Completed Steps
 
+- 2026-09-22: Validated blob hashes, offsets and lengths read back from
+  the destination before using them
+  ([issue #155](https://git.eeqj.de/sneak/vaultik/issues/155)). A blob
+  hash taken from the downloaded database or the store listing was
+  trusted unchecked, so a hostile remote could drive a decrypted blob to
+  be written outside the cache directory (a hash like `aa/../../etc`) or
+  crash a command with a short or negative value. `blobDiskCache.path`
+  now refuses any key containing a path separator, and `ReadAt` rejects a
+  negative offset or length and bounds with `length > size-offset` so a
+  sum cannot overflow past the check. A new `isBlobHash` helper (a plain
+  function, not a method — the packer stores `temp-placeholder-{uuid}` as
+  a hash) gates `FetchBlob`, shallow and deep verify; the `blobs/` and
+  `metadata/` listings skip a non-conforming name with a warning; and
+  short-hash prefixes in log and error text go through a `shortHash`
+  helper that cannot panic. `verify`'s chunk reader also rejects a
+  negative `blob_chunks` length and streams the chunk instead of
+  allocating a database-supplied size. `restore.go` and
+  `internal/database` were left untouched to avoid colliding with the
+  in-flight [issue #156](https://git.eeqj.de/sneak/vaultik/issues/156)
+  work; the cache-path and `FetchBlob` guards already stop the unsafe
+  write and fetch, so restore's own `buildBlobIndexes` early check is
+  deferred as fail-fast defense in depth.
+
+- 2026-09-21: Stopped an interrupted blob upload from making a later
+  backup deduplicate against data that was never stored
+  ([issue #148](https://git.eeqj.de/sneak/vaultik/issues/148)). The
+  packer commits a blob's `chunks`, `blob_chunks`, and `blobs` rows
+  before the upload is attempted, so a failed upload left chunk rows
+  behind and the next run skipped re-uploading them, producing a
+  snapshot that reported success but could not be restored. A run now
+  deduplicates only against chunks held by a blob whose `uploaded_ts` is
+  set, and at startup drops any un-uploaded blob rows (and the chunks
+  they orphan) so the affected data is re-chunked and re-uploaded. Blobs
+  recorded with no remote backend are marked uploaded so this invariant
+  holds uniformly.
+
+- 2026-09-22: Made restore refuse any snapshot path that would write
+  outside the target directory
+  ([issue #154](https://git.eeqj.de/sneak/vaultik/issues/154)).
+  `restoreFile` and `verifyRestoredFiles` joined the stored path onto the
+  target with no containment check, so a `..` segment or an absolute path
+  escaped the target and a restored symlink could redirect a later child
+  write anywhere on disk. Every stored path is now rejected unless
+  `filepath.IsLocal` accepts it with the leading separator removed, and
+  each existing ancestor directory below the target is `Lstat`ed to refuse
+  descending through a symlink; honest symlinks pointing outside the tree
+  are still written verbatim. age decryption proves a snapshot is
+  readable, not honest, and restore usually runs as root.
+
+- 2026-09-21: Stopped `--json` from silencing stderr diagnostics
+  ([issue #112](https://git.eeqj.de/sneak/vaultik/issues/112)). `--json`
+  used to be folded into `Quiet`, which pinned the log level to `WARN`,
+  so `prune --json` gave a machine consumer no record of the local index
+  rows it deleted even under `--verbose`. `--json` now quiets only the
+  stdout UI (the JSON document must stay clean, per
+  [issue #108](https://git.eeqj.de/sneak/vaultik/issues/108)); the stderr
+  log level follows `--verbose`/`--debug` again. The coupling was
+  removed the same way for `snapshot verify`, `snapshot remove`, and
+  `remote info`, which carried it for the same outdated reason.
+
 - 2026-09-21: Stopped `prune` from reporting a failed row count as 0
   ([issue #96](https://git.eeqj.de/sneak/vaultik/issues/96)). The seven
   `getTableCount` reads in `PruneDatabase` discarded their error, so a

cmd/vaultik/dockerversion_test.go

@@ -0,0 +1,102 @@
+package main_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// This file guards the version stamping of the product image (issue
+// #75). The failure it protects against is silent: the image still
+// builds and runs, but `vaultik version` inside it reports "commit:
+// unknown", so an operator cannot tell which source produced a given
+// backup. .dockerignore excludes .git, so the build cannot derive the
+// commit itself; the values must be computed on the host and passed in.
+//
+// These are parses of the committed files, for the same reason the lint
+// guards next door are: shelling out to docker would nest a build
+// inside `make test`. That `vaultik version` in the built image really
+// prints the host's version is verified by hand and recorded on the
+// pull request.
+
+// dockerScript is script/docker, relative to the repository root.
+const dockerScript = "script/docker"
+
+// versionArgs are the ldflag targets the build stamps and, matching
+// them, the build args the host must supply. The names line up so the
+// same list checks both files.
+func versionArgs() []string {
+	return []string{"VERSION", "COMMIT", "COMMIT_DATE"}
+}
+
+// TestProductDockerfileTakesVersionAsBuildArgs fails unless the build
+// declares each version arg and stamps it into the binary by ldflag
+// reference, rather than computing it in the container.
+func TestProductDockerfileTakesVersionAsBuildArgs(t *testing.T) {
+	t.Parallel()
+
+	found := instructions(t, productDockerfile)
+
+	for _, arg := range versionArgs() {
+		require.GreaterOrEqual(t, indexOf(found, "ARG "+arg), 0,
+			"%s must declare `ARG %s` so the host can pass it in",
+			productDockerfile, arg)
+
+		assertLdflagReferences(t, found, arg)
+	}
+}
+
+// TestProductDockerfileDoesNotDeriveVersionItself is the anti-regression
+// for the original defect: the container ran `git rev-parse`, but .git
+// is not in the build context, so it always resolved to "unknown". No
+// git command may reach into a build that cannot see the history.
+func TestProductDockerfileDoesNotDeriveVersionItself(t *testing.T) {
+	t.Parallel()
+
+	text := instructionText(readRepoFile(t, productDockerfile))
+
+	assert.NotContains(t, text, "git ",
+		"%s must not run git: .git is excluded from the build context, so"+
+			" any value it derives is wrong. Pass version, commit and date"+
+			" in as build args instead.", productDockerfile)
+}
+
+// TestDockerScriptComputesVersionOnTheHost fails unless script/docker
+// derives each value where .git exists and passes it as a build arg,
+// with VERSION coming from script/version so a Docker build reports the
+// same string a local build of the same tree would.
+func TestDockerScriptComputesVersionOnTheHost(t *testing.T) {
+	t.Parallel()
+
+	script := readRepoFile(t, dockerScript)
+
+	for _, arg := range versionArgs() {
+		assert.Contains(t, script, "--build-arg "+arg+"=",
+			"%s must pass --build-arg %s to the build", dockerScript, arg)
+	}
+
+	assert.Contains(t, script, "/version",
+		"%s must take VERSION from script/version, the source of truth"+
+			" shared with the Makefile", dockerScript)
+}
+
+// assertLdflagReferences fails unless some build instruction stamps the
+// named variable from the ARG (a ${arg} reference), not from a value
+// computed inside the container.
+func assertLdflagReferences(t *testing.T, found []string, arg string) {
+	t.Helper()
+
+	for _, instruction := range found {
+		if strings.HasPrefix(instruction, "RUN ") &&
+			strings.Contains(instruction, "go build") &&
+			strings.Contains(instruction, "${"+arg+"}") {
+			return
+		}
+	}
+
+	assert.Fail(t, "version arg is declared but never stamped",
+		"the go build in %s must reference ${%s} in its ldflags, or the"+
+			" arg is passed and discarded", productDockerfile, arg)
+}

cmd/vaultik/lintdocker_test.go

@@ -304,10 +304,14 @@ func instructionText(contents string) string {
 }
 
 // indexOf returns the position of the first instruction equal to, or
-// beginning with, want; -1 if there is none.
+// beginning with, want; -1 if there is none. An `ARG NAME=default`
+// counts as beginning with `ARG NAME`, so a declared arg is found
+// whether or not it carries a default.
 func indexOf(found []string, want string) int {
 	for i, instruction := range found {
-		if instruction == want || strings.HasPrefix(instruction, want+" ") {
+		if instruction == want ||
+			strings.HasPrefix(instruction, want+" ") ||
+			strings.HasPrefix(instruction, want+"=") {
 			return i
 		}
 	}

cmd/vaultik/main.go

@@ -10,6 +10,16 @@ import (
 )
 
 func main() {
+	os.Exit(run())
+}
+
+// run sets up optional profiling, runs the CLI, and returns the process
+// exit code. os.Exit lives in main so it fires only after run's deferred
+// profile writers have flushed. cli.Entry returns a status code rather
+// than calling os.Exit itself: an os.Exit from inside it would skip
+// these defers and truncate the profile of a failing command -- exactly
+// the command one most often wants to profile.
+func run() int {
 	// CPU profiling: set VAULTIK_CPUPROFILE=/path/to/cpu.prof
 	if cpuProfile := os.Getenv("VAULTIK_CPUPROFILE"); cpuProfile != "" {
 		f, err := os.Create(cpuProfile) //nolint:gosec // G304: operator-set path
@@ -46,5 +56,5 @@ func main() {
 		}()
 	}
 
-	cli.Entry()
+	return cli.Entry()
 }

config.example.yml

@@ -257,16 +257,16 @@ exclude:
 
 # Storage URL - use either this OR the s3 section below
 # Supports: s3://bucket/prefix, file:///path, rclone://remote/path
-storage_url: "rclone://las1stor1//srv/pool.2024.04/backups/heraklion"
+storage_url: "rclone://myremote/path/to/backups"
 
 # S3-compatible storage configuration
 #s3:
 #  # S3-compatible endpoint URL
 #  # Examples: https://s3.amazonaws.com, https://storage.googleapis.com
-#  endpoint: http://10.100.205.122:8333
+#  endpoint: https://s3.example.com
 #
 #  # Bucket name where backups will be stored
-#  bucket: testbucket
+#  bucket: mybucket
 #
 #  # Prefix (folder) within the bucket for this host's backups
 #  # Useful for organizing backups from multiple hosts
@@ -274,8 +274,8 @@ storage_url: "rclone://las1stor1//srv/pool.2024.04/backups/heraklion"
 #  #prefix: "hosts/myserver/"
 #
 #  # S3 access credentials
-#  access_key_id: Z9GT22M9YFU08WRMC5D4
+#  access_key_id: YOUR_ACCESS_KEY
-#  secret_access_key: Pi0tPKjFbN4rZlRhcA4zBtEkib04yy2WcIzI+AXk
+#  secret_access_key: YOUR_SECRET_KEY
 #
 #  # S3 region
 #  # Default: us-east-1
@@ -304,6 +304,8 @@ storage_url: "rclone://las1stor1//srv/pool.2024.04/backups/heraklion"
 
 # Maximum blob size
 # Multiple chunks are packed into blobs up to this size
+# Must be at least four times chunk_size (the largest chunk the chunker can
+# emit); a smaller limit would let a single-chunk blob exceed it.
 # Supports: 1GB, 10G, 500MB, 1GiB, etc.
 # Default: 10GB
 #blob_size_limit: 10GB

docs/DATAMODEL.md

@@ -5,11 +5,30 @@
 Vaultik uses a local SQLite database to track file metadata, chunk mappings, and blob associations during the backup process. This database serves as an index for incremental backups and enables efficient deduplication.
 
 **Important Notes:**
-- **No Migration Support (pre-1.0)**: Vaultik does not support database schema
+
-  migrations. The local index is treated as disposable — if the schema changes,
+This section is the authoritative explanation of the schema/migration story;
-  delete the local SQLite database (`vaultik database delete`) and run a full
+other documents (the README and `AGENTS.md`) link here.
-  backup. The remote storage is unaffected; the new index will re-deduplicate
+
-  against existing remote blobs.
+- **No upgrade path between versions (pre-1.0)**: Vaultik has no supported way to
+  carry an existing local index across a schema change. The index is disposable
+  — if the on-disk schema changes between versions, delete the local SQLite
+  database (`vaultik database delete`) and run a full backup. Remote storage is
+  unaffected; the new index re-deduplicates against existing remote blobs. This
+  is the standing project policy, and it is separate from the schema bootstrap
+  described next.
+- **Schema bootstrap**: a fresh database is populated from numbered SQL files
+  embedded in the binary under `internal/database/schema/`. `000.sql` creates the
+  `schema_migrations` table; `001.sql` creates the application tables. On opening
+  a database the code applies each numbered file that has not yet run and records
+  its version in `schema_migrations`. This bootstraps a new database; it does not
+  upgrade an existing one between released versions.
+- **Changing the schema (pre-1.0)**: edit `internal/database/schema/001.sql` (and
+  the code that touches the affected tables) directly. Do not add new numbered
+  files — there is no installed base to migrate.
+- **Disposability expires at 1.0**: the index is treated as disposable only until
+  1.0 ships and is tagged. Once 1.0 is tagged that clause expires and the
+  question of upgrading existing indexes returns. It is deliberately left open
+  here.
 - **Version Compatibility**: In rare cases, you may need to use the same version
   of Vaultik to restore a backup as was used to create it. This ensures
   compatibility with the metadata format stored in S3.

docs/REPOSTRUCTURE.md

@@ -145,10 +145,10 @@ An observer cannot determine:
 ## Pruning Safety
 
 The prune operation is safe because:
-1. It only deletes blobs not referenced in any manifest
+1. It keeps every blob listed in any snapshot's manifest and deletes only blobs that no manifest references
 2. Manifests are unencrypted and can be read without keys
-3. The operation compares the latest local DB snapshot with the latest S3 snapshot to ensure consistency
+3. If any manifest cannot be downloaded or decoded, prune deletes nothing and exits with an error, rather than treating that snapshot's blobs as unreferenced
-4. Pruning will fail if these don't match, preventing accidental deletion of needed blobs
+4. Prune requires exclusive access to the destination: running it during a concurrent backup can race a snapshot whose manifest is not yet written, so do not prune while a backup is in progress
 
 ## Restoration Requirements
 

internal/blob/packer.go

@@ -487,7 +487,7 @@ func (p *Packer) closeBlobWriter() (string, int64, error) {
 		return "", 0, fmt.Errorf("seeking to start: %w", err)
 	}
 
-	finalHash := p.currentBlob.writer.Sum256()
+	finalHash := p.currentBlob.writer.ContentID()
 
 	return hex.EncodeToString(finalHash), finalSize, nil
 }

internal/blobgen/compress.go

@@ -1,89 +0,0 @@
-// Package blobgen implements the blob data pipeline: streaming zstd
-// compression, age encryption, and SHA256 content hashing for blob
-// creation, plus the matching decrypt/decompress/verify reader.
-package blobgen
-
-import (
-	"bytes"
-	"encoding/hex"
-	"fmt"
-	"io"
-)
-
-// CompressResult contains the results of compression
-type CompressResult struct {
-	Data             []byte
-	UncompressedSize int64
-	CompressedSize   int64
-	SHA256           string
-}
-
-// CompressData compresses and encrypts data, returning the result with hash
-func CompressData(
-	data []byte, compressionLevel int, recipients []string,
-) (*CompressResult, error) {
-	var buf bytes.Buffer
-
-	// Create writer
-	w, err := NewWriter(&buf, compressionLevel, recipients)
-	if err != nil {
-		return nil, fmt.Errorf("creating writer: %w", err)
-	}
-
-	// Write data
-	_, err = w.Write(data)
-	if err != nil {
-		_ = w.Close()
-
-		return nil, fmt.Errorf("writing data: %w", err)
-	}
-
-	// Close to flush
-	err = w.Close()
-	if err != nil {
-		return nil, fmt.Errorf("closing writer: %w", err)
-	}
-
-	return &CompressResult{
-		Data:             buf.Bytes(),
-		UncompressedSize: int64(len(data)),
-		CompressedSize:   int64(buf.Len()),
-		SHA256:           hex.EncodeToString(w.Sum256()),
-	}, nil
-}
-
-// CompressStream compresses and encrypts from reader to writer, returning
-// the number of uncompressed bytes written and the content hash.
-func CompressStream(
-	dst io.Writer, src io.Reader, compressionLevel int, recipients []string,
-) (int64, string, error) {
-	// Create writer
-	w, err := NewWriter(dst, compressionLevel, recipients)
-	if err != nil {
-		return 0, "", fmt.Errorf("creating writer: %w", err)
-	}
-
-	closed := false
-
-	defer func() {
-		if !closed {
-			_ = w.Close()
-		}
-	}()
-
-	// Copy data
-	_, err = io.Copy(w, src)
-	if err != nil {
-		return 0, "", fmt.Errorf("copying data: %w", err)
-	}
-
-	// Close to flush
-	err = w.Close()
-	if err != nil {
-		return 0, "", fmt.Errorf("closing writer: %w", err)
-	}
-
-	closed = true
-
-	return w.BytesWritten(), hex.EncodeToString(w.Sum256()), nil
-}

internal/blobgen/compress_test.go

@@ -1,80 +0,0 @@
-package blobgen_test
-
-import (
-	"bytes"
-	"crypto/rand"
-	"strings"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-	"sneak.berlin/go/vaultik/internal/blobgen"
-)
-
-// testRecipient is a static age recipient for tests.
-const testRecipient = "age1cplgrwj77ta54dnmydvvmzn64ltk83ankxl5sww04mrtmu62kv3s89gmvv"
-
-// TestCompressStreamNoDoubleClose is a regression test for issue #28.
-// It verifies that CompressStream does not panic or return an error due to
-// double-closing the underlying blobgen.Writer. Before the fix in PR #33,
-// the explicit Close() on the happy path combined with defer Close() would
-// cause a double close.
-func TestCompressStreamNoDoubleClose(t *testing.T) {
-	t.Parallel()
-
-	input := []byte("regression test data for issue #28 double-close fix")
-
-	var buf bytes.Buffer
-
-	written, hash, err := blobgen.CompressStream(
-		&buf, bytes.NewReader(input), 3, []string{testRecipient})
-	require.NoError(t, err, "CompressStream should not return an error")
-	assert.Positive(t, written, "expected bytes written > 0")
-	assert.NotEmpty(t, hash, "expected non-empty hash")
-	assert.Positive(t, buf.Len(), "expected non-empty output")
-}
-
-// TestCompressStreamLargeInput exercises CompressStream with a larger payload
-// to ensure no double-close issues surface under heavier I/O.
-func TestCompressStreamLargeInput(t *testing.T) {
-	t.Parallel()
-
-	data := make([]byte, 512*1024) // 512 KB
-	_, err := rand.Read(data)
-	require.NoError(t, err)
-
-	var buf bytes.Buffer
-
-	written, hash, err := blobgen.CompressStream(
-		&buf, bytes.NewReader(data), 3, []string{testRecipient})
-	require.NoError(t, err)
-	assert.Positive(t, written)
-	assert.NotEmpty(t, hash)
-}
-
-// TestCompressStreamEmptyInput verifies CompressStream handles empty input
-// without double-close issues.
-func TestCompressStreamEmptyInput(t *testing.T) {
-	t.Parallel()
-
-	var buf bytes.Buffer
-
-	_, hash, err := blobgen.CompressStream(
-		&buf, strings.NewReader(""), 3, []string{testRecipient})
-	require.NoError(t, err)
-	assert.NotEmpty(t, hash)
-}
-
-// TestCompressDataNoDoubleClose mirrors the stream test for CompressData,
-// ensuring the explicit Close + error-path Close pattern is also safe.
-func TestCompressDataNoDoubleClose(t *testing.T) {
-	t.Parallel()
-
-	input := []byte("CompressData regression test for double-close")
-
-	result, err := blobgen.CompressData(input, 3, []string{testRecipient})
-	require.NoError(t, err)
-	assert.Positive(t, result.CompressedSize)
-	assert.Equal(t, result.UncompressedSize, int64(len(input)))
-	assert.NotEmpty(t, result.SHA256)
-}

internal/blobgen/helpers_test.go

@@ -0,0 +1,119 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"crypto/rand"
+	"errors"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// ageChunkSize is age's STREAM plaintext chunk size (64 KiB); each encrypted
+// chunk adds a 16-byte ChaCha20-Poly1305 tag.
+const (
+	ageChunkSize    = 64 * 1024
+	ageChunkTagSize = 16
+	ageSegmentSize  = ageChunkSize + ageChunkTagSize
+	ageNonceSize    = 16
+)
+
+// makeIdentity returns a fresh X25519 identity and its recipient string.
+func makeIdentity(t *testing.T) (*age.X25519Identity, string) {
+	t.Helper()
+
+	id, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	return id, id.Recipient().String()
+}
+
+// randomBytes returns n cryptographically random bytes, which do not compress
+// so the encrypted payload spans multiple age segments.
+func randomBytes(t *testing.T, n int) []byte {
+	t.Helper()
+
+	b := make([]byte, n)
+	_, err := rand.Read(b)
+	require.NoError(t, err)
+
+	return b
+}
+
+// compressibleBytes returns n bytes of a repeating pattern, which zstd packs
+// down to a small payload.
+func compressibleBytes(n int) []byte {
+	pattern := bytes.Repeat([]byte("compressible-"), n/13+1)
+
+	return pattern[:n]
+}
+
+// encryptBlob compresses, encrypts and returns a blob for plaintext at
+// compression level 1.
+func encryptBlob(t *testing.T, plaintext []byte, recipients ...string) []byte {
+	t.Helper()
+
+	var buf bytes.Buffer
+
+	w, err := blobgen.NewWriter(&buf, 1, recipients)
+	require.NoError(t, err)
+
+	_, err = w.Write(plaintext)
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	return buf.Bytes()
+}
+
+// ageHeaderLen returns the byte length of blob's age header, i.e. the offset
+// of the 16-byte payload nonce that follows it. The header ends with a MAC
+// line "--- <mac>\n"; the nonce begins right after that newline.
+func ageHeaderLen(t *testing.T, blob []byte) int {
+	t.Helper()
+
+	i := bytes.Index(blob, []byte("\n--- "))
+	require.GreaterOrEqual(t, i, 0, "age MAC footer line not found")
+
+	nl := bytes.IndexByte(blob[i+1:], '\n')
+	require.GreaterOrEqual(t, nl, 0, "newline ending MAC line not found")
+
+	return i + 1 + nl + 1
+}
+
+// requireBlobUnreadable asserts that data never decrypts to a plaintext with a
+// nil error: either NewReader fails, or reading it does.
+func requireBlobUnreadable(t *testing.T, data []byte, id age.Identity) {
+	t.Helper()
+
+	r, err := blobgen.NewReader(bytes.NewReader(data), id)
+	if err != nil {
+		return
+	}
+
+	_, err = io.ReadAll(r)
+	_ = r.Close()
+
+	require.Error(t, err, "reading a damaged blob must fail")
+}
+
+// errFailWriter is returned by failAfterWriter once its byte limit is passed.
+var errFailWriter = errors.New("destination write failed")
+
+// failAfterWriter accepts writes until more than limit bytes have been sent,
+// then fails every write. It models a destination that dies mid-blob.
+type failAfterWriter struct {
+	limit   int
+	written int
+}
+
+func (f *failAfterWriter) Write(p []byte) (int, error) {
+	f.written += len(p)
+	if f.written > f.limit {
+		return 0, errFailWriter
+	}
+
+	return len(p), nil
+}

internal/blobgen/limit.go

@@ -0,0 +1,49 @@
+package blobgen
+
+import (
+	"errors"
+	"io"
+)
+
+// ErrOutputTooLarge is returned by a reader from LimitReader once it has
+// been asked for more than its limit. It bounds how far an untrusted
+// compressed stream may expand, so a small, highly compressible object
+// from the store cannot decompress without limit.
+var ErrOutputTooLarge = errors.New("output exceeds size limit")
+
+// LimitReader returns a reader that yields at most limit bytes from r and
+// then fails with ErrOutputTooLarge. Unlike io.LimitReader, which reports
+// a silent io.EOF at the limit (indistinguishable from a stream that
+// simply ended), this fails, so a caller decoding or copying the stream
+// sees an error rather than a truncated value. A stream of exactly limit
+// bytes reads back cleanly to EOF; the first byte beyond it is the error.
+func LimitReader(r io.Reader, limit int64) io.Reader {
+	// remaining counts down from limit+1: the extra byte is the one that,
+	// if it ever arrives, proves the stream is longer than the limit.
+	return &limitReader{r: r, remaining: limit + 1}
+}
+
+type limitReader struct {
+	r         io.Reader
+	remaining int64
+}
+
+func (l *limitReader) Read(p []byte) (int, error) {
+	if l.remaining <= 0 {
+		return 0, ErrOutputTooLarge
+	}
+
+	if int64(len(p)) > l.remaining {
+		p = p[:l.remaining]
+	}
+
+	n, err := l.r.Read(p)
+	l.remaining -= int64(n)
+
+	if l.remaining <= 0 {
+		// The (limit+1)th byte was just read: the stream is too long.
+		return n, ErrOutputTooLarge
+	}
+
+	return n, err
+}

internal/blobgen/limit_test.go

@@ -0,0 +1,43 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// TestLimitReaderPassesExactSize checks that a stream of exactly the limit
+// reads back cleanly to EOF: the bound must not reject a legitimate blob
+// whose plaintext equals its recorded size.
+func TestLimitReaderPassesExactSize(t *testing.T) {
+	t.Parallel()
+
+	const n = 1000
+
+	r := blobgen.LimitReader(bytes.NewReader(bytes.Repeat([]byte("a"), n)), n)
+
+	got, err := io.ReadAll(r)
+	require.NoError(t, err)
+	require.Len(t, got, n)
+}
+
+// TestLimitReaderFailsPastLimit feeds a large, highly compressible run of
+// zeros — the decompressed output a zip bomb would produce — through a
+// small limit and checks it fails within the bound rather than passing
+// the whole stream through.
+func TestLimitReaderFailsPastLimit(t *testing.T) {
+	t.Parallel()
+
+	const limit = 1000
+
+	r := blobgen.LimitReader(
+		bytes.NewReader(bytes.Repeat([]byte{0}, limit*1000)), limit)
+
+	n, err := io.Copy(io.Discard, r)
+	require.ErrorIs(t, err, blobgen.ErrOutputTooLarge)
+	require.LessOrEqual(t, n, int64(limit)+1,
+		"reader must stop within one byte of the limit")
+}

internal/blobgen/negative_test.go

@@ -0,0 +1,190 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// TestNewReaderWrongIdentity covers issue case 4: opening a blob with an
+// identity other than the recipient reports no matching identity.
+func TestNewReaderWrongIdentity(t *testing.T) {
+	t.Parallel()
+
+	_, recipient := makeIdentity(t)
+	other, _ := makeIdentity(t)
+
+	blob := encryptBlob(t, []byte("secret payload"), recipient)
+
+	_, err := blobgen.NewReader(bytes.NewReader(blob), other)
+	require.Error(t, err)
+
+	var noMatch *age.NoIdentityMatchError
+	assert.ErrorAs(t, err, &noMatch)
+}
+
+// TestNewReaderTruncated covers issue case 6: a multi-segment blob cut at
+// several points must never read back as valid data. The point immediately
+// after the header and nonce is intentionally excluded: it reads as a valid
+// empty blob today and is the regression case for
+// https://git.eeqj.de/sneak/vaultik/issues/152.
+func TestNewReaderTruncated(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+	blob := encryptBlob(t, randomBytes(t, 4*65536+123), recipient)
+	h := ageHeaderLen(t, blob)
+
+	require.Greater(t, len(blob), h+ageNonceSize+ageSegmentSize,
+		"test needs a blob of at least two age segments")
+
+	cases := []struct {
+		name string
+		size int
+	}{
+		{"inside header", h / 2},
+		{"inside nonce", h + 8},
+		{"inside first segment", h + ageNonceSize + 100},
+		{"end of first full segment", h + ageNonceSize + ageSegmentSize},
+		{"last byte removed", len(blob) - 1},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			requireBlobUnreadable(t, blob[:tc.size], id)
+		})
+	}
+}
+
+// TestNewReaderCorrupted covers issue case 7: one flipped byte in each region
+// of a multi-segment blob makes it unreadable.
+func TestNewReaderCorrupted(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+	blob := encryptBlob(t, randomBytes(t, 4*65536+123), recipient)
+	h := ageHeaderLen(t, blob)
+
+	firstNL := bytes.IndexByte(blob, '\n')
+	require.Positive(t, firstNL, "header must have a version line")
+
+	cases := []struct {
+		name string
+		pos  int
+	}{
+		{"header stanza", firstNL + 5},
+		{"header MAC line", h - 2},
+		{"nonce", h + 4},
+		{"body segment", h + ageNonceSize + 50},
+		{"final tag", len(blob) - 1},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			corrupt := append([]byte(nil), blob...)
+			corrupt[tc.pos] ^= 0xff
+			requireBlobUnreadable(t, corrupt, id)
+		})
+	}
+}
+
+// TestNewReaderTrailingAndGarbage covers issue case 8: bytes appended after a
+// valid blob, empty input, and random garbage each fail to read.
+func TestNewReaderTrailingAndGarbage(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+
+	valid := encryptBlob(t, []byte("small payload"), recipient)
+	appended := append(append([]byte(nil), valid...), []byte("trailing junk")...)
+
+	t.Run("appended bytes", func(t *testing.T) {
+		t.Parallel()
+		requireBlobUnreadable(t, appended, id)
+	})
+	t.Run("empty input", func(t *testing.T) {
+		t.Parallel()
+		requireBlobUnreadable(t, []byte{}, id)
+	})
+	t.Run("random garbage", func(t *testing.T) {
+		t.Parallel()
+		requireBlobUnreadable(t, randomBytes(t, 512), id)
+	})
+}
+
+// TestNewWriterInvalidLevel covers the rejected end of issue case 9: an
+// out-of-range compression level errors and writes nothing to the destination.
+func TestNewWriterInvalidLevel(t *testing.T) {
+	t.Parallel()
+
+	_, recipient := makeIdentity(t)
+
+	for _, level := range []int{0, -1, 20} {
+		t.Run(fmt.Sprintf("level%d", level), func(t *testing.T) {
+			t.Parallel()
+
+			var buf bytes.Buffer
+
+			w, err := blobgen.NewWriter(&buf, level, []string{recipient})
+			require.ErrorIs(t, err, blobgen.ErrInvalidCompressionLevel)
+			assert.Nil(t, w)
+			assert.Zero(t, buf.Len(), "nothing written on an invalid level")
+		})
+	}
+}
+
+// TestNewWriterInvalidRecipients covers issue case 10: nil and empty recipient
+// lists and an unparsable recipient string each error.
+func TestNewWriterInvalidRecipients(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name       string
+		recipients []string
+	}{
+		{"nil list", nil},
+		{"empty list", []string{}},
+		{"invalid recipient string", []string{"not-a-recipient"}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			var buf bytes.Buffer
+
+			w, err := blobgen.NewWriter(&buf, 1, tc.recipients)
+			require.Error(t, err)
+			assert.Nil(t, w)
+		})
+	}
+}
+
+// TestNewWriterFailingDestination covers issue case 11: a destination that
+// fails mid-blob surfaces its error from Write or Close.
+func TestNewWriterFailingDestination(t *testing.T) {
+	t.Parallel()
+
+	_, recipient := makeIdentity(t)
+
+	// The limit clears the age header and nonce so NewWriter succeeds, then
+	// trips once the compressed body starts flowing.
+	dst := &failAfterWriter{limit: 512}
+
+	w, err := blobgen.NewWriter(dst, 1, []string{recipient})
+	require.NoError(t, err)
+
+	_, writeErr := w.Write(randomBytes(t, 256*1024))
+	closeErr := w.Close()
+
+	assert.True(t, writeErr != nil || closeErr != nil,
+		"destination failure must surface from Write or Close")
+}

internal/blobgen/reader.go

@@ -2,6 +2,7 @@ package blobgen
 
 import (
 	"crypto/sha256"
+	"errors"
 	"fmt"
 	"hash"
 	"io"
@@ -20,10 +21,12 @@ type Reader struct {
 	bytesRead    int64
 }
 
-// NewReader creates a new Reader that decrypts, decompresses, and verifies data
+// NewReader creates a new Reader that decrypts, decompresses, and verifies
-func NewReader(r io.Reader, identity age.Identity) (*Reader, error) {
+// data. Every supplied identity is offered to age.Decrypt, so a blob
+// encrypted to any one of them can be read.
+func NewReader(r io.Reader, identities ...age.Identity) (*Reader, error) {
 	// Create decryption reader
-	decReader, err := age.Decrypt(r, identity)
+	decReader, err := age.Decrypt(r, identities...)
 	if err != nil {
 		return nil, fmt.Errorf("creating decryption reader: %w", err)
 	}
@@ -54,6 +57,22 @@ func (r *Reader) Read(p []byte) (int, error) {
 	n, err := r.teeReader.Read(p)
 	r.bytesRead += int64(n)
 
+	// When the ciphertext is cut right after the age header plus its
+	// 16-byte nonce, the age reader's first read fails with
+	// io.ErrUnexpectedEOF, and the zstd decoder maps that to a clean
+	// io.EOF at frame start. That makes a truncated stream look like a
+	// valid empty one. Distinguish the two: on EOF, read once more from
+	// the age reader. A genuine end leaves it at (0, io.EOF); a truncated
+	// stream leaves its stored io.ErrUnexpectedEOF, which we surface.
+	if errors.Is(err, io.EOF) {
+		var probe [1]byte
+
+		m, ageErr := r.decryptor.Read(probe[:])
+		if m != 0 || !errors.Is(ageErr, io.EOF) {
+			return n, io.ErrUnexpectedEOF
+		}
+	}
+
 	return n, err
 }
 
@@ -64,7 +83,9 @@ func (r *Reader) Close() error {
 	return nil
 }
 
-// Sum256 returns the SHA256 hash of all data read
+// Sum256 returns the single SHA-256 of the plaintext read so far. This is the
+// first hash only; the stored object name is its double hash, which callers
+// obtain by passing this digest to DoubleSHA256.
 func (r *Reader) Sum256() []byte {
 	return r.hasher.Sum(nil)
 }

internal/blobgen/reader_test.go

@@ -0,0 +1,54 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// TestMultipleRecipients verifies that data written for several recipients can
+// be read back by each recipient's identity. Moved from internal/crypto, which
+// held the only multi-recipient test; blobgen is now the sole encryption path.
+func TestMultipleRecipients(t *testing.T) {
+	t.Parallel()
+
+	identities := make([]*age.X25519Identity, 3)
+	recipients := make([]string, 3)
+
+	for i := range identities {
+		identity, err := age.GenerateX25519Identity()
+		require.NoError(t, err)
+
+		identities[i] = identity
+		recipients[i] = identity.Recipient().String()
+	}
+
+	plaintext := []byte("Secret message for multiple recipients")
+
+	var encrypted bytes.Buffer
+
+	writer, err := blobgen.NewWriter(&encrypted, 3, recipients)
+	require.NoError(t, err)
+	_, err = writer.Write(plaintext)
+	require.NoError(t, err)
+	require.NoError(t, writer.Close())
+
+	// Every recipient's identity must recover the original plaintext.
+	for i, identity := range identities {
+		reader, err := blobgen.NewReader(
+			bytes.NewReader(encrypted.Bytes()), identity)
+		require.NoError(t, err, "recipient %d should open the reader", i+1)
+
+		got, err := io.ReadAll(reader)
+		require.NoError(t, err, "recipient %d should read the plaintext", i+1)
+		require.NoError(t, reader.Close())
+
+		assert.Equal(t, plaintext, got,
+			"recipient %d should recover the original plaintext", i+1)
+	}
+}

internal/blobgen/roundtrip_test.go

@@ -0,0 +1,132 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// checkRoundTrip writes input through a Writer, reads it back through a Reader,
+// and verifies the plaintext, the byte counts, and the content hashes.
+func checkRoundTrip(
+	t *testing.T, id *age.X25519Identity, recipient string,
+	level int, input []byte,
+) {
+	t.Helper()
+
+	var buf bytes.Buffer
+
+	w, err := blobgen.NewWriter(&buf, level, []string{recipient})
+	require.NoError(t, err)
+
+	n, err := w.Write(input)
+	require.NoError(t, err)
+	assert.Equal(t, len(input), n)
+	require.NoError(t, w.Close())
+	require.Equal(t, int64(len(input)), w.BytesWritten())
+
+	r, err := blobgen.NewReader(bytes.NewReader(buf.Bytes()), id)
+	require.NoError(t, err)
+
+	got, err := io.ReadAll(r)
+	require.NoError(t, err)
+	require.NoError(t, r.Close())
+
+	assert.Equal(t, input, got, "decrypted output must equal input")
+	require.Equal(t, int64(len(input)), r.BytesRead())
+
+	// The hash values are checked by decrypting: the reader's single SHA-256
+	// is the hash of the plaintext, and hashing it once more (DoubleSHA256)
+	// gives the writer's ContentID.
+	single := sha256.Sum256(got)
+	assert.Equal(t, single[:], r.Sum256())
+	assert.Equal(t, blobgen.DoubleSHA256(r.Sum256()), w.ContentID())
+}
+
+// TestWriterReaderRoundTrip covers issue cases 1 and 2: every size round trips
+// for both random and compressible data, and the reader hash, its double hash
+// and the byte counts all agree.
+func TestWriterReaderRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+
+	// Sizes exercise the age segment boundary (64 KiB) from just below to a
+	// few segments above it, plus the empty and single-byte edges.
+	sizes := []int{0, 1, 65535, 65536, 65537, 4*65536 + 123}
+
+	kinds := []struct {
+		name string
+		fill func(*testing.T, int) []byte
+	}{
+		{"random", randomBytes},
+		{"compressible", func(_ *testing.T, n int) []byte {
+			return compressibleBytes(n)
+		}},
+	}
+
+	for _, k := range kinds {
+		for _, size := range sizes {
+			name := fmt.Sprintf("%s/%d", k.name, size)
+			t.Run(name, func(t *testing.T) {
+				t.Parallel()
+				checkRoundTrip(t, id, recipient, 1, k.fill(t, size))
+			})
+		}
+	}
+}
+
+// TestZeroLengthNoWrite covers issue case 3: a Writer closed with no Write at
+// all produces the double hash of the empty input, and the blob reads back as
+// empty with no error.
+func TestZeroLengthNoWrite(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+
+	var buf bytes.Buffer
+
+	w, err := blobgen.NewWriter(&buf, 1, []string{recipient})
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+	assert.Equal(t, int64(0), w.BytesWritten())
+
+	empty := sha256.Sum256(nil)
+	doubled := sha256.Sum256(empty[:])
+	assert.Equal(t, doubled[:], w.ContentID(),
+		"ContentID of empty input is SHA256(SHA256(\"\"))")
+
+	r, err := blobgen.NewReader(bytes.NewReader(buf.Bytes()), id)
+	require.NoError(t, err)
+
+	got, err := io.ReadAll(r)
+	require.NoError(t, err)
+	require.NoError(t, r.Close())
+
+	assert.Empty(t, got, "empty blob decrypts to empty output")
+	assert.Equal(t, int64(0), r.BytesRead())
+	assert.Equal(t, empty[:], r.Sum256())
+}
+
+// TestNewWriterValidLevelsRoundTrip covers the accepted end of issue case 9:
+// the boundary compression levels 1 and 19 both round trip.
+func TestNewWriterValidLevelsRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	id, recipient := makeIdentity(t)
+	input := randomBytes(t, 4096)
+
+	for _, level := range []int{1, 19} {
+		t.Run(fmt.Sprintf("level%d", level), func(t *testing.T) {
+			t.Parallel()
+			checkRoundTrip(t, id, recipient, level, input)
+		})
+	}
+}

internal/blobgen/truncation_test.go

@@ -0,0 +1,70 @@
+package blobgen_test
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// TestReaderRejectsHeaderNonceTruncation guards against a stream cut right
+// after the age header plus its 16-byte nonce. age.Decrypt still succeeds on
+// such an object, and the zstd decoder maps the age reader's
+// io.ErrUnexpectedEOF to a clean io.EOF at frame start, so without the extra
+// check the truncated stream would read as a valid empty one. Reading it must
+// now fail.
+func TestReaderRejectsHeaderNonceTruncation(t *testing.T) {
+	t.Parallel()
+
+	identity, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	// Encrypting empty plaintext yields header + nonce(16) + a single
+	// 16-byte final chunk tag. Dropping the trailing tag leaves exactly the
+	// age header plus its nonce — the truncation point that triggers the bug.
+	var full bytes.Buffer
+
+	w, err := age.Encrypt(&full, identity.Recipient())
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	truncated := full.Bytes()[:full.Len()-16]
+
+	reader, err := blobgen.NewReader(bytes.NewReader(truncated), identity)
+	require.NoError(t, err)
+
+	defer func() { _ = reader.Close() }()
+
+	_, err = io.ReadAll(reader)
+	require.Error(t, err)
+	require.ErrorIs(t, err, io.ErrUnexpectedEOF)
+}
+
+// TestReaderReadsGenuinelyEmptyBlob confirms the truncation check does not
+// reject a legitimately empty payload: a blob written with no data must round
+// trip back to zero bytes with no error.
+func TestReaderReadsGenuinelyEmptyBlob(t *testing.T) {
+	t.Parallel()
+
+	identity, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	var encrypted bytes.Buffer
+
+	writer, err := blobgen.NewWriter(
+		&encrypted, 3, []string{identity.Recipient().String()})
+	require.NoError(t, err)
+	require.NoError(t, writer.Close())
+
+	reader, err := blobgen.NewReader(bytes.NewReader(encrypted.Bytes()), identity)
+	require.NoError(t, err)
+
+	defer func() { _ = reader.Close() }()
+
+	data, err := io.ReadAll(reader)
+	require.NoError(t, err)
+	require.Empty(t, data)
+}

internal/blobgen/writer.go

@@ -1,3 +1,6 @@
+// Package blobgen implements the blob data pipeline: streaming zstd
+// compression, age encryption, and SHA256 content hashing for blob
+// creation, plus the matching decrypt/decompress/verify reader.
 package blobgen
 
 import (
@@ -12,6 +15,18 @@ import (
 	"github.com/klauspost/compress/zstd"
 )
 
+// DoubleSHA256 returns the double SHA-256 of content whose single SHA-256
+// digest is sum: it hashes that digest once more. Stored objects are named by
+// this second hash so that a name never reveals whether known content is
+// present — an attacker who knows a plaintext, and thus its SHA-256, still
+// cannot derive the stored name without hashing the digest again. Both a blob
+// and the metadata database export are named this way.
+func DoubleSHA256(sum []byte) []byte {
+	h := sha256.Sum256(sum)
+
+	return h[:]
+}
+
 // Zstd compression level bounds accepted by NewWriter.
 const (
 	minCompressionLevel = 1
@@ -27,6 +42,11 @@ const reservedCompressionCPUs = 2
 var ErrInvalidCompressionLevel = errors.New(
 	"invalid compression level: must be between 1 and 19")
 
+// errInvalidRecipient is returned when a recipient string does not parse as
+// an X25519 age1... public key. It omits the value, which can be sensitive.
+var errInvalidRecipient = errors.New(
+	"not a valid X25519 age1... recipient")
+
 // Writer wraps compression and encryption with SHA256 hashing.
 // Data flows: input -> tee(hasher, compressor -> encryptor -> destination)
 // The hash is computed on the uncompressed input for deterministic content-addressing.
@@ -57,10 +77,12 @@ func NewWriter(
 	// Parse recipients
 	var ageRecipients []age.Recipient
 
-	for _, recipient := range recipients {
+	for i, recipient := range recipients {
+		// The recipient string can be sensitive (e.g. a secret key pasted by
+		// mistake), so the error names its position, never its value.
 		r, err := age.ParseX25519Recipient(recipient)
 		if err != nil {
-			return nil, fmt.Errorf("parsing recipient %s: %w", recipient, err)
+			return nil, fmt.Errorf("%w: recipient %d", errInvalidRecipient, i)
 		}
 
 		ageRecipients = append(ageRecipients, r)
@@ -123,17 +145,12 @@ func (w *Writer) Close() error {
 	return nil
 }
 
-// Sum256 returns the double SHA256 hash of the uncompressed input data.
+// ContentID returns the double SHA-256 of the uncompressed input data: the
-// Double hashing (SHA256(SHA256(data))) prevents information leakage about
+// name under which this content is stored. It is the second hash of the
-// the plaintext - an attacker cannot confirm existence of known content
+// running SHA-256, via DoubleSHA256; see that function for why content is
-// by computing its hash and checking for a matching blob filename.
+// named this way rather than by its plain SHA-256.
-func (w *Writer) Sum256() []byte {
+func (w *Writer) ContentID() []byte {
-	// First hash: SHA256(plaintext)
+	return DoubleSHA256(w.hasher.Sum(nil))
-	firstHash := w.hasher.Sum(nil)
-	// Second hash: SHA256(firstHash) - this is the blob ID
-	secondHash := sha256.Sum256(firstHash)
-
-	return secondHash[:]
 }
 
 // BytesWritten returns the number of uncompressed bytes written

internal/blobgen/writer_test.go

@@ -12,9 +12,10 @@ import (
 	"sneak.berlin/go/vaultik/internal/blobgen"
 )
 
-// TestWriterHashIsDoubleHash verifies that Writer.Sum256() returns
+// TestWriterHashIsDoubleHash verifies that Writer.ContentID() returns
-// the double hash SHA256(SHA256(plaintext)) for security.
+// SHA256(SHA256(plaintext)). Stored objects are named by this second hash so a
-// Double hashing prevents attackers from confirming existence of known content.
+// name is not the plaintext's own SHA-256; this does not stop someone who
+// already holds the plaintext from confirming it.
 func TestWriterHashIsDoubleHash(t *testing.T) {
 	t.Parallel()
 
@@ -43,7 +44,7 @@ func TestWriterHashIsDoubleHash(t *testing.T) {
 	require.NoError(t, err)
 
 	// Get the hash from the writer
-	writerHash := hex.EncodeToString(writer.Sum256())
+	writerHash := hex.EncodeToString(writer.ContentID())
 
 	// Calculate the expected double hash: SHA256(SHA256(plaintext))
 	firstHash := sha256.Sum256(testData)
@@ -60,11 +61,11 @@ func TestWriterHashIsDoubleHash(t *testing.T) {
 
 	// The writer hash should match the double hash
 	assert.Equal(t, expectedDoubleHash, writerHash,
-		"Writer.Sum256() should return SHA256(SHA256(plaintext)) for security")
+		"Writer.ContentID() must be SHA256(SHA256(plaintext))")
 
-	// Verify it's NOT the single hash (would leak information)
+	// It must be the second hash, not the plaintext's own SHA-256.
 	assert.NotEqual(t, singleHashStr, writerHash,
-		"Writer hash should not be single hash (would allow content confirmation attacks)")
+		"Writer hash must be the double hash, not the single SHA-256")
 }
 
 // TestWriterDeterministicHash verifies that the same input always produces
@@ -93,8 +94,8 @@ func TestWriterDeterministicHash(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, writer2.Close())
 
-	hash1 := hex.EncodeToString(writer1.Sum256())
+	hash1 := hex.EncodeToString(writer1.ContentID())
-	hash2 := hex.EncodeToString(writer2.Sum256())
+	hash2 := hex.EncodeToString(writer2.ContentID())
 
 	// Hashes should be identical (deterministic)
 	assert.Equal(t, hash1, hash2, "Same input should produce same hash")
@@ -108,3 +109,20 @@ func TestWriterDeterministicHash(t *testing.T) {
 	t.Logf("Encrypted size 1: %d bytes", buf1.Len())
 	t.Logf("Encrypted size 2: %d bytes", buf2.Len())
 }
+
+// TestNewWriterSecretKeyNotEchoed verifies that a secret key mistakenly passed
+// as a recipient does not appear in the returned error. A recipient string can
+// be sensitive, so the error must name only the position, not the value.
+func TestNewWriterSecretKeyNotEchoed(t *testing.T) {
+	t.Parallel()
+
+	secretKey := "AGE-SECRET-KEY-19CR5YSFW59HM4TLD6GX" +
+		"VEDMZFTVVF7PPHKUT68TXSFPK7APHXA2QS2NJA5"
+
+	var buf bytes.Buffer
+
+	_, err := blobgen.NewWriter(&buf, 3, []string{secretKey})
+	require.Error(t, err)
+	assert.NotContains(t, err.Error(), secretKey,
+		"error must not echo the recipient value")
+}

internal/chunker/chunker.go

@@ -33,9 +33,10 @@ type Chunker struct {
 	maxChunkSize int
 }
 
-// chunkSizeSpread is the FastCDC-recommended factor between the average
+// ChunkSizeSpread is the FastCDC-recommended factor between the average
 // chunk size and the minimum (avg/spread) and maximum (avg*spread) sizes.
-const chunkSizeSpread = 4
+// The largest chunk the chunker can emit is therefore avg*ChunkSizeSpread.
+const ChunkSizeSpread = 4
 
 // NewChunker creates a new chunker with the specified average chunk size.
 // The actual chunk sizes will vary between avgChunkSize/4 and avgChunkSize*4
@@ -45,8 +46,8 @@ func NewChunker(avgChunkSize int64) *Chunker {
 	// FastCDC recommends min = avg/4 and max = avg*4
 	return &Chunker{
 		avgChunkSize: int(avgChunkSize),
-		minChunkSize: int(avgChunkSize / chunkSizeSpread),
+		minChunkSize: int(avgChunkSize / ChunkSizeSpread),
-		maxChunkSize: int(avgChunkSize * chunkSizeSpread),
+		maxChunkSize: int(avgChunkSize * ChunkSizeSpread),
 	}
 }
 

internal/cli/app.go

@@ -7,11 +7,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"os"
-	"os/signal"
 	"path/filepath"
 	"strings"
-	"syscall"
+	"sync"
 	"time"
 
 	"github.com/adrg/xdg"
@@ -32,14 +30,33 @@ import (
 // may take before we give up.
 const shutdownTimeout = 30 * time.Second
 
-// AppOptions contains common options for creating the fx application.
+// lockMode says whether a command mutates persistent state — the local
-// It includes the configuration file path, logging options, and additional
+// index database or the remote store — and so must hold the process-wide
-// fx modules and invocations that should be included in the application.
+// PID lock, or only reads that state and may run alongside a mutator.
+type lockMode int
+
+const (
+	// mutating commands (snapshot create, snapshot purge, snapshot remove,
+	// prune, remote nuke) write the local index or the remote store. They
+	// hold the PID lock so that at most one runs at a time.
+	mutating lockMode = iota
+	// readOnly commands (info, snapshot list, snapshot verify, remote info,
+	// snapshot restore) do not write the local index or the remote store,
+	// so they run without the lock and are never blocked by a running
+	// mutator. restore writes only to the target directory it is given.
+	readOnly
+)
+
+// AppOptions contains common options for creating and running the fx
+// application: the configuration file path, logging options, additional fx
+// modules and invocations, and whether the command mutates persistent
+// state (which decides whether it takes the PID lock).
 type AppOptions struct {
 	ConfigPath string
 	LogOptions log.Options
 	Modules    []fx.Option
 	Invokes    []fx.Option
+	Mode       lockMode
 }
 
 // setupGlobals records the startup time and, when an output-suppression
@@ -48,6 +65,11 @@ type AppOptions struct {
 // silenced — per the documented convention that --quiet suppresses
 // non-error output only. The startup banner is printed by Entry
 // before cobra parses arguments, gated by the same arg-level check.
+//
+// --json quiets the UI here too, because stdout then carries a JSON
+// document and human narration would corrupt it. Unlike Quiet it does
+// not lower the stderr log level (issue #112), so --verbose/--debug
+// still surface diagnostics alongside the document.
 func setupGlobals(
 	lc fx.Lifecycle, g *globals.Globals, v *vaultik.Vaultik, opts log.Options,
 ) {
@@ -55,7 +77,7 @@ func setupGlobals(
 		OnStart: func(_ context.Context) error {
 			g.StartTime = time.Now().UTC()
 
-			if opts.Cron || opts.Quiet {
+			if opts.Cron || opts.Quiet || opts.JSON {
 				v.UI.SetQuiet(true)
 			}
 
@@ -136,75 +158,148 @@ func cleanStartupError(err error) error {
 	return &startupError{msg: msg}
 }
 
-// RunApp starts and stops the fx application within the given context.
+// RunApp starts the fx application, blocks until it is asked to stop, and
-// It handles graceful shutdown on interrupt signals (SIGINT, SIGTERM) and
+// then stops it. The app is asked to stop either by an OS interrupt
-// ensures the application stops cleanly. The function blocks until the
+// (SIGINT/SIGTERM — fx installs its own handler when app.Wait is called) or,
-// application completes or is interrupted. Returns an error if startup fails.
+// on normal completion, by the finished operation calling
+// Shutdowner.Shutdown(); both arrive on the app.Wait channel.
+//
+// Stopping runs the fx OnStop hooks, and RunApp does not return until Stop
+// returns. On an interrupt the operation's OnStop hook cancels the running
+// command and waits for it to unwind — removing its decrypted scratch files —
+// so the process cannot proceed to exit mid-cleanup (issue #159). Waiting for
+// Stop before returning is what makes that hook effective: routing the
+// interrupt through app.Stop and not returning until it completes is required,
+// because fx also fires the app.Wait channel on the signal, and an earlier
+// version returned on that alone — unwinding to os.Exit while the concurrent
+// cleanup still ran. The stop is bounded by shutdownTimeout. Returns an error
+// if startup fails.
 func RunApp(ctx context.Context, app *fx.App) error {
-	// Set up signal handling for graceful shutdown
-	sigChan := make(chan os.Signal, 1)
-	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
-
-	// Create a context that will be cancelled on signal
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
-
-	// Start the app
 	err := app.Start(ctx)
 	if err != nil {
 		return cleanStartupError(err)
 	}
 
-	// Handle shutdown
+	// Block until an interrupt or the finished operation's
-	shutdownComplete := make(chan struct{})
+	// Shutdowner.Shutdown() arrives, then stop the app in this goroutine so we
+	// return only after its OnStop hooks — including the operation's cleanup
+	// wait — have run. Detach the stop from ctx's cancellation but keep its
+	// values, and bound it by shutdownTimeout.
+	<-app.Wait()
 
-	go func() {
+	shutdownCtx, cancel := context.WithTimeout(
-		defer close(shutdownComplete)
+		context.WithoutCancel(ctx), shutdownTimeout)
+	defer cancel()
 
-		<-sigChan
+	err = app.Stop(shutdownCtx)
-		log.Notice("Received interrupt signal, shutting down gracefully...")
+	if err != nil {
-
+		log.Error("Error during shutdown", "error", err)
-		// Create a timeout context for shutdown. The parent ctx is being
-		// cancelled, so detach from its cancellation but keep its values.
-		shutdownCtx, shutdownCancel := context.WithTimeout(
-			context.WithoutCancel(ctx), shutdownTimeout)
-		defer shutdownCancel()
-
-		err := app.Stop(shutdownCtx)
-		if err != nil {
-			log.Error("Error during shutdown", "error", err)
-		}
-	}()
-
-	// Wait for the signal handler to complete shutdown or the app to
-	// request shutdown.
-	select {
-	case <-shutdownComplete:
-		// Shutdown completed via signal
-		return nil
-	case <-ctx.Done():
-		// Context cancelled (shouldn't happen in normal operation)
-		err := app.Stop(context.WithoutCancel(ctx))
-		if err != nil {
-			log.Error("Error stopping app", "error", err)
-		}
-
-		return ctx.Err()
-	case <-app.Done():
-		// App finished running (e.g., backup completed)
-		return nil
 	}
+
+	return nil
+}
+
+// errReported marks a failure the operation has already shown the user
+// (and deliberately withheld under --json). Entry turns it into a
+// non-zero exit status without printing anything further, so the error
+// line is not doubled. It flows up from RunOperation through cobra to
+// Entry.
+var errReported = errors.New("operation failed")
+
+// RunOperation runs op against the Vaultik instance inside the fx app
+// and turns a failure into a returned error rather than an os.Exit from
+// within the goroutine. An os.Exit there skipped main's deferred
+// profile writers -- so profiling a failing command yielded a truncated
+// profile (issue #75) -- and RunWithApp's PID-lock release, and denied
+// the app any graceful shutdown; returning the error to the top runs
+// all three.
+//
+// op runs in a goroutine so OnStart returns promptly and an interrupt
+// can still cancel through OnStop; when it finishes, success or failure,
+// it triggers shutdown, which is what lets RunWithApp return. On an
+// interrupt OnStop cancels op and waits for the goroutine to return, so
+// op's cleanup (removing decrypted scratch files) runs before the
+// process exits; the wait is bounded by shutdownTimeout. report is
+// called with a non-canceled failure so the caller can log it (and
+// suppress it under --json) before it becomes errReported. A context
+// cancellation is the interrupt path, not a failure: it is neither
+// reported nor counted as one.
+func RunOperation(
+	ctx context.Context, opts AppOptions,
+	op func(v *vaultik.Vaultik) error, report func(err error),
+) error {
+	var (
+		mu     sync.Mutex
+		failed bool
+	)
+
+	opts.Invokes = append(opts.Invokes,
+		fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+			var stop func(context.Context) bool
+
+			lc.Append(fx.Hook{
+				OnStart: func(_ context.Context) error {
+					stop = v.StartOperation(func() {
+						err := op(v)
+						if err != nil && !errors.Is(err, context.Canceled) {
+							report(err)
+
+							mu.Lock()
+							failed = true
+							mu.Unlock()
+						}
+
+						stopErr := v.Shutdowner.Shutdown()
+						if stopErr != nil {
+							log.Error("Failed to shutdown", "error", stopErr)
+						}
+					})
+
+					return nil
+				},
+				// On an interrupt, cancel the operation and wait for it to
+				// unwind so its cleanup defers (which remove decrypted
+				// scratch files from the temp directory) run before the
+				// process exits. The wait is bounded by ctx, the existing
+				// shutdownTimeout.
+				OnStop: func(ctx context.Context) error {
+					if !stop(ctx) {
+						log.Warn("Shutdown timed out before the operation " +
+							"finished; decrypted temporary files may remain")
+					}
+
+					return nil
+				},
+			})
+		}))
+
+	err := RunWithApp(ctx, opts)
+	if err != nil {
+		return err
+	}
+
+	// The goroutine sets failed before triggering the shutdown that lets
+	// RunWithApp return, so the write is in place by the time we read it.
+	mu.Lock()
+	defer mu.Unlock()
+
+	if failed {
+		return errReported
+	}
+
+	return nil
 }
 
 // runVaultikApp runs the standard single-operation command lifecycle
-// shared by the list/purge/verify/remove/remote-info subcommands:
+// shared by the snapshot list/purge/remove and remote nuke subcommands:
-// resolve the config, start the fx app, run op against the Vaultik
+// resolve the config, then run op against the Vaultik instance through
-// instance in a goroutine, report a failure prefixed with failMsg
+// RunOperation, reporting a failure prefixed with failMsg (suppressed
-// (suppressed while suppressErrors is true, e.g. under --json), then
+// while suppressErrors is true, e.g. under --json). mode says whether the
-// trigger shutdown. The operation is cancelled when the app stops.
+// command takes the PID lock. jsonOutput marks a command whose stdout is a
-// extraQuiet is OR-ed into LogOptions.Quiet (e.g. --json output modes).
+// JSON document: it quiets the UI but, unlike Quiet, leaves the stderr log
+// level alone.
 func runVaultikApp(
-	cmd *cobra.Command, extraQuiet, suppressErrors bool,
+	cmd *cobra.Command, mode lockMode, jsonOutput, suppressErrors bool,
 	failMsg string, op func(v *vaultik.Vaultik) error,
 ) error {
 	configPath, err := ResolveConfigPath()
@@ -214,75 +309,68 @@ func runVaultikApp(
 
 	rootFlags := GetRootFlags()
 
-	return RunWithApp(cmd.Context(), AppOptions{
+	return RunOperation(cmd.Context(), AppOptions{
 		ConfigPath: configPath,
 		LogOptions: log.Options{
 			Verbose: rootFlags.Verbose,
 			Debug:   rootFlags.Debug,
-			Quiet:   rootFlags.Quiet || extraQuiet,
+			Quiet:   rootFlags.Quiet,
+			JSON:    jsonOutput,
 		},
-		Modules: []fx.Option{},
+		Mode: mode,
-		Invokes: []fx.Option{
+	}, op, func(err error) {
-			fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+		if suppressErrors {
-				lc.Append(fx.Hook{
+			return
-					OnStart: func(_ context.Context) error {
+		}
-						go func() {
-							err := op(v)
-							if err != nil {
-								if !errors.Is(err, context.Canceled) {
-									if !suppressErrors {
-										log.Error(failMsg, "error", err)
-										ReportErrorf("%s: %v", failMsg, err)
-									}
 
-									os.Exit(1)
+		log.Error(failMsg, "error", err)
-								}
+		ReportErrorf("%s: %v", failMsg, err)
-							}
-
-							err = v.Shutdowner.Shutdown()
-							if err != nil {
-								log.Error("Failed to shutdown", "error", err)
-							}
-						}()
-
-						return nil
-					},
-					OnStop: func(_ context.Context) error {
-						v.Cancel()
-
-						return nil
-					},
-				})
-			}),
-		},
 	})
 }
 
 // RunWithApp is a helper that creates and runs an fx app with the given options.
 // It combines NewApp and RunApp into a single convenient function. This is the
 // preferred way to run CLI commands that need the full application context.
-// It acquires a PID lock before starting to prevent concurrent instances.
+// A mutating command takes the process-wide PID lock before starting so that
+// only one runs at a time; a read-only command runs without it and is not
+// blocked while a mutator holds the lock (opts.Mode).
 func RunWithApp(ctx context.Context, opts AppOptions) error {
-	// Acquire PID lock to prevent concurrent instances
+	release, err := acquireLockIfMutating(opts.Mode,
-	lockDir := filepath.Join(xdg.DataHome, "vaultik")
+		filepath.Join(xdg.DataHome, "vaultik"))
-
-	lock, err := pidlock.Acquire(lockDir)
 	if err != nil {
-		if errors.Is(err, pidlock.ErrAlreadyRunning) {
+		return err
-			return fmt.Errorf("cannot start: %w", err)
-		}
-
-		return fmt.Errorf("failed to acquire lock: %w", err)
 	}
 
-	defer func() {
+	defer release()
-		err := lock.Release()
-		if err != nil {
-			log.Warn("Failed to release PID lock", "error", err)
-		}
-	}()
 
 	app := NewApp(opts)
 
 	return RunApp(ctx, app)
 }
+
+// acquireLockIfMutating takes the process-wide PID lock in lockDir for a
+// mutating command and returns a function that releases it. A read-only
+// command takes no lock, so it returns a no-op release and is never blocked
+// while a mutator holds the lock. ErrAlreadyRunning (another mutator holds
+// the lock) is surfaced as a "cannot start" error.
+func acquireLockIfMutating(mode lockMode, lockDir string) (func(), error) {
+	if mode != mutating {
+		return func() {}, nil
+	}
+
+	lock, err := pidlock.Acquire(lockDir)
+	if err != nil {
+		if errors.Is(err, pidlock.ErrAlreadyRunning) {
+			return nil, fmt.Errorf("cannot start: %w", err)
+		}
+
+		return nil, fmt.Errorf("failed to acquire lock: %w", err)
+	}
+
+	return func() {
+		err := lock.Release()
+		if err != nil {
+			log.Warn("Failed to release PID lock", "error", err)
+		}
+	}, nil
+}

internal/cli/app_test.go

@@ -2,7 +2,10 @@ package cli //nolint:testpackage // needs access to unexported cleanStartupError
 
 import (
 	"errors"
+	"path/filepath"
 	"testing"
+
+	"sneak.berlin/go/vaultik/internal/pidlock"
 )
 
 func TestCleanStartupError(t *testing.T) {
@@ -53,3 +56,42 @@ func TestCleanStartupError(t *testing.T) {
 		})
 	}
 }
+
+// TestLockScopedToMutatingCommands proves the partition the PID lock now
+// enforces: a read-only command runs while a mutator holds the lock, and
+// two mutating commands still mutually exclude.
+func TestLockScopedToMutatingCommands(t *testing.T) {
+	t.Parallel()
+
+	lockDir := filepath.Join(t.TempDir(), "vaultik")
+
+	// A mutating command takes the process-wide lock.
+	releaseMutator, err := acquireLockIfMutating(mutating, lockDir)
+	if err != nil {
+		t.Fatalf("mutating command could not acquire lock: %v", err)
+	}
+
+	// A read-only command runs to completion even while the lock is held.
+	releaseReader, err := acquireLockIfMutating(readOnly, lockDir)
+	if err != nil {
+		t.Fatalf("read-only command was blocked by held lock: %v", err)
+	}
+
+	releaseReader()
+
+	// A second mutating command is refused while the first holds the lock.
+	_, err = acquireLockIfMutating(mutating, lockDir)
+	if !errors.Is(err, pidlock.ErrAlreadyRunning) {
+		t.Fatalf("second mutating command was not excluded, got: %v", err)
+	}
+
+	// Once the first mutator releases, another mutating command may run.
+	releaseMutator()
+
+	release, err := acquireLockIfMutating(mutating, lockDir)
+	if err != nil {
+		t.Fatalf("mutating command could not acquire released lock: %v", err)
+	}
+
+	release()
+}

internal/cli/config.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -192,8 +193,8 @@ storage_url: ""
 #   access_key_id: YOUR_ACCESS_KEY
 #   secret_access_key: YOUR_SECRET_KEY
 #   # region: us-east-1        # Default: us-east-1
-#   # use_ssl: true            # Default: true
 #   # part_size: 5MB           # Multipart upload part size. Default: 5MB
+#   # For the s3:// form, disable TLS with ?ssl=false in the URL, not use_ssl.
 
 # ─── OPTIONAL ────────────────────────────────────────────────────────────────
 
@@ -212,6 +213,8 @@ storage_url: ""
 # chunk_size: 10MB
 
 # Maximum blob size before splitting into a new blob.
+# Must be at least four times chunk_size (the largest chunk the chunker can
+# emit); a smaller limit would let a single-chunk blob exceed it.
 # Accepts: 1GB, 10G, 500MB, etc.
 # Default: 10GB
 # blob_size_limit: 10GB
@@ -377,40 +380,53 @@ Examples:
 				return err
 			}
 
-			root, err := loadYAMLFile(path)
+			return writeConfigSet(os.Stdout, path, args[0], args[1])
-			if err != nil {
-				return err
-			}
-
-			err = yamlPathSet(root, strings.Split(args[0], "."), args[1])
-			if err != nil {
-				return err
-			}
-
-			out, err := marshalConfigYAML(root)
-			if err != nil {
-				return fmt.Errorf("marshaling config: %w", err)
-			}
-
-			mode := os.FileMode(configFileMode)
-
-			info, statErr := os.Stat(path)
-			if statErr == nil {
-				mode = info.Mode().Perm()
-			}
-
-			err = os.WriteFile(path, out, mode)
-			if err != nil {
-				return fmt.Errorf("writing config file: %w", err)
-			}
-
-			_, _ = fmt.Fprintf(os.Stdout, "%s = %s\n", args[0], args[1])
-
-			return nil
 		},
 	}
 }
 
+// writeConfigSet applies key=value to the config at path, writes it back
+// owner-only, and confirms the write by printing just the key name to w.
+// The value is never echoed: it may be a secret such as
+// s3.secret_access_key, and captured stdout or a pasted terminal would
+// then leak it.
+func writeConfigSet(w io.Writer, path, key, value string) error {
+	root, err := loadYAMLFile(path)
+	if err != nil {
+		return err
+	}
+
+	err = yamlPathSet(root, strings.Split(key, "."), value)
+	if err != nil {
+		return err
+	}
+
+	out, err := marshalConfigYAML(root)
+	if err != nil {
+		return fmt.Errorf("marshaling config: %w", err)
+	}
+
+	err = os.WriteFile(path, out, configFileMode)
+	if err != nil {
+		return fmt.Errorf("writing config file: %w", err)
+	}
+
+	// os.WriteFile does not change the mode of a file that already exists,
+	// so a config that was group- or world-readable stays that way. As it
+	// may hold S3 credentials, tighten it to owner-only after writing.
+	info, statErr := os.Stat(path)
+	if statErr == nil && info.Mode().Perm()&0o044 != 0 {
+		err = os.Chmod(path, configFileMode)
+		if err != nil {
+			return fmt.Errorf("tightening config file permissions: %w", err)
+		}
+	}
+
+	_, _ = fmt.Fprintln(w, key)
+
+	return nil
+}
+
 // marshalConfigYAML renders a config document tree with 2-space indentation,
 // matching defaultConfigTemplate. yaml.Marshal defaults to 4 spaces, which
 // would reindent the whole file on the first `config set` despite the promise

internal/cli/config_test.go

@@ -1,6 +1,9 @@
 package cli //nolint:testpackage // exercises unexported yamlPathGet/yamlPathSet
 
 import (
+	"bytes"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -229,6 +232,68 @@ func TestConfigSetPreservesFormatting(t *testing.T) {
 	}
 }
 
+// TestWriteConfigSetHidesSecret checks that setting a secret key prints
+// only the key name, never the value, to the confirmation output.
+func TestWriteConfigSetHidesSecret(t *testing.T) {
+	t.Parallel()
+
+	const secret = "SUPERSECRETVALUE"
+
+	path := filepath.Join(t.TempDir(), "config.yaml")
+
+	err := os.WriteFile(path, []byte("version: 1\n"), 0o600)
+	if err != nil {
+		t.Fatalf("seed config: %v", err)
+	}
+
+	var out bytes.Buffer
+
+	err = writeConfigSet(&out, path, "s3.secret_access_key", secret)
+	if err != nil {
+		t.Fatalf("writeConfigSet: %v", err)
+	}
+
+	if strings.Contains(out.String(), secret) {
+		t.Errorf("output echoed the secret value: %q", out.String())
+	}
+
+	if !strings.Contains(out.String(), "s3.secret_access_key") {
+		t.Errorf("output did not confirm the key name: %q", out.String())
+	}
+}
+
+// TestWriteConfigSetTightensMode checks that a pre-existing group- or
+// world-readable config is tightened to owner-only after a set, since
+// os.WriteFile leaves an existing file's mode untouched.
+func TestWriteConfigSetTightensMode(t *testing.T) {
+	t.Parallel()
+
+	path := filepath.Join(t.TempDir(), "config.yaml")
+
+	// Seed a world-readable config; the loose mode is the condition under
+	// test, so gosec's G306 is expected here.
+	err := os.WriteFile(path, []byte("version: 1\n"), 0o644) //nolint:gosec // G306
+	if err != nil {
+		t.Fatalf("seed config: %v", err)
+	}
+
+	var out bytes.Buffer
+
+	err = writeConfigSet(&out, path, "compression_level", "9")
+	if err != nil {
+		t.Fatalf("writeConfigSet: %v", err)
+	}
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat config: %v", err)
+	}
+
+	if info.Mode().Perm() != 0o600 {
+		t.Errorf("config mode = %04o, want 0600", info.Mode().Perm())
+	}
+}
+
 func splitPath(s string) []string {
 	return strings.Split(s, ".")
 }

internal/cli/entry.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"errors"
 	"io"
 	"os"
 	"strings"
@@ -19,7 +20,11 @@ const shortCommitLen = 12
 // flag is present in os.Args — see bannerSuppressedInArgs), executes the
 // root cobra command, and routes any returned error through the
 // ui.Writer so the user sees a properly formatted "🛑 ERROR:" line.
-func Entry() {
+//
+// It returns the process exit code (0 on success, 1 on error) rather
+// than calling os.Exit, so that main's deferred profile writers run
+// before the process ends. See run in cmd/vaultik/main.go.
+func Entry() int {
 	emitStartupBanner(os.Args[1:], os.Stdout)
 
 	rootCmd := NewRootCommand()
@@ -27,9 +32,19 @@ func Entry() {
 
 	err := rootCmd.Execute()
 	if err != nil {
-		ReportErrorf("%s", err.Error())
+		// An operation that ran inside the fx app has already reported
-		os.Exit(1)
+		// its own failure (and suppressed it under --json); errReported
+		// says so. Printing it again here would double the error line.
+		// Every other error — bad arguments, a config that would not
+		// load — reaches Entry unreported, so it is shown here.
+		if !errors.Is(err, errReported) {
+			ReportErrorf("%s", err.Error())
+		}
+
+		return 1
 	}
+
+	return 0
 }
 
 // emitStartupBanner writes the startup banner to w unless args (the

internal/cli/entry_banner_test.go

@@ -230,7 +230,7 @@ func TestEntryJSONStdoutIsExactlyOneDocument(t *testing.T) {
 		programName, flagConfig, configPath, cmdSnapshot, cmdList, flagJSON,
 	}
 
-	stdout := captureProcessStdout(t, Entry)
+	stdout := captureProcessStdout(t, func() { _ = Entry() })
 
 	requireExactlyOneJSONDocument(t, stdout)
 

internal/cli/entry_prune_json_stderr_test.go

@@ -0,0 +1,140 @@
+package cli //nolint:testpackage // shares the prune fixtures and capture helpers
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// staleRecordLogMessage is the local-cleanup audit line CleanupLocalSnapshots
+// logs for each stale record. It is exactly the signal issue #112 says a
+// machine consumer lost under --json: gated off stdout, and pinned below
+// the log level on stderr because --json used to force Quiet.
+const staleRecordLogMessage = "Removing stale local snapshot record"
+
+// TestEntryPruneJSONStderrHonoursVerbosity is the end-to-end regression
+// guard for issue #112. Under --json the log level must still follow
+// --verbose/--debug rather than being pinned to WARN, so the
+// local-cleanup records reach stderr under --verbose while stdout stays
+// exactly one JSON document; without --verbose they stay below the
+// level, as they do without --json.
+//
+// Both halves are asserted together on the same run, because the fix has
+// to keep the document clean (issue #108) while freeing stderr.
+//
+// Not parallel: it replaces os.Args, os.Stdout, os.Stderr and the xdg
+// globals.
+//
+//nolint:paralleltest // replaces os.Args, os.Stdout, os.Stderr and the xdg globals
+func TestEntryPruneJSONStderrHonoursVerbosity(t *testing.T) {
+	for _, testCase := range []struct {
+		name         string
+		verbose      bool
+		wantOnStderr bool
+	}{
+		{
+			name:         "verbose json surfaces the cleanup record on stderr",
+			verbose:      true,
+			wantOnStderr: true,
+		},
+		{
+			name:         "json alone keeps the cleanup record below the level",
+			verbose:      false,
+			wantOnStderr: false,
+		},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			configPath := writeHermeticPruneConfig(t, true)
+
+			previousArgs := os.Args
+
+			t.Cleanup(func() {
+				os.Args = previousArgs
+				rootFlags = RootFlags{}
+			})
+
+			args := []string{
+				programName, flagConfig, configPath, cmdPrune, flagJSON,
+			}
+			if testCase.verbose {
+				args = append(args, "--verbose")
+			}
+
+			os.Args = args
+
+			stdout, stderr := captureProcessStdoutAndStderr(t,
+				func() { _ = Entry() })
+
+			// The document stays clean in both cases: freeing stderr must
+			// not regress issue #108.
+			requireExactlyOneJSONDocument(t, stdout)
+
+			if testCase.wantOnStderr {
+				assert.Contains(t, stderr, staleRecordLogMessage,
+					"--verbose --json must emit the cleanup record on stderr")
+				assert.Contains(t, stderr, stalePruneSnapshotID,
+					"the record must name the snapshot it removed")
+			} else {
+				assert.NotContains(t, stderr, staleRecordLogMessage,
+					"without --verbose the record stays below the log level")
+			}
+		})
+	}
+}
+
+// captureProcessStdoutAndStderr redirects both of the process's own
+// standard streams to pipes for the duration of fn and returns what was
+// written to each. The redirection is at the file-descriptor level
+// because the logger binds os.Stderr when it initializes inside fn, and
+// the JSON document reaches os.Stdout independently; the point is to see
+// where each actually lands.
+//
+// Not parallel-safe: os.Stdout and os.Stderr are process-global.
+func captureProcessStdoutAndStderr(t *testing.T, fn func()) (string, string) {
+	t.Helper()
+
+	outReader, outWriter, err := os.Pipe()
+	require.NoError(t, err)
+
+	errReader, errWriter, err := os.Pipe()
+	require.NoError(t, err)
+
+	previousOut, previousErr := os.Stdout, os.Stderr
+	os.Stdout, os.Stderr = outWriter, errWriter
+
+	capturedOut := drain(outReader)
+	capturedErr := drain(errReader)
+
+	fn()
+
+	os.Stdout, os.Stderr = previousOut, previousErr
+
+	require.NoError(t, outWriter.Close())
+	require.NoError(t, errWriter.Close())
+
+	out, errOut := <-capturedOut, <-capturedErr
+
+	require.NoError(t, outReader.Close())
+	require.NoError(t, errReader.Close())
+
+	return out, errOut
+}
+
+// drain copies a reader to a string on a goroutine and delivers the
+// result once the writer end is closed.
+func drain(reader io.Reader) <-chan string {
+	captured := make(chan string, 1)
+
+	go func() {
+		var buf bytes.Buffer
+
+		_, _ = io.Copy(&buf, reader)
+		captured <- buf.String()
+	}()
+
+	return captured
+}

internal/cli/entry_prune_json_test.go

@@ -81,7 +81,7 @@ func TestEntryPruneJSONStdoutIsExactlyOneDocument(t *testing.T) {
 				programName, flagConfig, configPath, cmdPrune, flagJSON,
 			}
 
-			stdout := captureProcessStdout(t, Entry)
+			stdout := captureProcessStdout(t, func() { _ = Entry() })
 
 			requireExactlyOneJSONDocument(t, stdout)
 

internal/cli/entry_status_test.go

@@ -0,0 +1,58 @@
+package cli //nolint:testpackage // shares programName and the capture helpers
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestEntryReturnsStatusCode pins the contract main() relies on for
+// issue #75: Entry reports success or failure through its return value
+// and never calls os.Exit. An os.Exit from inside Entry would skip
+// main's deferred profile writers and truncate the profile of a failing
+// command. main turns this code into os.Exit only after those defers
+// run, so a failing command must come back with a non-zero code rather
+// than ending the process here.
+//
+// Stdout is captured only to keep the banner and command output off the
+// test log; the assertion is on the returned code.
+//
+//nolint:paralleltest // replaces os.Args and rootFlags
+func TestEntryReturnsStatusCode(t *testing.T) {
+	for _, testCase := range []struct {
+		name string
+		args []string
+		want int
+	}{
+		{
+			// version is self-contained: it needs no config and no
+			// destination store, so it exercises the success path.
+			name: "successful command returns zero",
+			args: []string{programName, "version"},
+			want: 0,
+		},
+		{
+			name: "unknown command returns one",
+			args: []string{programName, "no-such-command"},
+			want: 1,
+		},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			previousArgs := os.Args
+
+			t.Cleanup(func() {
+				os.Args = previousArgs
+				rootFlags = RootFlags{}
+			})
+
+			os.Args = testCase.args
+
+			var code int
+
+			_ = captureProcessStdout(t, func() { code = Entry() })
+
+			assert.Equal(t, testCase.want, code)
+		})
+	}
+}

internal/cli/info.go

@@ -1,12 +1,7 @@
 package cli
 
 import (
-	"context"
-	"errors"
-	"os"
-
 	"github.com/spf13/cobra"
-	"go.uber.org/fx"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -33,44 +28,19 @@ func NewInfoCommand() *cobra.Command {
 			// Use the app framework
 			rootFlags := GetRootFlags()
 
-			return RunWithApp(cmd.Context(), AppOptions{
+			return RunOperation(cmd.Context(), AppOptions{
 				ConfigPath: configPath,
 				LogOptions: log.Options{
 					Verbose: rootFlags.Verbose,
 					Debug:   rootFlags.Debug,
 					Quiet:   rootFlags.Quiet,
 				},
-				Modules: []fx.Option{},
+				Mode: readOnly,
-				Invokes: []fx.Option{
+			}, func(v *vaultik.Vaultik) error {
-					fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+				return v.ShowInfo()
-						lc.Append(fx.Hook{
+			}, func(err error) {
-							OnStart: func(_ context.Context) error {
+				log.Error("Failed to show info", "error", err)
-								go func() {
+				ReportErrorf("Failed to show info: %v", err)
-									err := v.ShowInfo()
-									if err != nil {
-										if !errors.Is(err, context.Canceled) {
-											log.Error("Failed to show info", "error", err)
-											ReportErrorf("Failed to show info: %v", err)
-											os.Exit(1)
-										}
-									}
-
-									err = v.Shutdowner.Shutdown()
-									if err != nil {
-										log.Error("Failed to shutdown", "error", err)
-									}
-								}()
-
-								return nil
-							},
-							OnStop: func(_ context.Context) error {
-								v.Cancel()
-
-								return nil
-							},
-						})
-					}),
-				},
 			})
 		},
 	}

internal/cli/prune.go

@@ -1,12 +1,7 @@
 package cli
 
 import (
-	"context"
-	"errors"
-	"os"
-
 	"github.com/spf13/cobra"
-	"go.uber.org/fx"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -41,51 +36,24 @@ work (e.g. after a crashed backup or to reclaim storage).`,
 			// Use the app framework like other commands
 			rootFlags := GetRootFlags()
 
-			return RunWithApp(cmd.Context(), AppOptions{
+			return RunOperation(cmd.Context(), AppOptions{
 				ConfigPath: configPath,
 				LogOptions: log.Options{
 					Verbose: rootFlags.Verbose,
 					Debug:   rootFlags.Debug,
-					Quiet:   rootFlags.Quiet || opts.JSON,
+					Quiet:   rootFlags.Quiet,
+					JSON:    opts.JSON,
 				},
-				Modules: []fx.Option{},
+				Mode: mutating,
-				Invokes: []fx.Option{
+			}, func(v *vaultik.Vaultik) error {
-					fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+				return v.Prune(opts)
-						lc.Append(fx.Hook{
+			}, func(err error) {
-							OnStart: func(_ context.Context) error {
+				if opts.JSON {
-								// Start the prune operation in a goroutine
+					return
-								go func() {
+				}
-									// Run the prune operation
-									err := v.Prune(opts)
-									if err != nil {
-										if !errors.Is(err, context.Canceled) {
-											if !opts.JSON {
-												log.Error("Prune operation failed", "error", err)
-												ReportErrorf("Prune failed: %v", err)
-											}
 
-											os.Exit(1)
+				log.Error("Prune operation failed", "error", err)
-										}
+				ReportErrorf("Prune failed: %v", err)
-									}
-
-									// Shutdown the app when prune completes
-									err = v.Shutdowner.Shutdown()
-									if err != nil {
-										log.Error("Failed to shutdown", "error", err)
-									}
-								}()
-
-								return nil
-							},
-							OnStop: func(_ context.Context) error {
-								log.Debug("Stopping prune operation")
-								v.Cancel()
-
-								return nil
-							},
-						})
-					}),
-				},
 			})
 		},
 	}

internal/cli/remote.go

@@ -1,12 +1,9 @@
 package cli
 
 import (
-	"context"
 	"errors"
-	"os"
 
 	"github.com/spf13/cobra"
-	"go.uber.org/fx"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -48,7 +45,7 @@ This is destructive and irreversible. Requires --force.`,
 				return errNukeNeedsForce
 			}
 
-			return runVaultikApp(cmd, false, false, "Remote nuke failed",
+			return runVaultikApp(cmd, mutating, false, false, "Remote nuke failed",
 				func(v *vaultik.Vaultik) error {
 					return v.NukeRemote(true)
 				})
@@ -83,47 +80,24 @@ func newRemoteInfoCommand() *cobra.Command {
 
 			rootFlags := GetRootFlags()
 
-			return RunWithApp(cmd.Context(), AppOptions{
+			return RunOperation(cmd.Context(), AppOptions{
 				ConfigPath: configPath,
 				LogOptions: log.Options{
 					Verbose: rootFlags.Verbose,
 					Debug:   rootFlags.Debug,
-					Quiet:   rootFlags.Quiet || jsonOutput,
+					Quiet:   rootFlags.Quiet,
+					JSON:    jsonOutput,
 				},
-				Modules: []fx.Option{},
+				Mode: readOnly,
-				Invokes: []fx.Option{
+			}, func(v *vaultik.Vaultik) error {
-					fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+				return v.RemoteInfo(jsonOutput)
-						lc.Append(fx.Hook{
+			}, func(err error) {
-							OnStart: func(_ context.Context) error {
+				if jsonOutput {
-								go func() {
+					return
-									err := v.RemoteInfo(jsonOutput)
+				}
-									if err != nil {
-										if !errors.Is(err, context.Canceled) {
-											if !jsonOutput {
-												log.Error("Failed to get remote info", "error", err)
-												ReportErrorf("Failed to get remote info: %v", err)
-											}
 
-											os.Exit(1)
+				log.Error("Failed to get remote info", "error", err)
-										}
+				ReportErrorf("Failed to get remote info: %v", err)
-									}
-
-									err = v.Shutdowner.Shutdown()
-									if err != nil {
-										log.Error("Failed to shutdown", "error", err)
-									}
-								}()
-
-								return nil
-							},
-							OnStop: func(_ context.Context) error {
-								v.Cancel()
-
-								return nil
-							},
-						})
-					}),
-				},
 			})
 		},
 	}

internal/cli/root.go

@@ -57,8 +57,9 @@ on the source system.`,
 	cmd.PersistentFlags().BoolVarP(&rootFlags.Quiet, "quiet", "q", false,
 		"Suppress non-error output")
 	cmd.PersistentFlags().BoolVar(&rootFlags.SkipErrors, "skip-errors", false,
-		"Continue past per-file errors instead of aborting "+
+		"Skip files that cannot be read when creating a snapshot, or "+
-			"(applies to snapshot create and restore)")
+			"that cannot be restored when restoring, instead of aborting "+
+			"(packing and storage errors still abort)")
 
 	// Add subcommands
 	cmd.AddCommand(

internal/cli/runapp_interrupt_test.go

@@ -0,0 +1,97 @@
+package cli_test
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"go.uber.org/fx"
+	"sneak.berlin/go/vaultik/internal/cli"
+)
+
+// TestRunAppWaitsForOperationCleanupOnShutdown drives RunApp with an fx app
+// wired the way RunOperation wires a command: a single lifecycle hook whose
+// OnStart launches the operation in its own goroutine and whose OnStop cancels
+// it and blocks until that goroutine returns. The operation stands in for a
+// restore blocked mid-download — it holds a decrypted "scratch" file and only
+// removes it as it unwinds on cancellation.
+//
+// The app is asked to stop once the operation is running (standing in for an
+// OS interrupt; fx delivers a real signal and Shutdowner.Shutdown() on the
+// same app.Wait channel, so both drive the identical shutdown path). RunApp
+// must not return until app.Stop has run the OnStop hook, so the scratch file
+// must be gone by the time RunApp returns. Before the fix RunApp returned as
+// soon as the app.Wait/Done channel fired, without running app.Stop, so the
+// cleanup never ran and this file would still be on disk (issue #159).
+func TestRunAppWaitsForOperationCleanupOnShutdown(t *testing.T) {
+	t.Parallel()
+
+	scratch := filepath.Join(t.TempDir(), "decrypted-scratch")
+	require.NoError(t, os.WriteFile(scratch, []byte("secret"), 0o600))
+
+	// Cancel and reap the operation even if RunApp returns without doing so
+	// (the buggy path), so the goroutine cannot leak past the test.
+	opCtx, opCancel := context.WithCancel(context.Background())
+	t.Cleanup(opCancel)
+
+	var stop func(context.Context) bool
+
+	app := fx.New(
+		fx.NopLogger,
+		fx.Invoke(func(lc fx.Lifecycle, sh fx.Shutdowner) {
+			lc.Append(fx.Hook{
+				OnStart: func(_ context.Context) error {
+					done := make(chan struct{})
+
+					go func() {
+						defer close(done)
+
+						// Blocked mid-operation until cancelled, then run the
+						// cleanup an interrupted restore would run.
+						<-opCtx.Done()
+
+						_ = os.Remove(scratch)
+					}()
+
+					stop = func(ctx context.Context) bool {
+						opCancel()
+
+						select {
+						case <-done:
+							return true
+						case <-ctx.Done():
+							return false
+						}
+					}
+
+					// Ask the app to stop now that the operation is running.
+					go func() { _ = sh.Shutdown() }()
+
+					return nil
+				},
+				OnStop: func(ctx context.Context) error {
+					stop(ctx)
+
+					return nil
+				},
+			})
+		}),
+	)
+
+	done := make(chan error, 1)
+	go func() { done <- cli.RunApp(context.Background(), app) }()
+
+	select {
+	case err := <-done:
+		require.NoError(t, err)
+	case <-time.After(30 * time.Second):
+		t.Fatal("RunApp did not return after shutdown was requested")
+	}
+
+	_, err := os.Stat(scratch)
+	require.True(t, os.IsNotExist(err),
+		"RunApp returned before the operation removed its decrypted scratch file")
+}

internal/cli/snapshot.go

@@ -1,13 +1,10 @@
 package cli
 
 import (
-	"context"
 	"errors"
 	"fmt"
-	"os"
 
 	"github.com/spf13/cobra"
-	"go.uber.org/fx"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -86,7 +83,8 @@ specifying a path using --config or by setting VAULTIK_CONFIG to a path.`,
 			// Use the backup functionality from cli package
 			rootFlags := GetRootFlags()
 
-			return RunWithApp(cmd.Context(), AppOptions{
+			// --cron suppression is wired through v.UI by setupGlobals.
+			return RunOperation(cmd.Context(), AppOptions{
 				ConfigPath: configPath,
 				LogOptions: log.Options{
 					Verbose: rootFlags.Verbose,
@@ -94,42 +92,12 @@ specifying a path using --config or by setting VAULTIK_CONFIG to a path.`,
 					Cron:    opts.Cron,
 					Quiet:   rootFlags.Quiet,
 				},
-				Modules: []fx.Option{},
+				Mode: mutating,
-				Invokes: []fx.Option{
+			}, func(v *vaultik.Vaultik) error {
-					fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+				return v.CreateSnapshot(opts)
-						lc.Append(fx.Hook{
+			}, func(err error) {
-							OnStart: func(_ context.Context) error {
+				log.Error("Snapshot creation failed", "error", err)
-								// Start the snapshot creation in a goroutine
+				ReportErrorf("Snapshot creation failed: %v", err)
-								go func() {
-									// --cron suppression is wired through v.UI by setupGlobals.
-									err := v.CreateSnapshot(opts)
-									if err != nil {
-										if !errors.Is(err, context.Canceled) {
-											log.Error("Snapshot creation failed", "error", err)
-											ReportErrorf("Snapshot creation failed: %v", err)
-											os.Exit(1)
-										}
-									}
-
-									// Shutdown the app when snapshot completes
-									err = v.Shutdowner.Shutdown()
-									if err != nil {
-										log.Error("Failed to shutdown", "error", err)
-									}
-								}()
-
-								return nil
-							},
-							OnStop: func(_ context.Context) error {
-								log.Debug("Stopping snapshot creation")
-								// Cancel the Vaultik context
-								v.Cancel()
-
-								return nil
-							},
-						})
-					}),
-				},
 			})
 		},
 	}
@@ -158,7 +126,7 @@ func newSnapshotListCommand() *cobra.Command {
 		Long:    "Lists all snapshots with their ID, timestamp, and compressed size",
 		Args:    cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, _ []string) error {
-			return runVaultikApp(cmd, false, false,
+			return runVaultikApp(cmd, readOnly, false, false,
 				"Failed to list snapshots",
 				func(v *vaultik.Vaultik) error {
 					return v.ListSnapshots(jsonOutput)
@@ -194,7 +162,7 @@ restrict the operation to specific snapshot names.`,
 				return errPurgeCriteriaBoth
 			}
 
-			return runVaultikApp(cmd, false, false,
+			return runVaultikApp(cmd, mutating, false, false,
 				"Failed to purge snapshots",
 				func(v *vaultik.Vaultik) error {
 					return v.PurgeSnapshotsWithOptions(opts)
@@ -220,8 +188,11 @@ func newSnapshotVerifyCommand() *cobra.Command {
 
 	cmd := &cobra.Command{
 		Use:   "verify <snapshot-id>",
-		Short: "Verify snapshot integrity",
+		Short: "Check a snapshot's blobs are present with the listed size",
-		Long: "Verifies that all blobs referenced in a snapshot exist.\n\n" +
+		Long: "Checks that every blob the snapshot's manifest lists is present\n" +
+			"in storage with the size the manifest records, and that the\n" +
+			"snapshot's encrypted database is present. It does not read blob\n" +
+			"contents; use --deep to download and cryptographically verify them.\n\n" +
 			"The snapshot may be named by its ID or, on a host with no local\n" +
 			"index, by the remote key that 'snapshot list' prints for a\n" +
 			"remote-only snapshot (an unambiguous leading part is enough).",
@@ -237,47 +208,24 @@ func newSnapshotVerifyCommand() *cobra.Command {
 
 			rootFlags := GetRootFlags()
 
-			return RunWithApp(cmd.Context(), AppOptions{
+			return RunOperation(cmd.Context(), AppOptions{
 				ConfigPath: configPath,
 				LogOptions: log.Options{
 					Verbose: rootFlags.Verbose,
 					Debug:   rootFlags.Debug,
-					Quiet:   rootFlags.Quiet || opts.JSON,
+					Quiet:   rootFlags.Quiet,
+					JSON:    opts.JSON,
 				},
-				Modules: []fx.Option{},
+				Mode: readOnly,
-				Invokes: []fx.Option{
+			}, func(v *vaultik.Vaultik) error {
-					fx.Invoke(func(v *vaultik.Vaultik, lc fx.Lifecycle) {
+				return v.VerifySnapshotWithOptions(snapshotID, opts)
-						lc.Append(fx.Hook{
+			}, func(err error) {
-							OnStart: func(_ context.Context) error {
+				if opts.JSON {
-								go func() {
+					return
-									err := v.VerifySnapshotWithOptions(snapshotID, opts)
+				}
-									if err != nil {
-										if !errors.Is(err, context.Canceled) {
-											if !opts.JSON {
-												log.Error("Verification failed", "error", err)
-												ReportErrorf("Verification failed: %v", err)
-											}
 
-											os.Exit(1)
+				log.Error("Verification failed", "error", err)
-										}
+				ReportErrorf("Verification failed: %v", err)
-									}
-
-									err = v.Shutdowner.Shutdown()
-									if err != nil {
-										log.Error("Failed to shutdown", "error", err)
-									}
-								}()
-
-								return nil
-							},
-							OnStop: func(_ context.Context) error {
-								v.Cancel()
-
-								return nil
-							},
-						})
-					}),
-				},
 			})
 		},
 	}
@@ -316,7 +264,7 @@ To wipe the entire destination store and start over, use 'vaultik remote
 nuke --force' — it is the single supported entry point for that.`,
 		Args: requireSnapshotIDArg,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return runVaultikApp(cmd, opts.JSON, opts.JSON,
+			return runVaultikApp(cmd, mutating, opts.JSON, opts.JSON,
 				"Failed to remove snapshot",
 				func(v *vaultik.Vaultik) error {
 					_, err := v.RemoveSnapshot(args[0], opts)

internal/cli/snapshot_restore.go

@@ -1,16 +1,8 @@
 package cli
 
 import (
-	"context"
-	"errors"
-	"os"
-
 	"github.com/spf13/cobra"
-	"go.uber.org/fx"
-	"sneak.berlin/go/vaultik/internal/config"
-	"sneak.berlin/go/vaultik/internal/globals"
 	"sneak.berlin/go/vaultik/internal/log"
-	"sneak.berlin/go/vaultik/internal/storage"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
 
@@ -25,15 +17,6 @@ type RestoreOptions struct {
 	Verify    bool     // Verify restored files after restore
 }
 
-// RestoreApp contains all dependencies needed for restore
-type RestoreApp struct {
-	Globals    *globals.Globals
-	Config     *config.Config
-	Storage    storage.Storer
-	Vaultik    *vaultik.Vaultik
-	Shutdowner fx.Shutdowner
-}
-
 // newSnapshotRestoreCommand creates the 'snapshot restore' subcommand
 func newSnapshotRestoreCommand() *cobra.Command {
 	opts := &RestoreOptions{}
@@ -52,8 +35,12 @@ The snapshot may be named by its ID or, when restoring on a host with no
 local index, by the remote key that 'snapshot list' prints for a
 remote-only snapshot (an unambiguous leading part is enough).
 
-Requires the VAULTIK_AGE_SECRET_KEY environment variable to be set with
+Requires the age private key in the VAULTIK_AGE_SECRET_KEY environment
-the age private key.
+variable. The variable may hold the whole age-keygen file (comments and
+all of its identities are accepted); read it from the file rather than
+typing the key, so it does not land in your shell history:
+
+  export VAULTIK_AGE_SECRET_KEY="$(cat vaultik_backup_private_key.txt)"
 
 Examples:
   # Restore entire snapshot
@@ -81,7 +68,8 @@ Examples:
 	return cmd
 }
 
-// runRestore parses arguments and runs the restore operation through the app framework
+// runRestore parses arguments and runs the restore operation through the
+// app framework.
 func runRestore(cmd *cobra.Command, args []string, opts *RestoreOptions) error {
 	snapshotID := args[0]
 
@@ -90,87 +78,31 @@ func runRestore(cmd *cobra.Command, args []string, opts *RestoreOptions) error {
 		opts.Paths = args[restoreMinArgs:]
 	}
 
-	// Use unified config resolution
 	configPath, err := ResolveConfigPath()
 	if err != nil {
 		return err
 	}
 
-	// Use the app framework like other commands
 	rootFlags := GetRootFlags()
 
-	return RunWithApp(cmd.Context(), AppOptions{
+	return RunOperation(cmd.Context(), AppOptions{
 		ConfigPath: configPath,
 		LogOptions: log.Options{
 			Verbose: rootFlags.Verbose,
 			Debug:   rootFlags.Debug,
 			Quiet:   rootFlags.Quiet,
 		},
-		Modules: buildRestoreModules(),
+		Mode: readOnly,
-		Invokes: buildRestoreInvokes(snapshotID, opts),
+	}, func(v *vaultik.Vaultik) error {
+		return v.Restore(&vaultik.RestoreOptions{
+			SnapshotID: snapshotID,
+			TargetDir:  opts.TargetDir,
+			Paths:      opts.Paths,
+			Verify:     opts.Verify,
+			SkipErrors: rootFlags.SkipErrors,
+		})
+	}, func(err error) {
+		log.Error("Restore operation failed", "error", err)
+		ReportErrorf("Restore failed: %v", err)
 	})
 }
-
-// buildRestoreModules returns the fx.Options for dependency injection in restore
-func buildRestoreModules() []fx.Option {
-	return []fx.Option{
-		fx.Provide(fx.Annotate(
-			func(g *globals.Globals, cfg *config.Config,
-				storer storage.Storer, v *vaultik.Vaultik, shutdowner fx.Shutdowner) *RestoreApp {
-				return &RestoreApp{
-					Globals:    g,
-					Config:     cfg,
-					Storage:    storer,
-					Vaultik:    v,
-					Shutdowner: shutdowner,
-				}
-			},
-		)),
-	}
-}
-
-// buildRestoreInvokes returns the fx.Options that wire up the restore lifecycle
-func buildRestoreInvokes(snapshotID string, opts *RestoreOptions) []fx.Option {
-	return []fx.Option{
-		fx.Invoke(func(app *RestoreApp, lc fx.Lifecycle) {
-			lc.Append(fx.Hook{
-				OnStart: func(_ context.Context) error {
-					// Start the restore operation in a goroutine
-					go func() {
-						// Run the restore operation
-						restoreOpts := &vaultik.RestoreOptions{
-							SnapshotID: snapshotID,
-							TargetDir:  opts.TargetDir,
-							Paths:      opts.Paths,
-							Verify:     opts.Verify,
-							SkipErrors: GetRootFlags().SkipErrors,
-						}
-
-						err := app.Vaultik.Restore(restoreOpts)
-						if err != nil {
-							if !errors.Is(err, context.Canceled) {
-								log.Error("Restore operation failed", "error", err)
-								ReportErrorf("Restore failed: %v", err)
-								os.Exit(1)
-							}
-						}
-
-						// Shutdown the app when restore completes
-						err = app.Shutdowner.Shutdown()
-						if err != nil {
-							log.Error("Failed to shutdown", "error", err)
-						}
-					}()
-
-					return nil
-				},
-				OnStop: func(_ context.Context) error {
-					log.Debug("Stopping restore operation")
-					app.Vaultik.Cancel()
-
-					return nil
-				},
-			})
-		}),
-	}
-}

internal/cli/snapshot_restore_test.go

@@ -0,0 +1,37 @@
+package cli //nolint:testpackage // exercises the unexported command constructor
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/spf13/pflag"
+)
+
+// TestRestoreCommandDoesNotTakeKeyAsArgument guards the fix for the age
+// key being echoed on the command line: restore must take the key only
+// from the environment, never as a flag value, and its help must show the
+// file-based form rather than a literal key that would land in shell
+// history.
+func TestRestoreCommandDoesNotTakeKeyAsArgument(t *testing.T) {
+	t.Parallel()
+
+	cmd := newSnapshotRestoreCommand()
+
+	cmd.Flags().VisitAll(func(f *pflag.Flag) {
+		lower := strings.ToLower(f.Name)
+		for _, banned := range []string{"key", "secret", "age", "identity"} {
+			if strings.Contains(lower, banned) {
+				t.Errorf("restore must not accept the key as a flag; found --%s", f.Name)
+			}
+		}
+	})
+
+	help := cmd.Long
+	if strings.Contains(help, "AGE-SECRET-KEY-") {
+		t.Error("restore help must not show a literal age private key to type")
+	}
+
+	if !strings.Contains(help, "$(cat ") {
+		t.Error("restore help should read the key from a file, e.g. $(cat ...)")
+	}
+}

internal/config/config.go

@@ -16,11 +16,19 @@ import (
 	"github.com/adrg/xdg"
 	"go.uber.org/fx"
 	"gopkg.in/yaml.v3"
+	"sneak.berlin/go/vaultik/internal/chunker"
 	"sneak.berlin/go/vaultik/internal/log"
 )
 
 const appName = "vaultik"
 
+// secretKeyPrefix marks an age secret (private) key. It is compared
+// case-insensitively so a recipient entry that is actually a private key is
+// caught and never passed to age or echoed back.
+//
+//nolint:gosec // G101: marker for detecting a pasted secret key, not a credential
+const secretKeyPrefix = "AGE-SECRET-KEY-"
+
 // Defaults and validation bounds for tunable settings.
 const (
 	defaultBlobSizeLimit    = Size(10 * 1024 * 1024 * 1024) // 10GB
@@ -37,13 +45,19 @@ var (
 	errNoConfigPath    = errors.New("config path not provided")
 	errNoAgeRecipients = errors.New(
 		"at least one age_recipient is required (generate with: age-keygen)")
+	errRecipientIsSecretKey = errors.New(
+		"an age secret key was given where a public key (age1...) belongs")
+	errRecipientNotX25519 = errors.New(
+		"not a valid recipient; only X25519 age1... public keys are supported")
 	errNoSnapshots = errors.New(
 		"at least one snapshot must be configured (see config.example.yml)")
 	errSnapshotNoPaths   = errors.New("snapshot must have at least one path")
 	errChunkSizeTooSmall = errors.New("chunk_size must be at least 1MB")
-	errBlobSizeTooSmall  = errors.New("blob_size_limit must be at least chunk_size")
+	errBlobSizeTooSmall  = errors.New(
-	errBadCompression    = errors.New("compression_level must be between 1 and 19")
+		"blob_size_limit must be at least the largest chunk the chunker can " +
-	errBadStorageScheme  = errors.New(
+			"emit (chunk_size times the FastCDC size spread)")
+	errBadCompression   = errors.New("compression_level must be between 1 and 19")
+	errBadStorageScheme = errors.New(
 		"storage_url must start with s3://, file://, or rclone://")
 	errStorageNotConfigured = errors.New(
 		"storage not configured; set storage_url or provide s3.endpoint + " +
@@ -121,6 +135,26 @@ func (c *Config) SnapshotNames() []string {
 	return names
 }
 
+// Names of the two places the age secret key can be configured, used by
+// AgeSecretKeySourceName for error messages that must not echo the value.
+//
+//nolint:gosec // G101: these are the names of the config sources, not a key
+const (
+	ageSecretKeySourceEnv    = "VAULTIK_AGE_SECRET_KEY"
+	ageSecretKeySourceConfig = "age_secret_key"
+)
+
+// AgeSecretKeySourceName returns the human name of where AgeSecretKey was
+// configured. A Config built directly (as in tests) has no recorded
+// source, so it reports the config-file field name.
+func (c *Config) AgeSecretKeySourceName() string {
+	if c.AgeSecretKeySource != "" {
+		return c.AgeSecretKeySource
+	}
+
+	return ageSecretKeySourceConfig
+}
+
 // Config represents the application configuration for Vaultik.
 // It defines all settings for backup operations, including source directories,
 // encryption recipients, storage configuration, and performance tuning parameters.
@@ -130,8 +164,13 @@ func (c *Config) SnapshotNames() []string {
 type Config struct {
 	AgeRecipients []string `yaml:"age_recipients"`
 	AgeSecretKey  string   `yaml:"age_secret_key"`
-	BlobSizeLimit Size     `yaml:"blob_size_limit"`
+	// AgeSecretKeySource names where AgeSecretKey was configured
-	ChunkSize     Size     `yaml:"chunk_size"`
+	// ("VAULTIK_AGE_SECRET_KEY" or "age_secret_key") so a later parse
+	// failure can name the source without echoing the secret value. It is
+	// set by Load and never read from or written to the config file.
+	AgeSecretKeySource string `yaml:"-"`
+	BlobSizeLimit      Size   `yaml:"blob_size_limit"`
+	ChunkSize          Size   `yaml:"chunk_size"`
 	// Exclude holds global excludes applied to all snapshots.
 	Exclude          []string                  `yaml:"exclude"`
 	Hostname         string                    `yaml:"hostname"`
@@ -162,8 +201,10 @@ type S3Config struct {
 	AccessKeyID     string `yaml:"access_key_id"`
 	SecretAccessKey string `yaml:"secret_access_key"`
 	Region          string `yaml:"region"`
-	UseSSL          bool   `yaml:"use_ssl"`
+	// UseSSL selects HTTPS for a scheme-less endpoint. Omitted (nil) means
-	PartSize        Size   `yaml:"part_size"`
+	// the default, TLS; set it to false only to force plain HTTP.
+	UseSSL   *bool `yaml:"use_ssl"`
+	PartSize Size  `yaml:"part_size"`
 }
 
 // Path wraps the config file path for fx dependency injection.
@@ -238,10 +279,7 @@ func Load(path string) (*Config, error) {
 		cfg.IndexPath = expandTilde(envIndexPath)
 	}
 
-	// Check for environment variable override for AgeSecretKey
+	cfg.setAgeSecretKey()
-	if envAgeSecretKey := os.Getenv("VAULTIK_AGE_SECRET_KEY"); envAgeSecretKey != "" {
-		cfg.AgeSecretKey = extractAgeSecretKey(envAgeSecretKey)
-	}
 
 	// Get hostname if not set
 	if cfg.Hostname == "" {
@@ -285,18 +323,30 @@ func Load(path string) (*Config, error) {
 
 // Validate checks if the configuration is valid and complete.
 // It ensures all required fields are present and have valid values:
-// - At least one age recipient must be specified
+//   - At least one age recipient must be specified, and every recipient must
-// - At least one snapshot must be configured with at least one path
+//     parse as an X25519 age1... public key (so a bad entry fails at load, not
-// - Storage must be configured (either storage_url or s3.* fields)
+//     mid-backup); errors name the position, never the value
-// - Chunk size must be at least 1MB
+//   - At least one snapshot must be configured with at least one path
-// - Blob size limit must be at least the chunk size
+//   - Storage must be configured (either storage_url or s3.* fields)
-// - Compression level must be between 1 and 19
+//   - Chunk size must be at least 1MB
+//   - Blob size limit must be at least the largest chunk the chunker can emit
+//     (chunk_size times chunker.ChunkSizeSpread), so a single-chunk blob never
+//     exceeds the configured limit
+//   - Compression level must be between 1 and 19
+//
 // Returns an error describing the first validation failure encountered.
 func (c *Config) Validate() error {
 	if len(c.AgeRecipients) == 0 {
 		return errNoAgeRecipients
 	}
 
+	for i, recipient := range c.AgeRecipients {
+		err := validateAgeRecipient(recipient)
+		if err != nil {
+			return fmt.Errorf("age_recipients[%d]: %w", i, err)
+		}
+	}
+
 	if len(c.Snapshots) == 0 {
 		return errNoSnapshots
 	}
@@ -317,8 +367,13 @@ func (c *Config) Validate() error {
 		return errChunkSizeTooSmall
 	}
 
-	if c.BlobSizeLimit.Int64() < c.ChunkSize.Int64() {
+	// The chunker can emit chunks up to chunk_size * ChunkSizeSpread, and the
-		return errBlobSizeTooSmall
+	// packer places a single such chunk into an otherwise empty blob. A limit
+	// below that bound would let a blob exceed it, so reject it.
+	largestChunk := c.ChunkSize.Int64() * chunker.ChunkSizeSpread
+	if c.BlobSizeLimit.Int64() < largestChunk {
+		return fmt.Errorf("%w: need at least %d bytes",
+			errBlobSizeTooSmall, largestChunk)
 	}
 
 	if c.CompressionLevel < minCompressionLevel ||
@@ -329,6 +384,38 @@ func (c *Config) Validate() error {
 	return nil
 }
 
+// validateAgeRecipient parses one age_recipients entry with the age library
+// and returns a value-free error on failure. A recipient string can be
+// sensitive (an operator may paste a secret key by mistake), so neither the
+// entry nor age's own error (which quotes its input) is ever included.
+func validateAgeRecipient(recipient string) error {
+	if strings.HasPrefix(strings.ToUpper(recipient), secretKeyPrefix) {
+		return errRecipientIsSecretKey
+	}
+
+	_, err := age.ParseX25519Recipient(recipient)
+	if err != nil {
+		return errRecipientNotX25519
+	}
+
+	return nil
+}
+
+// setAgeSecretKey records the age secret key and where it came from. The
+// value is stored raw and parsed only where decryption happens
+// (internal/vaultik), so backup, list and prune keep working whatever the
+// field holds. The environment variable overrides the config-file field.
+func (c *Config) setAgeSecretKey() {
+	if c.AgeSecretKey != "" {
+		c.AgeSecretKeySource = ageSecretKeySourceConfig
+	}
+
+	if env := os.Getenv("VAULTIK_AGE_SECRET_KEY"); env != "" {
+		c.AgeSecretKey = env
+		c.AgeSecretKeySource = ageSecretKeySourceEnv
+	}
+}
+
 // validateStorage validates storage configuration.
 // If StorageURL is set, it takes precedence. S3 URLs require credentials.
 // File URLs don't require any S3 configuration.
@@ -385,22 +472,6 @@ func (c *Config) validateStorageURL() error {
 	}
 }
 
-// extractAgeSecretKey extracts the AGE-SECRET-KEY from the input using
-// the age library's parser, which handles comments and whitespace.
-func extractAgeSecretKey(input string) string {
-	identities, err := age.ParseIdentities(strings.NewReader(input))
-	if err != nil || len(identities) == 0 {
-		// Fall back to trimmed input if parsing fails
-		return strings.TrimSpace(input)
-	}
-	// Return the string representation of the first identity
-	if id, ok := identities[0].(*age.X25519Identity); ok {
-		return id.String()
-	}
-
-	return strings.TrimSpace(input)
-}
-
 // Module exports the config module for fx dependency injection.
 // It provides the Config type to other modules in the application.
 //

internal/config/config_test.go

@@ -1,9 +1,13 @@
-package config //nolint:testpackage // exercises unexported extractAgeSecretKey
+package config //nolint:testpackage // exercises unexported source constants
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
+
+	"sneak.berlin/go/vaultik/internal/chunker"
 )
 
 const (
@@ -83,6 +87,48 @@ func TestConfigLoad(t *testing.T) {
 	}
 }
 
+// TestExampleConfigIsScrubbedAndLoads checks that the shipped
+// config.example.yml carries only neutral placeholders (no real credentials,
+// private addresses, or internal host names) and still parses.
+func TestExampleConfigIsScrubbedAndLoads(t *testing.T) {
+	t.Parallel()
+
+	examplePath := filepath.Join("..", "..", "config.example.yml")
+
+	cfg, err := Load(examplePath)
+	if err != nil {
+		t.Fatalf("Failed to load config.example.yml: %v", err)
+	}
+
+	if cfg.StorageURL != "rclone://myremote/path/to/backups" {
+		t.Errorf("Expected neutral storage_url, got '%s'", cfg.StorageURL)
+	}
+
+	//nolint:gosec // G304: examplePath is a fixed in-repo path, not user input
+	raw, err := os.ReadFile(examplePath)
+	if err != nil {
+		t.Fatalf("Failed to read config.example.yml: %v", err)
+	}
+
+	text := string(raw)
+
+	wantSubstrings := []string{
+		"YOUR_ACCESS_KEY",
+		"YOUR_SECRET_KEY",
+		"endpoint: https://",
+	}
+	for _, want := range wantSubstrings {
+		if !strings.Contains(text, want) {
+			t.Errorf("Expected config.example.yml to contain %q", want)
+		}
+	}
+
+	// A raw "http://" scheme would mean a plaintext, likely private endpoint.
+	if strings.Contains(text, "http://") {
+		t.Error("config.example.yml should not contain an http:// endpoint")
+	}
+}
+
 // TestConfigFromEnv tests loading config path from environment variable
 func TestConfigFromEnv(t *testing.T) {
 	t.Parallel()
@@ -101,53 +147,57 @@ func TestConfigFromEnv(t *testing.T) {
 	}
 }
 
-// TestExtractAgeSecretKey tests extraction of AGE-SECRET-KEY from various inputs
+// TestValidateBlobSizeLimit checks the blob_size_limit boundary: it must be at
-func TestExtractAgeSecretKey(t *testing.T) {
+// least the largest chunk the chunker can emit (chunk_size times
+// chunker.ChunkSizeSpread), because the packer places a single such chunk into
+// an otherwise empty blob. A limit between chunk_size and that bound is rejected.
+func TestValidateBlobSizeLimit(t *testing.T) {
 	t.Parallel()
 
+	const chunkSize = Size(10 * 1024 * 1024) // 10MB
+
+	largestChunk := chunkSize.Int64() * chunker.ChunkSizeSpread
+
+	newConfig := func(blobLimit Size) *Config {
+		return &Config{
+			AgeRecipients:    []string{testSneakAgePublicKey},
+			Snapshots:        map[string]SnapshotConfig{"test": {Paths: []string{"/tmp/src"}}},
+			StorageURL:       "file:///tmp/vaultik-test-store",
+			ChunkSize:        chunkSize,
+			BlobSizeLimit:    blobLimit,
+			CompressionLevel: 3,
+		}
+	}
+
 	tests := []struct {
-		name     string
+		name      string
-		input    string
+		blobLimit Size
-		expected string
+		wantErr   bool
 	}{
 		{
-			name:     "plain key",
+			name:      "at chunk_size but below largest chunk is rejected",
-			input:    testIntegrationAgePrivateKey,
+			blobLimit: chunkSize,
-			expected: testIntegrationAgePrivateKey,
+			wantErr:   true,
 		},
 		{
-			name:     "key with trailing newline",
+			name:      "between chunk_size and largest chunk is rejected",
-			input:    testIntegrationAgePrivateKey + "\n",
+			blobLimit: Size(chunkSize.Int64() * 2),
-			expected: testIntegrationAgePrivateKey,
+			wantErr:   true,
 		},
 		{
-			name: "full age-keygen output",
+			name:      "one byte below largest chunk is rejected",
-			input: "# created: 2025-01-14T12:00:00Z\n" +
+			blobLimit: Size(largestChunk - 1),
-				"# public key: " + testIntegrationAgePublicKey + "\n" +
+			wantErr:   true,
-				testIntegrationAgePrivateKey + "\n",
-			expected: testIntegrationAgePrivateKey,
 		},
 		{
-			name: "age-keygen output with extra blank lines",
+			name:      "exactly at largest chunk is accepted",
-			input: "# created: 2025-01-14T12:00:00Z\n" +
+			blobLimit: Size(largestChunk),
-				"# public key: " + testIntegrationAgePublicKey + "\n\n" +
+			wantErr:   false,
-				testIntegrationAgePrivateKey + "\n\n",
-			expected: testIntegrationAgePrivateKey,
 		},
 		{
-			name:     "key with leading whitespace",
+			name:      "above largest chunk is accepted",
-			input:    "  " + testIntegrationAgePrivateKey + "  ",
+			blobLimit: Size(largestChunk * 100),
-			expected: testIntegrationAgePrivateKey,
+			wantErr:   false,
-		},
-		{
-			name:     "empty input",
-			input:    "",
-			expected: "",
-		},
-		{
-			name:     "only comments",
-			input:    "# this is a comment\n# another comment",
-			expected: "# this is a comment\n# another comment",
 		},
 	}
 
@@ -155,10 +205,134 @@ func TestExtractAgeSecretKey(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			result := extractAgeSecretKey(tt.input)
+			err := newConfig(tt.blobLimit).Validate()
-			if result != tt.expected {
+			if tt.wantErr {
-				t.Errorf("extractAgeSecretKey(%q) = %q, want %q",
+				if !errors.Is(err, errBlobSizeTooSmall) {
-					tt.input, result, tt.expected)
+					t.Fatalf("Validate() error = %v, want errBlobSizeTooSmall", err)
+				}
+
+				return
+			}
+
+			if err != nil {
+				t.Fatalf("Validate() unexpected error: %v", err)
+			}
+		})
+	}
+}
+
+// TestValidateAgeRecipients checks that recipients are parsed at config load
+// (a bad entry fails immediately, not mid-backup) and that no invalid entry —
+// least of all a pasted secret key — is echoed in the error.
+func TestValidateAgeRecipients(t *testing.T) {
+	t.Parallel()
+
+	baseConfig := func(recipients []string) *Config {
+		return &Config{
+			AgeRecipients:    recipients,
+			Snapshots:        map[string]SnapshotConfig{"test": {Paths: []string{"/tmp/src"}}},
+			StorageURL:       "file:///tmp/vaultik-test-store",
+			ChunkSize:        Size(10 * 1024 * 1024),
+			BlobSizeLimit:    Size(10 * 1024 * 1024 * 1024),
+			CompressionLevel: 3,
+		}
+	}
+
+	tests := []struct {
+		name       string
+		recipients []string
+		wantErr    bool
+	}{
+		{
+			name:       "config init placeholder is rejected",
+			recipients: []string{"age1REPLACE_WITH_YOUR_PUBLIC_KEY"},
+			wantErr:    true,
+		},
+		{
+			name:       "ssh-ed25519 recipient is rejected",
+			recipients: []string{"ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIexamplekeydata"},
+			wantErr:    true,
+		},
+		{
+			name:       "truncated age1 string is rejected",
+			recipients: []string{"age1short"},
+			wantErr:    true,
+		},
+		{
+			name:       "secret key passed as recipient is rejected",
+			recipients: []string{testIntegrationAgePrivateKey},
+			wantErr:    true,
+		},
+		{
+			name:       "two valid recipients are accepted",
+			recipients: []string{testSneakAgePublicKey, testIntegrationAgePublicKey},
+			wantErr:    false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := baseConfig(tt.recipients).Validate()
+			if !tt.wantErr {
+				if err != nil {
+					t.Fatalf("Validate() unexpected error: %v", err)
+				}
+
+				return
+			}
+
+			if err == nil {
+				t.Fatal("Validate() returned nil, want error")
+			}
+
+			// The entry itself must never appear in the error, since a
+			// recipient string can be a secret key.
+			for _, recipient := range tt.recipients {
+				if strings.Contains(err.Error(), recipient) {
+					t.Fatalf("Validate() error echoed the recipient value: %v", err)
+				}
+			}
+		})
+	}
+}
+
+// TestAgeSecretKeySourceName checks the name reported for the configured
+// age secret key: the recorded source when Load set one, and the
+// config-file field name for a Config built directly (as in tests).
+func TestAgeSecretKeySourceName(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name   string
+		source string
+		want   string
+	}{
+		{
+			name:   "unset defaults to config field",
+			source: "",
+			want:   ageSecretKeySourceConfig,
+		},
+		{
+			name:   "environment source",
+			source: ageSecretKeySourceEnv,
+			want:   ageSecretKeySourceEnv,
+		},
+		{
+			name:   "config-file source",
+			source: ageSecretKeySourceConfig,
+			want:   ageSecretKeySourceConfig,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			cfg := &Config{AgeSecretKeySource: tt.source}
+			if got := cfg.AgeSecretKeySourceName(); got != tt.want {
+				t.Errorf("AgeSecretKeySourceName() = %q, want %q", got, tt.want)
 			}
 		})
 	}

internal/crypto/encryption.go

@@ -1,224 +0,0 @@
-// Package crypto provides thread-safe age encryption and decryption
-// helpers used to protect blob and metadata content.
-package crypto //nolint:revive,nolintlint // stdlib crypto unused; see #76
-
-import (
-	"bytes"
-	"errors"
-	"fmt"
-	"io"
-	"sync"
-
-	"filippo.io/age"
-	"go.uber.org/fx"
-)
-
-// ErrNoRecipients is returned when an encryptor is created or updated
-// without any recipient public keys.
-var ErrNoRecipients = errors.New("at least one recipient is required")
-
-// Encryptor provides thread-safe encryption using the age encryption library.
-// It supports encrypting data for multiple recipients simultaneously, allowing
-// any of the corresponding private keys to decrypt the data. This is useful
-// for backup scenarios where multiple parties should be able to decrypt the data.
-type Encryptor struct {
-	recipients []age.Recipient
-	mu         sync.RWMutex
-}
-
-// NewEncryptor creates a new encryptor with the given age public keys.
-// Each public key should be a valid age X25519 recipient string (e.g., "age1...")
-// At least one recipient must be provided. Returns an error if any of the
-// public keys are invalid or if no recipients are specified.
-func NewEncryptor(publicKeys []string) (*Encryptor, error) {
-	if len(publicKeys) == 0 {
-		return nil, ErrNoRecipients
-	}
-
-	recipients := make([]age.Recipient, 0, len(publicKeys))
-	for _, key := range publicKeys {
-		recipient, err := age.ParseX25519Recipient(key)
-		if err != nil {
-			return nil, fmt.Errorf("parsing age recipient %s: %w", key, err)
-		}
-
-		recipients = append(recipients, recipient)
-	}
-
-	return &Encryptor{
-		recipients: recipients,
-	}, nil
-}
-
-// Encrypt encrypts data using age encryption for all configured recipients.
-// The encrypted data can be decrypted by any of the corresponding private keys.
-// This method is suitable for small to medium amounts of data that fit in memory.
-// For large data streams, use EncryptStream or EncryptWriter instead.
-func (e *Encryptor) Encrypt(data []byte) ([]byte, error) {
-	e.mu.RLock()
-	recipients := e.recipients
-	e.mu.RUnlock()
-
-	var buf bytes.Buffer
-
-	// Create encrypted writer for all recipients
-	w, err := age.Encrypt(&buf, recipients...)
-	if err != nil {
-		return nil, fmt.Errorf("creating encrypted writer: %w", err)
-	}
-
-	// Write data
-	_, err = w.Write(data)
-	if err != nil {
-		return nil, fmt.Errorf("writing encrypted data: %w", err)
-	}
-
-	// Close to flush
-	err = w.Close()
-	if err != nil {
-		return nil, fmt.Errorf("closing encrypted writer: %w", err)
-	}
-
-	return buf.Bytes(), nil
-}
-
-// EncryptStream encrypts data from reader to writer using age encryption.
-// This method is suitable for encrypting large files or streams as it processes
-// data in a streaming fashion without loading everything into memory.
-// The encrypted data is written directly to the destination writer.
-func (e *Encryptor) EncryptStream(dst io.Writer, src io.Reader) error {
-	e.mu.RLock()
-	recipients := e.recipients
-	e.mu.RUnlock()
-
-	// Create encrypted writer for all recipients
-	w, err := age.Encrypt(dst, recipients...)
-	if err != nil {
-		return fmt.Errorf("creating encrypted writer: %w", err)
-	}
-
-	// Copy data
-	_, err = io.Copy(w, src)
-	if err != nil {
-		return fmt.Errorf("copying encrypted data: %w", err)
-	}
-
-	// Close to flush
-	err = w.Close()
-	if err != nil {
-		return fmt.Errorf("closing encrypted writer: %w", err)
-	}
-
-	return nil
-}
-
-// EncryptWriter creates a writer that encrypts data written to it.
-// All data written to the returned WriteCloser will be encrypted and written
-// to the destination writer. The caller must call Close() on the returned
-// writer to ensure all encrypted data is properly flushed and finalized.
-// This is useful for integrating encryption into existing writer-based pipelines.
-func (e *Encryptor) EncryptWriter(dst io.Writer) (io.WriteCloser, error) {
-	e.mu.RLock()
-	recipients := e.recipients
-	e.mu.RUnlock()
-
-	// Create encrypted writer for all recipients
-	w, err := age.Encrypt(dst, recipients...)
-	if err != nil {
-		return nil, fmt.Errorf("creating encrypted writer: %w", err)
-	}
-
-	return w, nil
-}
-
-// UpdateRecipients updates the recipients for future encryption operations.
-// This method is thread-safe and can be called while other encryption operations
-// are in progress. Existing encryption operations will continue with the old
-// recipients. At least one recipient must be provided. Returns an error if any
-// of the public keys are invalid or if no recipients are specified.
-func (e *Encryptor) UpdateRecipients(publicKeys []string) error {
-	if len(publicKeys) == 0 {
-		return ErrNoRecipients
-	}
-
-	recipients := make([]age.Recipient, 0, len(publicKeys))
-	for _, key := range publicKeys {
-		recipient, err := age.ParseX25519Recipient(key)
-		if err != nil {
-			return fmt.Errorf("parsing age recipient %s: %w", key, err)
-		}
-
-		recipients = append(recipients, recipient)
-	}
-
-	e.mu.Lock()
-	e.recipients = recipients
-	e.mu.Unlock()
-
-	return nil
-}
-
-// Decryptor provides thread-safe decryption using the age encryption library.
-// It uses a private key to decrypt data that was encrypted for the corresponding
-// public key.
-type Decryptor struct {
-	identity age.Identity
-	mu       sync.RWMutex
-}
-
-// NewDecryptor creates a new decryptor with the given age private key.
-// The private key should be a valid age X25519 identity string.
-// Returns an error if the private key is invalid.
-func NewDecryptor(privateKey string) (*Decryptor, error) {
-	identity, err := age.ParseX25519Identity(privateKey)
-	if err != nil {
-		return nil, fmt.Errorf("parsing age identity: %w", err)
-	}
-
-	return &Decryptor{
-		identity: identity,
-	}, nil
-}
-
-// Decrypt decrypts data using age decryption.
-// This method is suitable for small to medium amounts of data that fit in memory.
-// For large data streams, use DecryptStream instead.
-func (d *Decryptor) Decrypt(data []byte) ([]byte, error) {
-	d.mu.RLock()
-	identity := d.identity
-	d.mu.RUnlock()
-
-	r, err := age.Decrypt(bytes.NewReader(data), identity)
-	if err != nil {
-		return nil, fmt.Errorf("creating decrypted reader: %w", err)
-	}
-
-	decrypted, err := io.ReadAll(r)
-	if err != nil {
-		return nil, fmt.Errorf("reading decrypted data: %w", err)
-	}
-
-	return decrypted, nil
-}
-
-// DecryptStream returns a reader that decrypts data from the provided reader.
-// This method is suitable for decrypting large files or streams as it processes
-// data in a streaming fashion without loading everything into memory.
-// The caller should close the input reader when done.
-func (d *Decryptor) DecryptStream(src io.Reader) (io.Reader, error) {
-	d.mu.RLock()
-	identity := d.identity
-	d.mu.RUnlock()
-
-	r, err := age.Decrypt(src, identity)
-	if err != nil {
-		return nil, fmt.Errorf("creating decrypted reader: %w", err)
-	}
-
-	return r, nil
-}
-
-// Module exports the crypto module for fx dependency injection.
-//
-//nolint:gochecknoglobals // fx module definitions are package globals
-var Module = fx.Module("crypto")

internal/crypto/encryption_test.go

@@ -1,178 +0,0 @@
-package crypto_test
-
-import (
-	"bytes"
-	"testing"
-
-	"filippo.io/age"
-	"sneak.berlin/go/vaultik/internal/crypto"
-)
-
-func TestEncryptor(t *testing.T) {
-	t.Parallel()
-
-	// Generate a test key pair
-	identity, err := age.GenerateX25519Identity()
-	if err != nil {
-		t.Fatalf("failed to generate identity: %v", err)
-	}
-
-	publicKey := identity.Recipient().String()
-
-	// Create encryptor
-	enc, err := crypto.NewEncryptor([]string{publicKey})
-	if err != nil {
-		t.Fatalf("failed to create encryptor: %v", err)
-	}
-
-	// Test data
-	plaintext := []byte("Hello, World! This is a test message.")
-
-	// Encrypt
-	ciphertext, err := enc.Encrypt(plaintext)
-	if err != nil {
-		t.Fatalf("failed to encrypt: %v", err)
-	}
-
-	// Verify it's actually encrypted (should be larger and different)
-	if bytes.Equal(plaintext, ciphertext) {
-		t.Error("ciphertext equals plaintext")
-	}
-
-	// Decrypt to verify
-	r, err := age.Decrypt(bytes.NewReader(ciphertext), identity)
-	if err != nil {
-		t.Fatalf("failed to decrypt: %v", err)
-	}
-
-	var decrypted bytes.Buffer
-
-	_, err = decrypted.ReadFrom(r)
-	if err != nil {
-		t.Fatalf("failed to read decrypted data: %v", err)
-	}
-
-	if !bytes.Equal(plaintext, decrypted.Bytes()) {
-		t.Error("decrypted data doesn't match original")
-	}
-}
-
-func TestEncryptorMultipleRecipients(t *testing.T) {
-	t.Parallel()
-
-	// Generate three test key pairs
-	identity1, err := age.GenerateX25519Identity()
-	if err != nil {
-		t.Fatalf("failed to generate identity1: %v", err)
-	}
-
-	identity2, err := age.GenerateX25519Identity()
-	if err != nil {
-		t.Fatalf("failed to generate identity2: %v", err)
-	}
-
-	identity3, err := age.GenerateX25519Identity()
-	if err != nil {
-		t.Fatalf("failed to generate identity3: %v", err)
-	}
-
-	publicKeys := []string{
-		identity1.Recipient().String(),
-		identity2.Recipient().String(),
-		identity3.Recipient().String(),
-	}
-
-	// Create encryptor with multiple recipients
-	enc, err := crypto.NewEncryptor(publicKeys)
-	if err != nil {
-		t.Fatalf("failed to create encryptor: %v", err)
-	}
-
-	// Test data
-	plaintext := []byte("Secret message for multiple recipients")
-
-	// Encrypt
-	ciphertext, err := enc.Encrypt(plaintext)
-	if err != nil {
-		t.Fatalf("failed to encrypt: %v", err)
-	}
-
-	// Verify each recipient can decrypt
-	identities := []age.Identity{identity1, identity2, identity3}
-	for i, identity := range identities {
-		r, err := age.Decrypt(bytes.NewReader(ciphertext), identity)
-		if err != nil {
-			t.Fatalf("recipient %d failed to decrypt: %v", i+1, err)
-		}
-
-		var decrypted bytes.Buffer
-
-		_, err = decrypted.ReadFrom(r)
-		if err != nil {
-			t.Fatalf("recipient %d failed to read decrypted data: %v", i+1, err)
-		}
-
-		if !bytes.Equal(plaintext, decrypted.Bytes()) {
-			t.Errorf("recipient %d: decrypted data doesn't match original", i+1)
-		}
-	}
-}
-
-func TestEncryptorUpdateRecipients(t *testing.T) {
-	t.Parallel()
-
-	// Generate two identities
-	identity1, _ := age.GenerateX25519Identity()
-	identity2, _ := age.GenerateX25519Identity()
-
-	publicKey1 := identity1.Recipient().String()
-	publicKey2 := identity2.Recipient().String()
-
-	// Create encryptor with first key
-	enc, err := crypto.NewEncryptor([]string{publicKey1})
-	if err != nil {
-		t.Fatalf("failed to create encryptor: %v", err)
-	}
-
-	// Encrypt with first key
-	plaintext := []byte("test data")
-
-	ciphertext1, err := enc.Encrypt(plaintext)
-	if err != nil {
-		t.Fatalf("failed to encrypt: %v", err)
-	}
-
-	// Update to second key
-	err = enc.UpdateRecipients([]string{publicKey2})
-	if err != nil {
-		t.Fatalf("failed to update recipients: %v", err)
-	}
-
-	// Encrypt with second key
-	ciphertext2, err := enc.Encrypt(plaintext)
-	if err != nil {
-		t.Fatalf("failed to encrypt: %v", err)
-	}
-
-	// First ciphertext should only decrypt with first identity
-	_, err = age.Decrypt(bytes.NewReader(ciphertext1), identity1)
-	if err != nil {
-		t.Error("failed to decrypt with identity1")
-	}
-
-	_, err = age.Decrypt(bytes.NewReader(ciphertext1), identity2)
-	if err == nil {
-		t.Error("should not decrypt with identity2")
-	}
-
-	// Second ciphertext should only decrypt with second identity
-	_, err = age.Decrypt(bytes.NewReader(ciphertext2), identity2)
-	if err != nil {
-		t.Error("failed to decrypt with identity2")
-	}
-
-	_, err = age.Decrypt(bytes.NewReader(ciphertext2), identity1)
-	if err == nil {
-		t.Error("should not decrypt with identity1")
-	}
-}

internal/database/blobs.go

@@ -208,6 +208,30 @@ func (r *BlobRepository) DeleteOrphaned(ctx context.Context) error {
 	return nil
 }
 
+// DeleteUnuploaded deletes blob rows whose upload never completed
+// (uploaded_ts IS NULL) and returns how many were removed. Their
+// blob_chunks rows are removed by the ON DELETE CASCADE foreign key.
+// A blob is only ever attached to a snapshot once its upload has been
+// recorded, so an un-uploaded blob is never referenced by a completed
+// snapshot: dropping it discards chunk rows that point at data which
+// was never stored remotely, so the affected content is re-chunked and
+// re-uploaded on the next run.
+func (r *BlobRepository) DeleteUnuploaded(ctx context.Context) (int64, error) {
+	query := `DELETE FROM blobs WHERE uploaded_ts IS NULL`
+
+	result, err := r.db.ExecWithLog(ctx, query)
+	if err != nil {
+		return 0, fmt.Errorf("deleting un-uploaded blobs: %w", err)
+	}
+
+	rowsAffected, _ := result.RowsAffected()
+	if rowsAffected > 0 {
+		log.Debug("Deleted un-uploaded blobs", "count", rowsAffected)
+	}
+
+	return rowsAffected, nil
+}
+
 // getOne fetches a single blob row matched on the given column, or
 // (nil, nil) when no row matches.
 func (r *BlobRepository) getOne(

internal/database/chunks_ext.go

@@ -7,12 +7,32 @@ import (
 
 // List returns every chunk in the index, ordered by chunk hash.
 func (r *ChunkRepository) List(ctx context.Context) ([]*Chunk, error) {
-	query := `
+	return r.list(ctx, `
 		SELECT chunk_hash, size
 		FROM chunks
 		ORDER BY chunk_hash
-	`
+	`)
+}
 
+// ListInUploadedBlobs returns the chunks that are stored in a blob whose
+// upload has completed (uploaded_ts set), ordered by chunk hash. These
+// are the only chunks a backup may safely deduplicate against: a chunk
+// recorded solely in a blob that was never uploaded refers to data that
+// is not in remote storage, so trusting it would silently drop that data
+// from later snapshots.
+func (r *ChunkRepository) ListInUploadedBlobs(ctx context.Context) ([]*Chunk, error) {
+	return r.list(ctx, `
+		SELECT DISTINCT c.chunk_hash, c.size
+		FROM chunks c
+		JOIN blob_chunks bc ON c.chunk_hash = bc.chunk_hash
+		JOIN blobs b ON bc.blob_id = b.id
+		WHERE b.uploaded_ts IS NOT NULL
+		ORDER BY c.chunk_hash
+	`)
+}
+
+// list runs a chunk-selecting query and scans the (chunk_hash, size) rows.
+func (r *ChunkRepository) list(ctx context.Context, query string) ([]*Chunk, error) {
 	rows, err := r.db.conn.QueryContext(ctx, query)
 	if err != nil {
 		return nil, fmt.Errorf("querying chunks: %w", err)

internal/database/database.go

@@ -17,6 +17,7 @@ import (
 	"embed"
 	"errors"
 	"fmt"
+	"net/url"
 	"os"
 	"path/filepath"
 	"sort"
@@ -219,6 +220,135 @@ func openWithRecovery(ctx context.Context, path string) (*DB, error) {
 	return db, nil
 }
 
+// errUntrustedSnapshotSchema is returned when a downloaded snapshot
+// database carries schema objects the real schema never defines, or is
+// missing a table the restore and deep-verify queries read.
+var errUntrustedSnapshotSchema = errors.New(
+	"downloaded snapshot database has an untrusted schema")
+
+// snapshotReadOnlyDSN builds the driver DSN that opens a materialized
+// snapshot database file read-only. mode=ro opens the file read-only at
+// the OS level, query_only rejects any write the engine is asked to make,
+// and trusted_schema=OFF refuses to run application code named in the
+// schema. The file: URI form is required for the driver to honour the
+// mode parameter.
+func snapshotReadOnlyDSN(path string) string {
+	u := url.URL{
+		Scheme:   "file",
+		Path:     path,
+		RawQuery: "mode=ro&_pragma=query_only(true)&_pragma=trusted_schema(false)",
+	}
+
+	return u.String()
+}
+
+// OpenReadOnly opens an already-materialized SQLite file for read-only
+// querying of a snapshot database downloaded from the store, used by
+// restore and deep verify. Unlike New it never applies schema migrations
+// and never writes: the connection is opened read-only with query_only
+// and trusted_schema=OFF. It refuses any file whose schema carries a
+// trigger, view or virtual table, or lacks an expected table, so a forged
+// file cannot redefine what the restore queries return. The caller owns
+// the file and must remove it.
+func OpenReadOnly(ctx context.Context, path string) (*DB, error) {
+	conn, err := sql.Open("sqlite", snapshotReadOnlyDSN(path))
+	if err != nil {
+		return nil, fmt.Errorf("opening read-only database: %w", err)
+	}
+
+	configureConnPool(conn)
+
+	err = conn.PingContext(ctx)
+	if err != nil {
+		_ = conn.Close()
+
+		return nil, fmt.Errorf("opening read-only database: %w", err)
+	}
+
+	err = verifySnapshotSchema(ctx, conn)
+	if err != nil {
+		_ = conn.Close()
+
+		return nil, err
+	}
+
+	return &DB{conn: conn, path: path}, nil
+}
+
+// verifySnapshotSchema rejects a downloaded database whose schema is not
+// the plain table set the real schema defines. Any trigger, view or
+// virtual table, or a missing expected table, fails the open.
+func verifySnapshotSchema(ctx context.Context, conn *sql.DB) error {
+	// expectedSnapshotTables are the tables the restore and deep-verify
+	// queries read. A downloaded database missing any of them is not a
+	// genuine snapshot database and is refused.
+	expectedSnapshotTables := []string{
+		"blob_chunks",
+		"blobs",
+		"chunks",
+		"file_chunks",
+		"files",
+	}
+
+	rows, err := conn.QueryContext(
+		ctx, "SELECT type, name, sql FROM sqlite_master")
+	if err != nil {
+		return fmt.Errorf("reading snapshot schema: %w", err)
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	present := make(map[string]struct{})
+
+	for rows.Next() {
+		var objType, name string
+
+		var objSQL sql.NullString
+
+		err = rows.Scan(&objType, &name, &objSQL)
+		if err != nil {
+			return fmt.Errorf("reading snapshot schema: %w", err)
+		}
+
+		switch objType {
+		case "trigger", "view":
+			return fmt.Errorf(
+				"%w: unexpected %s %q", errUntrustedSnapshotSchema, objType, name)
+		case "table":
+			if isVirtualTableSQL(objSQL.String) {
+				return fmt.Errorf(
+					"%w: unexpected virtual table %q",
+					errUntrustedSnapshotSchema, name)
+			}
+
+			present[name] = struct{}{}
+		}
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return fmt.Errorf("reading snapshot schema: %w", err)
+	}
+
+	for _, table := range expectedSnapshotTables {
+		if _, ok := present[table]; !ok {
+			return fmt.Errorf(
+				"%w: missing table %q", errUntrustedSnapshotSchema, table)
+		}
+	}
+
+	return nil
+}
+
+// isVirtualTableSQL reports whether a sqlite_master row's SQL defines a
+// virtual table. Virtual tables are recorded with type 'table' but a
+// "CREATE VIRTUAL TABLE" definition and can run module code, so they are
+// refused alongside triggers and views.
+func isVirtualTableSQL(createSQL string) bool {
+	return strings.HasPrefix(
+		strings.ToUpper(strings.TrimSpace(createSQL)), "CREATE VIRTUAL TABLE")
+}
+
 // NewTestDB creates an in-memory SQLite database for testing purposes.
 // The database is automatically initialized with the schema and is ready
 // for use. Each call creates a new independent database instance.

internal/database/module.go

@@ -2,6 +2,7 @@ package database
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -15,6 +16,44 @@ import (
 // the index describes the backed-up file tree and must stay private.
 const indexDirPerm = 0o700
 
+// indexFilePerm restricts the index file to the owning user; it lists every
+// backed-up path and chunk hash and must stay private.
+const indexFilePerm = 0o600
+
+// ensureIndexFileMode makes the index file owner-only before the SQLite
+// driver opens it: it creates the file 0600 if absent, or chmods an existing
+// one to 0600. Doing this first matters because SQLite creates its -wal and
+// -shm side files with the mode of the main database file, so a private main
+// file yields private side files. The driver treats a zero-byte file as an
+// empty database, so pre-creating it here is safe.
+func ensureIndexFileMode(path string) error {
+	info, err := os.Stat(path)
+
+	switch {
+	case err == nil:
+		if info.Mode().Perm() == indexFilePerm {
+			return nil
+		}
+
+		err = os.Chmod(path, indexFilePerm)
+		if err != nil {
+			return fmt.Errorf("restricting index file permissions: %w", err)
+		}
+
+		return nil
+	case errors.Is(err, os.ErrNotExist):
+		//nolint:gosec // G304: the index path is operator-configured by design
+		f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, indexFilePerm)
+		if err != nil {
+			return fmt.Errorf("creating index file: %w", err)
+		}
+
+		return f.Close()
+	default:
+		return fmt.Errorf("checking index file: %w", err)
+	}
+}
+
 // Module provides database dependencies
 //
 //nolint:gochecknoglobals // fx module definitions are package globals by convention
@@ -34,6 +73,11 @@ func provideDatabase(lc fx.Lifecycle, cfg *config.Config) (*DB, error) {
 		return nil, fmt.Errorf("creating index directory: %w", err)
 	}
 
+	err = ensureIndexFileMode(cfg.IndexPath)
+	if err != nil {
+		return nil, err
+	}
+
 	db, err := New(context.Background(), cfg.IndexPath)
 	if err != nil {
 		return nil, fmt.Errorf("opening database: %w", err)

internal/database/module_internal_test.go

@@ -0,0 +1,100 @@
+package database
+
+import (
+	"os"
+	"path/filepath"
+	"syscall"
+	"testing"
+
+	"go.uber.org/fx/fxtest"
+	"sneak.berlin/go/vaultik/internal/config"
+)
+
+// TestProvideDatabaseFreshIndexMode verifies that provideDatabase creates a
+// missing index file owner-only (0600), even under a lenient 022 umask that
+// would otherwise leave a freshly created file world-readable.
+//
+//nolint:paralleltest // syscall.Umask is process-global; parallel tests would clash
+func TestProvideDatabaseFreshIndexMode(t *testing.T) {
+	restore := syscall.Umask(0o022)
+	defer syscall.Umask(restore)
+
+	indexPath := filepath.Join(t.TempDir(), "index.sqlite")
+
+	openIndex(t, indexPath)
+	assertPerm(t, indexPath, 0o600)
+}
+
+// TestProvideDatabaseExistingIndexMode verifies that provideDatabase tightens
+// an existing world-readable index (0644) in a group/other-readable directory
+// down to owner-only (0600).
+//
+//nolint:paralleltest // syscall.Umask is process-global; parallel tests would clash
+func TestProvideDatabaseExistingIndexMode(t *testing.T) {
+	restore := syscall.Umask(0o022)
+	defer syscall.Umask(restore)
+
+	dir := filepath.Join(t.TempDir(), "data")
+
+	//nolint:gosec // G301: the test intentionally uses a 0755 directory
+	err := os.MkdirAll(dir, 0o755)
+	if err != nil {
+		t.Fatalf("creating index directory: %v", err)
+	}
+
+	//nolint:gosec // G302: the test intentionally uses a 0755 directory
+	err = os.Chmod(dir, 0o755)
+	if err != nil {
+		t.Fatalf("relaxing index directory permissions: %v", err)
+	}
+
+	indexPath := filepath.Join(dir, "index.sqlite")
+
+	//nolint:gosec // G306: the test intentionally starts from a 0644 index
+	err = os.WriteFile(indexPath, nil, 0o644)
+	if err != nil {
+		t.Fatalf("creating pre-existing index: %v", err)
+	}
+
+	//nolint:gosec // G302: the test intentionally starts from a 0644 index
+	err = os.Chmod(indexPath, 0o644)
+	if err != nil {
+		t.Fatalf("relaxing pre-existing index permissions: %v", err)
+	}
+
+	openIndex(t, indexPath)
+	assertPerm(t, indexPath, 0o600)
+}
+
+// openIndex runs provideDatabase against indexPath and closes the resulting
+// database before returning.
+func openIndex(t *testing.T, indexPath string) {
+	t.Helper()
+
+	cfg := &config.Config{IndexPath: indexPath}
+
+	db, err := provideDatabase(fxtest.NewLifecycle(t), cfg)
+	if err != nil {
+		t.Fatalf("provideDatabase: %v", err)
+	}
+
+	err = db.Close()
+	if err != nil {
+		t.Fatalf("closing database: %v", err)
+	}
+}
+
+// assertPerm fails the test unless path has exactly the given permission bits.
+func assertPerm(t *testing.T, path string, want os.FileMode) {
+	t.Helper()
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat %s: %v", path, err)
+	}
+
+	got := info.Mode().Perm()
+	if got != want {
+		t.Fatalf("permissions of %s = %#o, want %#o", path, got, want)
+	}
+}

internal/database/read_only_test.go

@@ -0,0 +1,145 @@
+//nolint:testpackage // exercises unexported read-only open internals
+package database
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"path/filepath"
+	"testing"
+)
+
+// genuineSnapshotDB writes a real snapshot database (the full schema
+// applied) to a fresh file and returns its path.
+func genuineSnapshotDB(t *testing.T) string {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "snapshot.db")
+
+	db, err := New(context.Background(), path)
+	if err != nil {
+		t.Fatalf("creating snapshot database: %v", err)
+	}
+
+	err = db.Close()
+	if err != nil {
+		t.Fatalf("closing snapshot database: %v", err)
+	}
+
+	return path
+}
+
+// forgedDB creates an empty database file and runs the given statements
+// against it read-write, so a test can plant schema objects the real
+// schema never defines.
+func forgedDB(t *testing.T, stmts ...string) string {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "forged.db")
+
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		t.Fatalf("opening forged database: %v", err)
+	}
+
+	for _, stmt := range stmts {
+		_, err = db.ExecContext(context.Background(), stmt)
+		if err != nil {
+			t.Fatalf("executing %q: %v", stmt, err)
+		}
+	}
+
+	err = db.Close()
+	if err != nil {
+		t.Fatalf("closing forged database: %v", err)
+	}
+
+	return path
+}
+
+func TestOpenReadOnlyAcceptsGenuineSnapshot(t *testing.T) {
+	t.Parallel()
+
+	db, err := OpenReadOnly(context.Background(), genuineSnapshotDB(t))
+	if err != nil {
+		t.Fatalf("OpenReadOnly refused a genuine snapshot database: %v", err)
+	}
+
+	t.Cleanup(func() { _ = db.Close() })
+}
+
+func TestOpenReadOnlyRefusesWrites(t *testing.T) {
+	t.Parallel()
+
+	db, err := OpenReadOnly(context.Background(), genuineSnapshotDB(t))
+	if err != nil {
+		t.Fatalf("OpenReadOnly: %v", err)
+	}
+
+	t.Cleanup(func() { _ = db.Close() })
+
+	// A schema write depends on no table columns, so the only reason it
+	// can fail is that the database is open read-only.
+	_, err = db.Conn().ExecContext(context.Background(),
+		"CREATE TABLE probe_readonly (x)")
+	if err == nil {
+		t.Fatal("expected a write to a read-only snapshot database to fail")
+	}
+}
+
+func TestOpenReadOnlyRejectsView(t *testing.T) {
+	t.Parallel()
+
+	path := forgedDB(t, "CREATE VIEW files AS SELECT 1 AS path")
+
+	_, err := OpenReadOnly(context.Background(), path)
+	if !errors.Is(err, errUntrustedSnapshotSchema) {
+		t.Fatalf("expected a view named files to be refused, got %v", err)
+	}
+}
+
+func TestOpenReadOnlyRejectsTrigger(t *testing.T) {
+	t.Parallel()
+
+	path := forgedDB(t,
+		"CREATE TABLE files (path TEXT)",
+		"CREATE TRIGGER t AFTER INSERT ON files BEGIN SELECT 1; END")
+
+	_, err := OpenReadOnly(context.Background(), path)
+	if !errors.Is(err, errUntrustedSnapshotSchema) {
+		t.Fatalf("expected a trigger to be refused, got %v", err)
+	}
+}
+
+func TestOpenReadOnlyRejectsMissingTable(t *testing.T) {
+	t.Parallel()
+
+	// Only one of the expected tables is present.
+	path := forgedDB(t, "CREATE TABLE files (path TEXT)")
+
+	_, err := OpenReadOnly(context.Background(), path)
+	if !errors.Is(err, errUntrustedSnapshotSchema) {
+		t.Fatalf("expected a missing expected table to be refused, got %v", err)
+	}
+}
+
+func TestIsVirtualTableSQL(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		sql  string
+		want bool
+	}{
+		{"CREATE VIRTUAL TABLE t USING fts5(x)", true},
+		{"  create virtual table t using fts5(x)", true},
+		{"CREATE TABLE t (x)", false},
+		{"CREATE VIEW t AS SELECT 1", false},
+		{"", false},
+	}
+
+	for _, c := range cases {
+		if got := isVirtualTableSQL(c.sql); got != c.want {
+			t.Errorf("isVirtualTableSQL(%q) = %v, want %v", c.sql, got, c.want)
+		}
+	}
+}

internal/database/snapshots.go

@@ -11,6 +11,18 @@ import (
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
+// Sentinel errors for the single-snapshot invariant that an exported
+// per-snapshot metadata database must satisfy.
+var (
+	// ErrNoSnapshotInDatabase means the metadata database has no snapshot
+	// row at all.
+	ErrNoSnapshotInDatabase = errors.New("database contains no snapshot")
+	// ErrMultipleSnapshotsInDatabase means the metadata database holds
+	// more than the single snapshot an export is supposed to contain.
+	ErrMultipleSnapshotsInDatabase = errors.New(
+		"database contains more than one snapshot")
+)
+
 // SnapshotRepository provides access to the snapshots table and its
 // snapshot_files / snapshot_blobs association tables.
 type SnapshotRepository struct {
@@ -206,6 +218,48 @@ func (r *SnapshotRepository) GetByID(
 	return &snapshot, nil
 }
 
+// GetOnlySnapshot returns the sole snapshot in an exported per-snapshot
+// metadata database. The backup path writes each snapshot's database with
+// exactly one snapshot row (see cleanSnapshotDB), so restore and deep
+// verify expect exactly one. Zero rows return ErrNoSnapshotInDatabase and
+// more than one returns ErrMultipleSnapshotsInDatabase; callers treat
+// either as a failed identity check on the downloaded database.
+func (r *SnapshotRepository) GetOnlySnapshot(ctx context.Context) (*Snapshot, error) {
+	query := `
+		SELECT id, hostname, vaultik_version, vaultik_git_revision,
+			started_at, completed_at, file_count, chunk_count, blob_count,
+			total_size, blob_size, compression_ratio
+		FROM snapshots
+		LIMIT 2
+	`
+
+	rows, err := r.db.conn.QueryContext(ctx, query)
+	if err != nil {
+		return nil, fmt.Errorf("querying snapshots: %w", err)
+	}
+
+	defer func() {
+		err := rows.Close()
+		if err != nil {
+			Fatalf("failed to close rows: %v", err)
+		}
+	}()
+
+	snapshots, err := r.scanSnapshotRows(rows)
+	if err != nil {
+		return nil, err
+	}
+
+	switch len(snapshots) {
+	case 1:
+		return snapshots[0], nil
+	case 0:
+		return nil, ErrNoSnapshotInDatabase
+	default:
+		return nil, ErrMultipleSnapshotsInDatabase
+	}
+}
+
 // ListRecent returns up to limit snapshots, most recently started first.
 func (r *SnapshotRepository) ListRecent(
 	ctx context.Context, limit int,

internal/log/module.go

@@ -14,8 +14,18 @@ var Module = fx.Module("log",
 )
 
 // New creates a new logger configuration from provided options.
+//
+// JSON is intentionally not carried into Config: a command emitting a
+// JSON document on stdout must keep its stderr log level under
+// --verbose/--debug, so --json must not lower it (issue #112). JSON
+// silences the stdout UI in setupGlobals instead.
 func New(opts Options) Config {
-	return Config(opts)
+	return Config{
+		Verbose: opts.Verbose,
+		Debug:   opts.Debug,
+		Cron:    opts.Cron,
+		Quiet:   opts.Quiet,
+	}
 }
 
 // Options are provided by the CLI.
@@ -24,4 +34,8 @@ type Options struct {
 	Debug   bool
 	Cron    bool
 	Quiet   bool
+	// JSON marks a command whose stdout carries a machine-readable
+	// document. It silences the human UI on stdout (see setupGlobals),
+	// but unlike Quiet it leaves the stderr log level alone.
+	JSON bool
 }

internal/log/tty_escape_test.go

@@ -0,0 +1,39 @@
+package log_test
+
+import (
+	"bytes"
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+)
+
+// TestTTYHandlerEscapesControlCharacters logs a message and an attribute
+// value that each carry an ESC and a newline — the shape a crafted path or
+// storage error from the destination would take — and checks neither raw
+// byte reaches the output. The handler's own colour codes (ESC ... m) are
+// stripped first; any ESC left after that came from the untrusted value.
+func TestTTYHandlerEscapesControlCharacters(t *testing.T) {
+	t.Parallel()
+
+	var buf bytes.Buffer
+
+	logger := slog.New(log.NewTTYHandler(&buf, debugHandlerOptions()))
+	logger.Info("start\x1b[31mZAP\nend", "target", "a\x1b[31mZAP\nb")
+
+	out := buf.String()
+
+	// The only newline is the line terminator; the injected ones were escaped.
+	require.Equal(t, 1, strings.Count(out, "\n"),
+		"a newline in the message or a value must be escaped, not emitted raw")
+
+	// After the handler's own colour codes are removed, no ESC survives.
+	stripped := ansiEscape.ReplaceAllString(out, "")
+	require.NotContains(t, stripped, "\x1b",
+		"a raw ESC from the message or a value must not reach the terminal")
+
+	// The escaped form is what appears instead.
+	require.Contains(t, out, `\x1b`)
+}

internal/log/tty_handler.go

@@ -5,9 +5,11 @@ import (
 	"fmt"
 	"io"
 	"log/slog"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
+	"unicode"
 )
 
 // groupSeparator joins an open group path to an attribute key. This
@@ -116,11 +118,14 @@ func (h *TTYHandler) Handle(_ context.Context, r slog.Record) error {
 		levelColor = colorReset
 	}
 
-	// Print main message
+	// Print main message. The message is escaped before the colour codes
+	// are written around it: it can carry text from an untrusted source
+	// (a storage error, for one), and a raw control character would
+	// otherwise reach the terminal.
 	_, _ = fmt.Fprintf(h.out, "%s%s%s %s%s%s %s%s%s",
 		colorGray, timestamp, colorReset,
 		levelColor, level, colorReset,
-		colorBold, r.Message, colorReset)
+		colorBold, sanitize(r.Message), colorReset)
 
 	// Attributes carried by the handler come first, then the record's
 	// own. Handler attributes were qualified when they were added; the
@@ -260,9 +265,29 @@ func (h *TTYHandler) writeAttr(a slog.Attr) {
 		// Future kinds also use the plain string form.
 	}
 
+	// Escape the key and value before the colour codes are written around
+	// them. Both can carry text from an untrusted source — a manifest
+	// timestamp, a storage error, a path or symlink target read back from
+	// the snapshot database — so a control character in one of them must
+	// be rendered as an escape sequence rather than reaching the terminal,
+	// where it could move the cursor or inject its own colours.
 	_, _ = fmt.Fprintf(h.out, " %s%s%s=%s%s%s",
-		colorCyan, a.Key, colorReset,
+		colorCyan, sanitize(a.Key), colorReset,
-		colorBlue, value, colorReset)
+		colorBlue, sanitize(value), colorReset)
+}
+
+// sanitize returns s unchanged when every rune in it is printable, and a
+// double-quoted, backslash-escaped form (\n, \x1b, …) otherwise. It is
+// applied to untrusted text before any colour code is written, so a
+// control character can never reach the terminal raw.
+func sanitize(s string) string {
+	for _, r := range s {
+		if !unicode.IsPrint(r) {
+			return strconv.Quote(s)
+		}
+	}
+
+	return s
 }
 
 // formatDuration formats a duration in a human-readable way

internal/snapshot/export_perm_test.go

@@ -0,0 +1,49 @@
+//nolint:testpackage // exercises the unexported copyFile helper
+package snapshot
+
+import (
+	"os"
+	"path/filepath"
+	"syscall"
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+// TestCopyFileExportCopyMode verifies that the exported snapshot database
+// copy is created owner-only (0600), even under a lenient 022 umask that
+// would otherwise leave a fresh file world-readable.
+//
+//nolint:paralleltest // syscall.Umask is process-global; parallel tests would clash
+func TestCopyFileExportCopyMode(t *testing.T) {
+	restore := syscall.Umask(0o022)
+	defer syscall.Umask(restore)
+
+	dir := t.TempDir()
+
+	src := filepath.Join(dir, "index.sqlite")
+
+	err := os.WriteFile(src, []byte("index data"), 0o600)
+	if err != nil {
+		t.Fatalf("creating source index: %v", err)
+	}
+
+	dst := filepath.Join(dir, "snapshot.db")
+
+	sm := &SnapshotManager{fs: afero.NewOsFs()}
+
+	err = sm.copyFile(src, dst)
+	if err != nil {
+		t.Fatalf("copyFile: %v", err)
+	}
+
+	info, err := os.Stat(dst)
+	if err != nil {
+		t.Fatalf("stat export copy: %v", err)
+	}
+
+	got := info.Mode().Perm()
+	if got != 0o600 {
+		t.Fatalf("export copy permissions = %#o, want %#o", got, 0o600)
+	}
+}

internal/snapshot/manifest.go

@@ -7,6 +7,19 @@ import (
 	"io"
 
 	"github.com/klauspost/compress/zstd"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// Manifest size bounds. A manifest lists one small entry per blob, and
+// blobs are large (the default target is 10 GB), so even a manifest for a
+// petabyte-scale backup is a few megabytes. These caps are far above any
+// manifest the writer can emit, yet stop a crafted, highly compressible
+// manifest from expanding without limit when decoded: the manifest is
+// fetched from the store, which is not trusted, and json.Decode buffers
+// the whole value in memory.
+const (
+	manifestMaxCompressed   = 256 * 1024 * 1024  // 256 MiB
+	manifestMaxDecompressed = 1024 * 1024 * 1024 // 1 GiB
 )
 
 // Manifest represents the structure of a snapshot's blob manifest
@@ -28,19 +41,31 @@ type BlobInfo struct {
 	CompressedSize int64  `json:"compressed_size"`
 }
 
-// DecodeManifest decodes a manifest from a reader containing compressed JSON
+// DecodeManifest decodes a manifest from a reader containing compressed
+// JSON, reading through byte limits on both the compressed input and the
+// decompressed output so an untrusted manifest cannot exhaust memory.
 func DecodeManifest(r io.Reader) (*Manifest, error) {
-	// Decompress using zstd
+	return decodeManifest(r, manifestMaxCompressed, manifestMaxDecompressed)
-	zr, err := zstd.NewReader(r)
+}
+
+// decodeManifest is DecodeManifest with explicit limits, so tests can drive
+// the bounds with small inputs instead of gigabyte-scale ones.
+func decodeManifest(
+	r io.Reader, maxCompressed, maxDecompressed int64,
+) (*Manifest, error) {
+	// Decompress using zstd, bounding how many compressed bytes are read.
+	zr, err := zstd.NewReader(blobgen.LimitReader(r, maxCompressed))
 	if err != nil {
 		return nil, fmt.Errorf("creating zstd reader: %w", err)
 	}
 	defer zr.Close()
 
-	// Decode JSON manifest
+	// Decode JSON manifest, bounding how far the compressed input may
+	// expand: json.Decode buffers the whole value, so without this a
+	// small, highly compressible manifest could expand to gigabytes.
 	var manifest Manifest
 
-	err = json.NewDecoder(zr).Decode(&manifest)
+	err = json.NewDecoder(blobgen.LimitReader(zr, maxDecompressed)).Decode(&manifest)
 	if err != nil {
 		return nil, fmt.Errorf("decoding manifest: %w", err)
 	}

internal/snapshot/manifest_bound_test.go

@@ -0,0 +1,79 @@
+//nolint:testpackage // exercises the unexported decodeManifest bounds
+package snapshot
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+)
+
+// testSnapshotID is a stand-in snapshot ID reused across the bound cases.
+const testSnapshotID = "host_home_2026-01-01T00:00:00Z"
+
+// TestDecodeManifestRoundTrip is the baseline: with generous bounds a
+// manifest the writer produced decodes back unchanged.
+func TestDecodeManifestRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	want := &Manifest{
+		SnapshotID:          testSnapshotID,
+		Timestamp:           "2026-01-01T00:00:00Z",
+		BlobCount:           2,
+		TotalCompressedSize: 42,
+		Blobs: []BlobInfo{
+			{Hash: "aa", CompressedSize: 21},
+			{Hash: "bb", CompressedSize: 21},
+		},
+	}
+
+	compressed, err := EncodeManifest(want, 3)
+	require.NoError(t, err)
+
+	got, err := decodeManifest(
+		bytes.NewReader(compressed), manifestMaxCompressed, manifestMaxDecompressed)
+	require.NoError(t, err)
+	require.Equal(t, want, got)
+}
+
+// TestDecodeManifestBoundsDecompressedOutput feeds a valid but highly
+// compressible manifest — one whose timestamp is a megabyte of the same
+// character — through a small decompressed bound. The compressed form is
+// tiny, so only the decompressed bound stops it; decoding must fail within
+// that bound rather than expanding the value in memory.
+func TestDecodeManifestBoundsDecompressedOutput(t *testing.T) {
+	t.Parallel()
+
+	bomb := &Manifest{
+		SnapshotID: testSnapshotID,
+		Timestamp:  strings.Repeat("a", 1<<20),
+	}
+
+	compressed, err := EncodeManifest(bomb, 3)
+	require.NoError(t, err)
+	require.Less(t, len(compressed), 4096,
+		"the compressible manifest must be small compressed")
+
+	_, err = decodeManifest(bytes.NewReader(compressed), 1<<20, 4096)
+	require.ErrorIs(t, err, blobgen.ErrOutputTooLarge)
+}
+
+// TestDecodeManifestBoundsCompressedInput checks the compressed-input
+// bound fires independently: a valid manifest with a generous decompressed
+// bound but a tiny compressed bound still fails.
+func TestDecodeManifestBoundsCompressedInput(t *testing.T) {
+	t.Parallel()
+
+	manifest := &Manifest{
+		SnapshotID: testSnapshotID,
+		Timestamp:  strings.Repeat("a", 4096),
+	}
+
+	compressed, err := EncodeManifest(manifest, 3)
+	require.NoError(t, err)
+
+	_, err = decodeManifest(bytes.NewReader(compressed), 8, manifestMaxDecompressed)
+	require.Error(t, err)
+}

internal/snapshot/manifest_gen_test.go

@@ -0,0 +1,64 @@
+//nolint:testpackage // exercises the unexported generateBlobManifest
+package snapshot
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/types"
+)
+
+// TestGenerateBlobManifest_MissingBlobFails is the regression guard for
+// issue #157: a blob the snapshot references but that is absent from the
+// blobs table used to be logged and skipped, yielding a manifest with
+// fewer blobs than the snapshot needs. Since prune trusts the manifest
+// alone, that omitted blob would be deleted at the next prune. Manifest
+// generation must fail instead.
+func TestGenerateBlobManifest_MissingBlobFails(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ctx := context.Background()
+	dbPath := filepath.Join(t.TempDir(), "snapshot.db")
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	// A real blob row satisfies the snapshot_blobs foreign key on
+	// blob_id; the snapshot then references a different, absent hash.
+	presentBlob := &database.Blob{
+		ID:        types.NewBlobID(),
+		Hash:      types.BlobHash("present-blob-hash"),
+		CreatedTS: time.Now().Truncate(time.Second),
+	}
+	require.NoError(t, repos.Blobs.Create(ctx, nil, presentBlob))
+
+	snap := &database.Snapshot{
+		ID:       "testhost_home_2026-05-01T00:00:00Z",
+		Hostname: "testhost",
+	}
+	require.NoError(t, repos.Snapshots.Create(ctx, nil, snap))
+	require.NoError(t, repos.Snapshots.AddBlob(ctx, nil,
+		snap.ID.String(), presentBlob.ID, types.BlobHash("absent-blob-hash")))
+
+	require.NoError(t, db.Close())
+
+	sm := &SnapshotManager{
+		config: &config.Config{CompressionLevel: 3},
+		fs:     afero.NewOsFs(),
+	}
+
+	_, err = sm.generateBlobManifest(ctx, dbPath, snap.ID.String())
+	require.Error(t, err, "manifest generation must fail on a missing blob")
+	assert.Contains(t, err.Error(), "absent-blob-hash")
+}

internal/snapshot/scanner.go

@@ -63,7 +63,9 @@ type Scanner struct {
 	exclude           []string          // Glob patterns for files/directories to exclude
 	compiledExclude   []compiledPattern // Compiled glob patterns
 	progress          *ProgressReporter
-	skipErrors        bool // Skip file read errors (log loudly but continue)
+	// skipErrors skips files that cannot be opened or read (logged loudly);
+	// packer, database, encryption, and upload errors still abort the run.
+	skipErrors bool
 	// ui is the user-facing output; never nil (defaults to a discarding writer).
 	ui *ui.Writer
 
@@ -121,7 +123,9 @@ type ScannerConfig struct {
 	EnableProgress   bool       // Enable the live progress reporter (ETAs, throughput)
 	UI               *ui.Writer // Where user-facing scanner messages go; nil = discard
 	Exclude          []string   // Glob patterns for files/directories to exclude
-	SkipErrors       bool       // Skip file read errors (log loudly but continue)
+	// SkipErrors skips files that cannot be opened or read (log loudly but
+	// continue); packer, database, encryption, and upload errors still abort.
+	SkipErrors bool
 }
 
 // ScanResult contains the results of a scan operation
@@ -220,7 +224,14 @@ func (s *Scanner) Scan(
 		defer s.progress.Stop()
 	}
 
-	// Phase 0: Load known files and chunks from database into memory for fast lookup
+	// Phase 0: Repair any state left by an interrupted previous run, then
+	// load known files and chunks from the database into memory for fast
+	// lookup.
+	err := s.repairInterruptedBlobs(ctx)
+	if err != nil {
+		return nil, err
+	}
+
 	knownFiles, err := s.loadDatabaseState(ctx, path)
 	if err != nil {
 		return nil, err
@@ -317,6 +328,38 @@ func (s *Scanner) loadDatabaseState(
 	return knownFiles, nil
 }
 
+// repairInterruptedBlobs discards blob rows left by a previous run whose
+// upload never completed. Such a blob has its chunks, blob_chunks, and
+// blobs rows committed to the local index before the upload is attempted,
+// so a crash or dropped connection mid-upload leaves them behind while the
+// data never reaches remote storage. Deduplicating against those chunks on
+// a later run would produce a snapshot that reports success but cannot be
+// restored. Dropping the un-uploaded blobs (their blob_chunks cascade) and
+// then any chunks left unreferenced forces the affected data to be
+// re-chunked and re-uploaded this run. A blob is attached to a snapshot
+// only once its upload is recorded, so this never touches a completed
+// snapshot's data.
+func (s *Scanner) repairInterruptedBlobs(ctx context.Context) error {
+	removed, err := s.repos.Blobs.DeleteUnuploaded(ctx)
+	if err != nil {
+		return fmt.Errorf("removing un-uploaded blob records: %w", err)
+	}
+
+	if removed == 0 {
+		return nil
+	}
+
+	log.Warn("Discarded blob records from an interrupted previous run; "+
+		"their data will be re-uploaded", "blobs", removed)
+
+	err = s.repos.Chunks.DeleteOrphaned(ctx)
+	if err != nil {
+		return fmt.Errorf("removing orphaned chunks: %w", err)
+	}
+
+	return nil
+}
+
 // summarizeScanPhase calculates total size to process, updates progress tracking,
 // and prints the scan phase summary with file counts and sizes
 func (s *Scanner) summarizeScanPhase(
@@ -392,11 +435,14 @@ func (s *Scanner) loadKnownFiles(
 	return result, nil
 }
 
-// loadKnownChunks loads all known chunk hashes from the database into a
+// loadKnownChunks loads the chunk hashes safe to deduplicate against into
-// map for fast lookup. This avoids per-chunk database queries during file
+// an in-memory map for fast lookup, avoiding per-chunk database queries
-// processing.
+// during file processing. Only chunks held by a blob whose upload
+// completed are loaded: a chunk left behind by an interrupted upload
+// refers to data that never reached remote storage, and deduplicating
+// against it would silently produce an unrestorable snapshot.
 func (s *Scanner) loadKnownChunks(ctx context.Context) error {
-	chunks, err := s.repos.Chunks.List(ctx)
+	chunks, err := s.repos.Chunks.ListInUploadedBlobs(ctx)
 	if err != nil {
 		return fmt.Errorf("listing chunks: %w", err)
 	}
@@ -1294,6 +1340,15 @@ func (s *Scanner) processFileWithErrorHandling(
 ) (bool, error) {
 	err := s.processFileStreaming(ctx, fileToProcess, result)
 	if err != nil {
+		// A packer/database/encryption/upload failure means the chunk's data
+		// may not have been stored. Skipping the file would let the snapshot
+		// record a file whose chunk is in no blob and cannot be restored, so
+		// abort the run even under --skip-errors. Only open and read errors
+		// are skipped below.
+		var pErr *packerError
+		if errors.As(err, &pErr) {
+			return false, fmt.Errorf("processing file %s: %w", fileToProcess.Path, err)
+		}
 		// Handle files that were deleted between scan and process phases
 		if errors.Is(err, os.ErrNotExist) {
 			log.Warn("File was deleted during backup, skipping",
@@ -1303,7 +1358,7 @@ func (s *Scanner) processFileWithErrorHandling(
 
 			return true, nil
 		}
-		// Skip file read errors if --skip-errors is enabled
+		// Skip open/read errors if --skip-errors is enabled
 		if s.skipErrors {
 			log.Error("Failed to process file (skipping due to --skip-errors)",
 				"path", fileToProcess.Path, "error", err)
@@ -1401,7 +1456,17 @@ func (s *Scanner) finalizeProcessPhase(ctx context.Context, result *ScanResult)
 				return fmt.Errorf("parsing blob ID: %w", err)
 			}
 
+			// With no remote backend the blob's lifecycle ends here, so
+			// mark it uploaded in the same transaction that attaches it to
+			// the snapshot. This keeps the invariant that any blob a
+			// snapshot references has uploaded_ts set, so deduplication and
+			// interrupted-run repair treat these blobs as trustworthy.
 			err = s.repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+				err := s.repos.Blobs.UpdateUploaded(ctx, tx, b.ID)
+				if err != nil {
+					return fmt.Errorf("marking blob uploaded: %w", err)
+				}
+
 				return s.repos.Snapshots.AddBlob(ctx, tx, s.snapshotID, blobID,
 					types.BlobHash(b.Hash))
 			})
@@ -1660,6 +1725,20 @@ type streamingChunkInfo struct {
 	size      int64
 }
 
+// packerError marks an error that came from adding a chunk to the packer
+// (packing, database, encryption, or upload). Such an error means the chunk's
+// data may not have been stored, so the run must abort even under --skip-errors:
+// skipping the file would leave the chunk recorded as backed up while it lives
+// in no blob, and a later snapshot could record a file that cannot be restored.
+// Only open and read errors are safe to skip.
+type packerError struct {
+	err error
+}
+
+func (e *packerError) Error() string { return e.err.Error() }
+
+func (e *packerError) Unwrap() error { return e.err }
+
 // processFileStreaming processes a file by streaming chunks directly to the packer
 func (s *Scanner) processFileStreaming(
 	ctx context.Context, fileToProcess *FileToProcess, result *ScanResult,
@@ -1710,7 +1789,11 @@ func (s *Scanner) processFileStreaming(
 		if !chunkExists {
 			err := s.addChunkToPacker(ctx, chunk)
 			if err != nil {
-				return err
+				// Mark as a packer error so --skip-errors cannot swallow it:
+				// the chunk was registered as pending before packing, so a
+				// skipped file here would be recorded as backed up while its
+				// data was never stored.
+				return &packerError{err: err}
 			}
 		}
 

internal/snapshot/skip_errors_test.go

@@ -0,0 +1,216 @@
+package snapshot_test
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+)
+
+// errSimTempFail is the one-time temp-file creation failure blobTempFailFs
+// injects, mirroring a full temp filesystem.
+var errSimTempFail = errors.New("simulated temp-file creation failure")
+
+// errSimRead is the read failure readFailFile injects for a file that opens
+// but cannot be read.
+var errSimRead = errors.New("simulated read failure")
+
+// blobTempFailFs fails the first temp-file creation for a packer blob, then
+// behaves normally, simulating a one-time failure to start a new blob.
+type blobTempFailFs struct {
+	afero.Fs
+
+	mu     sync.Mutex
+	failed bool
+}
+
+//nolint:ireturn // afero.Fs.OpenFile is defined to return the interface.
+func (f *blobTempFailFs) OpenFile(
+	name string, flag int, perm os.FileMode,
+) (afero.File, error) {
+	if strings.Contains(name, "vaultik-blob-") {
+		f.mu.Lock()
+		firstTime := !f.failed
+		f.failed = true
+		f.mu.Unlock()
+
+		if firstTime {
+			return nil, errSimTempFail
+		}
+	}
+
+	return f.Fs.OpenFile(name, flag, perm)
+}
+
+// readFailFile wraps an afero.File whose Read always fails.
+type readFailFile struct {
+	afero.File
+}
+
+func (readFailFile) Read([]byte) (int, error) {
+	return 0, errSimRead
+}
+
+// readFailFs fails reads of one target path after a successful open.
+type readFailFs struct {
+	afero.Fs
+
+	target string
+}
+
+//nolint:ireturn // afero.Fs.Open is defined to return the interface.
+func (f *readFailFs) Open(name string) (afero.File, error) {
+	file, err := f.Fs.Open(name)
+	if err != nil {
+		return nil, err
+	}
+
+	if name == f.target {
+		return readFailFile{File: file}, nil
+	}
+
+	return file, nil
+}
+
+// writeSkipErrorTestFile writes one file into fs with a fixed mtime.
+func writeSkipErrorTestFile(t *testing.T, fs afero.Fs, path, content string) {
+	t.Helper()
+
+	err := fs.MkdirAll(filepath.Dir(path), 0755)
+	if err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+
+	err = afero.WriteFile(fs, path, []byte(content), 0644)
+	if err != nil {
+		t.Fatalf("write %s: %v", path, err)
+	}
+
+	when := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)
+
+	err = fs.Chtimes(path, when, when)
+	if err != nil {
+		t.Fatalf("chtimes %s: %v", path, err)
+	}
+}
+
+// runSkipErrorScan scans /source on fs with the given skip-errors setting and
+// returns the repositories (for inspection) and the scan error.
+func runSkipErrorScan(
+	t *testing.T, fs afero.Fs, skipErrors bool,
+) (*database.Repositories, error) {
+	t.Helper()
+
+	db, err := database.NewTestDB()
+	if err != nil {
+		t.Fatalf("create test db: %v", err)
+	}
+
+	t.Cleanup(func() {
+		cerr := db.Close()
+		if cerr != nil {
+			t.Errorf("close db: %v", cerr)
+		}
+	})
+
+	repos := database.NewRepositories(db)
+
+	scanner := snapshot.NewScanner(snapshot.ScannerConfig{
+		FS:               fs,
+		ChunkSize:        int64(1024 * 16),
+		Repositories:     repos,
+		MaxBlobSize:      int64(1024 * 1024),
+		CompressionLevel: 3,
+		AgeRecipients:    []string{testAgePublicKey},
+		SkipErrors:       skipErrors,
+	})
+
+	ctx := context.Background()
+	snapshotID := "test-snapshot-skip-errors"
+	createTestSnapshotRecord(ctx, t, repos, snapshotID)
+
+	_, err = scanner.Scan(ctx, "/source", snapshotID)
+
+	return repos, err
+}
+
+// TestScannerPackingFailureAbortsUnderSkipErrors checks that a failure to start
+// a new blob aborts the run even with --skip-errors. Otherwise the file would
+// be skipped while its chunk had already been registered as pending, letting a
+// later blob record that chunk in the chunks table with no blob to back it —
+// a snapshot that completes with a file that cannot be restored.
+func TestScannerPackingFailureAbortsUnderSkipErrors(t *testing.T) {
+	t.Parallel()
+
+	// Two files with distinct content so each yields a distinct chunk: the
+	// first fails to start a blob, and without the fix the second's blob would
+	// commit the first's orphaned chunk row.
+	fs := &blobTempFailFs{Fs: afero.NewMemMapFs()}
+	writeSkipErrorTestFile(t, fs, "/source/file1.txt", "first file content")
+	writeSkipErrorTestFile(t, fs, "/source/file2.txt", "second file content")
+
+	repos, err := runSkipErrorScan(t, fs, true)
+	if err == nil {
+		t.Fatal("expected scan to abort on the packer error, got nil")
+	}
+
+	// ListUnpacked returns chunks recorded with no blob_chunks row: exactly the
+	// unrestorable state this fix prevents.
+	unpacked, err := repos.Chunks.ListUnpacked(context.Background(), 10)
+	if err != nil {
+		t.Fatalf("listing unpacked chunks: %v", err)
+	}
+
+	if len(unpacked) != 0 {
+		t.Fatalf("expected no chunk recorded without a blob, got %d", len(unpacked))
+	}
+}
+
+// TestScannerReadErrorAbortsWithoutSkipErrors checks that a file read error
+// aborts the run when --skip-errors is not set.
+func TestScannerReadErrorAbortsWithoutSkipErrors(t *testing.T) {
+	t.Parallel()
+
+	const target = "/source/unreadable.txt"
+
+	fs := &readFailFs{Fs: afero.NewMemMapFs(), target: target}
+	writeSkipErrorTestFile(t, fs, target, "content that cannot be read")
+
+	_, err := runSkipErrorScan(t, fs, false)
+	if err == nil {
+		t.Fatal("expected scan to fail on the read error, got nil")
+	}
+}
+
+// TestScannerReadErrorSkippedWithSkipErrors checks that a file read error is
+// skipped and the run completes when --skip-errors is set.
+func TestScannerReadErrorSkippedWithSkipErrors(t *testing.T) {
+	t.Parallel()
+
+	const target = "/source/unreadable.txt"
+
+	fs := &readFailFs{Fs: afero.NewMemMapFs(), target: target}
+	writeSkipErrorTestFile(t, fs, target, "content that cannot be read")
+
+	repos, err := runSkipErrorScan(t, fs, true)
+	if err != nil {
+		t.Fatalf("expected scan to complete with --skip-errors, got %v", err)
+	}
+
+	chunks, err := repos.FileChunks.GetByFile(context.Background(), target)
+	if err != nil {
+		t.Fatalf("getting file chunks: %v", err)
+	}
+
+	if len(chunks) != 0 {
+		t.Fatalf("expected unreadable file skipped, got %d chunks", len(chunks))
+	}
+}

internal/snapshot/snapshot.go

@@ -44,6 +44,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"path/filepath"
 	"strings"
 	"time"
@@ -294,68 +295,6 @@ func (sm *SnapshotManager) ExportSnapshotMetadata(
 	return nil
 }
 
-// CleanupIncompleteSnapshots removes incomplete snapshots that don't have
-// metadata in S3. This is critical for data safety: incomplete snapshots
-// can cause deduplication to skip files that were never successfully
-// backed up, resulting in data loss.
-func (sm *SnapshotManager) CleanupIncompleteSnapshots(
-	ctx context.Context, hostname string,
-) error {
-	log.Info("Checking for incomplete snapshots", "hostname", hostname)
-
-	// Get all incomplete snapshots for this hostname
-	incompleteSnapshots, err := sm.repos.Snapshots.GetIncompleteByHostname(ctx, hostname)
-	if err != nil {
-		return fmt.Errorf("getting incomplete snapshots: %w", err)
-	}
-
-	if len(incompleteSnapshots) == 0 {
-		log.Debug("No incomplete snapshots found")
-
-		return nil
-	}
-
-	log.Info("Found incomplete snapshots", "count", len(incompleteSnapshots))
-
-	// Check each incomplete snapshot for metadata in storage
-	for _, snapshot := range incompleteSnapshots {
-		// Check if metadata exists in storage (paths use the hashed
-		// remote key so we don't leak host info to the listing).
-		metadataKey := fmt.Sprintf("metadata/%s/db.zst",
-			RemoteSnapshotKey(snapshot.ID.String()))
-
-		_, err := sm.storage.Stat(ctx, metadataKey)
-		if err != nil {
-			// Metadata doesn't exist in S3 - this is an incomplete snapshot
-			log.Info("Cleaning up incomplete snapshot record",
-				"snapshot_id", snapshot.ID, "started_at", snapshot.StartedAt)
-
-			// Delete the snapshot and all its associations
-			err := sm.deleteSnapshot(ctx, snapshot.ID.String())
-			if err != nil {
-				return fmt.Errorf("deleting incomplete snapshot %s: %w",
-					snapshot.ID, err)
-			}
-
-			log.Info("Deleted incomplete snapshot record and associated data",
-				"snapshot_id", snapshot.ID)
-		} else {
-			// Metadata exists - this snapshot was completed but database wasn't updated
-			// This shouldn't happen in normal operation, but mark it complete
-			log.Warn("Found snapshot with remote metadata but incomplete in database",
-				"snapshot_id", snapshot.ID)
-
-			err := sm.repos.Snapshots.MarkComplete(ctx, nil, snapshot.ID.String())
-			if err != nil {
-				log.Error("Failed to mark snapshot as complete in database",
-					"snapshot_id", snapshot.ID, "error", err)
-			}
-		}
-	}
-
-	return nil
-}
-
 // CleanupOrphanedData removes files, chunks, and blobs that are no longer
 // referenced by any snapshot. This should be called periodically to clean
 // up data from deleted or incomplete snapshots.
@@ -758,12 +697,18 @@ func (sm *SnapshotManager) compressFile(inputPath, outputPath string) error {
 
 	writerClosed = true
 
-	log.Debug("Compression complete", "hash", hex.EncodeToString(writer.Sum256()))
+	log.Debug("Compression complete", "hash", hex.EncodeToString(writer.ContentID()))
 
 	return nil
 }
 
-// copyFile copies a file from src to dst
+// exportCopyPerm restricts the exported snapshot database copy to the owning
+// user; it holds the same private index data as the local index file.
+const exportCopyPerm = 0o600
+
+// copyFile copies a file from src to dst. The destination is the exported
+// snapshot database, so it is created owner-only rather than with the
+// umask-dependent default.
 func (sm *SnapshotManager) copyFile(src, dst string) error {
 	log.Debug("Opening source file for copy", "path", src)
 
@@ -783,7 +728,9 @@ func (sm *SnapshotManager) copyFile(src, dst string) error {
 
 	log.Debug("Creating destination file", "path", dst)
 
-	destFile, err := sm.fs.Create(dst)
+	destFile, err := sm.fs.OpenFile(
+		dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, exportCopyPerm,
+	)
 	if err != nil {
 		return err
 	}
@@ -809,6 +756,11 @@ func (sm *SnapshotManager) copyFile(src, dst string) error {
 	return nil
 }
 
+// errBlobMissingFromDatabase means a snapshot references a blob that is
+// absent from the blobs table, so a complete manifest cannot be built.
+var errBlobMissingFromDatabase = errors.New(
+	"blob referenced by snapshot is not in the database")
+
 // generateBlobManifest creates a compressed JSON list of all blobs in the snapshot
 func (sm *SnapshotManager) generateBlobManifest(
 	ctx context.Context, dbPath string, snapshotID string,
@@ -839,20 +791,26 @@ func (sm *SnapshotManager) generateBlobManifest(
 	totalCompressedSize := int64(0)
 
 	for _, hash := range blobHashes {
+		// Every blob the snapshot references must appear in the manifest.
+		// Prune consults only the manifest to decide what is still in use,
+		// so silently dropping a blob here would let a later prune delete
+		// it while this snapshot still needs it. A lookup failure or a
+		// missing blob row therefore fails manifest generation.
 		blob, err := repos.Blobs.GetByHash(ctx, hash)
 		if err != nil {
-			log.Warn("Failed to get blob details", "hash", hash, "error", err)
+			return nil, fmt.Errorf("getting blob details for %s: %w", hash, err)
-
-			continue
 		}
 
-		if blob != nil {
+		if blob == nil {
-			blobs = append(blobs, BlobInfo{
+			return nil, fmt.Errorf("%w: blob %s, snapshot %s",
-				Hash:           hash,
+				errBlobMissingFromDatabase, hash, snapshotID)
-				CompressedSize: blob.CompressedSize,
-			})
-			totalCompressedSize += blob.CompressedSize
 		}
+
+		blobs = append(blobs, BlobInfo{
+			Hash:           hash,
+			CompressedSize: blob.CompressedSize,
+		})
+		totalCompressedSize += blob.CompressedSize
 	}
 
 	// Create manifest. SnapshotID in the unencrypted manifest is the
@@ -913,45 +871,6 @@ type ExtendedBackupStats struct {
 	UploadDurationMs     int64 // Total milliseconds spent uploading to S3
 }
 
-// deleteSnapshot removes a snapshot and all its associations from the database
-func (sm *SnapshotManager) deleteSnapshot(
-	ctx context.Context, snapshotID string,
-) error {
-	// Delete snapshot_files entries
-	err := sm.repos.Snapshots.DeleteSnapshotFiles(ctx, snapshotID)
-	if err != nil {
-		return fmt.Errorf("deleting snapshot files: %w", err)
-	}
-
-	// Delete snapshot_blobs entries
-	err = sm.repos.Snapshots.DeleteSnapshotBlobs(ctx, snapshotID)
-	if err != nil {
-		return fmt.Errorf("deleting snapshot blobs: %w", err)
-	}
-
-	// Delete uploads entries (has foreign key to snapshots without CASCADE)
-	err = sm.repos.Snapshots.DeleteSnapshotUploads(ctx, snapshotID)
-	if err != nil {
-		return fmt.Errorf("deleting snapshot uploads: %w", err)
-	}
-
-	// Delete the snapshot itself
-	err = sm.repos.Snapshots.Delete(ctx, snapshotID)
-	if err != nil {
-		return fmt.Errorf("deleting snapshot: %w", err)
-	}
-
-	// Clean up orphaned data
-	log.Debug("Cleaning up orphaned records in main database")
-
-	err = sm.CleanupOrphanedData(ctx)
-	if err != nil {
-		return fmt.Errorf("cleaning up orphaned data: %w", err)
-	}
-
-	return nil
-}
-
 // deleteOtherSnapshots deletes all snapshots except the current one
 func (sm *SnapshotManager) deleteOtherSnapshots(
 	ctx context.Context, tx *sql.Tx, currentSnapshotID string,

internal/storage/conformance_test.go

@@ -0,0 +1,198 @@
+package storage_test
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"reflect"
+	"sort"
+	"testing"
+
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// runStorerConformance is the shared Storer contract. Every backend that
+// can run in-process is expected to pass it: TestFileStorer runs it against
+// file://, TestS3Storer against s3://. A new backend inherits this coverage
+// by passing its own constructor, so the contract is defined once.
+//
+// It exercises the public Storer interface: round-trip, stat, list with
+// prefix filtering, overwrite, delete, delete-of-missing, and not-found on
+// Get and Stat. Each section takes its own fresh backend instance, so the
+// order of sections never matters and no section sees another's objects.
+func runStorerConformance(t *testing.T, newStorer func(*testing.T) storage.Storer) {
+	t.Helper()
+
+	conformanceRoundTrip(t, newStorer(t))
+	conformanceOverwrite(t, newStorer(t))
+	conformanceList(t, newStorer(t))
+	conformanceDelete(t, newStorer(t))
+	conformanceNotFound(t, newStorer(t))
+}
+
+// conformanceRoundTrip stores a nested key, then reads it back and stats it.
+func conformanceRoundTrip(t *testing.T, s storage.Storer) {
+	t.Helper()
+
+	ctx := context.Background()
+	key := "blobs/aa/bb/object.bin"
+	want := []byte("round-trip payload")
+
+	err := s.Put(ctx, key, bytes.NewReader(want))
+	if err != nil {
+		t.Fatalf("Put: %v", err)
+	}
+
+	got := getBytes(t, s, key)
+	if !bytes.Equal(got, want) {
+		t.Errorf("Get returned %q, want %q", got, want)
+	}
+
+	info, err := s.Stat(ctx, key)
+	if err != nil {
+		t.Fatalf("Stat: %v", err)
+	}
+
+	if info.Key != key {
+		t.Errorf("Stat key = %q, want %q", info.Key, key)
+	}
+
+	if info.Size != int64(len(want)) {
+		t.Errorf("Stat size = %d, want %d", info.Size, len(want))
+	}
+}
+
+// conformanceOverwrite checks that a second Put replaces the first.
+func conformanceOverwrite(t *testing.T, s storage.Storer) {
+	t.Helper()
+
+	ctx := context.Background()
+	key := "meta/snapshot.json"
+
+	err := s.Put(ctx, key, bytes.NewReader([]byte("first")))
+	if err != nil {
+		t.Fatalf("first Put: %v", err)
+	}
+
+	want := []byte("second and longer payload")
+
+	err = s.Put(ctx, key, bytes.NewReader(want))
+	if err != nil {
+		t.Fatalf("second Put: %v", err)
+	}
+
+	got := getBytes(t, s, key)
+	if !bytes.Equal(got, want) {
+		t.Errorf("after overwrite Get returned %q, want %q", got, want)
+	}
+}
+
+// conformanceList checks prefix filtering and the empty result for a
+// prefix that matches nothing.
+func conformanceList(t *testing.T, s storage.Storer) {
+	t.Helper()
+
+	ctx := context.Background()
+	keys := []string{"blobs/aa/one", "blobs/bb/two", "meta/three"}
+
+	for _, k := range keys {
+		err := s.Put(ctx, k, bytes.NewReader([]byte("data")))
+		if err != nil {
+			t.Fatalf("Put %q: %v", k, err)
+		}
+	}
+
+	if got := listSorted(t, s, ""); !reflect.DeepEqual(got, keys) {
+		t.Errorf("List(\"\") = %v, want %v", got, keys)
+	}
+
+	wantBlobs := []string{"blobs/aa/one", "blobs/bb/two"}
+	if got := listSorted(t, s, "blobs/"); !reflect.DeepEqual(got, wantBlobs) {
+		t.Errorf("List(\"blobs/\") = %v, want %v", got, wantBlobs)
+	}
+
+	if got := listSorted(t, s, "absent/"); len(got) != 0 {
+		t.Errorf("List(\"absent/\") = %v, want empty", got)
+	}
+}
+
+// conformanceDelete checks that Delete removes an object and that deleting
+// a missing key is not an error.
+func conformanceDelete(t *testing.T, s storage.Storer) {
+	t.Helper()
+
+	ctx := context.Background()
+	key := "blobs/cc/gone.bin"
+
+	err := s.Put(ctx, key, bytes.NewReader([]byte("temporary")))
+	if err != nil {
+		t.Fatalf("Put: %v", err)
+	}
+
+	err = s.Delete(ctx, key)
+	if err != nil {
+		t.Fatalf("Delete: %v", err)
+	}
+
+	_, err = s.Get(ctx, key)
+	if !errors.Is(err, storage.ErrNotFound) {
+		t.Errorf("Get after Delete error = %v, want ErrNotFound", err)
+	}
+
+	err = s.Delete(ctx, key)
+	if err != nil {
+		t.Errorf("Delete of missing key = %v, want nil", err)
+	}
+}
+
+// conformanceNotFound checks Get and Stat on an absent key.
+func conformanceNotFound(t *testing.T, s storage.Storer) {
+	t.Helper()
+
+	ctx := context.Background()
+	key := "never/written"
+
+	_, err := s.Get(ctx, key)
+	if !errors.Is(err, storage.ErrNotFound) {
+		t.Errorf("Get error = %v, want ErrNotFound", err)
+	}
+
+	_, err = s.Stat(ctx, key)
+	if !errors.Is(err, storage.ErrNotFound) {
+		t.Errorf("Stat error = %v, want ErrNotFound", err)
+	}
+}
+
+// getBytes reads a key fully and closes the reader.
+func getBytes(t *testing.T, s storage.Storer, key string) []byte {
+	t.Helper()
+
+	rc, err := s.Get(context.Background(), key)
+	if err != nil {
+		t.Fatalf("Get %q: %v", key, err)
+	}
+
+	defer func() { _ = rc.Close() }()
+
+	data, err := io.ReadAll(rc)
+	if err != nil {
+		t.Fatalf("read %q: %v", key, err)
+	}
+
+	return data
+}
+
+// listSorted returns the keys under a prefix in a stable order.
+func listSorted(t *testing.T, s storage.Storer, prefix string) []string {
+	t.Helper()
+
+	keys, err := s.List(context.Background(), prefix)
+	if err != nil {
+		t.Fatalf("List %q: %v", prefix, err)
+	}
+
+	sort.Strings(keys)
+
+	return keys
+}

internal/storage/faultstore/faultstore.go

@@ -0,0 +1,209 @@
+// Package faultstore provides a storage.Storer wrapper that injects
+// faults on demand, so tests can reproduce the failure modes a real
+// backend exhibits: an upload that fails partway, a backend that reports
+// success while storing nothing, and reads that return corrupt or
+// truncated bytes. It is the seam called for by the fault-injection
+// tests (sneak/vaultik issue 72) and is meant to be reused by future
+// tests rather than re-implemented per case.
+//
+// The wrapper delegates every method to the inner Storer. Two hooks
+// change that: OnPut decides the fate of each write, and OnGet decides
+// how each read's bytes are returned. Both are keyed by the object key,
+// so a test can fault only blobs, only metadata, or a single object.
+package faultstore
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// ErrInjectedUpload is returned by a Put the OnPut hook chose to fail.
+var ErrInjectedUpload = errors.New("faultstore: injected upload failure")
+
+// PutAction is the disposition OnPut assigns to a write.
+type PutAction int
+
+const (
+	// PutNormal writes through to the inner Storer.
+	PutNormal PutAction = iota
+	// PutFail reads part of the stream, then fails without storing the
+	// object — a network upload that dies partway through.
+	PutFail
+	// PutSwallow reports success but stores nothing — a backend that
+	// lies about durability.
+	PutSwallow
+)
+
+// GetFault is how OnGet chooses to damage a read.
+type GetFault int
+
+const (
+	// GetNormal returns the stored bytes unchanged.
+	GetNormal GetFault = iota
+	// GetCorrupt flips a byte so the returned object no longer matches
+	// what was stored.
+	GetCorrupt
+	// GetTruncate returns a short read: the object's bytes cut off
+	// before the end.
+	GetTruncate
+)
+
+// Storer wraps an inner storage.Storer with fault-injection hooks. A
+// zero-valued hook means "no fault": construct with New and set only the
+// hook a test needs.
+type Storer struct {
+	inner storage.Storer
+
+	// OnPut, when set, is consulted before every Put and
+	// PutWithProgress with the object key.
+	OnPut func(key string) PutAction
+
+	// OnGet, when set, is consulted for every Get with the object key
+	// and damages the returned bytes accordingly.
+	OnGet func(key string) GetFault
+}
+
+// New wraps inner. inner must be non-nil.
+func New(inner storage.Storer) *Storer {
+	return &Storer{inner: inner}
+}
+
+// midStreamBytes is how far a PutFail reads before failing, enough to be
+// past the start of any real blob without depending on the blob's size.
+const midStreamBytes = 512
+
+// Put stores data unless OnPut faults the write.
+func (f *Storer) Put(ctx context.Context, key string, data io.Reader) error {
+	handled, err := f.injectPut(key, data)
+	if handled {
+		return err
+	}
+
+	return f.inner.Put(ctx, key, data)
+}
+
+// PutWithProgress stores data unless OnPut faults the write.
+func (f *Storer) PutWithProgress(
+	ctx context.Context, key string, data io.Reader,
+	size int64, progress storage.ProgressCallback,
+) error {
+	handled, err := f.injectPut(key, data)
+	if handled {
+		return err
+	}
+
+	return f.inner.PutWithProgress(ctx, key, data, size, progress)
+}
+
+// Get retrieves data, damaging it if OnGet faults the read.
+func (f *Storer) Get(ctx context.Context, key string) (io.ReadCloser, error) {
+	rc, err := f.inner.Get(ctx, key)
+	if err != nil {
+		return nil, err
+	}
+
+	fault := GetNormal
+	if f.OnGet != nil {
+		fault = f.OnGet(key)
+	}
+
+	if fault == GetNormal {
+		return rc, nil
+	}
+
+	data, err := io.ReadAll(rc)
+	_ = rc.Close()
+
+	if err != nil {
+		return nil, err
+	}
+
+	return io.NopCloser(bytes.NewReader(damage(fault, data))), nil
+}
+
+// damage returns a faulted copy of the stored bytes. GetCorrupt flips a
+// byte in the middle so decryption authentication fails; GetTruncate
+// drops the final byte so the read ends short. Both are no-ops on empty
+// input, which cannot be damaged into something distinguishable.
+func damage(fault GetFault, data []byte) []byte {
+	out := make([]byte, len(data))
+	copy(out, data)
+
+	if len(out) == 0 {
+		return out
+	}
+
+	switch fault {
+	case GetCorrupt:
+		out[len(out)/2] ^= 0xff
+	case GetTruncate:
+		out = out[:len(out)-1]
+	case GetNormal:
+	}
+
+	return out
+}
+
+// Stat delegates unchanged.
+func (f *Storer) Stat(ctx context.Context, key string) (*storage.ObjectInfo, error) {
+	return f.inner.Stat(ctx, key)
+}
+
+// Delete delegates unchanged.
+func (f *Storer) Delete(ctx context.Context, key string) error {
+	return f.inner.Delete(ctx, key)
+}
+
+// List delegates unchanged.
+func (f *Storer) List(ctx context.Context, prefix string) ([]string, error) {
+	return f.inner.List(ctx, prefix)
+}
+
+// ListStream delegates unchanged.
+func (f *Storer) ListStream(
+	ctx context.Context, prefix string,
+) <-chan storage.ObjectInfo {
+	return f.inner.ListStream(ctx, prefix)
+}
+
+// Info delegates unchanged.
+func (f *Storer) Info() storage.Info {
+	return f.inner.Info()
+}
+
+func (f *Storer) putAction(key string) PutAction {
+	if f.OnPut == nil {
+		return PutNormal
+	}
+
+	return f.OnPut(key)
+}
+
+// injectPut handles the non-normal write dispositions. It reports
+// whether it handled the write and, if so, with what error.
+func (f *Storer) injectPut(key string, data io.Reader) (bool, error) {
+	switch f.putAction(key) {
+	case PutFail:
+		// Consume part of the stream so the failure lands mid-transfer,
+		// the way a dropped connection would, then error without
+		// storing anything.
+		_, _ = io.CopyN(io.Discard, data, midStreamBytes)
+
+		return true, fmt.Errorf("%w for %q", ErrInjectedUpload, key)
+	case PutSwallow:
+		// A lying backend still drains the request body, then keeps
+		// nothing.
+		_, _ = io.Copy(io.Discard, data)
+
+		return true, nil
+	case PutNormal:
+		return false, nil
+	default:
+		return false, nil
+	}
+}

internal/storage/file_backend_test.go

@@ -0,0 +1,27 @@
+package storage_test
+
+import (
+	"testing"
+
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// newFileStorer builds a file:// backend rooted at a fresh temp directory.
+//
+//nolint:ireturn // conformance runs against the Storer interface by design
+func newFileStorer(t *testing.T) storage.Storer {
+	t.Helper()
+
+	s, err := storage.NewFileStorer(t.TempDir())
+	if err != nil {
+		t.Fatalf("NewFileStorer: %v", err)
+	}
+
+	return s
+}
+
+// TestFileStorer runs the shared Storer contract against the file:// backend.
+func TestFileStorer(t *testing.T) {
+	t.Parallel()
+	runStorerConformance(t, newFileStorer)
+}

internal/storage/module.go

@@ -111,10 +111,11 @@ func storerFromParsedS3URL(parsed *URL, cfg *config.Config) (Storer, error) {
 func storerFromLegacyS3Config(cfg *config.Config) (Storer, error) {
 	endpoint := cfg.S3.Endpoint
 
-	// Ensure protocol is present
+	// Ensure protocol is present. Absent an explicit use_ssl, default to TLS;
+	// plain HTTP only when use_ssl is written as false.
 	if !strings.HasPrefix(endpoint, "http://") &&
 		!strings.HasPrefix(endpoint, "https://") {
-		if cfg.S3.UseSSL {
+		if cfg.S3.UseSSL == nil || *cfg.S3.UseSSL {
 			endpoint = "https://" + endpoint
 		} else {
 			endpoint = "http://" + endpoint

internal/storage/module_test.go

@@ -0,0 +1,61 @@
+package storage_test
+
+import (
+	"strings"
+	"testing"
+
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// legacyS3Config returns a minimal s3.* (no storage_url) configuration with a
+// scheme-less endpoint. useSSL mirrors the config file: nil means the key is
+// omitted, a pointer means it was written explicitly.
+func legacyS3Config(useSSL *bool) *config.Config {
+	return &config.Config{
+		S3: config.S3Config{
+			Endpoint:        "s3.example.com",
+			Bucket:          "bucket",
+			AccessKeyID:     "key",
+			SecretAccessKey: "secret",
+			Region:          "us-east-1",
+			UseSSL:          useSSL,
+		},
+	}
+}
+
+// endpointScheme builds the storer from cfg and returns the scheme its
+// resolved endpoint carries (Info().Location is "endpoint/bucket").
+func endpointScheme(t *testing.T, cfg *config.Config) string {
+	t.Helper()
+
+	storer, err := storage.NewStorer(cfg)
+	if err != nil {
+		t.Fatalf("NewStorer: %v", err)
+	}
+
+	location := storer.Info().Location
+	switch {
+	case strings.HasPrefix(location, "https://"):
+		return "https"
+	case strings.HasPrefix(location, "http://"):
+		return "http"
+	default:
+		t.Fatalf("endpoint has no http(s) scheme: %q", location)
+
+		return ""
+	}
+}
+
+func TestLegacyS3SchemelessEndpointDefaultsToTLS(t *testing.T) {
+	t.Parallel()
+
+	if got := endpointScheme(t, legacyS3Config(nil)); got != "https" {
+		t.Errorf("use_ssl omitted: got %q scheme, want https", got)
+	}
+
+	no := false
+	if got := endpointScheme(t, legacyS3Config(&no)); got != "http" {
+		t.Errorf("use_ssl: false: got %q scheme, want http", got)
+	}
+}

internal/storage/rclone_test.go

@@ -0,0 +1,58 @@
+package storage_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// The rclone backend is a thin adapter over the rclone library: it turns a
+// (remote, path) pair into rclone's "remote:path" string, hands it to
+// rclone, and maps rclone's own results back to the Storer interface. What
+// can be tested in-process, without a configured remote or network, is that
+// adapter layer — how the arguments are shaped and how construction errors
+// are reported. The data-plane operations (Put/Get/List/Delete) are rclone's
+// own, exercised against a real provider (drive, s3-via-rclone, ...), which
+// needs a configured remote with credentials and network access and so is
+// out of reach of a unit test. The shared Storer conformance suite therefore
+// runs against the in-process file and s3 backends; the rclone backend
+// inherits that contract once a remote is configured.
+//
+// These tests use rclone's ":local:" on-the-fly backend, which addresses the
+// local filesystem directly without any configured remote, so construction
+// runs entirely in-process.
+
+// TestNewRcloneStorerConstruction checks that a valid remote constructs a
+// backend and that Info() reports the shaped "remote:path" location.
+//
+//nolint:paralleltest // NewRcloneStorer installs the process-global rclone config
+func TestNewRcloneStorerConstruction(t *testing.T) {
+	dir := t.TempDir()
+
+	s, err := storage.NewRcloneStorer(context.Background(), ":local", dir)
+	if err != nil {
+		t.Fatalf("NewRcloneStorer: %v", err)
+	}
+
+	// Info().Location is the "remote:path" string the adapter builds from
+	// its two arguments, so asserting it confirms the argument shaping.
+	want := ":local:" + dir
+	if got := s.Info().Location; got != want {
+		t.Errorf("Info().Location = %q, want %q", got, want)
+	}
+}
+
+// TestNewRcloneStorerUnknownRemote checks that a remote that is not in the
+// rclone config fails construction with the ErrRemoteNotFound sentinel,
+// rather than silently returning a backend pointed nowhere.
+//
+//nolint:paralleltest // NewRcloneStorer installs the process-global rclone config
+func TestNewRcloneStorerUnknownRemote(t *testing.T) {
+	_, err := storage.NewRcloneStorer(
+		context.Background(), "vaultik-no-such-remote", "path")
+	if !errors.Is(err, storage.ErrRemoteNotFound) {
+		t.Errorf("NewRcloneStorer error = %v, want ErrRemoteNotFound", err)
+	}
+}

internal/storage/s3_test.go

@@ -13,18 +13,23 @@ import (
 	"sneak.berlin/go/vaultik/internal/storage"
 )
 
-// TestS3StorerMissingKeyMapsToErrNotFound verifies that the s3 backend reports
+// s3TestBucket is the bucket created for each in-process S3 server.
-// a missing object as storage.ErrNotFound, matching the file and rclone
+const s3TestBucket = "test-bucket"
-// backends and the Storer contract. Without the mapping, Get and Stat leak the
+
-// raw SDK error and errors.Is(err, storage.ErrNotFound) is false.
+// newS3Storer builds an s3:// backend backed by a fresh in-process
+// S3 server. It reuses the same in-memory S3 harness (gofakes3 + s3mem
+// over httptest) that internal/s3 and the not-found regression test use,
+// so no new mock or dependency is introduced. Each call gets its own
+// server, bucket, and client, so the conformance suite's per-section
+// instances stay isolated.
 //
-//nolint:paralleltest // shares an in-process S3 server via t.Cleanup
+//nolint:ireturn // conformance runs against the Storer interface by design
-func TestS3StorerMissingKeyMapsToErrNotFound(t *testing.T) {
+func newS3Storer(t *testing.T) storage.Storer {
-	const bucket = "test-bucket"
+	t.Helper()
 
 	backend := s3mem.New()
 
-	err := backend.CreateBucket(bucket)
+	err := backend.CreateBucket(s3TestBucket)
 	if err != nil {
 		t.Fatalf("create bucket: %v", err)
 	}
@@ -32,11 +37,9 @@ func TestS3StorerMissingKeyMapsToErrNotFound(t *testing.T) {
 	srv := httptest.NewServer(gofakes3.New(backend).Server())
 	t.Cleanup(srv.Close)
 
-	ctx := context.Background()
+	client, err := s3.NewClient(context.Background(), s3.Config{
-
-	client, err := s3.NewClient(ctx, s3.Config{
 		Endpoint:        srv.URL,
-		Bucket:          bucket,
+		Bucket:          s3TestBucket,
 		AccessKeyID:     "test",
 		SecretAccessKey: "test",
 		Region:          "us-east-1",
@@ -45,9 +48,28 @@ func TestS3StorerMissingKeyMapsToErrNotFound(t *testing.T) {
 		t.Fatalf("new client: %v", err)
 	}
 
-	storer := storage.NewS3Storer(client)
+	return storage.NewS3Storer(client)
+}
 
-	_, err = storer.Get(ctx, "does-not-exist")
+// TestS3Storer runs the shared Storer contract against the s3:// backend,
+// so it is held to the same round-trip, list, delete, and not-found
+// behaviour as the file:// backend.
+func TestS3Storer(t *testing.T) {
+	t.Parallel()
+	runStorerConformance(t, newS3Storer)
+}
+
+// TestS3StorerMissingKeyMapsToErrNotFound pins the specific contract that a
+// missing object surfaces as storage.ErrNotFound rather than the raw AWS SDK
+// error. Without the mapping, errors.Is(err, storage.ErrNotFound) is false on
+// s3 and callers would branch differently per backend.
+func TestS3StorerMissingKeyMapsToErrNotFound(t *testing.T) {
+	t.Parallel()
+
+	storer := newS3Storer(t)
+	ctx := context.Background()
+
+	_, err := storer.Get(ctx, "does-not-exist")
 	if !errors.Is(err, storage.ErrNotFound) {
 		t.Errorf("Get on missing key: got %v, want ErrNotFound", err)
 	}

internal/storage/url.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
+	"slices"
 	"strings"
 )
 
@@ -23,6 +24,10 @@ var (
 	ErrUnsupportedScheme = errors.New(
 		"unsupported URL scheme: must start with s3://, file://, or rclone://")
 	ErrUnsupportedStorage = errors.New("unsupported storage scheme")
+	ErrURLCredentials     = errors.New(
+		"storage URL must not carry credentials; " +
+			"set s3.access_key_id and s3.secret_access_key in the config instead")
+	ErrURLUnknownParam = errors.New("unknown query parameter in storage URL")
 )
 
 // URL represents a parsed storage URL.
@@ -59,61 +64,111 @@ func ParseStorageURL(rawURL string) (*URL, error) {
 		}, nil
 	}
 
-	// Handle s3:// URLs
 	if strings.HasPrefix(rawURL, "s3://") {
-		u, err := url.Parse(rawURL)
+		return parseS3URL(rawURL)
-		if err != nil {
-			return nil, fmt.Errorf("invalid URL: %w", err)
-		}
-
-		bucket := u.Host
-		if bucket == "" {
-			return nil, ErrMissingBucket
-		}
-
-		prefix := strings.TrimPrefix(u.Path, "/")
-
-		query := u.Query()
-
-		useSSL := true
-		if query.Get("ssl") == "false" {
-			useSSL = false
-		}
-
-		return &URL{
-			Scheme:   schemeS3,
-			Bucket:   bucket,
-			Prefix:   prefix,
-			Endpoint: query.Get("endpoint"),
-			Region:   query.Get("region"),
-			UseSSL:   useSSL,
-		}, nil
 	}
 
-	// Handle rclone:// URLs
 	if strings.HasPrefix(rawURL, "rclone://") {
-		u, err := url.Parse(rawURL)
+		return parseRcloneURL(rawURL)
-		if err != nil {
-			return nil, fmt.Errorf("invalid URL: %w", err)
-		}
-
-		remote := u.Host
-		if remote == "" {
-			return nil, ErrMissingRemote
-		}
-
-		path := strings.TrimPrefix(u.Path, "/")
-
-		return &URL{
-			Scheme:       schemeRclone,
-			Prefix:       path,
-			RcloneRemote: remote,
-		}, nil
 	}
 
 	return nil, ErrUnsupportedScheme
 }
 
+// parseS3URL parses an s3://bucket/prefix URL. It rejects credentials in
+// the userinfo and any query parameter other than endpoint, region and
+// ssl, so a credential-bearing URL is never stored or echoed.
+func parseS3URL(rawURL string) (*URL, error) {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, wrapParseError(err)
+	}
+
+	if u.User != nil {
+		return nil, ErrURLCredentials
+	}
+
+	bucket := u.Host
+	if bucket == "" {
+		return nil, ErrMissingBucket
+	}
+
+	query := u.Query()
+
+	err = rejectUnknownParams(query, "endpoint", "region", "ssl")
+	if err != nil {
+		return nil, err
+	}
+
+	return &URL{
+		Scheme:   schemeS3,
+		Bucket:   bucket,
+		Prefix:   strings.TrimPrefix(u.Path, "/"),
+		Endpoint: query.Get("endpoint"),
+		Region:   query.Get("region"),
+		UseSSL:   query.Get("ssl") != "false",
+	}, nil
+}
+
+// parseRcloneURL parses an rclone://remote/path URL. rclone:// takes no
+// query parameters, so credentials in the userinfo and any parameter at
+// all are rejected rather than silently ignored.
+func parseRcloneURL(rawURL string) (*URL, error) {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, wrapParseError(err)
+	}
+
+	if u.User != nil {
+		return nil, ErrURLCredentials
+	}
+
+	remote := u.Host
+	if remote == "" {
+		return nil, ErrMissingRemote
+	}
+
+	err = rejectUnknownParams(u.Query())
+	if err != nil {
+		return nil, err
+	}
+
+	return &URL{
+		Scheme:       schemeRclone,
+		Prefix:       strings.TrimPrefix(u.Path, "/"),
+		RcloneRemote: remote,
+	}, nil
+}
+
+// rejectUnknownParams returns an error naming the first query parameter
+// not in allowed. The parameter's name is included (so a misspelt
+// endpoint= is caught), but never its value, which could be a secret,
+// and never the whole URL.
+func rejectUnknownParams(query url.Values, allowed ...string) error {
+	for name := range query {
+		if !slices.Contains(allowed, name) {
+			return fmt.Errorf(
+				"%w: %q; put credentials in s3.access_key_id and "+
+					"s3.secret_access_key, not the URL",
+				ErrURLUnknownParam, name)
+		}
+	}
+
+	return nil
+}
+
+// wrapParseError wraps only the inner cause of a url.Parse failure. The
+// *url.Error that url.Parse returns embeds the raw URL in its message, so
+// wrapping it directly would echo a credential-bearing URL into logs.
+func wrapParseError(err error) error {
+	var uerr *url.Error
+	if errors.As(err, &uerr) {
+		return fmt.Errorf("invalid URL: %w", uerr.Err)
+	}
+
+	return fmt.Errorf("invalid URL: %w", err)
+}
+
 // String returns a human-readable representation of the storage URL.
 func (u *URL) String() string {
 	switch u.Scheme {

internal/storage/url_parse_test.go

@@ -0,0 +1,208 @@
+package storage_test
+
+import (
+	"errors"
+	"reflect"
+	"strings"
+	"testing"
+
+	"sneak.berlin/go/vaultik/internal/storage"
+)
+
+// TestParseStorageURLValid checks that each supported scheme parses into
+// the expected fields, since those fields decide which backend is built.
+func TestParseStorageURLValid(t *testing.T) {
+	t.Parallel()
+
+	const bucket = "mybucket"
+
+	cases := []struct {
+		name string
+		raw  string
+		want *storage.URL
+	}{
+		{
+			name: "file absolute path",
+			raw:  "file:///var/backups/vaultik",
+			want: &storage.URL{Scheme: "file", Prefix: "/var/backups/vaultik"},
+		},
+		{
+			name: "s3 bucket and prefix, ssl defaults on",
+			raw:  "s3://mybucket/backups/host",
+			want: &storage.URL{
+				Scheme: "s3", Bucket: bucket,
+				Prefix: "backups/host", UseSSL: true,
+			},
+		},
+		{
+			name: "s3 bucket only",
+			raw:  "s3://mybucket",
+			want: &storage.URL{Scheme: "s3", Bucket: bucket, UseSSL: true},
+		},
+		{
+			name: "s3 with endpoint, region, ssl off",
+			raw:  "s3://mybucket?endpoint=minio.example.com&region=us-west-2&ssl=false",
+			want: &storage.URL{
+				Scheme: "s3", Bucket: bucket,
+				Endpoint: "minio.example.com", Region: "us-west-2", UseSSL: false,
+			},
+		},
+		{
+			name: "rclone remote and path",
+			raw:  "rclone://gdrive/backups/host",
+			want: &storage.URL{
+				Scheme: "rclone", RcloneRemote: "gdrive", Prefix: "backups/host",
+			},
+		},
+		{
+			name: "rclone remote only",
+			raw:  "rclone://gdrive",
+			want: &storage.URL{Scheme: "rclone", RcloneRemote: "gdrive"},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			got, err := storage.ParseStorageURL(tc.raw)
+			if err != nil {
+				t.Fatalf("ParseStorageURL(%q) returned error: %v", tc.raw, err)
+			}
+
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("ParseStorageURL(%q) = %+v, want %+v", tc.raw, got, tc.want)
+			}
+		})
+	}
+}
+
+// TestParseStorageURLErrors checks that empty, missing, and unknown-scheme
+// inputs fail with the documented sentinel errors instead of parsing to a
+// wrong destination.
+func TestParseStorageURLErrors(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name    string
+		raw     string
+		wantErr error
+	}{
+		{"empty url", "", storage.ErrEmptyStorageURL},
+		{"file empty path", "file://", storage.ErrEmptyFilePath},
+		{"s3 missing bucket", "s3://", storage.ErrMissingBucket},
+		{"s3 missing bucket with path", "s3:///justprefix", storage.ErrMissingBucket},
+		{"rclone missing remote", "rclone://", storage.ErrMissingRemote},
+		{"unknown scheme", "gs://bucket/x", storage.ErrUnsupportedScheme},
+		{"no scheme", "/local/path", storage.ErrUnsupportedScheme},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := storage.ParseStorageURL(tc.raw)
+			if !errors.Is(err, tc.wantErr) {
+				t.Errorf("ParseStorageURL(%q) error = %v, want %v",
+					tc.raw, err, tc.wantErr)
+			}
+		})
+	}
+}
+
+// TestParseStorageURLRejectsCredentials checks that a URL carrying
+// credentials in its userinfo or in an unknown query parameter is
+// rejected, and that the error never echoes the secret-bearing URL back
+// into logs or output.
+func TestParseStorageURLRejectsCredentials(t *testing.T) {
+	t.Parallel()
+
+	// Split so the literals never form a "user:pass@" URL pattern that
+	// tooling would flag as a real hardcoded credential.
+	const (
+		key    = "AKIAKEY"
+		secret = "topsecret"
+	)
+
+	cases := []struct {
+		name    string
+		raw     string
+		wantErr error
+		secrets []string // must not appear in the error message
+	}{
+		{
+			name:    "s3 userinfo",
+			raw:     "s3://" + key + ":" + secret + "@mybucket/prefix",
+			wantErr: storage.ErrURLCredentials,
+			secrets: []string{key, secret, "mybucket"},
+		},
+		{
+			name:    "s3 unknown query param",
+			raw:     "s3://mybucket?access_key=" + key + "&secret=" + secret,
+			wantErr: storage.ErrURLUnknownParam,
+			secrets: []string{key, secret},
+		},
+		{
+			name:    "s3 misspelt endpoint",
+			raw:     "s3://mybucket?endpiont=minio.example.com",
+			wantErr: storage.ErrURLUnknownParam,
+			secrets: nil,
+		},
+		{
+			name:    "rclone userinfo",
+			raw:     "rclone://user:" + secret + "@gdrive/backups",
+			wantErr: storage.ErrURLCredentials,
+			secrets: []string{secret},
+		},
+		{
+			name:    "rclone query param",
+			raw:     "rclone://gdrive/backups?token=" + secret,
+			wantErr: storage.ErrURLUnknownParam,
+			secrets: []string{secret},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := storage.ParseStorageURL(tc.raw)
+			if !errors.Is(err, tc.wantErr) {
+				t.Fatalf("ParseStorageURL(%q) error = %v, want %v",
+					tc.raw, err, tc.wantErr)
+			}
+
+			// The rejection must name the proper config keys so the
+			// operator knows where credentials belong.
+			for _, key := range []string{"s3.access_key_id", "s3.secret_access_key"} {
+				if !strings.Contains(err.Error(), key) {
+					t.Errorf("error %q does not name %q", err.Error(), key)
+				}
+			}
+
+			for _, secret := range tc.secrets {
+				if strings.Contains(err.Error(), secret) {
+					t.Errorf("error message leaked %q: %v", secret, err.Error())
+				}
+			}
+		})
+	}
+}
+
+// TestParseStorageURLParseFailureHidesURL checks that when url.Parse
+// itself fails, the wrapped error carries only the inner cause, not the
+// *url.Error whose text embeds the raw (possibly credential-bearing) URL.
+func TestParseStorageURLParseFailureHidesURL(t *testing.T) {
+	t.Parallel()
+
+	const raw = "s3://mybucket/%zz"
+
+	_, err := storage.ParseStorageURL(raw)
+	if err == nil {
+		t.Fatalf("ParseStorageURL(%q) returned no error", raw)
+	}
+
+	if strings.Contains(err.Error(), "mybucket") {
+		t.Errorf("error message echoed the raw URL: %v", err.Error())
+	}
+}

internal/types/types.go

@@ -1,7 +1,7 @@
 // Package types provides custom types for better type safety across the
-// vaultik codebase. Using distinct types for IDs, hashes, paths, and
+// vaultik codebase. Using distinct types for IDs, hashes, and paths prevents
-// credentials prevents accidental mixing of semantically different values
+// accidental mixing of semantically different values that happen to share the
-// that happen to share the same underlying type.
+// same underlying type.
 package types //nolint:revive,nolintlint // rename decision tracked in #76
 
 import (
@@ -157,34 +157,6 @@ type FilePath string
 // Used during restore to strip the source prefix from paths.
 type SourcePath string
 
-// AgeRecipient is an age public key used for encryption.
-// Format: age1... (Bech32-encoded X25519 public key)
-type AgeRecipient string
-
-// AgeSecretKey is an age private key used for decryption.
-// Format: AGE-SECRET-KEY-... (Bech32-encoded X25519 private key)
-// This type should never be logged or serialized in plaintext.
-type AgeSecretKey string
-
-// S3Endpoint is the URL of an S3-compatible storage endpoint.
-type S3Endpoint string
-
-// BucketName is the name of an S3 bucket.
-type BucketName string
-
-// S3Prefix is the path prefix within an S3 bucket.
-type S3Prefix string
-
-// AWSRegion is an AWS region identifier (e.g., "us-east-1").
-type AWSRegion string
-
-// AWSAccessKeyID is an AWS access key ID for authentication.
-type AWSAccessKeyID string
-
-// AWSSecretAccessKey is an AWS secret access key for authentication.
-// This type should never be logged or serialized in plaintext.
-type AWSSecretAccessKey string
-
 // Hostname identifies a host machine.
 type Hostname string
 
@@ -199,31 +171,14 @@ type GlobPattern string
 
 // String methods for Stringer interface
 
-func (id FileID) String() string        { return uuid.UUID(id).String() }
+func (id FileID) String() string     { return uuid.UUID(id).String() }
-func (id BlobID) String() string        { return uuid.UUID(id).String() }
+func (id BlobID) String() string     { return uuid.UUID(id).String() }
-func (id SnapshotID) String() string    { return string(id) }
+func (id SnapshotID) String() string { return string(id) }
-func (h ChunkHash) String() string      { return string(h) }
+func (h ChunkHash) String() string   { return string(h) }
-func (h BlobHash) String() string       { return string(h) }
+func (h BlobHash) String() string    { return string(h) }
-func (p FilePath) String() string       { return string(p) }
+func (p FilePath) String() string    { return string(p) }
-func (p SourcePath) String() string     { return string(p) }
+func (p SourcePath) String() string  { return string(p) }
-func (r AgeRecipient) String() string   { return string(r) }
+func (h Hostname) String() string    { return string(h) }
-func (e S3Endpoint) String() string     { return string(e) }
+func (v Version) String() string     { return string(v) }
-func (b BucketName) String() string     { return string(b) }
+func (r GitRevision) String() string { return string(r) }
-func (p S3Prefix) String() string       { return string(p) }
+func (p GlobPattern) String() string { return string(p) }
-func (r AWSRegion) String() string      { return string(r) }
-func (k AWSAccessKeyID) String() string { return string(k) }
-func (h Hostname) String() string       { return string(h) }
-func (v Version) String() string        { return string(v) }
-func (r GitRevision) String() string    { return string(r) }
-func (p GlobPattern) String() string    { return string(p) }
-
-// Redacted String methods for sensitive types - prevents accidental logging
-
-func (k AgeSecretKey) String() string       { return "[REDACTED]" }
-func (k AWSSecretAccessKey) String() string { return "[REDACTED]" }
-
-// Raw returns the actual value for sensitive types when explicitly needed.
-func (k AgeSecretKey) Raw() string { return string(k) }
-
-// Raw returns the actual value for sensitive types when explicitly needed.
-func (k AWSSecretAccessKey) Raw() string { return string(k) }

internal/types/types_test.go

@@ -0,0 +1,136 @@
+package types_test
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/types"
+)
+
+// scannableID is the shared behaviour of the UUID-backed id types. A pointer
+// to FileID or BlobID satisfies it, so both are tested through one set of
+// cases.
+type scannableID interface {
+	driver.Valuer
+	sql.Scanner
+	fmt.Stringer
+	IsZero() bool
+}
+
+// idKind adapts one id type to the generic tests below.
+type idKind struct {
+	name      string
+	newZero   func() scannableID
+	newRandom func() scannableID
+	parse     func(string) (scannableID, error)
+}
+
+func idKinds() []idKind {
+	return []idKind{
+		{
+			name:    "FileID",
+			newZero: func() scannableID { return &types.FileID{} },
+			newRandom: func() scannableID {
+				id := types.NewFileID()
+
+				return &id
+			},
+			parse: func(s string) (scannableID, error) {
+				id, err := types.ParseFileID(s)
+
+				return &id, err
+			},
+		},
+		{
+			name:    "BlobID",
+			newZero: func() scannableID { return &types.BlobID{} },
+			newRandom: func() scannableID {
+				id := types.NewBlobID()
+
+				return &id
+			},
+			parse: func(s string) (scannableID, error) {
+				id, err := types.ParseBlobID(s)
+
+				return &id, err
+			},
+		},
+	}
+}
+
+// TestIDValueScan checks that Value then Scan round trips from both a string
+// and a []byte, that a NULL scans to the zero id, and that a non-string type
+// and malformed text are rejected.
+func TestIDValueScan(t *testing.T) {
+	t.Parallel()
+
+	for _, k := range idKinds() {
+		t.Run(k.name, func(t *testing.T) {
+			t.Parallel()
+
+			orig := k.newRandom()
+			v, err := orig.Value()
+			require.NoError(t, err)
+
+			s, ok := v.(string)
+			require.True(t, ok, "Value must yield a string")
+
+			fromString := k.newZero()
+			require.NoError(t, fromString.Scan(s))
+			assert.Equal(t, orig.String(), fromString.String())
+			assert.False(t, fromString.IsZero())
+
+			fromBytes := k.newZero()
+			require.NoError(t, fromBytes.Scan([]byte(s)))
+			assert.Equal(t, orig.String(), fromBytes.String())
+
+			nulled := k.newRandom()
+			require.NoError(t, nulled.Scan(nil))
+			assert.True(t, nulled.IsZero(), "NULL scans to the zero id")
+
+			require.Error(t, k.newZero().Scan(42),
+				"a non-string type must be rejected")
+			assert.Error(t, k.newZero().Scan("not-a-uuid"),
+				"malformed text must be rejected")
+		})
+	}
+}
+
+// TestIDParse checks that the Parse function accepts a canonical id and
+// rejects malformed text.
+func TestIDParse(t *testing.T) {
+	t.Parallel()
+
+	for _, k := range idKinds() {
+		t.Run(k.name, func(t *testing.T) {
+			t.Parallel()
+
+			canonical := k.newRandom().String()
+
+			parsed, err := k.parse(canonical)
+			require.NoError(t, err)
+			assert.Equal(t, canonical, parsed.String())
+
+			_, err = k.parse("not-a-uuid")
+			assert.Error(t, err)
+		})
+	}
+}
+
+// TestIDIsZero checks IsZero on the zero and on a freshly generated id.
+func TestIDIsZero(t *testing.T) {
+	t.Parallel()
+
+	for _, k := range idKinds() {
+		t.Run(k.name, func(t *testing.T) {
+			t.Parallel()
+
+			assert.True(t, k.newZero().IsZero())
+			assert.False(t, k.newRandom().IsZero())
+		})
+	}
+}

internal/ui/ui.go

@@ -23,7 +23,9 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strconv"
 	"time"
+	"unicode"
 
 	"github.com/dustin/go-humanize"
 	"golang.org/x/term"
@@ -225,17 +227,17 @@ func (w *Writer) Hex(s string) string {
 		short = s[:hexAbbrevLen] + "..."
 	}
 
-	return w.paint(ansiCyan, short)
+	return w.paint(ansiCyan, sanitize(short))
 }
 
 // Snapshot colorizes a snapshot ID (full, no abbreviation).
 func (w *Writer) Snapshot(id string) string {
-	return w.paint(ansiCyan+ansiBold, id)
+	return w.paint(ansiCyan+ansiBold, sanitize(id))
 }
 
 // Path colorizes a filesystem path.
 func (w *Writer) Path(p string) string {
-	return w.paint(ansiBlue, p)
+	return w.paint(ansiBlue, sanitize(p))
 }
 
 // Size colorizes a byte count using humanize.Bytes.
@@ -310,6 +312,23 @@ func (w *Writer) paint(color, s string) string {
 	return color + s + ansiReset
 }
 
+// sanitize returns s unchanged when every rune in it is printable, and a
+// double-quoted, backslash-escaped form (\n, \x1b, …) otherwise. The
+// string value formatters escape their argument through this before
+// painting: identifiers, paths and symlink targets they render come from
+// the snapshot database, which is not trusted, and escaping must happen
+// before colour is applied — the painted result already contains the
+// escape codes the raw text would otherwise be indistinguishable from.
+func sanitize(s string) string {
+	for _, r := range s {
+		if !unicode.IsPrint(r) {
+			return strconv.Quote(s)
+		}
+	}
+
+	return s
+}
+
 // emit writes "<prefix> <body>\n" with the prefix painted in prefixColor
 // and the body optionally painted in bodyColor (empty = no body color).
 func (w *Writer) emit(prefixColor, prefix, bodyColor, format string, args []any) {

internal/ui/ui_escape_test.go

@@ -0,0 +1,32 @@
+package ui_test
+
+import (
+	"strings"
+	"testing"
+)
+
+// TestValueFormattersEscapeControlCharacters checks that a path carrying an
+// ESC and a newline — the shape a symlink target read back from the
+// snapshot database could take — is escaped before it reaches the output.
+// Colour is off here, so the only way a control byte could appear is from
+// the value itself.
+func TestValueFormattersEscapeControlCharacters(t *testing.T) {
+	t.Parallel()
+
+	w, buf := newTestWriter(false)
+	w.Infof("restoring %s", w.Path("a\x1b[31mZAP\nb"))
+
+	out := buf.String()
+
+	if strings.ContainsRune(out, '\x1b') {
+		t.Fatalf("raw ESC from a value survived in output: %q", out)
+	}
+
+	if strings.Count(out, "\n") != 1 {
+		t.Fatalf("a newline in a value must be escaped, not emitted raw: %q", out)
+	}
+
+	if !strings.Contains(out, `\x1b`) {
+		t.Fatalf("expected the escaped form of ESC in output: %q", out)
+	}
+}

internal/vaultik/blob_fetch.go

@@ -2,35 +2,40 @@ package vaultik
 
 import (
 	"context"
-	"crypto/sha256"
 	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
-	"time"
 
 	"filippo.io/age"
 	"sneak.berlin/go/vaultik/internal/blobgen"
-	"sneak.berlin/go/vaultik/internal/log"
 )
 
 // errBlobHashMismatch is returned when a fetched blob's content hash does
 // not match the expected double-SHA-256 hash.
 var errBlobHashMismatch = errors.New("blob hash mismatch")
 
+// errBlobNotFullyRead is returned when the verifying reader is closed
+// before its plaintext reached EOF. The hash can only be checked once
+// the whole stream has been read, so an early or short-read close must
+// fail rather than silently skip verification.
+var errBlobNotFullyRead = errors.New(
+	"blob closed before fully read; hash not verified")
+
 // hashVerifyReader wraps a blobgen.Reader and verifies the double-SHA-256 hash
 // of decrypted plaintext when Close is called. It reuses the hash that
 // blobgen.Reader already computes internally via its TeeReader, avoiding
 // redundant SHA-256 computation.
 type hashVerifyReader struct {
 	reader   *blobgen.Reader // underlying decrypted blob reader (has internal hasher)
+	limited  io.Reader       // reader bounded to the blob's recorded plaintext size
 	fetcher  io.ReadCloser   // raw fetched stream (closed on Close)
 	blobHash string          // expected double-SHA-256 hex
 	done     bool            // EOF reached
 }
 
 func (h *hashVerifyReader) Read(p []byte) (int, error) {
-	n, err := h.reader.Read(p)
+	n, err := h.limited.Read(p)
 	if errors.Is(err, io.EOF) {
 		h.done = true
 	}
@@ -38,21 +43,22 @@ func (h *hashVerifyReader) Read(p []byte) (int, error) {
 	return n, err
 }
 
-// Close verifies the hash (if the stream was fully read) and closes underlying readers.
+// Close closes the underlying readers and verifies the blob hash. The
+// hash check cannot be skipped: closing before the plaintext reached
+// EOF (a short read or an early close) is an error, so a caller can
+// never obtain unverified blob bytes.
 func (h *hashVerifyReader) Close() error {
 	readerErr := h.reader.Close()
 	fetcherErr := h.fetcher.Close()
 
-	if h.done {
+	if !h.done {
-		firstHash := h.reader.Sum256()
+		return errBlobNotFullyRead
-		secondHasher := sha256.New()
+	}
-		secondHasher.Write(firstHash)
 
-		actualHashHex := hex.EncodeToString(secondHasher.Sum(nil))
+	actualHashHex := hex.EncodeToString(blobgen.DoubleSHA256(h.reader.Sum256()))
-		if actualHashHex != h.blobHash {
+	if actualHashHex != h.blobHash {
-			return fmt.Errorf("%w: expected %s, got %s",
+		return fmt.Errorf("%w: expected %s, got %s",
-				errBlobHashMismatch, h.blobHash[:16], actualHashHex[:16])
+			errBlobHashMismatch, shortHash(h.blobHash), shortHash(actualHashHex))
-		}
 	}
 
 	if readerErr != nil {
@@ -66,15 +72,22 @@ func (h *hashVerifyReader) Close() error {
 // returns a streaming reader that computes the double-SHA-256 hash on the fly.
 // The hash is verified when the returned reader is closed (after fully reading).
 // This avoids buffering the entire blob in memory.
+//
+// maxPlaintextSize is the blob's uncompressed_size as recorded in the
+// snapshot database. Decompression stops with blobgen.ErrOutputTooLarge
+// once the plaintext exceeds it, so a tampered blob cannot expand without
+// limit — using the recorded size, not the restoring host's
+// blob_size_limit, since that config may differ from the backup host's.
 func (v *Vaultik) FetchAndDecryptBlob(
-	ctx context.Context, blobHash string, expectedSize int64, identity age.Identity,
+	ctx context.Context, blobHash string, maxPlaintextSize int64,
+	identities ...age.Identity,
 ) (io.ReadCloser, error) {
-	rc, _, err := v.FetchBlob(ctx, blobHash, expectedSize)
+	rc, err := v.FetchBlob(ctx, blobHash)
 	if err != nil {
 		return nil, err
 	}
 
-	reader, err := blobgen.NewReader(rc, identity)
+	reader, err := blobgen.NewReader(rc, identities...)
 	if err != nil {
 		_ = rc.Close()
 
@@ -83,45 +96,29 @@ func (v *Vaultik) FetchAndDecryptBlob(
 
 	return &hashVerifyReader{
 		reader:   reader,
+		limited:  blobgen.LimitReader(reader, maxPlaintextSize),
 		fetcher:  rc,
 		blobHash: blobHash,
 	}, nil
 }
 
 // FetchBlob downloads a blob and returns a reader for the encrypted data.
-// Times the Storage.Get and Storage.Stat round-trips separately at
-// debug level so we can see whether the size-only Stat (which is an
-// extra request on every fetch) is hurting throughput.
 func (v *Vaultik) FetchBlob(
-	ctx context.Context, blobHash string, expectedSize int64,
+	ctx context.Context, blobHash string,
-) (io.ReadCloser, int64, error) {
+) (io.ReadCloser, error) {
+	// blobHash reaches here from the snapshot database, which is not
+	// trusted. Reject a malformed hash before it is spliced into a storage
+	// path (blobHash[:2]/blobHash[2:4]) or a fetch is attempted.
+	if !isBlobHash(blobHash) {
+		return nil, fmt.Errorf("%w: %s", errInvalidBlobHash, shortHash(blobHash))
+	}
+
 	blobPath := fmt.Sprintf("blobs/%s/%s/%s", blobHash[:2], blobHash[2:4], blobHash)
 
-	t0 := time.Now()
 	rc, err := v.Storage.Get(ctx, blobPath)
-	getDur := time.Since(t0)
-
 	if err != nil {
-		return nil, 0, fmt.Errorf("downloading blob %s: %w", blobHash[:16], err)
+		return nil, fmt.Errorf("downloading blob %s: %w", shortHash(blobHash), err)
 	}
 
-	t0 = time.Now()
+	return rc, nil
-	info, err := v.Storage.Stat(ctx, blobPath)
-	statDur := time.Since(t0)
-
-	if err != nil {
-		_ = rc.Close()
-
-		return nil, 0, fmt.Errorf("stat blob %s: %w", blobHash[:16], err)
-	}
-
-	log.Debug("FetchBlob round-trips",
-		"hash", blobHash[:16],
-		"ms_storage_get", getDur.Milliseconds(),
-		"ms_storage_stat", statDur.Milliseconds(),
-		"expected_size", expectedSize,
-		"stat_size", info.Size,
-	)
-
-	return rc, info.Size, nil
 }

internal/vaultik/blob_fetch_bound_test.go

@@ -0,0 +1,50 @@
+package vaultik_test
+
+import (
+	"context"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestFetchAndDecryptBlobBoundsPlaintext feeds a small, highly
+// compressible blob (256 KiB of zeros) whose decompressed size far exceeds
+// the plaintext bound passed to FetchAndDecryptBlob. Decompression must
+// stop with blobgen.ErrOutputTooLarge within the bound rather than
+// expanding the whole blob into the restore cache.
+func TestFetchAndDecryptBlobBoundsPlaintext(t *testing.T) {
+	t.Parallel()
+
+	identity, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	plaintext := make([]byte, 256*1024)
+	encryptedData, correctHash := buildHashTestBlob(t, identity, plaintext)
+
+	mockStorage := NewMockStorer()
+	blobPath := "blobs/" + correctHash[:2] + "/" +
+		correctHash[2:4] + "/" + correctHash
+
+	mockStorage.mu.Lock()
+	mockStorage.data[blobPath] = encryptedData
+	mockStorage.mu.Unlock()
+
+	tv := vaultik.NewForTesting(mockStorage)
+
+	const maxPlaintext = 1024
+
+	rc, err := tv.FetchAndDecryptBlob(
+		context.Background(), correctHash, maxPlaintext, identity)
+	require.NoError(t, err)
+
+	n, copyErr := io.Copy(io.Discard, rc)
+	_ = rc.Close()
+
+	require.ErrorIs(t, copyErr, blobgen.ErrOutputTooLarge)
+	require.LessOrEqual(t, n, int64(maxPlaintext)+1,
+		"decompression must stop within the recorded plaintext bound")
+}

internal/vaultik/blob_fetch_hash_test.go

@@ -40,13 +40,13 @@ func buildHashTestBlob(
 	}
 
 	// Compute the double-SHA-256 hash of the plaintext (matches
-	// blobgen.Writer.Sum256).
+	// blobgen.Writer.ContentID).
 	firstHash := sha256.Sum256(plaintext)
 	secondHash := sha256.Sum256(firstHash[:])
 	correctHash := hex.EncodeToString(secondHash[:])
 
 	// Verify our hash matches what blobgen.Writer produces
-	writerHash := hex.EncodeToString(writer.Sum256())
+	writerHash := hex.EncodeToString(writer.ContentID())
 	if correctHash != writerHash {
 		t.Fatalf("hash computation mismatch: manual=%s, writer=%s",
 			correctHash, writerHash)
@@ -55,6 +55,35 @@ func buildHashTestBlob(
 	return encBuf.Bytes(), correctHash
 }
 
+// TestFetchBlobRejectsMalformedHash verifies FetchBlob refuses a blob hash
+// that is not 64 lowercase hex characters before it builds a storage path
+// or issues any request. The hash reaches FetchBlob from the snapshot
+// database, which is not trusted, so a value such as one containing "/.."
+// must never reach the store.
+func TestFetchBlobRejectsMalformedHash(t *testing.T) {
+	t.Parallel()
+
+	mockStorage := NewMockStorer()
+	tv := vaultik.NewForTesting(mockStorage)
+	ctx := context.Background()
+
+	for _, bad := range []string{
+		"aa/../../../home/u/.profile",
+		"abc",
+		strings.Repeat("A", 64), // uppercase hex is not accepted
+		strings.Repeat("g", 64), // not hex
+	} {
+		_, err := tv.FetchBlob(ctx, bad)
+		if err == nil {
+			t.Fatalf("expected error for malformed hash %q, got nil", bad)
+		}
+	}
+
+	if calls := mockStorage.GetCalls(); len(calls) != 0 {
+		t.Fatalf("storage was accessed for a malformed hash: %v", calls)
+	}
+}
+
 // TestFetchAndDecryptBlobVerifiesHash verifies that FetchAndDecryptBlob checks
 // the double-SHA-256 hash of the decrypted plaintext against the expected blob hash.
 func TestFetchAndDecryptBlobVerifiesHash(t *testing.T) {
@@ -84,7 +113,7 @@ func TestFetchAndDecryptBlobVerifiesHash(t *testing.T) {
 		t.Parallel()
 
 		rc, err := tv.FetchAndDecryptBlob(
-			ctx, correctHash, int64(len(encryptedData)), identity)
+			ctx, correctHash, int64(len(plaintext)), identity)
 		if err != nil {
 			t.Fatalf("expected success, got error: %v", err)
 		}
@@ -116,7 +145,7 @@ func TestFetchAndDecryptBlobVerifiesHash(t *testing.T) {
 		mockStorage.mu.Unlock()
 
 		rc, err := tv.FetchAndDecryptBlob(
-			ctx, fakeHash, int64(len(encryptedData)), identity)
+			ctx, fakeHash, int64(len(plaintext)), identity)
 		if err != nil {
 			t.Fatalf("unexpected error opening stream: %v", err)
 		}
@@ -133,3 +162,51 @@ func TestFetchAndDecryptBlobVerifiesHash(t *testing.T) {
 		}
 	})
 }
+
+// TestFetchAndDecryptBlobCloseBeforeEOFFails verifies the hash check
+// cannot be skipped: a caller that reads only part of the blob and then
+// closes gets an error rather than silently unverified bytes.
+func TestFetchAndDecryptBlobCloseBeforeEOFFails(t *testing.T) {
+	t.Parallel()
+
+	identity, err := age.GenerateX25519Identity()
+	if err != nil {
+		t.Fatalf("generating identity: %v", err)
+	}
+
+	plaintext := []byte("hello world test data for blob hash verification")
+	encryptedData, correctHash := buildHashTestBlob(t, identity, plaintext)
+
+	mockStorage := NewMockStorer()
+	blobPath := "blobs/" + correctHash[:2] + "/" +
+		correctHash[2:4] + "/" + correctHash
+
+	mockStorage.mu.Lock()
+	mockStorage.data[blobPath] = encryptedData
+	mockStorage.mu.Unlock()
+
+	tv := vaultik.NewForTesting(mockStorage)
+
+	rc, err := tv.FetchAndDecryptBlob(
+		context.Background(), correctHash, int64(len(plaintext)), identity)
+	if err != nil {
+		t.Fatalf("unexpected error opening stream: %v", err)
+	}
+
+	// Read one byte, far short of the plaintext length, then close.
+	buf := make([]byte, 1)
+
+	_, err = rc.Read(buf)
+	if err != nil {
+		t.Fatalf("reading first byte: %v", err)
+	}
+
+	err = rc.Close()
+	if err == nil {
+		t.Fatal("expected error closing before EOF, got nil")
+	}
+
+	if !strings.Contains(err.Error(), "hash not verified") {
+		t.Fatalf("expected not-verified error, got: %v", err)
+	}
+}

internal/vaultik/blobcache.go

@@ -6,13 +6,17 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 )
 
 // Sentinel errors for blob cache lookups.
 var (
-	errCacheKeyMissing     = errors.New("key not in cache")
+	errCacheKeyMissing      = errors.New("key not in cache")
-	errCacheReadBeyondBlob = errors.New("read beyond blob size")
+	errCacheReadBeyondBlob  = errors.New("read beyond blob size")
+	errCacheKeyHasSeparator = errors.New(
+		"cache key contains a path separator")
+	errCacheNegativeRead = errors.New("negative offset or length")
 )
 
 // blobCacheFileMode is the permission mode for cached blob files.
@@ -74,6 +78,11 @@ func newBlobDiskCache(maxBytes int64) (*blobDiskCache, error) {
 // Put writes blob data to disk cache. Entries larger than maxBytes are
 // silently skipped.
 func (c *blobDiskCache) Put(key string, data []byte) error {
+	p, err := c.path(key)
+	if err != nil {
+		return err
+	}
+
 	entrySize := int64(len(data))
 
 	c.mu.Lock()
@@ -87,11 +96,12 @@ func (c *blobDiskCache) Put(key string, data []byte) error {
 	if e, ok := c.items[key]; ok {
 		c.unlink(e)
 		c.curBytes -= e.size
-		_ = os.Remove(c.path(key))
+		_ = os.Remove(p)
+
 		delete(c.items, key)
 	}
 
-	err := os.WriteFile(c.path(key), data, blobCacheFileMode)
+	err = os.WriteFile(p, data, blobCacheFileMode)
 	if err != nil {
 		return fmt.Errorf("writing blob to cache: %w", err)
 	}
@@ -119,19 +129,26 @@ func (c *blobDiskCache) Put(key string, data []byte) error {
 // disk without buffering its entire plaintext (which may be tens of GB)
 // in RAM.
 func (c *blobDiskCache) PutFromReader(key string, r io.Reader) (int64, error) {
+	p, err := c.path(key)
+	if err != nil {
+		return 0, err
+	}
+
 	c.mu.Lock()
 	// Remove any prior entry first; we'll re-link after the file is
 	// written successfully.
 	if e, ok := c.items[key]; ok {
 		c.unlink(e)
 		c.curBytes -= e.size
-		_ = os.Remove(c.path(key))
+		_ = os.Remove(p)
+
 		delete(c.items, key)
 	}
 	c.mu.Unlock()
 
+	//nolint:gosec // G304: path() rejects keys with a separator
 	f, err := os.OpenFile(
-		c.path(key), os.O_CREATE|os.O_TRUNC|os.O_WRONLY, blobCacheFileMode)
+		p, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, blobCacheFileMode)
 	if err != nil {
 		return 0, fmt.Errorf("creating cache file: %w", err)
 	}
@@ -140,13 +157,13 @@ func (c *blobDiskCache) PutFromReader(key string, r io.Reader) (int64, error) {
 	closeErr := f.Close()
 
 	if copyErr != nil {
-		_ = os.Remove(c.path(key))
+		_ = os.Remove(p)
 
 		return written, fmt.Errorf("streaming to cache file: %w", copyErr)
 	}
 
 	if closeErr != nil {
-		_ = os.Remove(c.path(key))
+		_ = os.Remove(p)
 
 		return written, fmt.Errorf("closing cache file: %w", closeErr)
 	}
@@ -158,7 +175,7 @@ func (c *blobDiskCache) PutFromReader(key string, r io.Reader) (int64, error) {
 	// floor — but the restore path passes math.MaxInt64 as maxBytes
 	// so this branch is effectively unreachable there.
 	if written > c.maxBytes {
-		_ = os.Remove(c.path(key))
+		_ = os.Remove(p)
 
 		return written, nil
 	}
@@ -181,6 +198,11 @@ func (c *blobDiskCache) PutFromReader(key string, r io.Reader) (int64, error) {
 
 // Get reads a cached blob from disk. Returns data and true on hit.
 func (c *blobDiskCache) Get(key string) ([]byte, bool) {
+	p, err := c.path(key)
+	if err != nil {
+		return nil, false
+	}
+
 	c.mu.Lock()
 	c.getCalls++
 
@@ -195,7 +217,8 @@ func (c *blobDiskCache) Get(key string) ([]byte, bool) {
 	c.pushFront(e)
 	c.mu.Unlock()
 
-	data, err := os.ReadFile(c.path(key))
+	//nolint:gosec // G304: path() rejects keys with a separator
+	data, err := os.ReadFile(p)
 	if err != nil {
 		c.mu.Lock()
 		if e2, ok2 := c.items[key]; ok2 && e2 == e {
@@ -213,6 +236,20 @@ func (c *blobDiskCache) Get(key string) ([]byte, bool) {
 
 // ReadAt reads a slice of a cached blob without loading the entire blob into memory.
 func (c *blobDiskCache) ReadAt(key string, offset, length int64) ([]byte, error) {
+	p, err := c.path(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// offset and length come from a blob_chunks row read back from the
+	// destination. A negative value must be rejected outright; the upper
+	// bound is checked as length > size-offset (a subtraction) so a huge
+	// offset+length cannot overflow int64 and slip past the check.
+	if offset < 0 || length < 0 {
+		return nil, fmt.Errorf("%w: offset=%d length=%d",
+			errCacheNegativeRead, offset, length)
+	}
+
 	c.mu.Lock()
 	c.readAtCalls++
 
@@ -223,7 +260,7 @@ func (c *blobDiskCache) ReadAt(key string, offset, length int64) ([]byte, error)
 		return nil, fmt.Errorf("%w: %q", errCacheKeyMissing, key)
 	}
 
-	if offset+length > e.size {
+	if length > e.size-offset {
 		c.mu.Unlock()
 
 		return nil, fmt.Errorf("%w: offset=%d length=%d size=%d",
@@ -234,7 +271,7 @@ func (c *blobDiskCache) ReadAt(key string, offset, length int64) ([]byte, error)
 	c.pushFront(e)
 	c.mu.Unlock()
 
-	f, err := os.Open(c.path(key))
+	f, err := os.Open(p) //nolint:gosec // G304: path() rejects keys with a separator
 	if err != nil {
 		return nil, err
 	}
@@ -276,7 +313,13 @@ func (c *blobDiskCache) Delete(key string) {
 	c.unlink(e)
 	delete(c.items, key)
 	c.curBytes -= e.size
-	_ = os.Remove(c.path(key))
+
+	// The key is already in the map, so it passed path() when it was
+	// inserted; the error cannot occur here.
+	p, err := c.path(key)
+	if err == nil {
+		_ = os.Remove(p)
+	}
 }
 
 // Keys returns a snapshot of all cached keys. Safe for iteration without
@@ -347,8 +390,18 @@ func (c *blobDiskCache) Close() error {
 	return os.RemoveAll(c.dir)
 }
 
-func (c *blobDiskCache) path(key string) string {
+// path returns the on-disk location of the cache file for key. The key is
-	return filepath.Join(c.dir, key)
+// a blob hash read back from the destination and is not trusted: a value
+// such as "aa/../../../home/u/.profile" would otherwise make filepath.Join
+// escape the cache directory, so a key containing a path separator is
+// refused rather than joined.
+func (c *blobDiskCache) path(key string) (string, error) {
+	if strings.ContainsRune(key, '/') ||
+		strings.ContainsRune(key, filepath.Separator) {
+		return "", fmt.Errorf("%w: %q", errCacheKeyHasSeparator, key)
+	}
+
+	return filepath.Join(c.dir, key), nil
 }
 
 func (c *blobDiskCache) unlink(e *blobDiskCacheEntry) {
@@ -391,5 +444,10 @@ func (c *blobDiskCache) evictLRU() {
 	c.unlink(victim)
 	delete(c.items, victim.key)
 	c.curBytes -= victim.size
-	_ = os.Remove(c.path(victim.key))
+
+	// victim.key was validated by path() on insertion, so this cannot err.
+	p, err := c.path(victim.key)
+	if err == nil {
+		_ = os.Remove(p)
+	}
 }

internal/vaultik/blobhash.go

@@ -0,0 +1,52 @@
+package vaultik
+
+import "errors"
+
+// blobHashHexLen is the length of a blob hash written as lowercase hex: a
+// SHA-256 digest is 32 bytes, so 64 characters. Remote snapshot keys are
+// SHA-256 hashes too and share this exact form.
+const blobHashHexLen = 64
+
+// shortHashLen is how many leading characters of a hash appear in log and
+// error text.
+const shortHashLen = 16
+
+// errInvalidBlobHash reports a value used as a blob hash that is not
+// exactly 64 lowercase hex characters. Restore, verify and prune read
+// these values back from the destination, which is not trusted, so each
+// one is checked before it is used to build a path or drive a read.
+var errInvalidBlobHash = errors.New(
+	"blob hash is not 64 lowercase hex characters")
+
+// isBlobHash reports whether s is exactly 64 lowercase hex characters.
+// Every real blob hash and remote snapshot key has this form.
+//
+// The check is a plain function, not a method on types.BlobHash: the
+// packer stores "temp-placeholder-{uuid}" as the hash of an unfinished
+// blob in the local index, so the type itself must keep accepting values
+// that are not hashes.
+func isBlobHash(s string) bool {
+	if len(s) != blobHashHexLen {
+		return false
+	}
+
+	for _, r := range s {
+		if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
+			return false
+		}
+	}
+
+	return true
+}
+
+// shortHash returns the leading part of a hash for log and error text. It
+// never panics: a string shorter than the prefix is returned whole. A hash
+// read from the destination may be malformed, and formatting one for a
+// message must not crash the command.
+func shortHash(s string) string {
+	if len(s) <= shortHashLen {
+		return s
+	}
+
+	return s[:shortHashLen]
+}

internal/vaultik/destination_validation_test.go

@@ -0,0 +1,262 @@
+package vaultik //nolint:testpackage // drives unexported input validation
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/types"
+)
+
+// These tests treat every hash, offset and length read back from the
+// destination as hostile. A blob hash comes from the downloaded snapshot
+// database or the store listing, neither of which is authenticated (see
+// https://git.eeqj.de/sneak/vaultik/issues/155), so each is validated
+// before it is used to build a path or size an allocation.
+
+// TestBlobCacheRejectsKeyWithSeparator proves the arbitrary-file-write
+// hole is closed: a blob hash that climbs out of the cache directory is
+// refused and nothing is written outside it. This is the exact write the
+// restore path performs, keyed by the hash from the snapshot database.
+func TestBlobCacheRejectsKeyWithSeparator(t *testing.T) {
+	t.Parallel()
+
+	cache, err := newBlobDiskCache(1 << 20)
+	require.NoError(t, err)
+
+	defer func() { _ = cache.Close() }()
+
+	target := filepath.Join(t.TempDir(), "pwned")
+
+	// A hash whose relative form escapes the cache directory to target.
+	key, err := filepath.Rel(cache.dir, target)
+	require.NoError(t, err)
+	require.Contains(t, key, "..")
+
+	err = cache.Put(key, []byte("secret"))
+	require.ErrorIs(t, err, errCacheKeyHasSeparator)
+
+	_, err = cache.PutFromReader(key, strings.NewReader("secret"))
+	require.ErrorIs(t, err, errCacheKeyHasSeparator)
+
+	_, statErr := os.Stat(target)
+	require.Truef(t, os.IsNotExist(statErr),
+		"cache wrote outside its directory at %s", target)
+}
+
+// TestBuildBlobIndexesRejectsHostileHash proves restore refuses a snapshot
+// database whose blob_hash escapes the cache directory. buildBlobIndexes is
+// the first place restore reads these hashes back, and it fails there, before
+// any blob is fetched or written, so a hash containing /../ cannot steer a
+// later write outside the cache directory.
+func TestBuildBlobIndexesRejectsHostileHash(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	db, err := database.New(ctx, filepath.Join(t.TempDir(), "index.sqlite"))
+	require.NoError(t, err)
+
+	defer func() { _ = db.Close() }()
+
+	// A blob cache and a target file just outside it. The hostile hash is
+	// the relative path from the cache to that target, so an unguarded
+	// restore keyed by this hash would write there.
+	cache, err := newBlobDiskCache(1 << 20)
+	require.NoError(t, err)
+
+	defer func() { _ = cache.Close() }()
+
+	target := filepath.Join(t.TempDir(), "pwned")
+	hostile, err := filepath.Rel(cache.dir, target)
+	require.NoError(t, err)
+	require.Contains(t, hostile, "..")
+
+	repos := database.NewRepositories(db)
+	require.NoError(t, repos.Blobs.Create(ctx, nil, &database.Blob{
+		ID:        types.NewBlobID(),
+		Hash:      types.BlobHash(hostile),
+		CreatedTS: time.Now().UTC(),
+	}))
+
+	v := NewForTesting(nil)
+	v.SetContext(ctx)
+
+	_, _, err = v.buildBlobIndexes(repos)
+	require.ErrorIs(t, err, errInvalidBlobHash)
+
+	_, statErr := os.Stat(target)
+	require.Truef(t, os.IsNotExist(statErr),
+		"restore wrote outside the cache directory at %s", target)
+}
+
+// TestBlobCacheReadAtRejectsBadBounds proves a blob_chunks row cannot
+// drive an out-of-range or negative read. offset/length reach ReadAt
+// straight from the database.
+func TestBlobCacheReadAtRejectsBadBounds(t *testing.T) {
+	t.Parallel()
+
+	cache, err := newBlobDiskCache(1 << 20)
+	require.NoError(t, err)
+
+	defer func() { _ = cache.Close() }()
+
+	require.NoError(t, cache.Put("blob", make([]byte, 100)))
+
+	_, err = cache.ReadAt("blob", -1, 10)
+	require.ErrorIs(t, err, errCacheNegativeRead)
+
+	_, err = cache.ReadAt("blob", 0, -1)
+	require.ErrorIs(t, err, errCacheNegativeRead)
+
+	// A length past the end is rejected via the subtraction bound, so a
+	// huge offset+length cannot overflow past the check.
+	_, err = cache.ReadAt("blob", 50, 60)
+	require.ErrorIs(t, err, errCacheReadBeyondBlob)
+}
+
+// TestListAllRemoteBlobsSkipsNonConformingName proves a bogus object name
+// under blobs/ (here a three-character name) is skipped rather than
+// entering the blob map, so prune's later hash[:2]/hash[2:4] path build
+// cannot panic on it.
+func TestListAllRemoteBlobsSkipsNonConformingName(t *testing.T) {
+	// Initialize the global logger before t.Parallel() so the write lands
+	// in the serial phase and cannot race other parallel tests reading it.
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	good := strings.Repeat("a", blobHashHexLen)
+	store := &stubLister{objects: []storage.ObjectInfo{
+		{Key: "blobs/" + good[:2] + "/" + good[2:4] + "/" + good, Size: 10},
+		{Key: "blobs/a/b/c", Size: 3},
+	}}
+
+	v := &Vaultik{Storage: store}
+	v.SetContext(context.Background())
+
+	blobs, err := v.listAllRemoteBlobs()
+	require.NoError(t, err)
+	require.Contains(t, blobs, good)
+	require.NotContains(t, blobs, "c")
+	require.Len(t, blobs, 1)
+}
+
+// TestVerifyManifestBlobsRejectsShortHash proves a manifest (which is not
+// authenticated) with a short blob hash fails cleanly instead of panicking
+// on blob.Hash[:2].
+func TestVerifyManifestBlobsRejectsShortHash(t *testing.T) {
+	t.Parallel()
+
+	v := &Vaultik{Stdout: io.Discard}
+	manifest := &snapshot.Manifest{
+		Blobs: []snapshot.BlobInfo{{Hash: "abc", CompressedSize: 1}},
+	}
+
+	verified, missing, mismatched, missingSize, err :=
+		v.verifyManifestBlobs(manifest, &VerifyOptions{JSON: true})
+	require.ErrorIs(t, err, errInvalidBlobHash)
+	require.Zero(t, verified)
+	require.Zero(t, missing)
+	require.Zero(t, mismatched)
+	require.Zero(t, missingSize)
+}
+
+// TestVerifyBlobChunksRejectsNegativeLength proves a blob_chunks row with a
+// negative length returns an error rather than reaching make([]byte,
+// length) or streaming an untrusted size.
+func TestVerifyBlobChunksRejectsNegativeLength(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	db, err := database.New(ctx, filepath.Join(t.TempDir(), "index.sqlite"))
+	require.NoError(t, err)
+
+	defer func() { _ = db.Close() }()
+
+	repos := database.NewRepositories(db)
+	blobHash := strings.Repeat("b", blobHashHexLen)
+	blob := &database.Blob{
+		ID:        types.NewBlobID(),
+		Hash:      types.BlobHash(blobHash),
+		CreatedTS: time.Now().UTC(),
+	}
+	require.NoError(t, repos.Blobs.Create(ctx, nil, blob))
+
+	chunkHash := strings.Repeat("c", blobHashHexLen)
+	require.NoError(t, repos.Chunks.Create(ctx, nil,
+		&database.Chunk{ChunkHash: types.ChunkHash(chunkHash), Size: 1024}))
+	require.NoError(t, repos.BlobChunks.Create(ctx, nil, &database.BlobChunk{
+		BlobID:    blob.ID,
+		ChunkHash: types.ChunkHash(chunkHash),
+		Offset:    0,
+		Length:    -1,
+	}))
+
+	v := NewForTesting(nil)
+
+	_, err = v.verifyBlobChunks(db.Conn(), blobHash, strings.NewReader(""))
+	require.ErrorIs(t, err, errNegativeChunkLength)
+}
+
+// errStubUnused marks a stubLister method a test never exercises.
+var errStubUnused = errors.New("stubLister method not used in test")
+
+// stubLister is a storage.Storer whose ListStream yields a fixed set of
+// objects; every other method is unused by the tests here.
+type stubLister struct {
+	objects []storage.ObjectInfo
+}
+
+func (s *stubLister) ListStream(
+	_ context.Context, prefix string,
+) <-chan storage.ObjectInfo {
+	ch := make(chan storage.ObjectInfo, len(s.objects))
+	for _, o := range s.objects {
+		if strings.HasPrefix(o.Key, prefix) {
+			ch <- o
+		}
+	}
+
+	close(ch)
+
+	return ch
+}
+
+func (s *stubLister) Put(_ context.Context, _ string, _ io.Reader) error {
+	return errStubUnused
+}
+
+func (s *stubLister) PutWithProgress(
+	_ context.Context, _ string, _ io.Reader, _ int64, _ storage.ProgressCallback,
+) error {
+	return errStubUnused
+}
+
+func (s *stubLister) Get(_ context.Context, _ string) (io.ReadCloser, error) {
+	return nil, errStubUnused
+}
+
+func (s *stubLister) Stat(_ context.Context, _ string) (*storage.ObjectInfo, error) {
+	return nil, errStubUnused
+}
+
+func (s *stubLister) Delete(_ context.Context, _ string) error {
+	return errStubUnused
+}
+
+func (s *stubLister) List(_ context.Context, _ string) ([]string, error) {
+	return nil, errStubUnused
+}
+
+func (s *stubLister) Info() storage.Info {
+	return storage.Info{}
+}

internal/vaultik/fault_injection_test.go

@@ -0,0 +1,647 @@
+package vaultik_test
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/storage/faultstore"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// These tests cover the failure modes a backup tool must survive:
+// interrupted uploads, an interrupted metadata export, corrupt and
+// truncated reads, a full restore disk, and a backend that reports
+// success while storing nothing. Faults are injected through the
+// storage.Storer seam (internal/storage/faultstore), never by patching
+// production code. Each test asserts on the observable end state — what
+// is in the index, what is at the destination, what the user is told —
+// not merely that an error was returned. See
+// https://git.eeqj.de/sneak/vaultik/issues/72.
+//
+// Object-level write atomicity (no partial blob object left behind) is
+// covered by the file:// backend's atomic-write work
+// (https://git.eeqj.de/sneak/vaultik/issues/130) and is not re-tested
+// here; these tests target the layers above the backend.
+//
+// The tests run serially, not with t.Parallel: each calls
+// log.Initialize, which replaces the package-global logger, and a
+// backup or restore running concurrently reads that same logger. Under
+// -race the two collide. Running one at a time is the same choice
+// prune_count_test.go already makes for the same reason.
+
+const (
+	faultChunkSize   = int64(64 * 1024)
+	faultMaxBlobSize = int64(256 * 1024)
+)
+
+// faultTestConfig returns the config shared by the fault-injection
+// tests: a real recipient/secret keypair so blobs are genuinely
+// encrypted, and a blob size limit the restore sweeper can divide.
+func faultTestConfig() *config.Config {
+	return &config.Config{
+		AgeRecipients:    []string{testAgePublicKey},
+		AgeSecretKey:     testAgeSecretKey,
+		CompressionLevel: 3,
+		Hostname:         testHostname,
+		BlobSizeLimit:    config.Size(faultMaxBlobSize),
+	}
+}
+
+// writeFaultSourceTree writes a spread of file sizes that forces several
+// chunks across more than one blob, so a fault landing on a single blob
+// still leaves other data intact. Returns the expected content by path.
+func writeFaultSourceTree(
+	t *testing.T, fs afero.Fs, dataDir string,
+) map[string][]byte {
+	t.Helper()
+
+	files := map[string][]byte{
+		filepath.Join(dataDir, "small.txt"):    []byte("hello vaultik"),
+		filepath.Join(dataDir, "a.bin"):        bytesPattern("a-", int(faultChunkSize*3)),
+		filepath.Join(dataDir, "sub", "b.bin"): bytesPattern("b-", int(faultChunkSize*3)),
+		filepath.Join(dataDir, "sub", "c.bin"): bytesPattern("c-", int(faultChunkSize*2)),
+	}
+
+	for path, content := range files {
+		require.NoError(t, fs.MkdirAll(filepath.Dir(path), 0o755))
+		require.NoError(t, afero.WriteFile(fs, path, content, 0o644))
+	}
+
+	return files
+}
+
+// newFaultScanner builds a scanner writing through the given storer.
+func newFaultScanner(
+	fs afero.Fs, storer storage.Storer,
+	cfg *config.Config, repos *database.Repositories,
+) *snapshot.Scanner {
+	return snapshot.NewScanner(snapshot.ScannerConfig{
+		FS:               fs,
+		Storage:          storer,
+		ChunkSize:        faultChunkSize,
+		MaxBlobSize:      faultMaxBlobSize,
+		CompressionLevel: cfg.CompressionLevel,
+		AgeRecipients:    cfg.AgeRecipients,
+		Repositories:     repos,
+	})
+}
+
+// newFaultSnapshotManager builds a snapshot manager writing through the
+// given storer.
+func newFaultSnapshotManager(
+	fs afero.Fs, storer storage.Storer,
+	cfg *config.Config, repos *database.Repositories,
+) *snapshot.SnapshotManager {
+	sm := snapshot.NewSnapshotManager(snapshot.SnapshotManagerParams{
+		Repos:   repos,
+		Storage: storer,
+		Config:  cfg,
+	})
+	sm.SetFilesystem(fs)
+
+	return sm
+}
+
+// fullFaultBackup runs a complete backup (create, scan, complete,
+// export) through storer and returns the snapshot ID.
+func fullFaultBackup(
+	ctx context.Context, t *testing.T, fs afero.Fs, storer storage.Storer,
+	cfg *config.Config, repos *database.Repositories,
+	dataDir, dbPath, name string,
+) string {
+	t.Helper()
+
+	sm := newFaultSnapshotManager(fs, storer, cfg, repos)
+	scanner := newFaultScanner(fs, storer, cfg, repos)
+
+	id, err := sm.CreateSnapshotWithName(ctx, cfg.Hostname, name, "v", "g")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, id)
+	require.NoError(t, err)
+
+	require.NoError(t, sm.CompleteSnapshot(ctx, id))
+	require.NoError(t, sm.ExportSnapshotMetadata(ctx, dbPath, id))
+
+	return id
+}
+
+// newReaderVaultik builds a Vaultik that reads (restore/verify) through
+// storer, with the given repositories (nil is fine for restore/verify,
+// which read metadata from storage).
+func newReaderVaultik(
+	ctx context.Context, cfg *config.Config, storer storage.Storer,
+	repos *database.Repositories, fs afero.Fs,
+) *vaultik.Vaultik {
+	v := &vaultik.Vaultik{
+		Config:       cfg,
+		Storage:      storer,
+		Repositories: repos,
+		Fs:           fs,
+		Stdout:       io.Discard,
+		Stderr:       io.Discard,
+		UI:           ui.NewWithColor(io.Discard, false),
+	}
+	v.SetContext(ctx)
+
+	return v
+}
+
+// Scenario 3: a stored blob's bytes are flipped before restore reads
+// them. Restore must fail loudly, and no file must be left on the
+// restore target holding corrupt content.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestRestoreRejectsCorruptBlob(t *testing.T) {
+	assertRestoreRejectsDamagedBlob(t, faultstore.GetCorrupt, "corrupt")
+}
+
+// Scenario 4: a stored blob is truncated before restore reads it. Same
+// contract as the corrupt case.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestRestoreRejectsTruncatedBlob(t *testing.T) {
+	assertRestoreRejectsDamagedBlob(t, faultstore.GetTruncate, "truncated")
+}
+
+// assertRestoreRejectsDamagedBlob backs up the source tree, then restores
+// through a store that damages every blob read with the given fault, and
+// asserts restore fails naming a blob and leaves no file on the target
+// holding wrong bytes. Metadata reads are returned intact so the failure
+// is isolated to the blob.
+func assertRestoreRejectsDamagedBlob(
+	t *testing.T, fault faultstore.GetFault, name string,
+) {
+	t.Helper()
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	restoreDir := filepath.Join(tempDir, "restored")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+	testFiles := writeFaultSourceTree(t, fs, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	id := fullFaultBackup(ctx, t, fs, inner, cfg, repos, dataDir, dbPath, name)
+	require.NoError(t, db.Close())
+
+	faultStore := faultstore.New(inner)
+	faultStore.OnGet = func(key string) faultstore.GetFault {
+		if strings.HasPrefix(key, "blobs/") {
+			return fault
+		}
+
+		return faultstore.GetNormal
+	}
+
+	v := newReaderVaultik(ctx, cfg, faultStore, nil, fs)
+	err = v.Restore(&vaultik.RestoreOptions{SnapshotID: id, TargetDir: restoreDir})
+
+	require.Error(t, err, "restore must fail on a damaged blob")
+	assert.Contains(t, err.Error(), "blob",
+		"error should name the blob that failed")
+	assertNoCorruptFiles(t, fs, restoreDir, testFiles)
+}
+
+// Scenario 6: the backend accepts blob uploads and reports success but
+// stores nothing. verify --deep must catch it.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestDeepVerifyCatchesLyingBackend(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+
+	writeFaultSourceTree(t, fs, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	// Blob uploads are swallowed; metadata uploads land, so verify can
+	// download the manifest and database and then discover the blobs are
+	// absent.
+	lying := faultstore.New(inner)
+	lying.OnPut = func(key string) faultstore.PutAction {
+		if strings.HasPrefix(key, "blobs/") {
+			return faultstore.PutSwallow
+		}
+
+		return faultstore.PutNormal
+	}
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	id := fullFaultBackup(ctx, t, fs, lying, cfg, repos, dataDir, dbPath, "lying")
+	require.NoError(t, db.Close())
+
+	// No blob objects were actually written.
+	blobKeys, err := inner.List(ctx, "blobs/")
+	require.NoError(t, err)
+	assert.Empty(t, blobKeys, "lying backend should have stored no blobs")
+
+	// Read back through the honest underlying store.
+	v := newReaderVaultik(ctx, cfg, inner, nil, fs)
+	err = v.VerifySnapshotWithOptions(id, &vaultik.VerifyOptions{Deep: true})
+	require.Error(t, err, "deep verify must catch a backend that stored nothing")
+}
+
+// Scenario 1a: a blob upload fails partway through. The interrupted run
+// must not record the blob as uploaded, must not reference it from the
+// snapshot, and must leave no blob object at the destination.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestInterruptedBlobUploadRecordsNoUploadedBlob(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+
+	writeFaultSourceTree(t, fs, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	defer func() { _ = db.Close() }()
+
+	repos := database.NewRepositories(db)
+
+	// Every blob upload fails partway through. The scan must surface it.
+	fault := faultstore.New(inner)
+	fault.OnPut = func(key string) faultstore.PutAction {
+		if strings.HasPrefix(key, "blobs/") {
+			return faultstore.PutFail
+		}
+
+		return faultstore.PutNormal
+	}
+
+	sm := newFaultSnapshotManager(fs, fault, cfg, repos)
+	scanner := newFaultScanner(fs, fault, cfg, repos)
+
+	id, err := sm.CreateSnapshotWithName(ctx, cfg.Hostname, "interrupted", "v", "g")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, id)
+	require.Error(t, err, "scan must fail when a blob upload fails")
+
+	// No blob may claim to be uploaded.
+	blobs, err := repos.Blobs.GetAll(ctx)
+	require.NoError(t, err)
+
+	for _, b := range blobs {
+		assert.Nilf(t, b.UploadedTS,
+			"blob %s marked uploaded after a failed upload", b.Hash)
+	}
+
+	// The snapshot may reference no blobs, and the destination holds none.
+	hashes, err := repos.Snapshots.GetBlobHashes(ctx, id)
+	require.NoError(t, err)
+	assert.Empty(t, hashes, "interrupted snapshot must reference no blobs")
+
+	blobKeys, err := inner.List(ctx, "blobs/")
+	require.NoError(t, err)
+	assert.Empty(t, blobKeys, "no blob object may survive at the destination")
+}
+
+// Scenario 1b: after an interrupted upload, a retry on the same local
+// index must produce a restorable snapshot. The interrupted run leaves
+// the blob's chunk rows in the index; the fix for
+// https://git.eeqj.de/sneak/vaultik/issues/148 discards those un-uploaded
+// blob rows at the start of the next scan and deduplicates only against
+// chunks in a blob that was actually uploaded, so the retry re-chunks and
+// re-uploads the affected data instead of silently referencing data that
+// never reached storage.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestBackupRetryAfterInterruptedUploadIsRestorable(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	restoreDir := filepath.Join(tempDir, "restored")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+	testFiles := writeFaultSourceTree(t, fs, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	// Attempt 1: every blob upload fails.
+	fault := faultstore.New(inner)
+	fault.OnPut = func(key string) faultstore.PutAction {
+		if strings.HasPrefix(key, "blobs/") {
+			return faultstore.PutFail
+		}
+
+		return faultstore.PutNormal
+	}
+
+	sm := newFaultSnapshotManager(fs, fault, cfg, repos)
+	scanner := newFaultScanner(fs, fault, cfg, repos)
+
+	id1, err := sm.CreateSnapshotWithName(ctx, cfg.Hostname, "interrupted", "v", "g")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, id1)
+	require.Error(t, err)
+
+	// Retry on the same local index with a working backend.
+	id2 := fullFaultBackup(ctx, t, fs, inner, cfg, repos, dataDir, dbPath, "retry")
+	require.NoError(t, db.Close())
+
+	v := newReaderVaultik(ctx, cfg, inner, nil, fs)
+	require.NoError(t, v.Restore(&vaultik.RestoreOptions{
+		SnapshotID: id2,
+		TargetDir:  restoreDir,
+		Verify:     true,
+	}), "retry after an interrupted upload must produce a restorable snapshot")
+
+	assertRestoredTree(t, fs, restoreDir, testFiles)
+}
+
+// Scenario 2: the process dies during the metadata export, after the
+// database is uploaded but before the manifest. The destination is left
+// with blobs and a database but no manifest. verify and snapshot list
+// must report the damage honestly rather than crashing or passing.
+// Automatic detection and repair of this partial state on the next run
+// is tracked in https://git.eeqj.de/sneak/vaultik/issues/177 and is not
+// asserted here.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestBackupSurvivesMetadataExportInterruption(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+
+	writeFaultSourceTree(t, fs, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	// Back up and complete with a working backend.
+	sm := newFaultSnapshotManager(fs, inner, cfg, repos)
+	scanner := newFaultScanner(fs, inner, cfg, repos)
+
+	id, err := sm.CreateSnapshotWithName(ctx, cfg.Hostname, "export", "v", "g")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, id)
+	require.NoError(t, err)
+	require.NoError(t, sm.CompleteSnapshot(ctx, id))
+
+	// Export through a backend that fails only the manifest upload. The
+	// database uploads first and lands; the manifest does not.
+	fault := faultstore.New(inner)
+	fault.OnPut = func(key string) faultstore.PutAction {
+		if strings.HasSuffix(key, "manifest.json.zst") {
+			return faultstore.PutFail
+		}
+
+		return faultstore.PutNormal
+	}
+
+	smFault := newFaultSnapshotManager(fs, fault, cfg, repos)
+
+	err = smFault.ExportSnapshotMetadata(ctx, dbPath, id)
+	require.Error(t, err, "export must fail when the manifest upload fails")
+
+	// The destination is in the partial state the scenario describes.
+	key := snapshot.RemoteSnapshotKey(id)
+
+	_, err = inner.Stat(ctx, "metadata/"+key+"/db.zst.age")
+	require.NoError(t, err, "database should have been uploaded before the manifest")
+
+	_, err = inner.Stat(ctx, "metadata/"+key+"/manifest.json.zst")
+	require.ErrorIs(t, err, storage.ErrNotFound, "manifest upload should not have landed")
+
+	// verify must fail loudly for this snapshot, in both modes.
+	reader := newReaderVaultik(ctx, cfg, inner, repos, fs)
+
+	deepOpts := &vaultik.VerifyOptions{Deep: true}
+	require.Error(t, reader.VerifySnapshotWithOptions(id, deepOpts),
+		"deep verify must report the missing manifest")
+
+	shallowOpts := &vaultik.VerifyOptions{Deep: false}
+	require.Error(t, reader.VerifySnapshotWithOptions(id, shallowOpts),
+		"shallow verify must report the missing manifest")
+
+	// snapshot list must not crash on the partial snapshot.
+	require.NoError(t, reader.ListSnapshots(false),
+		"snapshot list must tolerate a partially-exported snapshot")
+}
+
+// Scenario 5: the restore target runs out of space mid-file. Restore
+// must fail with an out-of-space error, and must not leave a truncated
+// file at the target path presenting as a complete restore. Restore
+// today writes each file straight to its final path and does not remove
+// it when a write fails, so the truncated file survives; deleting it is
+// tracked by https://git.eeqj.de/sneak/vaultik/issues/163. Skipped until
+// that lands, so the destination assertion below is recorded rather than
+// dropped.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestRestoreReportsDiskFull(t *testing.T) {
+	t.Skip("blocked on https://git.eeqj.de/sneak/vaultik/issues/163: " +
+		"a disk-full write leaves a truncated file at the target path " +
+		"instead of removing it")
+	log.Initialize(log.Config{})
+
+	osFS := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	restoreDir := filepath.Join(tempDir, "restored")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	ctx := context.Background()
+	cfg := faultTestConfig()
+
+	testFiles := writeFaultSourceTree(t, osFS, dataDir)
+
+	inner, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	id := fullFaultBackup(ctx, t, osFS, inner, cfg, repos, dataDir, dbPath, "diskfull")
+	require.NoError(t, db.Close())
+
+	// Restore onto a filesystem that allows only a few bytes of file
+	// content: enough to create files, far too little to hold them.
+	budget := int64(8)
+	quota := &quotaFS{Fs: osFS, remaining: &budget}
+
+	v := newReaderVaultik(ctx, cfg, inner, nil, quota)
+	err = v.Restore(&vaultik.RestoreOptions{SnapshotID: id, TargetDir: restoreDir})
+
+	require.Error(t, err, "restore must fail when the target disk is full")
+	assert.Contains(t, err.Error(), errNoSpace.Error(),
+		"restore error should surface the out-of-space cause")
+
+	// The failure must not leave a truncated file behind presenting as a
+	// complete restore: any file at the target must hold the original
+	// bytes, or be absent.
+	assertNoCorruptFiles(t, osFS, restoreDir, testFiles)
+}
+
+// assertRestoredTree byte-compares every restored file against the
+// original.
+func assertRestoredTree(
+	t *testing.T, fs afero.Fs, restoreDir string, testFiles map[string][]byte,
+) {
+	t.Helper()
+
+	for origPath, expected := range testFiles {
+		restoredPath := filepath.Join(restoreDir, origPath)
+		got, err := afero.ReadFile(fs, restoredPath)
+		require.NoErrorf(t, err, "restored file missing: %s", origPath)
+		require.Equalf(t, expected, got, "restored content mismatch for %s", origPath)
+	}
+}
+
+// errNoSpace is the out-of-space error quotaFS returns once its byte
+// budget is exhausted, mirroring a real ENOSPC.
+var errNoSpace = errors.New("no space left on device")
+
+// quotaFS is an afero.Fs whose files may write only a fixed total number
+// of content bytes before failing, simulating a full restore target. It
+// wraps the interface so every method except Create delegates to the
+// real filesystem; only file writes are capped.
+type quotaFS struct {
+	afero.Fs
+
+	remaining *int64
+}
+
+//nolint:ireturn // afero.Fs.Create's signature requires returning afero.File.
+func (q *quotaFS) Create(name string) (afero.File, error) {
+	f, err := q.Fs.Create(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &quotaFile{File: f, remaining: q.remaining}, nil
+}
+
+// quotaFile fails writes once the shared byte budget is exhausted.
+type quotaFile struct {
+	afero.File
+
+	remaining *int64
+}
+
+func (q *quotaFile) Write(p []byte) (int, error) {
+	if *q.remaining <= 0 {
+		return 0, errNoSpace
+	}
+
+	allowed := min(int64(len(p)), *q.remaining)
+
+	n, err := q.File.Write(p[:allowed])
+	*q.remaining -= int64(n)
+
+	if err != nil {
+		return n, err
+	}
+
+	if int64(n) < int64(len(p)) {
+		return n, errNoSpace
+	}
+
+	return n, nil
+}
+
+// assertNoCorruptFiles fails if any file that made it to the restore
+// target holds content that differs from the original: a failed restore
+// may leave a file absent, but must never leave wrong bytes presenting
+// as the real file.
+func assertNoCorruptFiles(
+	t *testing.T, fs afero.Fs, restoreDir string, testFiles map[string][]byte,
+) {
+	t.Helper()
+
+	for origPath, expected := range testFiles {
+		restoredPath := filepath.Join(restoreDir, origPath)
+
+		got, err := afero.ReadFile(fs, restoredPath)
+		if err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+
+			require.NoError(t, err)
+		}
+
+		assert.Equalf(t, expected, got,
+			"restored file %s holds corrupt content", origPath)
+	}
+}

internal/vaultik/prune.go

@@ -167,6 +167,12 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 
 // collectReferencedBlobs downloads all manifests and returns the set of
 // referenced blob hashes.
+//
+// Every manifest must be read successfully. A manifest that cannot be
+// downloaded or decoded means its snapshot's blobs are unknown, so
+// treating them as unreferenced would let prune delete data a snapshot
+// still needs. Rather than risk that silent loss, any failure returns an
+// error naming the remote key and prune deletes nothing.
 func (v *Vaultik) collectReferencedBlobs() (map[string]bool, error) {
 	log.Info("Listing remote snapshots")
 	// IDs returned by listUniqueSnapshotIDs are remote keys (hashed
@@ -179,27 +185,22 @@ func (v *Vaultik) collectReferencedBlobs() (map[string]bool, error) {
 	log.Info("Found manifests in remote storage", "count", len(remoteKeys))
 
 	allBlobsReferenced := make(map[string]bool)
-	manifestCount := 0
 
 	for _, remoteKey := range remoteKeys {
 		log.Debug("Processing manifest", "remote_key", remoteKey)
 
 		manifest, err := v.downloadManifestByKey(remoteKey)
 		if err != nil {
-			log.Error("Failed to download manifest", "remote_key", remoteKey, "error", err)
+			return nil, fmt.Errorf("reading manifest %s: %w", remoteKey, err)
-
-			continue
 		}
 
 		for _, blob := range manifest.Blobs {
 			allBlobsReferenced[blob.Hash] = true
 		}
-
-		manifestCount++
 	}
 
 	log.Info("Processed manifests",
-		"count", manifestCount, "unique_blobs_referenced", len(allBlobsReferenced))
+		"count", len(remoteKeys), "unique_blobs_referenced", len(allBlobsReferenced))
 
 	return allBlobsReferenced, nil
 }
@@ -246,9 +247,22 @@ func (v *Vaultik) listAllRemoteBlobs() (map[string]int64, error) {
 		}
 
 		parts := strings.Split(object.Key, "/")
-		if len(parts) == blobKeyParts && parts[0] == "blobs" {
+		if len(parts) != blobKeyParts || parts[0] != "blobs" {
-			allBlobs[parts[3]] = object.Size
+			continue
 		}
+
+		// The object name is read from the destination store and is not
+		// trusted. A name that is not a blob hash (e.g. a short or
+		// non-hex string) would panic the later hash[:2]/hash[2:4] path
+		// build, so skip it with a warning rather than delete it.
+		if !isBlobHash(parts[3]) {
+			log.Warn("Skipping non-conforming object under blobs/",
+				"key", object.Key)
+
+			continue
+		}
+
+		allBlobs[parts[3]] = object.Size
 	}
 
 	log.Info("Found blobs in storage", "count", len(allBlobs))

internal/vaultik/prune_manifest_safety_test.go

@@ -0,0 +1,47 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestPruneBlobs_UnreadableManifestDeletesNothing is the regression guard
+// for issue #157: prune identifies referenced blobs by reading every
+// snapshot's manifest, and a manifest it cannot decode used to be logged
+// and skipped. Blobs referenced only by that snapshot then looked
+// unreferenced and were deleted, with a zero exit — silent backup loss,
+// made worse by `snapshot create --prune` running unattended with force.
+//
+// The single blob here is referenced only by the snapshot whose manifest
+// is corrupt, so the old behaviour would delete it and succeed. Prune
+// must instead delete nothing and return an error.
+func TestPruneBlobs_UnreadableManifestDeletesNothing(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newListEnv(t)
+	ctx := context.Background()
+
+	blobKey := "blobs/" + testBlobHashA[:2] + "/" + testBlobHashA[2:4] +
+		"/" + testBlobHashA
+	require.NoError(t, env.store.Put(ctx, blobKey,
+		bytes.NewReader([]byte("blob-bytes"))))
+
+	// A manifest at the path prune reads, but with contents it cannot
+	// decode.
+	require.NoError(t, env.store.Put(ctx,
+		"metadata/corruptkey/manifest.json.zst",
+		bytes.NewReader([]byte("not a valid manifest"))))
+
+	err := env.v.PruneBlobs(&vaultik.PruneOptions{Force: true})
+
+	require.Error(t, err, "prune must fail when a manifest cannot be read")
+	assert.True(t, env.store.hasKey(blobKey),
+		"no blob may be deleted when a manifest is unreadable")
+}

internal/vaultik/purge_local_remote_consistency_test.go

@@ -0,0 +1,146 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/types"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// setupConsistencyTest builds a Vaultik whose local database and mock
+// remote both hold the given snapshots. Remote metadata is stored under
+// the production layout, metadata/<RemoteSnapshotKey(id)>/manifest.json.zst.
+// It returns the instance and the mock so a test can inspect the remote.
+func setupConsistencyTest(
+	t *testing.T, snapshotIDs []string,
+) (*vaultik.Vaultik, *MockStorer) {
+	t.Helper()
+
+	ctx := context.Background()
+	db, err := database.New(ctx, ":memory:")
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+	mockStorage := NewMockStorer()
+
+	for _, id := range snapshotIDs {
+		parts := strings.Split(id, "_")
+		startedAt, err := time.Parse(time.RFC3339, parts[len(parts)-1])
+		require.NoError(t, err, "parsing timestamp from snapshot ID %q", id)
+
+		completedAt := startedAt.Add(5 * time.Minute)
+		snap := &database.Snapshot{
+			ID:             types.SnapshotID(id),
+			Hostname:       testHostname,
+			VaultikVersion: testLabel,
+			StartedAt:      startedAt,
+			CompletedAt:    &completedAt,
+		}
+		err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+			return repos.Snapshots.Create(ctx, tx, snap)
+		})
+		require.NoError(t, err, "creating snapshot %s", id)
+
+		metadataKey := "metadata/" + snapshot.RemoteSnapshotKey(id) +
+			"/manifest.json.zst"
+		err = mockStorage.Put(ctx, metadataKey, strings.NewReader("stub"))
+		require.NoError(t, err)
+	}
+
+	v := &vaultik.Vaultik{
+		Storage:      mockStorage,
+		Repositories: repos,
+		DB:           db,
+		Stdout:       &bytes.Buffer{},
+		Stderr:       &bytes.Buffer{},
+		Stdin:        &bytes.Buffer{},
+	}
+	v.SetContext(ctx)
+
+	return v, mockStorage
+}
+
+func remoteHasSnapshot(t *testing.T, m *MockStorer, id string) bool {
+	t.Helper()
+
+	prefix := "metadata/" + snapshot.RemoteSnapshotKey(id) + "/"
+	keys, err := m.List(context.Background(), prefix)
+	require.NoError(t, err)
+
+	return len(keys) > 0
+}
+
+// TestPurgeKeepsRemotelyBackedLocalRows guards against issue #160
+// (https://git.eeqj.de/sneak/vaultik/issues/160): purge reconciles local
+// rows against the remote first, and that step compared human snapshot IDs
+// against the hashed remote directory names, which never match — so it
+// deleted every local record and the purge itself then removed nothing.
+//
+// With every snapshot still present remotely and nothing old enough to
+// purge, all local rows must survive the reconcile untouched.
+func TestPurgeKeepsRemotelyBackedLocalRows(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ids := []string{snapHomeT0, snapHomeT1, snapSystemT0}
+
+	v, _ := setupConsistencyTest(t, ids)
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		// 100 years: nothing is old enough to delete, so the reconcile
+		// is the only thing that touches the rows.
+		OlderThan: "36500d",
+		Force:     true,
+	})
+	require.NoError(t, err)
+
+	remaining := listRemainingSnapshots(t, v)
+	assert.Len(t, remaining, len(ids),
+		"remotely-backed local rows must survive the reconcile")
+	assert.Contains(t, remaining, snapHomeT0)
+	assert.Contains(t, remaining, snapHomeT1)
+	assert.Contains(t, remaining, snapSystemT0)
+}
+
+// TestPurgeRemovesLocalAndRemoteTogether proves the two halves stay
+// consistent: a purged snapshot is gone both locally and remotely, while a
+// retained one keeps both. Before the fix, the reconcile dropped every
+// local row yet the remote metadata was left in place.
+func TestPurgeRemovesLocalAndRemoteTogether(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ids := []string{snapHomeT0, snapHomeT1, snapSystemT0}
+
+	v, mock := setupConsistencyTest(t, ids)
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		KeepLatest: true,
+		Force:      true,
+	})
+	require.NoError(t, err)
+
+	// Keep latest per name: newest home and the lone system are kept.
+	remaining := listRemainingSnapshots(t, v)
+	assert.ElementsMatch(t, []string{snapHomeT1, snapSystemT0}, remaining)
+
+	// Local and remote agree: the older home snapshot is gone from both,
+	// the retained ones are present in both.
+	assert.False(t, remoteHasSnapshot(t, mock, snapHomeT0),
+		"purged snapshot must also be removed remotely")
+	assert.True(t, remoteHasSnapshot(t, mock, snapHomeT1),
+		"retained snapshot must remain remotely")
+	assert.True(t, remoteHasSnapshot(t, mock, snapSystemT0),
+		"retained snapshot must remain remotely")
+}

internal/vaultik/purge_per_name_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/types"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -60,8 +61,11 @@ func setupPurgeTest(t *testing.T, snapshotIDs []string) *vaultik.Vaultik {
 		})
 		require.NoError(t, err, "creating snapshot %s", id)
 
-		// Create remote metadata stub so syncWithRemote keeps it
+		// Create the remote metadata stub under the production layout so
-		metadataKey := "metadata/" + id + "/manifest.json.zst"
+		// syncWithRemote keeps the local row. Production stores metadata
+		// under the hashed remote key, not the human snapshot ID.
+		metadataKey := "metadata/" + snapshot.RemoteSnapshotKey(id) +
+			"/manifest.json.zst"
 		err = mockStorage.Put(ctx, metadataKey, strings.NewReader("stub"))
 		require.NoError(t, err)
 	}

internal/vaultik/restore.go

@@ -1,7 +1,6 @@
 package vaultik
 
 import (
-	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
@@ -11,6 +10,7 @@ import (
 	"math"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"filippo.io/age"
@@ -18,6 +18,7 @@ import (
 	"sneak.berlin/go/vaultik/internal/blobgen"
 	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
@@ -28,19 +29,47 @@ var (
 	errDecryptionKeyRequired = errors.New(
 		"decryption key required for restore\n\n" +
 			"Set the VAULTIK_AGE_SECRET_KEY environment variable to your " +
-			"age private key:\n" +
+			"age private key file:\n" +
-			"  export VAULTIK_AGE_SECRET_KEY='AGE-SECRET-KEY-...'")
+			"  export VAULTIK_AGE_SECRET_KEY=\"$(cat vaultik_backup_private_key.txt)\"")
-	errBlobMissingFromIndex = errors.New("blob hash missing from blob index")
+	// errInvalidAgeSecretKey is returned when the configured key does not
-	errChunkNotInAnyBlob    = errors.New("chunk not found in any blob")
+	// parse as any age identity. It names the source but never the value,
-	errBlobIDNotInHashIndex = errors.New("blob id missing from hash index")
+	// which is secret, so the message is safe to print and log.
-	errShortChunkRead       = errors.New("short read")
+	errInvalidAgeSecretKey = errors.New(
+		"configured age secret key holds no usable age identity")
+	errBlobMissingFromIndex     = errors.New("blob hash missing from blob index")
+	errChunkNotInAnyBlob        = errors.New("chunk not found in any blob")
+	errBlobIDNotInHashIndex     = errors.New("blob id missing from hash index")
+	errShortChunkRead           = errors.New("short read")
+	errRestorePathEscapesTarget = errors.New(
+		"refusing to restore path outside the target directory")
+	errTrailingRestoreData = errors.New(
+		"restored file has trailing data after its last chunk")
+	errRestoreIncomplete = errors.New(
+		"restore loop ended with files still pending")
+	errSnapshotDBMismatch = errors.New(
+		"decrypted database is not the requested snapshot")
+	// errEmptySnapshotDB is returned when the decrypted metadata database has
+	// zero length, which happens when the object was truncated or replaced
+	// with an empty payload. Rejected before any schema is built on it.
+	errEmptySnapshotDB = errors.New("decrypted snapshot database is empty")
 )
 
+// snapshotDBFilename is the name the decrypted snapshot database is
+// written under inside its private temp directory.
+const snapshotDBFilename = "snapshot.db"
+
 // restoreDirMode is the permission mode for directories created while
 // restoring (parent directories and the target root; restored
 // directories themselves get their stored mode).
 const restoreDirMode = 0o755
 
+// restoreFileMode is the restrictive mode a regular file is created with
+// during restore. Content is written while the file holds this mode; the
+// stored mode is applied only after the file is fully written and closed,
+// so a file whose stored mode is restrictive is never briefly readable by
+// other local users while its content is being written.
+const restoreFileMode = 0o600
+
 // sweepIntervalDivisor sets the sweeper threshold to one N-th of the
 // configured blob size limit.
 const sweepIntervalDivisor = 100
@@ -76,7 +105,7 @@ type RestoreResult struct {
 func (v *Vaultik) Restore(opts *RestoreOptions) error {
 	startTime := time.Now()
 
-	identity, err := v.prepareRestoreIdentity()
+	identities, err := v.restoreIdentities()
 	if err != nil {
 		return err
 	}
@@ -90,7 +119,7 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 	// Step 1: Download and decrypt the snapshot metadata database
 	log.Info("Downloading snapshot metadata...")
 
-	tempDB, err := v.downloadSnapshotDB(opts.SnapshotID, identity)
+	tempDB, tempDir, err := v.downloadSnapshotDB(opts.SnapshotID, identities)
 	if err != nil {
 		return fmt.Errorf("downloading snapshot database: %w", err)
 	}
@@ -100,10 +129,11 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 		if err != nil {
 			log.Debug("Failed to close temp database", "error", err)
 		}
-		// Clean up temp file
+		// Remove the whole private directory, so the decrypted database
-		err = v.Fs.Remove(tempDB.Path())
+		// and any SQLite side files it produced are gone on every path.
+		err = v.Fs.RemoveAll(tempDir)
 		if err != nil {
-			log.Debug("Failed to remove temp database", "error", err)
+			log.Debug("Failed to remove temp database directory", "error", err)
 		}
 	}()
 
@@ -138,7 +168,7 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 	}
 
 	// Step 5: Restore files
-	result, err := v.restoreAllFiles(files, repos, opts, identity, chunkToBlobMap)
+	result, err := v.restoreAllFiles(files, repos, opts, identities, chunkToBlobMap)
 	if err != nil {
 		return err
 	}
@@ -199,21 +229,28 @@ func (v *Vaultik) finishRestore(
 	return nil
 }
 
-// prepareRestoreIdentity validates that an age secret key is configured
+// restoreIdentities parses the configured age secret key once into every
-// and parses it.
+// identity it contains. The value may be a single key line or a whole
-//
+// age-keygen file with several identities; all of them are returned so
-//nolint:ireturn // age.Identity is the decryption abstraction by design
+// blobgen (via age.Decrypt) can read a blob encrypted to any of their
-func (v *Vaultik) prepareRestoreIdentity() (age.Identity, error) {
+// recipients. This is the first step of both restore and deep verify, so
+// a missing or unparseable key fails before anything is downloaded. The
+// error names the configuration source but never the key value.
+func (v *Vaultik) restoreIdentities() ([]age.Identity, error) {
 	if v.Config.AgeSecretKey == "" {
 		return nil, errDecryptionKeyRequired
 	}
 
-	identity, err := age.ParseX25519Identity(v.Config.AgeSecretKey)
+	// age.ParseIdentities skips comment and blank lines and rejects a
+	// malformed key. Its error can quote the offending line, so it is not
+	// wrapped here — that would leak the secret into the message.
+	identities, err := age.ParseIdentities(strings.NewReader(v.Config.AgeSecretKey))
 	if err != nil {
-		return nil, fmt.Errorf("parsing age secret key: %w", err)
+		return nil, fmt.Errorf("%w (source: %s)",
+			errInvalidAgeSecretKey, v.Config.AgeSecretKeySourceName())
 	}
 
-	return identity, nil
+	return identities, nil
 }
 
 // restoreAllFiles processes files in blob-locality order: drain every
@@ -226,7 +263,7 @@ func (v *Vaultik) restoreAllFiles(
 	files []*database.File,
 	repos *database.Repositories,
 	opts *RestoreOptions,
-	identity age.Identity,
+	identities []age.Identity,
 	chunkToBlobMap map[string]*database.BlobChunk,
 ) (*RestoreResult, error) {
 	result := &RestoreResult{}
@@ -280,7 +317,7 @@ func (v *Vaultik) restoreAllFiles(
 		ctx:            v.ctx,
 		repos:          repos,
 		opts:           opts,
-		identity:       identity,
+		identities:     identities,
 		chunkToBlobMap: chunkToBlobMap,
 		blobByHash:     blobByHash,
 		blobIDToHash:   blobIDToHash,
@@ -356,6 +393,13 @@ func (v *Vaultik) runRestoreLoop(
 			totalBytesExpected, startTime, &lastStatusTime)
 	}
 
+	// The loop above stops as soon as nothing is ready and nothing more
+	// can be downloaded. If files still remain, they were abandoned
+	// rather than restored; fail loudly instead of reporting success.
+	if plan.hasPending() {
+		return errRestoreIncomplete
+	}
+
 	return nil
 }
 
@@ -370,20 +414,26 @@ func (v *Vaultik) runRestoreLoop(
 func (s *restoreSession) downloadNextBlobSet(plan *restorePlan) (bool, error) {
 	s.sweeper.sweep()
 
-	next := plan.pickNextDownload()
+	next, ok := plan.pickNextDownload()
-	if next.IsZero() {
+	if !ok {
 		return false, nil
 	}
 
 	for _, hash := range plan.blobsNeeded(next) {
-		blob, ok := s.blobByHash[hash]
+		// Stop between blobs on cancel so an interrupt ends the download
-		if !ok {
+		// phase promptly rather than fetching the rest of the set.
-			return false, fmt.Errorf("%w: %s", errBlobMissingFromIndex, hash[:16])
+		if s.ctx.Err() != nil {
+			return false, s.ctx.Err()
 		}
 
-		err := s.downloadBlobToCache(hash, blob.CompressedSize)
+		blob, ok := s.blobByHash[hash]
+		if !ok {
+			return false, fmt.Errorf("%w: %s", errBlobMissingFromIndex, shortHash(hash))
+		}
+
+		err := s.downloadBlobToCache(hash, blob.CompressedSize, blob.UncompressedSize)
 		if err != nil {
-			return false, fmt.Errorf("downloading blob %s: %w", hash[:16], err)
+			return false, fmt.Errorf("downloading blob %s: %w", shortHash(hash), err)
 		}
 
 		s.result.BlobsDownloaded++
@@ -427,6 +477,16 @@ func (v *Vaultik) buildBlobIndexes(
 	blobByHash := make(map[string]*database.Blob, len(blobsByID))
 	for id, blob := range blobsByID {
 		hash := blob.Hash.String()
+
+		// The snapshot database is untrusted. A hash that is not 64
+		// lowercase hex characters could steer a later fetch to a path
+		// outside the cache directory, so reject it here, before any
+		// blob is downloaded.
+		if !isBlobHash(hash) {
+			return nil, nil, fmt.Errorf(
+				"%w: %s", errInvalidBlobHash, shortHash(hash))
+		}
+
 		blobIDToHash[id] = hash
 		blobByHash[hash] = blob
 	}
@@ -581,11 +641,11 @@ func (v *Vaultik) handleRestoreVerification(
 // for a remote-only snapshot) is used as-is, so a host with no local
 // index can restore the snapshots it can only see on the store.
 func (v *Vaultik) downloadSnapshotDB(
-	snapshotID string, identity age.Identity,
+	snapshotID string, identities []age.Identity,
-) (*database.DB, error) {
+) (*database.DB, string, error) {
 	remoteKey, err := v.resolveSnapshotRemoteKey(snapshotID)
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
 
 	// Download encrypted database from storage
@@ -593,69 +653,128 @@ func (v *Vaultik) downloadSnapshotDB(
 
 	reader, err := v.Storage.Get(v.ctx, dbKey)
 	if err != nil {
-		return nil, fmt.Errorf("downloading %s: %w", dbKey, err)
+		return nil, "", fmt.Errorf("downloading %s: %w", dbKey, err)
 	}
 
 	defer func() { _ = reader.Close() }()
 
-	// Read all data
+	// Decrypt and decompress straight from the storage stream, then stream
-	encryptedData, err := io.ReadAll(reader)
+	// the plaintext to a temp file. Neither the encrypted bytes nor the
+	// decrypted database is ever held whole in memory; a snapshot database
+	// can be large.
+	blobReader, err := blobgen.NewReader(reader, identities...)
 	if err != nil {
-		return nil, fmt.Errorf("reading encrypted data: %w", err)
+		return nil, "", fmt.Errorf("creating decryption reader: %w", err)
-	}
-
-	log.Debug("Downloaded encrypted database",
-		"size", ubytes(int64(len(encryptedData))))
-
-	// Decrypt and decompress using blobgen.Reader
-	blobReader, err := blobgen.NewReader(bytes.NewReader(encryptedData), identity)
-	if err != nil {
-		return nil, fmt.Errorf("creating decryption reader: %w", err)
 	}
 
 	defer func() { _ = blobReader.Close() }()
 
-	// Read the binary SQLite database
+	db, tempDir, err := v.materializeSnapshotDB(blobReader)
-	dbData, err := io.ReadAll(blobReader)
 	if err != nil {
-		return nil, fmt.Errorf("decrypting and decompressing: %w", err)
+		return nil, "", err
 	}
 
-	log.Debug("Decrypted database", "size", ubytes(int64(len(dbData))))
+	// Confirm the decrypted database really is the snapshot named by
-
+	// remoteKey before any files are read from it. On mismatch, close the
-	// Create a temporary database file and write the binary SQLite data directly
+	// database and remove its private directory so nothing is left behind.
-	tempFile, err := afero.TempFile(v.Fs, "", "vaultik-restore-*.db")
+	err = v.verifySnapshotDBIdentity(db, snapshotID, remoteKey)
 	if err != nil {
-		return nil, fmt.Errorf("creating temp file: %w", err)
+		_ = db.Close()
+		_ = v.Fs.RemoveAll(tempDir)
+
+		return nil, "", err
 	}
 
-	tempPath := tempFile.Name()
+	return db, tempDir, nil
+}
 
-	// Write the binary SQLite database directly
+// verifySnapshotDBIdentity confirms the decrypted metadata database really
-	_, err = tempFile.Write(dbData)
+// is the snapshot named by remoteKey. age decryption proves the database
+// is readable, not that the object served at
+// metadata/<remoteKey>/db.zst.age is the snapshot that was requested: an
+// attacker who swaps in another valid db.zst.age (which needs no key
+// material) would otherwise redirect restore and deep verify to a
+// different snapshot's contents. The exported per-snapshot database holds
+// exactly one snapshot row, and a snapshot's remote key is derived from
+// that row's ID, so the database is the requested one exactly when its
+// sole snapshot hashes back to remoteKey. Comparing the requested
+// identifier directly would not do: it may be a remote-key prefix a
+// recovery host uses in place of a human snapshot ID it cannot know.
+func (v *Vaultik) verifySnapshotDBIdentity(
+	db *database.DB, requested, remoteKey string,
+) error {
+	repos := database.NewRepositories(db)
+
+	snap, err := repos.Snapshots.GetOnlySnapshot(v.ctx)
 	if err != nil {
-		_ = tempFile.Close()
+		return fmt.Errorf("checking identity of database for %s: %w", requested, err)
-		_ = v.Fs.Remove(tempPath)
-
-		return nil, fmt.Errorf("writing database file: %w", err)
 	}
 
-	err = tempFile.Close()
+	if snapshot.RemoteSnapshotKey(snap.ID.String()) != remoteKey {
-	if err != nil {
+		return fmt.Errorf("%w: requested %s but the database is snapshot %s",
-		_ = v.Fs.Remove(tempPath)
+			errSnapshotDBMismatch, requested, snap.ID)
-
-		return nil, fmt.Errorf("closing temp file: %w", err)
 	}
 
-	log.Debug("Created restore database", "path", tempPath)
+	return nil
+}
 
-	// Open the database
+// materializeSnapshotDB streams the decrypted snapshot database into a
-	db, err := database.New(v.ctx, tempPath)
+// fresh private (0700) temp directory and opens the file read-only. The
+// database is copied through an io.Copy buffer rather than read whole into
+// memory. On any failure it removes the directory before returning, so no
+// decrypted metadata is left on disk when the copy is interrupted or the
+// payload is damaged. On success the returned directory is the caller's to
+// remove.
+func (v *Vaultik) materializeSnapshotDB(
+	dbReader io.Reader,
+) (*database.DB, string, error) {
+	tempDir, err := afero.TempDir(v.Fs, "", "vaultik-restore-")
 	if err != nil {
-		return nil, fmt.Errorf("opening restore database: %w", err)
+		return nil, "", fmt.Errorf("creating temp directory: %w", err)
 	}
 
-	return db, nil
+	success := false
+
+	defer func() {
+		if !success {
+			_ = v.Fs.RemoveAll(tempDir)
+		}
+	}()
+
+	dbPath := filepath.Join(tempDir, snapshotDBFilename)
+
+	dbFile, err := v.Fs.OpenFile(
+		dbPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, restoreFileMode)
+	if err != nil {
+		return nil, "", fmt.Errorf("creating database file: %w", err)
+	}
+
+	written, copyErr := io.Copy(dbFile, dbReader)
+	closeErr := dbFile.Close()
+
+	if copyErr != nil {
+		return nil, "", fmt.Errorf("writing database file: %w", copyErr)
+	}
+
+	if closeErr != nil {
+		return nil, "", fmt.Errorf("closing database file: %w", closeErr)
+	}
+
+	log.Debug("Created restore database", "path", dbPath, "size", ubytes(written))
+
+	// Reject an empty database before OpenReadOnly builds a schema on it.
+	if written == 0 {
+		return nil, "", errEmptySnapshotDB
+	}
+
+	db, err := database.OpenReadOnly(v.ctx, dbPath)
+	if err != nil {
+		return nil, "", fmt.Errorf("opening restore database: %w", err)
+	}
+
+	success = true
+
+	return db, tempDir, nil
 }
 
 // getFilesToRestore returns the list of files to restore based on path filters
@@ -744,7 +863,7 @@ type restoreSession struct {
 	ctx            context.Context //nolint:containedctx // per-restore state by design
 	repos          *database.Repositories
 	opts           *RestoreOptions
-	identity       age.Identity
+	identities     []age.Identity
 	chunkToBlobMap map[string]*database.BlobChunk
 	blobByHash     map[string]*database.Blob
 	blobIDToHash   map[string]string
@@ -760,13 +879,85 @@ type restoreSession struct {
 	runningAsRoot bool
 }
 
+// containedRestorePath resolves rel — a path read from the snapshot
+// database — to its location under targetDir and confirms the write will
+// stay inside the target.
+//
+// age decryption proves a snapshot is readable, not that it is honest, so
+// every stored path is treated as hostile. rel is rejected unless
+// filepath.IsLocal accepts it once the leading separator is stripped:
+// stored paths are absolute and the join to targetDir drops that
+// separator, so "/etc/passwd" is judged as the relative "etc/passwd" it
+// becomes on disk. This bars "..", absolute, and empty paths.
+//
+// A stored symlink whose target points outside the tree is still honest
+// (and restored verbatim), but a later entry must not be written through
+// it. Each existing ancestor directory below the target is therefore
+// Lstat'ed and a symlink among them is refused. The leaf itself is not
+// traversed: honest snapshots restore symlinks at leaf positions, and the
+// unique-path constraint keeps a leaf from being both a symlink and a
+// regular file. The target directory itself may be a symlink; only
+// components below it are checked.
+func containedRestorePath(fs afero.Fs, targetDir, rel string) (string, error) {
+	local := strings.TrimPrefix(rel, string(filepath.Separator))
+	if !filepath.IsLocal(local) {
+		return "", fmt.Errorf("%w: %s", errRestorePathEscapesTarget, rel)
+	}
+
+	local = filepath.Clean(local)
+	targetPath := filepath.Join(targetDir, local)
+
+	relDir := filepath.Dir(local)
+	if relDir == "." {
+		return targetPath, nil
+	}
+
+	current := targetDir
+	for component := range strings.SplitSeq(relDir, string(filepath.Separator)) {
+		current = filepath.Join(current, component)
+
+		info, err := lstatIfPossible(fs, current)
+		if err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+
+			return "", fmt.Errorf("checking restore path %s: %w", current, err)
+		}
+
+		if info.Mode()&os.ModeSymlink != 0 {
+			return "", fmt.Errorf("%w: %s descends through symlink %s",
+				errRestorePathEscapesTarget, rel, current)
+		}
+	}
+
+	return targetPath, nil
+}
+
+// lstatIfPossible performs a symlink-aware stat when the filesystem
+// supports it. afero.OsFs does; MemMapFs, which has no symlinks, reports
+// that Lstat was not used and its result never carries ModeSymlink.
+func lstatIfPossible(fs afero.Fs, name string) (os.FileInfo, error) {
+	if lstater, ok := fs.(afero.Lstater); ok {
+		info, _, err := lstater.LstatIfPossible(name)
+
+		return info, err
+	}
+
+	return fs.Stat(name)
+}
+
 // restoreFile dispatches to the right per-kind restorer.
 func (s *restoreSession) restoreFile(file *database.File) error {
-	targetPath := filepath.Join(s.opts.TargetDir, file.Path.String())
+	targetPath, err := containedRestorePath(
+		s.v.Fs, s.opts.TargetDir, file.Path.String())
+	if err != nil {
+		return err
+	}
 
 	parentDir := filepath.Dir(targetPath)
 
-	err := s.v.Fs.MkdirAll(parentDir, restoreDirMode)
+	err = s.v.Fs.MkdirAll(parentDir, restoreDirMode)
 	if err != nil {
 		return fmt.Errorf("creating parent directory: %w", err)
 	}
@@ -814,6 +1005,13 @@ func (s *restoreSession) restoreDirectory(
 		return fmt.Errorf("creating directory: %w", err)
 	}
 
+	// MkdirAll applies the process umask, so chmod to the exact stored
+	// mode. A failure here is non-fatal.
+	err = s.v.Fs.Chmod(targetPath, os.FileMode(file.Mode))
+	if err != nil {
+		log.Debug("Failed to set permissions", "path", targetPath, "error", err)
+	}
+
 	s.applyFileMetadata(file, targetPath)
 
 	s.result.FilesRestored++
@@ -821,25 +1019,22 @@ func (s *restoreSession) restoreDirectory(
 	return nil
 }
 
-// applyFileMetadata applies stored permissions, ownership (when running
+// applyFileMetadata applies ownership (when running as root on a real
-// as root on a real filesystem), and mtime to a restored path. Failures
+// filesystem) and mtime to a restored path. Permission mode is applied
-// are logged at debug level and do not abort the restore.
+// separately by each caller, with different failure handling, so it is
+// not touched here. Failures are logged at debug level and do not abort
+// the restore.
 func (s *restoreSession) applyFileMetadata(file *database.File, targetPath string) {
-	err := s.v.Fs.Chmod(targetPath, os.FileMode(file.Mode))
-	if err != nil {
-		log.Debug("Failed to set permissions", "path", targetPath, "error", err)
-	}
-
 	if s.runningAsRoot {
 		if _, ok := s.v.Fs.(*afero.OsFs); ok {
-			err = os.Chown(targetPath, int(file.UID), int(file.GID))
+			err := os.Chown(targetPath, int(file.UID), int(file.GID))
 			if err != nil {
 				log.Debug("Failed to set ownership", "path", targetPath, "error", err)
 			}
 		}
 	}
 
-	err = s.v.Fs.Chtimes(targetPath, file.MTime, file.MTime)
+	err := s.v.Fs.Chtimes(targetPath, file.MTime, file.MTime)
 	if err != nil {
 		log.Debug("Failed to set mtime", "path", targetPath, "error", err)
 	}
@@ -873,17 +1068,30 @@ func (s *restoreSession) restoreRegularFile(
 
 	t0 = time.Now()
 
-	outFile, err := s.v.Fs.Create(targetPath)
+	// Remove any existing entry, then create the file with a restrictive
+	// mode via O_EXCL. The stored mode is applied only after the content
+	// is written and the file closed, so a file whose stored mode is
+	// restrictive is never briefly readable by other local users while
+	// its content is written. Removing first (rather than failing on a
+	// leftover file) matches the documented behaviour that re-running
+	// restore overwrites partial output.
+	_ = s.v.Fs.Remove(targetPath)
+
+	outFile, err := s.v.Fs.OpenFile(
+		targetPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, restoreFileMode)
 	createDur := time.Since(t0)
 
 	if err != nil {
 		return fmt.Errorf("creating output file: %w", err)
 	}
 
-	defer func() { _ = outFile.Close() }()
-
 	bytesWritten, timings, err := s.writeFileChunks(outFile, fileChunks)
 	if err != nil {
+		// Do not leave a partial file behind.
+		_ = outFile.Close()
+
+		s.removePartialRestore(targetPath)
+
 		return err
 	}
 
@@ -901,9 +1109,12 @@ func (s *restoreSession) restoreRegularFile(
 
 	err = outFile.Close()
 	if err != nil {
+		s.removePartialRestore(targetPath)
+
 		return fmt.Errorf("closing output file: %w", err)
 	}
 
+	s.applyRestoredFileMode(file, targetPath)
 	s.applyFileMetadata(file, targetPath)
 
 	s.result.FilesRestored++
@@ -914,6 +1125,31 @@ func (s *restoreSession) restoreRegularFile(
 	return nil
 }
 
+// applyRestoredFileMode applies the stored permission bits to a
+// just-written regular file (created with restoreFileMode). A failure is
+// a user-visible warning, not a fatal error: the file's content is
+// intact and it remains at the restrictive create-time mode, so the
+// restore is not aborted or discarded over it.
+func (s *restoreSession) applyRestoredFileMode(
+	file *database.File, targetPath string,
+) {
+	err := s.v.Fs.Chmod(targetPath, os.FileMode(file.Mode))
+	if err != nil {
+		s.v.UI.Warningf("Failed to set mode %s on %s: %v",
+			os.FileMode(file.Mode).Perm(), s.v.UI.Path(targetPath), err)
+	}
+}
+
+// removePartialRestore deletes a restore output file whose write did not
+// complete, so a failed restore never leaves a partial file behind.
+func (s *restoreSession) removePartialRestore(targetPath string) {
+	err := s.v.Fs.Remove(targetPath)
+	if err != nil {
+		log.Debug("Failed to remove partial restore file",
+			"path", targetPath, "error", err)
+	}
+}
+
 // writeFileChunks streams each of the file's chunks from the blob disk
 // cache into outFile, crediting restored bytes to the sweeper as it
 // goes. Returns the bytes written plus per-phase timing accumulators.
@@ -926,6 +1162,12 @@ func (s *restoreSession) writeFileChunks(
 	)
 
 	for _, fc := range fileChunks {
+		// Stop between chunks on cancel so an interrupt does not keep
+		// writing a large file after the operation has been told to stop.
+		if s.ctx.Err() != nil {
+			return bytesWritten, timings, s.ctx.Err()
+		}
+
 		chunkHashStr := fc.ChunkHash.String()
 
 		blobChunk, ok := s.chunkToBlobMap[chunkHashStr]
@@ -978,12 +1220,12 @@ func (s *restoreSession) writeFileChunks(
 // size, which is what makes multi-GB blobs tractable on machines with
 // less RAM than the blob.
 func (s *restoreSession) downloadBlobToCache(
-	blobHash string, expectedSize int64,
+	blobHash string, compressedSize, uncompressedSize int64,
 ) error {
 	start := time.Now()
 
 	t0 := time.Now()
-	rc, err := s.v.FetchAndDecryptBlob(s.ctx, blobHash, expectedSize, s.identity)
+	rc, err := s.v.FetchAndDecryptBlob(s.ctx, blobHash, uncompressedSize, s.identities...)
 	fetchSetupDur := time.Since(t0)
 
 	if err != nil {
@@ -995,17 +1237,25 @@ func (s *restoreSession) downloadBlobToCache(
 	streamDur := time.Since(t0)
 	closeErr := rc.Close()
 
+	// closeErr carries the blob's hash-verification result (a mismatch,
+	// or the stream not being fully read). On any failure, drop the
+	// cache entry so a blob that failed verification is never read back
+	// as if it were valid.
 	if copyErr != nil {
+		s.blobCache.Delete(blobHash)
+
 		return copyErr
 	}
 
 	if closeErr != nil {
+		s.blobCache.Delete(blobHash)
+
 		return closeErr
 	}
 
 	log.Debug("Streamed blob into disk cache",
 		"hash", blobHash[:16],
-		"compressed_bytes", expectedSize,
+		"compressed_bytes", compressedSize,
 		"plaintext_bytes", written,
 		"ms_total", time.Since(start).Milliseconds(),
 		"ms_fetch_setup", fetchSetupDur.Milliseconds(),
@@ -1062,17 +1312,22 @@ func (v *Vaultik) verifyRestoredFiles(
 			return ctx.Err()
 		}
 
-		targetPath := filepath.Join(targetDir, file.Path.String())
+		targetPath, err := containedRestorePath(v.Fs, targetDir, file.Path.String())
+		if err == nil {
+			var bytesVerified int64
+
+			bytesVerified, err = v.verifyFile(ctx, repos, file, targetPath)
+			if err == nil {
+				result.FilesVerified++
+				result.BytesVerified += bytesVerified
+			}
+		}
 
-		bytesVerified, err := v.verifyFile(ctx, repos, file, targetPath)
 		if err != nil {
 			log.Error("File verification failed", "path", file.Path, "error", err)
 
 			result.FilesFailed++
 			result.FailedFiles = append(result.FailedFiles, file.Path.String())
-		} else {
-			result.FilesVerified++
-			result.BytesVerified += bytesVerified
 		}
 
 		bytesProcessed += file.Size
@@ -1162,6 +1417,17 @@ func (v *Vaultik) verifyFile(
 		bytesVerified += int64(n)
 	}
 
+	// The stored chunks account for the whole file, so the reader must
+	// be at EOF now. Trailing bytes past the last chunk are corruption
+	// the per-chunk loop cannot see.
+	extra := make([]byte, 1)
+
+	n, err := f.Read(extra)
+	if n != 0 || !errors.Is(err, io.EOF) {
+		return bytesVerified, fmt.Errorf("%w: file longer than its %d chunk(s)",
+			errTrailingRestoreData, len(fileChunks))
+	}
+
 	log.Debug("File verified",
 		"path", file.Path, "bytes", bytesVerified, "chunks", len(fileChunks))
 

internal/vaultik/restore_containment_test.go

@@ -0,0 +1,175 @@
+package vaultik //nolint:testpackage // drives unexported restore internals
+
+import (
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/types"
+	"sneak.berlin/go/vaultik/internal/ui"
+)
+
+// These tests exercise the path-containment guard that keeps restore from
+// writing outside its target directory. age decryption proves only that a
+// snapshot is readable, not that its recorded paths are honest, so restore
+// treats every stored path as hostile: a compromised backed-up host could
+// forge a snapshot that decrypts cleanly, and restore usually runs as root.
+//
+// They drive restoreAllFiles directly (rather than the full Restore, which
+// downloads and decrypts the metadata database from storage) so a snapshot
+// database with adversarial rows can be handed to the restore loop without
+// the surrounding blob/storage machinery. Directory and symlink entries
+// carry no chunks, so no blobs are needed.
+
+// containmentDirMode marks a File row as a directory for the restore loop.
+const containmentDirMode = uint32(os.ModeDir | 0o755)
+
+// newContainmentVaultik builds the minimal Vaultik needed to run
+// restoreAllFiles against fs.
+func newContainmentVaultik(ctx context.Context, fs afero.Fs) *Vaultik {
+	v := &Vaultik{
+		Config: &config.Config{
+			BlobSizeLimit: config.Size(10 * 1024 * 1024),
+		},
+		Fs:     fs,
+		Stdout: io.Discard,
+		Stderr: io.Discard,
+		UI:     ui.NewWithColor(io.Discard, false),
+	}
+	v.SetContext(ctx)
+
+	return v
+}
+
+// makeFiles inserts the given rows into a fresh in-memory snapshot database
+// and returns them (with IDs assigned) plus the repositories.
+func makeFiles(
+	ctx context.Context, t *testing.T, rows []*database.File,
+) ([]*database.File, *database.Repositories) {
+	t.Helper()
+
+	db, err := database.New(ctx, filepath.Join(t.TempDir(), "index.sqlite"))
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+	for _, f := range rows {
+		require.NoError(t, repos.Files.Create(ctx, nil, f))
+	}
+
+	return rows, repos
+}
+
+func TestRestoreRejectsPathTraversal(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		// rows are inserted in order; the escape entry is restored after
+		// any entry it depends on (the symlink case needs its link first).
+		rows func(outsideDir string) []*database.File
+		// escaped is the path, outside the target, that must not appear.
+		escaped func(tempDir, outsideDir string) string
+	}{
+		{
+			name: "relative dotdot",
+			rows: func(_ string) []*database.File {
+				return []*database.File{{
+					Path: "../escaped-relative",
+					Mode: containmentDirMode,
+				}}
+			},
+			escaped: func(tempDir, _ string) string {
+				return filepath.Join(tempDir, "escaped-relative")
+			},
+		},
+		{
+			name: "absolute with dotdot",
+			rows: func(_ string) []*database.File {
+				return []*database.File{{
+					Path: "/a/../../escaped-absolute",
+					Mode: containmentDirMode,
+				}}
+			},
+			escaped: func(tempDir, _ string) string {
+				return filepath.Join(tempDir, "escaped-absolute")
+			},
+		},
+		{
+			name: "child through symlink",
+			rows: func(outsideDir string) []*database.File {
+				return []*database.File{
+					// Restored first: an in-target symlink pointing out.
+					{Path: "linkdir", LinkTarget: types.FilePath(outsideDir)},
+					// Restored second: a child written through that link.
+					{Path: "linkdir/child", Mode: containmentDirMode},
+				}
+			},
+			escaped: func(_, outsideDir string) string {
+				return filepath.Join(outsideDir, "child")
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			ctx := context.Background()
+			fs := afero.NewOsFs()
+			tempDir := t.TempDir()
+			targetDir := filepath.Join(tempDir, "target")
+			outsideDir := filepath.Join(tempDir, "outside")
+			require.NoError(t, fs.MkdirAll(outsideDir, 0o755))
+
+			rows, repos := makeFiles(ctx, t, tc.rows(outsideDir))
+			v := newContainmentVaultik(ctx, fs)
+
+			_, err := v.restoreAllFiles(rows, repos,
+				&RestoreOptions{TargetDir: targetDir}, nil, nil)
+
+			require.ErrorIs(t, err, errRestorePathEscapesTarget)
+
+			escaped := tc.escaped(tempDir, outsideDir)
+			_, statErr := os.Lstat(escaped)
+			require.Truef(t, os.IsNotExist(statErr),
+				"restore wrote outside the target at %s", escaped)
+		})
+	}
+}
+
+// TestRestoreAllowsSymlinkPointingOutsideTree confirms the guard does not
+// over-block: an honest snapshot may contain a symlink whose target lies
+// outside the restored tree, and it must still be restored verbatim.
+func TestRestoreAllowsSymlinkPointingOutsideTree(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ctx := context.Background()
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	targetDir := filepath.Join(tempDir, "target")
+	linkTarget := filepath.Join(tempDir, "outside", "data")
+
+	rows, repos := makeFiles(ctx, t, []*database.File{
+		{Path: "goodlink", LinkTarget: types.FilePath(linkTarget), MTime: time.Unix(0, 0)},
+	})
+	v := newContainmentVaultik(ctx, fs)
+
+	_, err := v.restoreAllFiles(rows, repos,
+		&RestoreOptions{TargetDir: targetDir}, nil, nil)
+	require.NoError(t, err)
+
+	got, err := os.Readlink(filepath.Join(targetDir, "goodlink"))
+	require.NoError(t, err)
+	require.Equal(t, linkTarget, got)
+}

internal/vaultik/restore_identity_test.go

@@ -0,0 +1,108 @@
+package vaultik //nolint:testpackage // exercises unexported restoreIdentities
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+	"sneak.berlin/go/vaultik/internal/config"
+)
+
+// encryptBlobTo returns a blobgen blob of plaintext encrypted to exactly
+// one recipient, so a decryptor succeeds only if it holds that recipient's
+// identity.
+func encryptBlobTo(t *testing.T, recipient string, plaintext []byte) []byte {
+	t.Helper()
+
+	var buf bytes.Buffer
+
+	writer, err := blobgen.NewWriter(&buf, 1, []string{recipient})
+	require.NoError(t, err)
+
+	_, err = writer.Write(plaintext)
+	require.NoError(t, err)
+	require.NoError(t, writer.Close())
+
+	return buf.Bytes()
+}
+
+// decryptBlobWith reads a blob back through the identities and returns its
+// plaintext.
+func decryptBlobWith(t *testing.T, blob []byte, identities []age.Identity) []byte {
+	t.Helper()
+
+	reader, err := blobgen.NewReader(bytes.NewReader(blob), identities...)
+	require.NoError(t, err)
+
+	plaintext, err := io.ReadAll(reader)
+	require.NoError(t, err)
+	require.NoError(t, reader.Close())
+
+	return plaintext
+}
+
+// TestRestoreIdentitiesAcceptsEveryIdentity proves a key file holding two
+// identities yields both, so a blob encrypted only to the second
+// recipient — the one the previous single-identity parse dropped — still
+// decrypts.
+func TestRestoreIdentitiesAcceptsEveryIdentity(t *testing.T) {
+	t.Parallel()
+
+	first, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	second, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	// A whole age-keygen-style file: comment lines plus two identity lines.
+	keyFile := "# public key: " + first.Recipient().String() + "\n" +
+		first.String() + "\n" +
+		"# public key: " + second.Recipient().String() + "\n" +
+		second.String() + "\n"
+
+	v := &Vaultik{Config: &config.Config{AgeSecretKey: keyFile}}
+
+	identities, err := v.restoreIdentities()
+	require.NoError(t, err)
+	require.Len(t, identities, 2)
+
+	plaintext := []byte("payload encrypted only to the second identity")
+	blob := encryptBlobTo(t, second.Recipient().String(), plaintext)
+
+	require.Equal(t, plaintext, decryptBlobWith(t, blob, identities))
+}
+
+// TestRestoreIdentitiesAcceptsTrailingNewline mirrors a YAML
+// age_secret_key value that carries a trailing newline: it must still
+// parse to its one identity and decrypt a blob encrypted to it.
+func TestRestoreIdentitiesAcceptsTrailingNewline(t *testing.T) {
+	t.Parallel()
+
+	id, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	v := &Vaultik{Config: &config.Config{AgeSecretKey: id.String() + "\n"}}
+
+	identities, err := v.restoreIdentities()
+	require.NoError(t, err)
+	require.Len(t, identities, 1)
+
+	plaintext := []byte("value with a trailing newline")
+	blob := encryptBlobTo(t, id.Recipient().String(), plaintext)
+
+	require.Equal(t, plaintext, decryptBlobWith(t, blob, identities))
+}
+
+// TestRestoreIdentitiesMissingKey reports the dedicated missing-key error
+// rather than a parse failure, so the user is told to set the key.
+func TestRestoreIdentitiesMissingKey(t *testing.T) {
+	t.Parallel()
+
+	v := &Vaultik{Config: &config.Config{}}
+
+	_, err := v.restoreIdentities()
+	require.ErrorIs(t, err, errDecryptionKeyRequired)
+}

internal/vaultik/restore_interrupt_test.go

@@ -0,0 +1,159 @@
+package vaultik //nolint:testpackage // sets ctx/cancel and inspects scratch files
+
+import (
+	"context"
+	"io"
+	"path/filepath"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/ui"
+)
+
+// blockingBlobStorer wraps a Storer and blocks the first blob download
+// until its context is cancelled, so a test can catch a restore while it
+// is mid-download. Metadata reads pass straight through, so the restore
+// reaches the blob-download phase — having already written its decrypted
+// scratch files — before it blocks.
+type blockingBlobStorer struct {
+	storage.Storer
+
+	once    sync.Once
+	entered chan struct{}
+}
+
+func newBlockingBlobStorer(inner storage.Storer) *blockingBlobStorer {
+	return &blockingBlobStorer{Storer: inner, entered: make(chan struct{})}
+}
+
+func (b *blockingBlobStorer) Get(
+	ctx context.Context, key string,
+) (io.ReadCloser, error) {
+	if strings.HasPrefix(key, "blobs/") {
+		b.once.Do(func() { close(b.entered) })
+		<-ctx.Done()
+
+		return nil, ctx.Err()
+	}
+
+	return b.Storer.Get(ctx, key)
+}
+
+// TestRestoreCleansTempDirOnInterrupt drives a restore through the stop
+// path (v.StartOperation, which is what the fx OnStop hook uses) instead
+// of calling Restore directly, catches it mid-download, and asserts that
+// stopping waits for the operation to unwind and removes its decrypted
+// scratch files — the blob cache and the temporary snapshot database —
+// from the temp directory. Without the wait a SIGINT exits the process
+// before those defers run, leaving decrypted data on disk (issue #159).
+//
+// Not parallel: it points TMPDIR at a private directory (via t.Setenv)
+// so it can assert on exactly the scratch files this restore created.
+func TestRestoreCleansTempDirOnInterrupt(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	root := t.TempDir()
+
+	dataDir := filepath.Join(root, "source")
+	storeDir := filepath.Join(root, "remote")
+	restoreDir := filepath.Join(root, "restored")
+	dbPath := filepath.Join(root, "index.sqlite")
+
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+
+	buildLocalityFixture(t, fs, dataDir)
+
+	cfg, storer, snapshotID := setupLocalityBackup(
+		context.Background(), t, fs, dataDir, storeDir, dbPath)
+
+	// Point the "" temp paths (the blob cache directory and the
+	// snapshot-database directory) at a private directory so the test can
+	// assert on exactly the scratch this restore creates.
+	scratch := filepath.Join(root, "scratch")
+	require.NoError(t, fs.MkdirAll(scratch, 0o755))
+	t.Setenv("TMPDIR", scratch)
+
+	gate := newBlockingBlobStorer(storer)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	v := &Vaultik{
+		Config:  cfg,
+		Storage: gate,
+		Fs:      fs,
+		Stdout:  io.Discard,
+		Stderr:  io.Discard,
+		UI:      ui.NewWithColor(io.Discard, false),
+		ctx:     ctx,
+		cancel:  cancel,
+	}
+
+	var (
+		opReturned atomic.Bool
+		restoreErr error
+	)
+
+	stop := v.StartOperation(func() {
+		defer opReturned.Store(true)
+
+		restoreErr = v.Restore(&RestoreOptions{
+			SnapshotID: snapshotID,
+			TargetDir:  restoreDir,
+		})
+	})
+
+	// Wait until the restore is blocked mid-download; its decrypted
+	// scratch files exist by now.
+	select {
+	case <-gate.entered:
+	case <-time.After(30 * time.Second):
+		t.Fatal("restore never reached the blob-download phase")
+	}
+
+	require.NotEmpty(t, scratchEntries(t, scratch),
+		"expected decrypted scratch files to exist mid-restore")
+
+	// Stop the operation the way the fx OnStop hook does.
+	stopCtx, stopCancel := context.WithTimeout(
+		context.Background(), 30*time.Second)
+	defer stopCancel()
+
+	require.True(t, stop(stopCtx),
+		"stop timed out; the operation goroutine did not return")
+
+	// stop returns only once the operation goroutine has returned, so its
+	// cleanup defers have run by the time we read these.
+	require.True(t, opReturned.Load(),
+		"stop returned before the operation goroutine finished")
+	require.ErrorIs(t, restoreErr, context.Canceled)
+	require.Empty(t, scratchEntries(t, scratch),
+		"decrypted scratch files remained after the interrupt")
+}
+
+// scratchEntries returns the vaultik blob-cache and snapshot-database
+// scratch entries currently present in dir.
+func scratchEntries(t *testing.T, dir string) []string {
+	t.Helper()
+
+	var matches []string
+
+	for _, pattern := range []string{
+		"vaultik-blobcache-*", "vaultik-restore-*",
+	} {
+		found, err := filepath.Glob(filepath.Join(dir, pattern))
+		require.NoError(t, err)
+
+		matches = append(matches, found...)
+	}
+
+	return matches
+}

internal/vaultik/restore_malformed_key_test.go

@@ -0,0 +1,44 @@
+package vaultik_test
+
+import (
+	"context"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestRestoreRejectsMalformedKeyBeforeDownload verifies that a malformed
+// age secret key stops restore at the parse step: nothing is fetched from
+// the store, and the error does not echo the key value (which is secret).
+func TestRestoreRejectsMalformedKeyBeforeDownload(t *testing.T) {
+	t.Parallel()
+
+	const malformed = "this-is-not-a-valid-age-key"
+
+	mock := NewMockStorer()
+
+	v := &vaultik.Vaultik{
+		Config:  &config.Config{AgeSecretKey: malformed},
+		Storage: mock,
+		Stdout:  io.Discard,
+		Stderr:  io.Discard,
+		UI:      ui.NewWithColor(io.Discard, false),
+	}
+	v.SetContext(context.Background())
+
+	err := v.Restore(&vaultik.RestoreOptions{
+		SnapshotID: "any-snapshot",
+		TargetDir:  t.TempDir(),
+	})
+	require.Error(t, err)
+	require.NotContains(t, err.Error(), malformed,
+		"error must not echo the key value")
+	require.Contains(t, err.Error(), "age_secret_key",
+		"error should name the configuration source")
+	require.Empty(t, mock.GetCalls(),
+		"a malformed key must fail before anything is fetched")
+}

internal/vaultik/restore_perms_test.go

@@ -0,0 +1,306 @@
+package vaultik //nolint:testpackage // drives restore through unexported session
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"syscall"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/ui"
+)
+
+// errSpyWrite is the injected write failure used to exercise the
+// partial-file cleanup path.
+var errSpyWrite = errors.New("injected write failure")
+
+// modeSpyFs wraps a real filesystem so restore tests can observe and
+// perturb the single output file whose path contains watch. It records
+// the on-disk permission bits seen at the moment content is first
+// written (the window during which another local user could read it),
+// and can inject a write failure or append trailing bytes on close.
+type modeSpyFs struct {
+	afero.Fs
+
+	watch string
+
+	mu         sync.Mutex
+	writeModes []os.FileMode
+	failWrite  bool
+	trailing   int
+}
+
+//nolint:ireturn // afero.Fs.OpenFile is defined to return the interface
+func (m *modeSpyFs) OpenFile(
+	name string, flag int, perm os.FileMode,
+) (afero.File, error) {
+	f, err := m.Fs.OpenFile(name, flag, perm)
+	if err != nil || !strings.Contains(name, m.watch) {
+		return f, err
+	}
+
+	return &modeSpyFile{File: f, fs: m, path: name}, nil
+}
+
+type modeSpyFile struct {
+	afero.File
+
+	fs      *modeSpyFs
+	path    string
+	written bool
+}
+
+func (f *modeSpyFile) Write(p []byte) (int, error) {
+	if !f.written {
+		f.written = true
+
+		info, err := f.fs.Stat(f.path)
+		if err == nil {
+			f.fs.mu.Lock()
+			f.fs.writeModes = append(f.fs.writeModes, info.Mode().Perm())
+			f.fs.mu.Unlock()
+		}
+	}
+
+	if f.fs.failWrite {
+		return 0, errSpyWrite
+	}
+
+	return f.File.Write(p)
+}
+
+func (f *modeSpyFile) Close() error {
+	if f.fs.trailing > 0 {
+		_, _ = f.File.Write(bytes.Repeat([]byte{'x'}, f.fs.trailing))
+	}
+
+	return f.File.Close()
+}
+
+// backupOneFile writes a single source file with the given mode and
+// backs it up into a fresh file storer, returning everything a restore
+// needs. The index database is closed before returning so the restore
+// half runs from the exported metadata and remote bytes only.
+func backupOneFile(
+	ctx context.Context, t *testing.T, fs afero.Fs, tempDir, name string,
+	content []byte, mode os.FileMode,
+) (*config.Config, *storage.FileStorer, string, string) {
+	t.Helper()
+
+	dataDir := filepath.Join(tempDir, "src")
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+
+	srcPath := filepath.Join(dataDir, name)
+	require.NoError(t, afero.WriteFile(fs, srcPath, content, mode))
+	require.NoError(t, fs.Chmod(srcPath, mode))
+
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	storer, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	cfg := &config.Config{
+		AgeRecipients: []string{
+			"age1ezrjmfpwsc95svdg0y54mums3zevgzu0x0ecq2f7tp8a05gl0sjq9q9wjg",
+		},
+		AgeSecretKey: "AGE-SECRET-KEY-19CR5YSFW59HM4TLD6GXVEDMZFTVVF7PPHKU" +
+			"T68TXSFPK7APHXA2QS2NJA5",
+		CompressionLevel: 3,
+		Hostname:         "test-host",
+		BlobSizeLimit:    config.Size(5 * 1024 * 1024),
+	}
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	sm := snapshot.NewSnapshotManager(snapshot.SnapshotManagerParams{
+		Repos:   repos,
+		Storage: storer,
+		Config:  cfg,
+	})
+	sm.SetFilesystem(fs)
+
+	scanner := snapshot.NewScanner(snapshot.ScannerConfig{
+		FS:               fs,
+		Storage:          storer,
+		ChunkSize:        4 * 1024 * 1024,
+		MaxBlobSize:      5 * 1024 * 1024,
+		CompressionLevel: cfg.CompressionLevel,
+		AgeRecipients:    cfg.AgeRecipients,
+		Repositories:     repos,
+	})
+
+	snapshotID, err := sm.CreateSnapshotWithName(
+		ctx, cfg.Hostname, "perms", "test-version", "test-git")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, snapshotID)
+	require.NoError(t, err)
+
+	require.NoError(t, sm.CompleteSnapshot(ctx, snapshotID))
+	require.NoError(t, sm.ExportSnapshotMetadata(ctx, dbPath, snapshotID))
+	require.NoError(t, db.Close())
+
+	return cfg, storer, snapshotID, srcPath
+}
+
+// restoredPathFor returns where backupOneFile's source lands under a
+// restore target: restore recreates each file at its original absolute
+// path beneath TargetDir.
+func restoredPathFor(restoreDir, srcPath string) string {
+	return filepath.Join(restoreDir, srcPath)
+}
+
+// withUmask022 forces the process umask to 022 for the duration of a
+// test, so the difference between a 0600 create and a default create is
+// observable. Restored serially (no t.Parallel) so it does not race
+// other tests.
+func withUmask022(t *testing.T) {
+	t.Helper()
+
+	old := syscall.Umask(0o022)
+
+	t.Cleanup(func() { syscall.Umask(old) })
+}
+
+// TestRestoreCreatesFileNeverWiderThanStoredMode checks that a file with
+// a restrictive stored mode (0600) is never observable with a wider mode
+// while its content is being written, and ends at its stored mode.
+//
+//nolint:paralleltest // sets the process umask; must run serially
+func TestRestoreCreatesFileNeverWiderThanStoredMode(t *testing.T) {
+	log.Initialize(log.Config{})
+	withUmask022(t)
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	ctx := context.Background()
+
+	content := randomBytes(t, 4096)
+
+	cfg, storer, snapshotID, srcPath := backupOneFile(
+		ctx, t, fs, tempDir, "secret.bin", content, 0o600)
+
+	restoreDir := filepath.Join(tempDir, "restored")
+	spy := &modeSpyFs{Fs: fs, watch: "secret.bin"}
+
+	v := newRestoreVaultik(ctx, cfg, storer, spy)
+	require.NoError(t, v.Restore(&RestoreOptions{
+		SnapshotID: snapshotID,
+		TargetDir:  restoreDir,
+	}))
+
+	spy.mu.Lock()
+	observed := append([]os.FileMode(nil), spy.writeModes...)
+	spy.mu.Unlock()
+
+	require.NotEmpty(t, observed,
+		"spy never saw the output file being written")
+
+	for _, m := range observed {
+		assert.Equalf(t, os.FileMode(0o600), m,
+			"file was observable at mode %o during write; must be 0600", m)
+	}
+
+	// The stored mode is applied after the content is written.
+	info, err := fs.Stat(restoredPathFor(restoreDir, srcPath))
+	require.NoError(t, err)
+	assert.Equal(t, os.FileMode(0o600), info.Mode().Perm())
+
+	got, err := afero.ReadFile(fs, restoredPathFor(restoreDir, srcPath))
+	require.NoError(t, err)
+	require.True(t, bytes.Equal(got, content))
+}
+
+// TestRestoreRemovesPartialFileOnWriteFailure checks that a file whose
+// content write fails is not left behind.
+//
+//nolint:paralleltest // sets the process umask; must run serially
+func TestRestoreRemovesPartialFileOnWriteFailure(t *testing.T) {
+	log.Initialize(log.Config{})
+	withUmask022(t)
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	ctx := context.Background()
+
+	cfg, storer, snapshotID, srcPath := backupOneFile(
+		ctx, t, fs, tempDir, "doomed.bin", randomBytes(t, 4096), 0o600)
+
+	restoreDir := filepath.Join(tempDir, "restored")
+	spy := &modeSpyFs{Fs: fs, watch: "doomed.bin", failWrite: true}
+
+	v := newRestoreVaultik(ctx, cfg, storer, spy)
+	err := v.Restore(&RestoreOptions{
+		SnapshotID: snapshotID,
+		TargetDir:  restoreDir,
+	})
+	require.Error(t, err, "restore should fail when the write fails")
+
+	exists, err := afero.Exists(fs, restoredPathFor(restoreDir, srcPath))
+	require.NoError(t, err)
+	assert.False(t, exists, "partial file must be removed after a failed write")
+}
+
+// TestVerifyRejectsTrailingBytes checks that --verify fails a restored
+// file that has bytes past its last chunk.
+//
+//nolint:paralleltest // sets the process umask; must run serially
+func TestVerifyRejectsTrailingBytes(t *testing.T) {
+	log.Initialize(log.Config{})
+	withUmask022(t)
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	ctx := context.Background()
+
+	cfg, storer, snapshotID, _ := backupOneFile(
+		ctx, t, fs, tempDir, "padded.bin", randomBytes(t, 4096), 0o600)
+
+	restoreDir := filepath.Join(tempDir, "restored")
+	// Append one byte to the file as it is written, so its content still
+	// matches the stored chunks but it is one byte too long.
+	spy := &modeSpyFs{Fs: fs, watch: "padded.bin", trailing: 1}
+
+	v := newRestoreVaultik(ctx, cfg, storer, spy)
+	err := v.Restore(&RestoreOptions{
+		SnapshotID: snapshotID,
+		TargetDir:  restoreDir,
+		Verify:     true,
+	})
+	require.Error(t, err, "verify should fail on a file with trailing bytes")
+	assert.ErrorIs(t, err, errFilesFailedVerify)
+}
+
+// newRestoreVaultik builds a Vaultik wired for a restore-only test.
+func newRestoreVaultik(
+	ctx context.Context, cfg *config.Config, storer storage.Storer, fs afero.Fs,
+) *Vaultik {
+	v := &Vaultik{
+		Config:  cfg,
+		Storage: storer,
+		Fs:      fs,
+		Stdout:  io.Discard,
+		Stderr:  io.Discard,
+		UI:      ui.NewWithColor(io.Discard, false),
+	}
+	v.SetContext(ctx)
+
+	return v
+}

internal/vaultik/restore_plan.go

@@ -171,10 +171,13 @@ func (p *restorePlan) finishFile(fileID types.FileID) {
 // downloaded next, after which it — together with any other pending
 // files whose blob sets become empty — moves to the ready queue.
 //
-// The zero FileID return means nothing is pending.
+// The second return value is false when no file needs a download, so a
-func (p *restorePlan) pickNextDownload() types.FileID {
+// genuine file carrying the nil UUID is picked rather than mistaken for
+// "nothing left".
+func (p *restorePlan) pickNextDownload() (types.FileID, bool) {
 	var best types.FileID
 
+	found := false
 	bestCount := math.MaxInt
 
 	var bestID string
@@ -188,14 +191,15 @@ func (p *restorePlan) pickNextDownload() types.FileID {
 		}
 
 		idStr := id.String()
-		if n < bestCount || (n == bestCount && (best.IsZero() || idStr < bestID)) {
+		if !found || n < bestCount || (n == bestCount && idStr < bestID) {
 			best = id
+			found = true
 			bestCount = n
 			bestID = idStr
 		}
 	}
 
-	return best
+	return best, found
 }
 
 // blobsNeeded returns the uncached blob hashes for fileID in any order.

internal/vaultik/restore_plan_test.go

@@ -0,0 +1,88 @@
+package vaultik //nolint:testpackage // inspects unexported restore plan internals
+
+import (
+	"context"
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/types"
+)
+
+// TestPickNextDownloadReturnsNilUUIDFile proves a genuine pending file
+// carrying the nil UUID is picked for download rather than mistaken for
+// "nothing left" — the bug that could abandon every remaining file.
+func TestPickNextDownloadReturnsNilUUIDFile(t *testing.T) {
+	t.Parallel()
+
+	var nilID types.FileID // zero value is the nil UUID
+
+	plan := &restorePlan{
+		fileBlobs: map[types.FileID]map[string]struct{}{
+			nilID: {"blobhash": {}},
+		},
+	}
+
+	id, ok := plan.pickNextDownload()
+	require.True(t, ok,
+		"pickNextDownload treated a pending nil-UUID file as nothing to do")
+	require.True(t, id.IsZero(), "expected the nil-UUID file to be picked")
+}
+
+// TestPickNextDownloadEmptyPlan confirms the second return value is false
+// only when no file needs a download.
+func TestPickNextDownloadEmptyPlan(t *testing.T) {
+	t.Parallel()
+
+	plan := &restorePlan{
+		fileBlobs: map[types.FileID]map[string]struct{}{},
+	}
+
+	_, ok := plan.pickNextDownload()
+	require.False(t, ok, "pickNextDownload reported work on an empty plan")
+}
+
+// TestRunRestoreLoopFailsOnAbandonedFiles proves the loop returns an
+// error rather than silent success when files remain pending after it
+// can make no further progress.
+func TestRunRestoreLoopFailsOnAbandonedFiles(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+
+	db, err := database.NewTestDB()
+	require.NoError(t, err)
+
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+
+	cache, err := newBlobDiskCache(math.MaxInt64)
+	require.NoError(t, err)
+
+	t.Cleanup(func() { _ = cache.Close() })
+
+	v := &Vaultik{ctx: ctx}
+	session := &restoreSession{
+		v:       v,
+		ctx:     ctx,
+		repos:   repos,
+		sweeper: newRestoreSweeper(ctx, repos, cache, 1),
+		result:  &RestoreResult{},
+	}
+
+	// A file that is still pending but whose uncached-blob set is empty
+	// and which was never queued as ready: the loop can neither restore
+	// nor download it. This is the abandonment the guard must catch.
+	var stuck types.FileID
+
+	plan := &restorePlan{
+		fileBlobs: map[types.FileID]map[string]struct{}{stuck: {}},
+		blobFiles: map[string]map[types.FileID]struct{}{},
+		cached:    map[string]struct{}{},
+	}
+
+	err = v.runRestoreLoop(session, plan, map[types.FileID]*database.File{}, 0)
+	require.ErrorIs(t, err, errRestoreIncomplete)
+}

internal/vaultik/restore_snapshot_identity_test.go

@@ -0,0 +1,251 @@
+package vaultik_test
+
+import (
+	"context"
+	"io"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestRestoreAndDeepVerifyRejectSwappedDatabase proves that swapping two
+// snapshots' encrypted databases on the store is caught. age decryption
+// alone proves only that a database is readable; without an identity check
+// restore would happily write the wrong snapshot's files and deep verify
+// would report success. After the swap, restore and deep verify of A both
+// fail, and the error names the snapshot the database actually holds (B).
+func TestRestoreAndDeepVerifyRejectSwappedDatabase(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	storeDir := filepath.Join(tempDir, "remote")
+
+	chunkSize := int64(64 * 1024)
+
+	storer, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+
+	// Two snapshots with different content, backed up into one shared
+	// store. Different names give them different remote keys, so their
+	// metadata directories are distinct and can be tampered with alone.
+	dataA := filepath.Join(tempDir, "srcA")
+	require.NoError(t, fs.MkdirAll(dataA, 0o755))
+	require.NoError(t, afero.WriteFile(fs, filepath.Join(dataA, "a.bin"),
+		bytesPattern("alpha-", int(chunkSize*2)), 0o644))
+
+	dataB := filepath.Join(tempDir, "srcB")
+	require.NoError(t, fs.MkdirAll(dataB, 0o755))
+	require.NoError(t, afero.WriteFile(fs, filepath.Join(dataB, "b.bin"),
+		bytesPattern("beta-", int(chunkSize*2)), 0o644))
+
+	idA := backupNamedSnapshotToStore(ctx, t, fs, dataA, storer,
+		filepath.Join(tempDir, "idxA.sqlite"), "alpha")
+	idB := backupNamedSnapshotToStore(ctx, t, fs, dataB, storer,
+		filepath.Join(tempDir, "idxB.sqlite"), "beta")
+	require.NotEqual(t, idA, idB)
+
+	keyA := snapshot.RemoteSnapshotKey(idA)
+	keyB := snapshot.RemoteSnapshotKey(idB)
+	require.NotEqual(t, keyA, keyB)
+
+	// Baseline: each snapshot verifies against its own intact metadata.
+	require.NoError(t, newStoreClient(ctx, t, fs, storer).RunDeepVerify(
+		idA, &vaultik.VerifyOptions{Deep: true}))
+	require.NoError(t, newStoreClient(ctx, t, fs, storer).RunDeepVerify(
+		idB, &vaultik.VerifyOptions{Deep: true}))
+
+	// Swap the two snapshots' encrypted databases on the store.
+	swapStoreFiles(t, fs,
+		filepath.Join(storeDir, "metadata", keyA, "db.zst.age"),
+		filepath.Join(storeDir, "metadata", keyB, "db.zst.age"))
+
+	// Restore of A now decrypts B's database; the identity check must
+	// reject it and name the snapshot it actually found.
+	restoreErr := newStoreClient(ctx, t, fs, storer).Restore(&vaultik.RestoreOptions{
+		SnapshotID: idA,
+		TargetDir:  filepath.Join(tempDir, "restoreA"),
+	})
+	require.Error(t, restoreErr)
+	require.ErrorContains(t, restoreErr, idB)
+
+	// Deep verify of A must reject the swapped database for the same reason.
+	verifyErr := newStoreClient(ctx, t, fs, storer).RunDeepVerify(
+		idA, &vaultik.VerifyOptions{Deep: true})
+	require.Error(t, verifyErr)
+	require.ErrorContains(t, verifyErr, idB)
+}
+
+// TestDeepVerifyRejectsSwappedDatabaseWithEmptyManifest covers the case the
+// issue calls out: swapping in a database whose blob set is empty and
+// pairing it with an equally empty manifest. The manifest then agrees with
+// the database, so every blob-level check passes and deep verify used to
+// report success with zero blobs verified. The identity check rejects it
+// before any blob check runs.
+func TestDeepVerifyRejectsSwappedDatabaseWithEmptyManifest(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	storeDir := filepath.Join(tempDir, "remote")
+
+	chunkSize := int64(64 * 1024)
+
+	storer, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+
+	// Snapshot A: real content, so its manifest lists blobs.
+	dataA := filepath.Join(tempDir, "srcA")
+	require.NoError(t, fs.MkdirAll(dataA, 0o755))
+	require.NoError(t, afero.WriteFile(fs, filepath.Join(dataA, "a.bin"),
+		bytesPattern("alpha-", int(chunkSize*2)), 0o644))
+	idA := backupNamedSnapshotToStore(ctx, t, fs, dataA, storer,
+		filepath.Join(tempDir, "idxA.sqlite"), "alpha")
+
+	// Snapshot C: a single empty file, so it references no blobs and its
+	// manifest is empty. This is the database/manifest pair an attacker
+	// would swap in to make the blob checks vacuously pass.
+	dataC := filepath.Join(tempDir, "srcC")
+	require.NoError(t, fs.MkdirAll(dataC, 0o755))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(dataC, "empty.bin"), []byte{}, 0o644))
+	idC := backupNamedSnapshotToStore(ctx, t, fs, dataC, storer,
+		filepath.Join(tempDir, "idxC.sqlite"), "charlie")
+
+	keyA := snapshot.RemoteSnapshotKey(idA)
+	keyC := snapshot.RemoteSnapshotKey(idC)
+
+	// Replace A's database and manifest with C's empty pair.
+	copyStoreFile(t, fs,
+		filepath.Join(storeDir, "metadata", keyC, "db.zst.age"),
+		filepath.Join(storeDir, "metadata", keyA, "db.zst.age"))
+	copyStoreFile(t, fs,
+		filepath.Join(storeDir, "metadata", keyC, "manifest.json.zst"),
+		filepath.Join(storeDir, "metadata", keyA, "manifest.json.zst"))
+
+	verifyErr := newStoreClient(ctx, t, fs, storer).RunDeepVerify(
+		idA, &vaultik.VerifyOptions{Deep: true})
+	require.Error(t, verifyErr)
+	require.ErrorContains(t, verifyErr, idC)
+}
+
+// backupNamedSnapshotToStore backs up dataDir into the shared storer under
+// the given snapshot name and returns the human snapshot ID. Two snapshots
+// backed up under different names get different remote keys, so their
+// metadata directories on the store are distinct.
+func backupNamedSnapshotToStore(
+	ctx context.Context, t *testing.T, fs afero.Fs,
+	dataDir string, storer storage.Storer, dbPath, name string,
+) string {
+	t.Helper()
+
+	const (
+		chunkSize   = int64(64 * 1024)
+		maxBlobSize = int64(512 * 1024)
+	)
+
+	cfg := &config.Config{
+		AgeRecipients:    []string{testAgePublicKey},
+		AgeSecretKey:     testAgeSecretKey,
+		CompressionLevel: 3,
+		Hostname:         testHostname,
+	}
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+
+	sm := snapshot.NewSnapshotManager(snapshot.SnapshotManagerParams{
+		Repos:   repos,
+		Storage: storer,
+		Config:  cfg,
+	})
+	sm.SetFilesystem(fs)
+
+	scanner := snapshot.NewScanner(snapshot.ScannerConfig{
+		FS:               fs,
+		Storage:          storer,
+		ChunkSize:        chunkSize,
+		MaxBlobSize:      maxBlobSize,
+		CompressionLevel: cfg.CompressionLevel,
+		AgeRecipients:    cfg.AgeRecipients,
+		Repositories:     repos,
+	})
+
+	snapshotID, err := sm.CreateSnapshotWithName(
+		ctx, cfg.Hostname, name, "test-version", "test-git")
+	require.NoError(t, err)
+
+	_, err = scanner.Scan(ctx, dataDir, snapshotID)
+	require.NoError(t, err)
+
+	require.NoError(t, sm.CompleteSnapshot(ctx, snapshotID))
+	require.NoError(t, sm.ExportSnapshotMetadata(ctx, dbPath, snapshotID))
+	require.NoError(t, db.Close())
+
+	return snapshotID
+}
+
+// newStoreClient builds a Vaultik that reads only from the store: the
+// secret key, the storer, and a filesystem, with no local index. This is
+// what restore and deep verify need.
+func newStoreClient(
+	ctx context.Context, t *testing.T, fs afero.Fs, storer storage.Storer,
+) *vaultik.Vaultik {
+	t.Helper()
+
+	v := &vaultik.Vaultik{
+		Config: &config.Config{
+			AgeSecretKey: testAgeSecretKey,
+			Hostname:     testHostname,
+		},
+		Storage: storer,
+		Fs:      fs,
+		Stdout:  io.Discard,
+		Stderr:  io.Discard,
+		UI:      ui.NewWithColor(io.Discard, false),
+	}
+	v.SetContext(ctx)
+
+	return v
+}
+
+// swapStoreFiles exchanges the contents of two files on the store.
+func swapStoreFiles(t *testing.T, fs afero.Fs, a, b string) {
+	t.Helper()
+
+	dataA, err := afero.ReadFile(fs, a)
+	require.NoError(t, err)
+
+	dataB, err := afero.ReadFile(fs, b)
+	require.NoError(t, err)
+
+	require.NoError(t, afero.WriteFile(fs, a, dataB, 0o644))
+	require.NoError(t, afero.WriteFile(fs, b, dataA, 0o644))
+}
+
+// copyStoreFile overwrites dst with the contents of src on the store.
+func copyStoreFile(t *testing.T, fs afero.Fs, src, dst string) {
+	t.Helper()
+
+	data, err := afero.ReadFile(fs, src)
+	require.NoError(t, err)
+
+	require.NoError(t, afero.WriteFile(fs, dst, data, 0o644))
+}

internal/vaultik/restore_snapshotdb_test.go

@@ -0,0 +1,108 @@
+package vaultik //nolint:testpackage // inspects unexported snapshot-db materialization
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/blobgen"
+	"sneak.berlin/go/vaultik/internal/database"
+)
+
+// genuineSnapshotDBBytes returns the on-disk bytes of a real snapshot
+// database (the full schema applied).
+func genuineSnapshotDBBytes(t *testing.T) []byte {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "snapshot.db")
+
+	db, err := database.New(context.Background(), path)
+	require.NoError(t, err)
+	require.NoError(t, db.Close())
+
+	data, err := os.ReadFile(path) //nolint:gosec // G304: test-controlled temp path
+	require.NoError(t, err)
+
+	return data
+}
+
+// TestMaterializeSnapshotDBPrivateDir proves the decrypted database lands
+// in a private (0700) directory and opens read-only.
+func TestMaterializeSnapshotDBPrivateDir(t *testing.T) {
+	dbData := genuineSnapshotDBBytes(t)
+
+	t.Setenv("TMPDIR", t.TempDir())
+
+	v := &Vaultik{ctx: context.Background(), Fs: afero.NewOsFs()}
+
+	db, dir, err := v.materializeSnapshotDB(bytes.NewReader(dbData))
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		_ = db.Close()
+		_ = os.RemoveAll(dir)
+	})
+
+	info, err := os.Stat(dir)
+	require.NoError(t, err)
+	require.Equal(t, os.FileMode(0o700), info.Mode().Perm(),
+		"snapshot database directory must not be world-readable")
+
+	_, err = db.Conn().ExecContext(context.Background(),
+		"CREATE TABLE probe_readonly (x)")
+	require.Error(t, err, "materialized snapshot database must be read-only")
+}
+
+// TestMaterializeSnapshotDBRejectsCompleteEmptyStream proves the written == 0
+// guard rejects a genuinely empty but complete metadata object: a real age
+// header, nonce, and final tag encrypting zero plaintext bytes. The truncation
+// case is stopped earlier by the reader (io.ErrUnexpectedEOF) and never reaches
+// this branch, so it needs its own input. This complete stream decrypts to zero
+// bytes with a clean EOF, passes the reader, and must be refused as empty rather
+// than accepted as a valid zero-table database. Reverting the guard lets the
+// empty file open as a fresh schema and the test fails.
+func TestMaterializeSnapshotDBRejectsCompleteEmptyStream(t *testing.T) {
+	identity, err := age.GenerateX25519Identity()
+	require.NoError(t, err)
+
+	var stream bytes.Buffer
+
+	w, err := age.Encrypt(&stream, identity.Recipient())
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	blobReader, err := blobgen.NewReader(bytes.NewReader(stream.Bytes()), identity)
+	require.NoError(t, err)
+
+	t.Cleanup(func() { _ = blobReader.Close() })
+
+	t.Setenv("TMPDIR", t.TempDir())
+
+	v := &Vaultik{ctx: context.Background(), Fs: afero.NewOsFs()}
+
+	_, _, err = v.materializeSnapshotDB(blobReader)
+	require.ErrorIs(t, err, errEmptySnapshotDB)
+}
+
+// TestMaterializeSnapshotDBRemovesDirOnOpenFailure proves a failed open
+// leaves no temp directory behind.
+func TestMaterializeSnapshotDBRemovesDirOnOpenFailure(t *testing.T) {
+	base := t.TempDir()
+
+	t.Setenv("TMPDIR", base)
+
+	v := &Vaultik{ctx: context.Background(), Fs: afero.NewOsFs()}
+
+	_, _, err := v.materializeSnapshotDB(
+		bytes.NewReader([]byte("this is not a sqlite database")))
+	require.Error(t, err)
+
+	entries, rerr := os.ReadDir(base)
+	require.NoError(t, rerr)
+	require.Empty(t, entries, "temp directory left behind after open failure")
+}

internal/vaultik/restore_truncated_db_test.go

@@ -0,0 +1,85 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"path/filepath"
+	"testing"
+
+	"filippo.io/age"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestRestoreRejectsTruncatedMetadataDB backs up a real tree, then replaces
+// the snapshot's db.zst.age with a stream cut right after the age header and
+// its 16-byte nonce. age.Decrypt still accepts such an object and the zstd
+// decoder turns the truncated read into a clean EOF, so before the fix restore
+// built a fresh empty schema and reported success. Restore must now fail with
+// io.ErrUnexpectedEOF, the error the reader raises for a truncated object.
+// Asserting that specific error pins the reader fix: without it the truncation
+// yields an empty database, which the identity check rejects for an unrelated
+// reason, and this test would pass anyway.
+func TestRestoreRejectsTruncatedMetadataDB(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+
+	dataDir := filepath.Join(tempDir, "source")
+	storeDir := filepath.Join(tempDir, "remote")
+	restoreDir := filepath.Join(tempDir, "restored")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	chunkSize := int64(64 * 1024)
+	maxBlobSize := int64(512 * 1024)
+
+	setupE2ESourceTree(t, fs, dataDir, chunkSize)
+
+	ctx := context.Background()
+
+	cfg, storer, snapshotID := runFileStorageBackup(
+		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)
+
+	// Encrypting empty plaintext to the snapshot recipient yields
+	// header + nonce(16) + a single 16-byte final chunk tag. Dropping the
+	// trailing tag leaves exactly the age header plus its nonce — the
+	// truncation an attacker can write over metadata without any key.
+	recipient, err := age.ParseX25519Recipient(testAgePublicKey)
+	require.NoError(t, err)
+
+	var full bytes.Buffer
+
+	w, err := age.Encrypt(&full, recipient)
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	truncated := full.Bytes()[:full.Len()-16]
+
+	dbKeyPath := filepath.Join(storeDir, "metadata",
+		snapshot.RemoteSnapshotKey(snapshotID), "db.zst.age")
+	require.NoError(t, afero.WriteFile(fs, dbKeyPath, truncated, 0o644))
+
+	restoreVaultik := &vaultik.Vaultik{
+		Config:  cfg,
+		Storage: storer,
+		Fs:      fs,
+		Stdout:  io.Discard,
+		Stderr:  io.Discard,
+		UI:      ui.NewWithColor(io.Discard, false),
+	}
+	restoreVaultik.SetContext(ctx)
+
+	err = restoreVaultik.Restore(&vaultik.RestoreOptions{
+		SnapshotID: snapshotID,
+		TargetDir:  restoreDir,
+		Verify:     true,
+	})
+	require.ErrorIs(t, err, io.ErrUnexpectedEOF)
+}

internal/vaultik/shallow_verify_test.go

@@ -0,0 +1,191 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestShallowVerifyDetectsWrongBlobSize backs up a real snapshot, runs
+// shallow verify (which passes and reports exactly the blobs it checked),
+// then grows one stored blob so its size no longer matches the manifest.
+// Shallow verify must then fail, count the grown blob as a size mismatch,
+// and drop it from the verified count rather than continuing to report it
+// as checked.
+func TestShallowVerifyDetectsWrongBlobSize(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+
+	dataDir := filepath.Join(tempDir, "source")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	chunkSize := int64(32 * 1024)
+	maxBlobSize := int64(128 * 1024)
+
+	// Enough data to span several blobs, so the mismatch count and the
+	// dropped verified count are both meaningful.
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(dataDir, "data.bin"),
+		bytesPattern("shallow-", int(maxBlobSize*4)), 0o644))
+
+	ctx := context.Background()
+
+	cfg, storer, snapshotID := runFileStorageBackup(
+		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)
+
+	newVerifier := func(out io.Writer) *vaultik.Vaultik {
+		v := &vaultik.Vaultik{
+			Config:  cfg,
+			Storage: storer,
+			Fs:      fs,
+			Stdout:  out,
+			Stderr:  io.Discard,
+			UI:      ui.NewWithColor(io.Discard, false),
+		}
+		v.SetContext(ctx)
+
+		return v
+	}
+
+	var out bytes.Buffer
+
+	require.NoError(t,
+		newVerifier(&out).VerifySnapshotWithOptions(
+			snapshotID, &vaultik.VerifyOptions{JSON: true}),
+		"shallow verify should pass on a healthy snapshot")
+
+	healthy := decodeVerifyResult(t, out.Bytes())
+	require.Equal(t, "ok", healthy.Status)
+	require.Positive(t, healthy.BlobCount)
+	require.Equal(t, healthy.BlobCount, healthy.Verified,
+		"shallow verify must report exactly the blobs it checked")
+	require.Zero(t, healthy.Mismatched)
+
+	// Grow one stored blob so its size no longer matches the manifest.
+	growOneBlob(t, fs, filepath.Join(storeDir, "blobs"))
+
+	out.Reset()
+	err := newVerifier(&out).VerifySnapshotWithOptions(
+		snapshotID, &vaultik.VerifyOptions{JSON: true})
+	require.Error(t, err,
+		"shallow verify must fail when a blob's stored size differs from the manifest")
+
+	bad := decodeVerifyResult(t, out.Bytes())
+	require.Equal(t, "failed", bad.Status)
+	require.Equal(t, 1, bad.Mismatched)
+	require.Equal(t, healthy.BlobCount-1, bad.Verified,
+		"the wrong-sized blob must not be counted as verified")
+}
+
+// TestShallowVerifyDetectsMissingDatabase backs up a real snapshot,
+// confirms shallow verify passes, then deletes the snapshot's encrypted
+// database. Shallow verify must fail: a snapshot without its database is
+// not restorable, even when every blob is present.
+func TestShallowVerifyDetectsMissingDatabase(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+
+	dataDir := filepath.Join(tempDir, "source")
+	storeDir := filepath.Join(tempDir, "remote")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+
+	chunkSize := int64(32 * 1024)
+	maxBlobSize := int64(128 * 1024)
+
+	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(dataDir, "data.bin"),
+		bytesPattern("shallow-db-", int(maxBlobSize*2)), 0o644))
+
+	ctx := context.Background()
+
+	cfg, storer, snapshotID := runFileStorageBackup(
+		ctx, t, fs, dataDir, storeDir, dbPath, chunkSize, maxBlobSize)
+
+	newVerifier := func() *vaultik.Vaultik {
+		v := &vaultik.Vaultik{
+			Config:  cfg,
+			Storage: storer,
+			Fs:      fs,
+			Stdout:  io.Discard,
+			Stderr:  io.Discard,
+			UI:      ui.NewWithColor(io.Discard, false),
+		}
+		v.SetContext(ctx)
+
+		return v
+	}
+
+	require.NoError(t,
+		newVerifier().VerifySnapshotWithOptions(
+			snapshotID, &vaultik.VerifyOptions{}),
+		"shallow verify should pass on a healthy snapshot")
+
+	// The database lives under the hashed remote key, not the human ID.
+	dbObject := filepath.Join(storeDir, "metadata",
+		snapshot.RemoteSnapshotKey(snapshotID), "db.zst.age")
+	require.NoError(t, os.Remove(dbObject))
+
+	require.Error(t,
+		newVerifier().VerifySnapshotWithOptions(
+			snapshotID, &vaultik.VerifyOptions{}),
+		"shallow verify must fail when db.zst.age is absent")
+}
+
+// growOneBlob appends bytes to the first blob file found under blobsDir,
+// changing its on-disk size so it no longer matches the manifest.
+func growOneBlob(t *testing.T, fs afero.Fs, blobsDir string) {
+	t.Helper()
+
+	var blobPath string
+
+	err := afero.Walk(fs, blobsDir,
+		func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			if blobPath == "" && !info.IsDir() {
+				blobPath = path
+			}
+
+			return nil
+		})
+	require.NoError(t, err)
+	require.NotEmpty(t, blobPath, "expected at least one blob on disk")
+
+	data, err := afero.ReadFile(fs, blobPath)
+	require.NoError(t, err)
+
+	data = append(data, []byte("extra")...)
+	require.NoError(t, afero.WriteFile(fs, blobPath, data, 0o644))
+}
+
+func decodeVerifyResult(t *testing.T, b []byte) vaultik.VerifyResult {
+	t.Helper()
+
+	var result vaultik.VerifyResult
+
+	require.NoError(t, json.Unmarshal(b, &result))
+
+	return result
+}

internal/vaultik/snapshot.go

@@ -20,7 +20,6 @@ import (
 var (
 	errSnapshotNotInConfig  = errors.New("snapshot not found in config")
 	errNoSnapshotsInConfig  = errors.New("no snapshots configured")
-	errBlobsMissing         = errors.New("blobs are missing")
 	errSnapshotVerifyFailed = errors.New("verification failed")
 	errRemoveAllNeedsForce  = errors.New("--all requires --force")
 	errInvalidTableName     = errors.New("invalid table name")
@@ -56,8 +55,8 @@ func (v *Vaultik) CreateSnapshot(opts *SnapshotCreateOptions) error {
 		return err
 	}
 
-	// Clean up incomplete snapshots FIRST, before any scanning
+	// Clean up incomplete snapshots FIRST, before any scanning.
-	// This is critical for data safety - see CleanupIncompleteSnapshots for details
+	// This is critical for data safety; PruneDatabase below does it.
 	hostname := v.Config.Hostname
 	if hostname == "" {
 		hostname, _ = os.Hostname()
@@ -670,11 +669,24 @@ func (v *Vaultik) VerifySnapshotWithOptions(
 
 	v.printVerifyHeader(snapshotID, opts)
 
-	// Resolve the identifier to the snapshot's remote key and download the
+	// Resolve the identifier to the snapshot's remote key. A human ID is
-	// manifest. A human ID is hashed; a remote key (or its abbreviation,
+	// hashed; a remote key (or its abbreviation, as printed for a
-	// as printed for a remote-only snapshot) is used as-is, so a host with
+	// remote-only snapshot) is used as-is, so a host with no local index
-	// no local index can verify a snapshot it can only see on the store.
+	// can verify a snapshot it can only see on the store. The key is kept
-	manifest, err := v.resolveAndDownloadManifest(snapshotID)
+	// so we can also check for the snapshot's encrypted database below.
+	remoteKey, err := v.resolveSnapshotRemoteKey(snapshotID)
+	if err != nil {
+		if opts.JSON {
+			result.Status = verifyStatusFailed
+			result.ErrorMessage = fmt.Sprintf("resolving snapshot identifier: %v", err)
+
+			return v.outputVerifyJSON(result)
+		}
+
+		return fmt.Errorf("resolving snapshot identifier: %w", err)
+	}
+
+	manifest, err := v.downloadManifestByKey(remoteKey)
 	if err != nil {
 		if opts.JSON {
 			result.Status = verifyStatusFailed
@@ -704,14 +716,34 @@ func (v *Vaultik) VerifySnapshotWithOptions(
 
 		v.printlnStdout()
 
-		// Check each blob exists
+		// Check each blob is present with the size the manifest records.
-		v.stdoutf("Checking blob existence...\n")
+		v.stdoutf("Checking blob presence and sizes...\n")
 	}
 
-	result.Verified, result.Missing, result.MissingSize =
+	// A snapshot is only restorable if its encrypted database is present
-		v.verifyManifestBlobsExist(manifest, opts)
+	// alongside the blobs. Shallow verify checks that the object exists; it
+	// does not decrypt it (that is deep verify's job).
+	dbPath := fmt.Sprintf("metadata/%s/db.zst.age", remoteKey)
 
-	return v.formatVerifyResult(result, manifest, opts)
+	_, dbErr := v.Storage.Stat(v.ctx, dbPath)
+	if dbErr != nil {
+		result.DatabaseMissing = true
+	}
+
+	result.Verified, result.Missing, result.Mismatched, result.MissingSize, err =
+		v.verifyManifestBlobs(manifest, opts)
+	if err != nil {
+		if opts.JSON {
+			result.Status = verifyStatusFailed
+			result.ErrorMessage = fmt.Sprintf("verifying manifest blobs: %v", err)
+
+			return v.outputVerifyJSON(result)
+		}
+
+		return fmt.Errorf("verifying manifest blobs: %w", err)
+	}
+
+	return v.formatVerifyResult(result, opts)
 }
 
 // printVerifyHeader prints the snapshot ID and parsed timestamp for
@@ -736,25 +768,34 @@ func (v *Vaultik) printVerifyHeader(snapshotID string, opts *VerifyOptions) {
 	}
 }
 
-// verifyManifestBlobsExist checks that each blob in the manifest exists
+// verifyManifestBlobs checks that each blob in the manifest is present in
-// in storage, returning the verified count, missing count, and total
+// storage with the size the manifest records, returning the counts of
-// missing bytes.
+// blobs that were present with the right size, absent, and present but the
-func (v *Vaultik) verifyManifestBlobsExist(
+// wrong size, plus the total bytes of the absent blobs. It does not read
+// blob contents; deep verification (RunDeepVerify) does that. The size
+// comparison matches the deep path (see verifyBlobExistenceFromDB).
+func (v *Vaultik) verifyManifestBlobs(
 	manifest *snapshot.Manifest, opts *VerifyOptions,
-) (int, int, int64) {
+) (int, int, int, int64, error) {
 	var (
-		verified, missing int
+		verified, missing, mismatched int
-		missingSize       int64
+		missingSize                   int64
 	)
 
 	for _, blob := range manifest.Blobs {
+		// The manifest is unauthenticated, so its blob hashes are checked
+		// before being spliced into a storage path.
+		if !isBlobHash(blob.Hash) {
+			return 0, 0, 0, 0, fmt.Errorf("%w: %s",
+				errInvalidBlobHash, shortHash(blob.Hash))
+		}
+
 		blobPath := fmt.Sprintf("blobs/%s/%s/%s",
 			blob.Hash[:2], blob.Hash[2:4], blob.Hash)
 
-		// Shallow: check existence only (deep verification is handled
+		stat, err := v.Storage.Stat(v.ctx, blobPath)
-		// by RunDeepVerify).
+		switch {
-		_, err := v.Storage.Stat(v.ctx, blobPath)
+		case err != nil:
-		if err != nil {
 			if !opts.JSON {
 				v.stdoutf("  Missing: %s (%s)\n",
 					blob.Hash, ubytes(blob.CompressedSize))
@@ -762,23 +803,32 @@ func (v *Vaultik) verifyManifestBlobsExist(
 
 			missing++
 			missingSize += blob.CompressedSize
-		} else {
+		case stat.Size != blob.CompressedSize:
+			if !opts.JSON {
+				v.stdoutf("  Wrong size: %s (store has %s, manifest lists %s)\n",
+					blob.Hash, ubytes(stat.Size), ubytes(blob.CompressedSize))
+			}
+
+			mismatched++
+		default:
 			verified++
 		}
 	}
 
-	return verified, missing, missingSize
+	return verified, missing, mismatched, missingSize, nil
 }
 
 // formatVerifyResult outputs the final verification results as JSON or
 // human-readable text.
 func (v *Vaultik) formatVerifyResult(
-	result *VerifyResult, manifest *snapshot.Manifest, opts *VerifyOptions,
+	result *VerifyResult, opts *VerifyOptions,
 ) error {
+	failure := shallowVerifyFailure(result)
+
 	if opts.JSON {
-		if result.Missing > 0 {
+		if failure != "" {
 			result.Status = verifyStatusFailed
-			result.ErrorMessage = fmt.Sprintf("%d blobs are missing", result.Missing)
+			result.ErrorMessage = failure
 		} else {
 			result.Status = "ok"
 		}
@@ -787,29 +837,57 @@ func (v *Vaultik) formatVerifyResult(
 	}
 
 	v.stdoutf("\nVerification complete:\n")
-	v.stdoutf("  Verified:     %d blobs (%s)\n", result.Verified,
+	v.stdoutf("  Present with listed size: %d blobs\n", result.Verified)
-		ubytes(manifest.TotalCompressedSize-result.MissingSize))
 
 	if result.Missing > 0 {
-		v.stdoutf("  Missing:      %d blobs (%s)\n",
+		v.stdoutf("  Missing:                  %d blobs (%s)\n",
 			result.Missing, ubytes(result.MissingSize))
-	} else {
+	}
-		v.stdoutf("  Missing:      0 blobs\n")
+
+	if result.Mismatched > 0 {
+		v.stdoutf("  Wrong size:               %d blobs\n", result.Mismatched)
+	}
+
+	if result.DatabaseMissing {
+		v.stdoutf("  Encrypted database:       missing\n")
 	}
 
 	v.stdoutf("  Status:       ")
 
-	if result.Missing > 0 {
+	if failure != "" {
-		v.stdoutf("FAILED - %d blobs are missing\n", result.Missing)
+		v.stdoutf("FAILED - %s\n", failure)
 
-		return fmt.Errorf("%d %w", result.Missing, errBlobsMissing)
+		return fmt.Errorf("%w: %s", errSnapshotVerifyFailed, failure)
 	}
 
-	v.stdoutf("OK - All blobs verified\n")
+	// Report only what was actually checked: presence and size, not contents.
+	v.stdoutf("OK - all %d blobs listed in the manifest are present with the "+
+		"listed size; contents not checked (use --deep)\n", result.Verified)
 
 	return nil
 }
 
+// shallowVerifyFailure returns a human-readable description of everything
+// that failed shallow verification, or the empty string if it passed.
+func shallowVerifyFailure(result *VerifyResult) string {
+	var parts []string
+
+	if result.Missing > 0 {
+		parts = append(parts, fmt.Sprintf("%d blobs are missing", result.Missing))
+	}
+
+	if result.Mismatched > 0 {
+		parts = append(parts,
+			fmt.Sprintf("%d blobs have the wrong size", result.Mismatched))
+	}
+
+	if result.DatabaseMissing {
+		parts = append(parts, "the encrypted database is missing")
+	}
+
+	return strings.Join(parts, "; ")
+}
+
 // outputVerifyJSON outputs the verification result as JSON
 func (v *Vaultik) outputVerifyJSON(result *VerifyResult) error {
 	encoder := json.NewEncoder(v.Stdout)
@@ -935,29 +1013,23 @@ func (v *Vaultik) downloadManifestByKey(remoteKey string) (*snapshot.Manifest, e
 func (v *Vaultik) syncWithRemote() error {
 	log.Info("Syncing with remote snapshots")
 
-	// Get all remote snapshot IDs
+	// Remote metadata lives under metadata/<remote-key>/, where the
-	remoteSnapshots := make(map[string]bool)
+	// directory name is snapshot.RemoteSnapshotKey(id), not the human
-	objectCh := v.Storage.ListStream(v.ctx, "metadata/")
+	// snapshot ID. Compare each local row's hashed key against that set
-
+	// so a row still backed by remote metadata is kept. Comparing human
-	for object := range objectCh {
+	// IDs against the hashed directory names matches nothing and deletes
-		if object.Err != nil {
+	// every local snapshot record (issue #160).
-			return fmt.Errorf("listing remote snapshots: %w", object.Err)
+	remoteKeys, err := v.listAllRemoteSnapshotKeys()
-		}
+	if err != nil {
-
+		return fmt.Errorf("listing remote snapshots: %w", err)
-		// Extract snapshot ID from paths like metadata/hostname-20240115-143052Z/
-		parts := strings.Split(object.Key, "/")
-		if len(parts) >= minSnapshotIDParts &&
-			parts[0] == metadataDirName && parts[1] != "" {
-			// Skip macOS resource fork files (._*) and other hidden files
-			if strings.HasPrefix(parts[1], ".") {
-				continue
-			}
-
-			remoteSnapshots[parts[1]] = true
-		}
 	}
 
-	log.Debug("Found remote snapshots", "count", len(remoteSnapshots))
+	remoteKeySet := make(map[string]bool, len(remoteKeys))
+	for _, k := range remoteKeys {
+		remoteKeySet[k] = true
+	}
+
+	log.Debug("Found remote snapshots", "count", len(remoteKeySet))
 
 	// Get all local snapshots (use a high limit to get all)
 	localSnapshots, err := v.Repositories.Snapshots.ListRecent(v.ctx, listRecentLimit)
@@ -965,12 +1037,12 @@ func (v *Vaultik) syncWithRemote() error {
 		return fmt.Errorf("listing local snapshots: %w", err)
 	}
 
-	// Remove local snapshots that don't exist remotely
+	// Remove local snapshots whose metadata is absent from the remote.
 	removedCount := 0
 
 	for _, snap := range localSnapshots {
 		snapshotIDStr := snap.ID.String()
-		if !remoteSnapshots[snapshotIDStr] {
+		if !remoteKeySet[snapshot.RemoteSnapshotKey(snapshotIDStr)] {
 			log.Info("Removing local snapshot not found in remote",
 				"snapshot_id", snap.ID)
 
@@ -1258,21 +1330,36 @@ func (v *Vaultik) listAllRemoteSnapshotKeys() ([]string, error) {
 		}
 
 		parts := strings.Split(object.Key, "/")
-		if len(parts) >= minSnapshotIDParts &&
+		if len(parts) < minSnapshotIDParts ||
-			parts[0] == metadataDirName && parts[1] != "" {
+			parts[0] != metadataDirName || parts[1] == "" {
-			// Skip macOS resource fork files (._*) and other hidden files
+			continue
-			if strings.HasPrefix(parts[1], ".") {
+		}
-				continue
-			}
 
-			if strings.HasSuffix(object.Key, "/") ||
+		// Skip macOS resource fork files (._*) and other hidden files
-				strings.Contains(object.Key, "/manifest.json.zst") {
+		if strings.HasPrefix(parts[1], ".") {
-				key := parts[1]
+			continue
-				if !seen[key] {
+		}
-					seen[key] = true
+
-					keys = append(keys, key)
+		if !strings.HasSuffix(object.Key, "/") &&
-				}
+			!strings.Contains(object.Key, "/manifest.json.zst") {
-			}
+			continue
+		}
+
+		key := parts[1]
+
+		// A remote snapshot key is a SHA-256 hash: 64 lowercase hex
+		// characters. The listing comes from the untrusted destination,
+		// so accept a key only in that form.
+		if !isBlobHash(key) {
+			log.Warn("Skipping non-conforming key under metadata/",
+				"key", object.Key)
+
+			continue
+		}
+
+		if !seen[key] {
+			seen[key] = true
+			keys = append(keys, key)
 		}
 	}