Stop a backup on a symlink whose target cannot be read (closes #269)

When readlink failed, the scanner logged at debug level and left the
symlink out of the snapshot, and the run reported success even without
--skip-errors. The error now goes through the same handling as any
other entry the walk cannot read: the run aborts, or with --skip-errors
the symlink is skipped with the usual "Failed to access" error line.

A symlink removed between the walk's lstat and the readlink also
aborts the run, as an entry that vanishes during the walk already does.

Model: opus-5-5

ARCHITECTURE.md

@@ -54,10 +54,12 @@ The database tracks five primary entities and their relationships:
 
 #### File (`database.File`)
 Represents a file, directory, or symlink in the backup system. Stores metadata needed for restoration:
-- Path, source_path (for restore path stripping), mtime
+- Path, mtime
 - Size, mode, ownership (uid, gid)
 - Symlink target (if applicable)
 
+It also stores `source_path`, the source directory the scan found it under, made absolute and with symlinks resolved. Restore does not read it.
+
 #### Chunk (`database.Chunk`)
 A content-addressed unit of data. Files are split into variable-size chunks using the FastCDC algorithm:
 - `ChunkHash`: SHA256 hash of chunk content (primary key)
@@ -82,9 +84,11 @@ The final storage unit uploaded to S3. Contains many compressed and encrypted ch
 Blob creation process:
 1. Chunks are accumulated (up to MaxBlobSize, typically 10GB)
 2. As each chunk is added, its uncompressed bytes are fed to a running SHA-256
-3. Concurrently, the same bytes are compressed with zstd, then encrypted with age (recipients configured in config), and streamed to storage
+3. Concurrently, the same bytes are compressed with zstd, then encrypted with age (recipients configured in config), and written to a temporary file
 4. On finalize, the blob's name is the double SHA-256 of the uncompressed contents — `hex(SHA256(SHA256(...)))` — not a hash of the compressed, encrypted bytes
-5. Uploaded to `blobs/{hash[0:2]}/{hash[2:4]}/{hash}`
+5. The finished file is uploaded to `blobs/{hash[0:2]}/{hash[2:4]}/{hash}` and then deleted
+
+A backup needs free temporary space, because each blob is written whole to a temporary file before it is uploaded (up to about `blob_size_limit`; an rclone destination that cannot stream uploads needs about twice that) and the metadata export writes copies of the local index. Temporary files go to `$TMPDIR` (default `/tmp`); with `TMPDIR` unset, SQLite writes one of those copies to `/var/tmp`.
 
 #### BlobChunk (`database.BlobChunk`)
 Maps chunks to their position within blobs:

README.md

@@ -390,7 +390,13 @@ recipients, and local database statistics.
 
 **`remote info`**: Show storage backend type and location plus detailed
 remote storage inventory: per-snapshot metadata sizes, blob counts, and
-orphaned blob detection.
+orphaned blob detection. A name under `metadata/` that is not a remote
+key is skipped with a warning and is not printed. If a listed
+`manifest.json.zst` cannot be read, or sits under a skipped name, the
+orphaned blob figures are reported as unknown; `--json` gives them as
+`null`, lists the remote key of each unreadable manifest in
+`unreadable_manifests` and counts the manifests under skipped names in
+`skipped_manifest_count`.
 * `--json`: Output as JSON
 
 **`remote nuke`**: Delete every snapshot's metadata and every blob from the
@@ -540,7 +546,7 @@ complete annotated example also lives in
 | `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. Must be at least four times `chunk_size` (the largest chunk the chunker can emit), otherwise a single-chunk blob could exceed the limit |
+| `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. A backup needs free temporary space, because each blob is written whole to a temporary file before it is uploaded (up to about `blob_size_limit`; an rclone destination that cannot stream uploads needs about twice that) and the metadata export writes copies of the local index. Temporary files go to `$TMPDIR` (default `/tmp`); with `TMPDIR` unset, SQLite writes one of those copies to `/var/tmp` |
 | `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 |
@@ -799,7 +805,8 @@ them. We provide:
   in the `Dockerfile` together.
 * `script/release` — cross-compile and publish the release artifacts
   with the pinned `goreleaser`. Refuses a `goreleaser` on `PATH` whose
-  version is not the pinned one, on the same reasoning as `script/lint`.
+  version is not the pinned one, because a different version would build
+  a different release from the same tag.
 * `script/release-snapshot` — the same build with no publishing and no
   tagging, into `./dist`
 * `script/test` — run the test suite by building the `test` phase of
@@ -909,14 +916,14 @@ It is passed to `goreleaser` as `GITEA_TOKEN`. The runner's automatic
 token is deliberately not used: it is not guaranteed to carry release
 write access.
 
-The Go toolchain that compiles the released binaries comes from an
-`actions/setup-go` step pinned by commit sha, reading its version from
-`go.mod` (currently `1.26.1`, the same version the `Dockerfile` builder
-stage pins by digest). `goreleaser` shells out to `go` for every
+The Go toolchain that compiles the released binaries is installed by
+`script/install-go`, which downloads the version named by `go.mod`
+(currently `1.26.1`, the same version the `Dockerfile` builder stage
+pins by digest) and refuses the archive unless its sha256 matches the
+value committed in the script. `goreleaser` shells out to `go` for every
 cross-compile, so without that step the release would either fail
 outright or ship binaries built by whatever unpinned toolchain the
-runner happened to carry — the one unpinned thing in an otherwise
-hash-pinned release path.
+runner happened to carry.
 
 To rehearse the whole build without publishing or tagging anything:
 

TODO.md

@@ -22,6 +22,124 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 2026-10-07: Made a symlink whose target cannot be read stop the backup
+  ([issue #269](https://git.eeqj.de/sneak/vaultik/issues/269)). It was
+  left out of the snapshot with only a debug log line, even without
+  `--skip-errors`. It now aborts the run, or with `--skip-errors` is
+  skipped with the `Failed to access` error line that any other entry
+  the scan cannot read gets.
+
+- 2026-10-07: Made an interrupted command exit 130 and say so
+  ([issue #267](https://git.eeqj.de/sneak/vaultik/issues/267)). Ctrl-C
+  or SIGTERM during `snapshot create`, `snapshot restore` or `snapshot
+  verify` exited 0 with no error line (`snapshot verify --json` exited
+  1, also without one), so a `--cron` run that never finished looked
+  like a success. A command stopped by either signal now exits 130 and
+  prints `interrupted before the command finished` on stderr, under
+  `--cron` and `--json` too.
+
+- 2026-10-07: Corrected documentation, help text and comments that were
+  false about the code
+  ([issue #233](https://git.eeqj.de/sneak/vaultik/issues/233)). A blob
+  is not streamed to storage. The README, `ARCHITECTURE.md` and
+  `config.example.yml` now say a backup needs free temporary space,
+  because each blob is written whole to a temporary file before it is
+  uploaded (up to about `blob_size_limit`; an rclone destination that
+  cannot stream uploads needs about twice that) and the metadata export
+  writes copies of the local index. Temporary files go to `$TMPDIR`
+  (default `/tmp`); with `TMPDIR` unset, SQLite writes one of those
+  copies to `/var/tmp`. Also corrected: the snapshot ID format, what restore
+  reads and how incomplete snapshots are removed in `docs/DATAMODEL.md`,
+  what `source_path` holds, the `index_path` and config file defaults,
+  what `snapshot remove` cleans up, how the release gets its Go
+  toolchain, and the `script/release` and `script/fmt-check` comments.
+
+- 2026-10-07: Cut the time the `internal/vaultik` and `internal/database`
+  tests take ([issue #235](https://git.eeqj.de/sneak/vaultik/issues/235)).
+  Most of the `internal/vaultik` time went to 24 tests that ran one at a
+  time only because they call `log.Initialize`; they now call it before
+  `t.Parallel()`, as the package's other tests do. `TestLargeDatasets`
+  committed each of its 1,500 inserts on its own and now makes them in
+  one transaction. `TestDedupOnlySnapshotRestores` gives its second
+  backup its own snapshot name instead of sleeping past the one-second
+  timestamp in the snapshot ID.
+
+- 2026-10-07: Made two messages say only what is true
+  ([issue #240](https://git.eeqj.de/sneak/vaultik/issues/240)). A config
+  file that others can read was warned about as containing S3
+  credentials even when it set none, as a `file://` config does. The
+  warning now says the file may contain S3 credentials only when
+  `s3.access_key_id` or `s3.secret_access_key` is set, since either may
+  come from a `${...}` reference rather than the file, and otherwise
+  says the file is readable by others. `snapshot purge` against a
+  destination store it could not list gave an error with
+  `listing remote snapshots:` in it twice; the prefix now appears once.
+
+- 2026-10-07: Made `s3.part_size` set the multipart upload part size
+  ([issue #232](https://git.eeqj.de/sneak/vaultik/issues/232)). It was
+  loaded and defaulted but never passed to the S3 client, whose uploader
+  used a fixed 10MiB part. It now reaches the uploader for `storage_url`
+  and for the `s3.*` fields, and a part size S3 refuses, below 5MiB or
+  above 5GiB, `0` included, fails at config load. A blob too large for
+  S3's limit of 10,000 parts at the configured size is uploaded in larger
+  parts. The docs gave the default as `5MB`, which the config file reads
+  as 5,000,000 bytes, below the minimum; they now say `5MiB`.
+
+- 2026-10-07: Made per-name retention work when the hostname contains `_`
+  ([issue #230](https://git.eeqj.de/sneak/vaultik/issues/230)). A
+  snapshot ID is `hostname_name_timestamp`, and the name was read as
+  everything between the first and the last `_`, so with
+  `hostname: my_host` the name `home` came out as `host_home`.
+  `snapshot purge --keep-latest --snapshot home` then printed "No
+  snapshots to delete", and `snapshot create --prune` purged nothing
+  without a message. The name is now read using the hostname the
+  `snapshots` table stores with each snapshot, cut at its first `.` as it
+  is in the ID.
+
+- 2026-10-07: Made `remote info` stop reporting a snapshot's blobs as
+  orphaned when its manifest cannot be read, and stop printing raw
+  names from under `metadata/`
+  ([issue #228](https://git.eeqj.de/sneak/vaultik/issues/228)). A
+  manifest it failed to read was skipped, so that snapshot's blobs were
+  counted as orphaned and the report advised running `vaultik prune`.
+  The orphan figures are now unknown in that case, with no prune
+  advice, and `--json` gives them as `null` with the unreadable remote
+  keys in `unreadable_manifests`. A name under `metadata/` that is not
+  64 lowercase hex characters is now skipped with a warning instead of
+  being printed, control characters included. A manifest under a
+  skipped name is then not read either, so it also leaves the orphan
+  figures unknown, and `--json` counts such manifests in
+  `skipped_manifest_count`. A directory with no manifest in it, as left
+  by an interrupted backup, leaves the figures known.
+
+- 2026-10-07: Made `config set` keep a string that looks like a number
+  ([issue #229](https://git.eeqj.de/sneak/vaultik/issues/229)). It wrote
+  every value unquoted, and `config.Load` reads the file through untyped
+  YAML, so an access key `00112233` loaded as `38043` and a hostname `007`
+  as `7`. A value for a string setting in `config.Config` is now tagged as
+  a YAML string, which the file quotes wherever YAML would read a number or
+  a boolean; other settings are still written unquoted.
+
+- 2026-10-07: Made a backup notice a file rewritten with its size
+  unchanged and a new mtime in the same second as the one in the index
+  ([issue #226](https://git.eeqj.de/sneak/vaultik/issues/226)). The
+  `files` table held mtime in whole seconds and the scanner compared
+  whole seconds, so every later snapshot kept the old content. A new
+  `mtime_nsec` column holds the nanoseconds within the second that
+  `mtime` holds, and the scanner compares the full mtime. A local index
+  created before the change lacks the column and is rebuilt with
+  `vaultik database delete` and a full backup.
+
+- 2026-10-07: Made taking the process-wide lock atomic
+  ([issue #227](https://git.eeqj.de/sneak/vaultik/issues/227)). The lock
+  read `vaultik.pid`, checked whether that PID was alive and then wrote
+  its own, so two writers started together could both pass the check and
+  both run. It is now an `flock` on `vaultik.pid`, held until the run
+  ends; the kernel drops it when the process exits, so a crash leaves no
+  lock behind. A clean exit now empties the file instead of deleting it,
+  because deleting it would let two later runs each lock a different
+  file.
+
 - 2026-10-06: Made `snapshot remove --json` write only its document to
   stdout when the destination store cannot be reached
   ([issue #251](https://git.eeqj.de/sneak/vaultik/issues/251)). Its

config.example.yml

@@ -287,15 +287,18 @@ storage_url: "rclone://myremote/path/to/backups"
 #  #use_ssl: true
 #
 #  # Part size for multipart uploads
-#  # Minimum 5MB, affects memory usage during upload
-#  # Supports: 5MB, 10M, 100MiB, etc.
-#  # Default: 5MB
-#  #part_size: 5MB
+#  # Minimum 5MiB, maximum 5GiB; affects memory usage during upload
+#  # A blob too large for 10,000 parts of this size gets larger parts
+#  # Supports: 10MB, 16MiB, 100MiB, etc. (5MB is below the minimum)
+#  # Default: 5MiB
+#  #part_size: 5MiB
 
 # Path to local SQLite index database
 # This database tracks file state for incremental backups
-# Default: /var/lib/vaultik/index.sqlite
-#index_path: /var/lib/vaultik/index.sqlite
+# Default: the platform data directory, e.g.
+#   macOS: ~/Library/Application Support/vaultik/index.sqlite
+#   Linux: ~/.local/share/vaultik/index.sqlite
+#index_path: /path/to/index.sqlite
 
 # Average chunk size for content-defined chunking
 # Smaller chunks = better deduplication but more metadata
@@ -310,6 +313,12 @@ storage_url: "rclone://myremote/path/to/backups"
 # Chunking uses no secret (the FastCDC parameters are fixed and public). At a
 # large limit a blob holds hundreds of chunks, so individual chunk lengths are
 # not visible in its size; lowering the limit toward chunk_size exposes them.
+# A backup needs free temporary space, because each blob is written whole to
+# a temporary file before it is uploaded (up to about blob_size_limit; an
+# rclone destination that cannot stream uploads needs about twice that) and
+# the metadata export writes copies of the local index. Temporary files go to
+# $TMPDIR (default /tmp); with TMPDIR unset, SQLite writes one of those copies
+# to /var/tmp.
 # Supports: 1GB, 10G, 500MB, 1GiB, etc.
 # Default: 10GB
 #blob_size_limit: 10GB

docs/DATAMODEL.md

@@ -36,7 +36,8 @@ Stores metadata about files in the filesystem being backed up.
 **Columns:**
 - `id` (TEXT PRIMARY KEY) - UUID for the file record
 - `path` (TEXT NOT NULL UNIQUE) - Absolute file path
-- `mtime` (INTEGER NOT NULL) - Modification time as Unix timestamp
+- `mtime` (INTEGER NOT NULL) - Modification time, whole seconds since the Unix epoch
+- `mtime_nsec` (INTEGER NOT NULL) - Nanoseconds within that second, 0 to 999999999
 - `size` (INTEGER NOT NULL) - File size in bytes
 - `mode` (INTEGER NOT NULL) - Unix file permissions and type
 - `uid` (INTEGER NOT NULL) - User ID of file owner
@@ -110,7 +111,7 @@ Maps chunks to the blobs that contain them.
 Tracks backup snapshots.
 
 **Columns:**
-- `id` (TEXT PRIMARY KEY) - Snapshot ID (format: hostname-YYYYMMDD-HHMMSSZ)
+- `id` (TEXT PRIMARY KEY) - Snapshot ID (format: `hostname_name_timestamp`, e.g. `server1_home_2025-06-01T12:00:00Z`: the hostname up to its first `.`, the snapshot name, and an RFC 3339 UTC timestamp)
 - `hostname` (TEXT) - Hostname where backup was created
 - `vaultik_version` (TEXT) - Version of Vaultik used
 - `vaultik_git_revision` (TEXT) - Git revision of Vaultik used
@@ -217,8 +218,8 @@ The `{remote-key}` directory name is a one-way hash of the human snapshot ID, so
 ### 4. Restore Process
 
 The restore process doesn't use the local database. Instead:
-1. Downloads snapshot metadata from S3
-2. Downloads required blobs based on manifest
+1. Downloads and decrypts the snapshot's metadata database (`db.zst.age`) from S3
+2. Downloads the blobs holding the chunks of the files being restored, found through that database's `blob_chunks` table; the manifest is not read
 3. Reconstructs files from decrypted and decompressed chunks
 
 ### 5. Pruning
@@ -231,9 +232,8 @@ The restore process doesn't use the local database. Instead:
 
 Before each backup:
 1. Query incomplete snapshots (where `completed_at IS NULL`)
-2. Check if metadata exists in S3
-3. If no metadata, delete snapshot and all associations
-4. Clean up orphaned files, chunks, and blobs
+2. Delete each one and all its associations, without checking S3 for its metadata
+3. Clean up orphaned files, chunks, and blobs
 
 ## Repository Pattern
 

internal/cli/app.go

@@ -206,6 +206,10 @@ func RunApp(ctx context.Context, app *fx.App) error {
 // RunOperation through cobra to Entry.
 var errReported = errors.New("operation failed")
 
+// errInterrupted marks an operation that SIGINT or SIGTERM stopped
+// before it finished. Entry shows it and returns exitCodeInterrupted.
+var errInterrupted = errors.New("interrupted before the command finished")
+
 // 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
@@ -220,17 +224,21 @@ var errReported = errors.New("operation failed")
 // 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 show it to the
-// user before it becomes errReported. A context cancellation is the
-// interrupt path, not a failure: it is neither reported nor counted as
-// one.
+// called with a failure so the caller can show it to the user before
+// it becomes errReported.
+//
+// The run counts as interrupted unless op returned, without an
+// interrupt having cancelled it, before RunWithApp returned. An
+// interrupted op is not reported, whatever it returned; RunOperation
+// returns errInterrupted instead.
 func RunOperation(
 	ctx context.Context, opts AppOptions,
 	op func(v *vaultik.Vaultik) error, report func(err error),
 ) error {
 	var (
-		mu     sync.Mutex
-		failed bool
+		mu       sync.Mutex
+		finished bool // op returned before any interrupt cancelled it
+		failed   bool // op finished with an error
 	)
 
 	opts.Invokes = append(opts.Invokes,
@@ -241,11 +249,21 @@ func RunOperation(
 				OnStart: func(_ context.Context) error {
 					stop = v.StartOperation(func() {
 						err := op(v)
-						if err != nil && !errors.Is(err, context.Canceled) {
-							report(err)
+
+						// Only stop, called from OnStop below, cancels the
+						// Vaultik context, so a live context means no
+						// interrupt cancelled op. Check the context, not
+						// err: an interrupted op need not return
+						// context.Canceled (`snapshot verify --json`
+						// returns a verification failure).
+						if v.Context().Err() == nil {
+							if err != nil {
+								report(err)
+							}
 
 							mu.Lock()
-							failed = true
+							finished = true
+							failed = err != nil
 							mu.Unlock()
 						}
 
@@ -278,16 +296,23 @@ func RunOperation(
 		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.
+	// RunWithApp returns only after the app was asked to stop, either by
+	// an interrupt or by the goroutine's Shutdown call. When op finished
+	// without being cancelled, the goroutine set finished before that
+	// call. So if finished is unset here, an interrupt stopped the app,
+	// and op either returned after it was cancelled or is still running
+	// because the shutdown timed out.
 	mu.Lock()
 	defer mu.Unlock()
 
-	if failed {
+	switch {
+	case !finished:
+		return errInterrupted
+	case failed:
 		return errReported
+	default:
+		return nil
 	}
-
-	return nil
 }
 
 // runVaultikApp runs the standard single-operation command lifecycle

internal/cli/config.go

@@ -7,11 +7,14 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"reflect"
 	"strconv"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/spf13/cobra"
 	"gopkg.in/yaml.v3"
+	"sneak.berlin/go/vaultik/internal/config"
 	"sneak.berlin/go/vaultik/internal/ui"
 )
 
@@ -31,6 +34,9 @@ const configDirMode = 0o755
 // yaml.Marshal's 4-space default.
 const configYAMLIndent = 2
 
+// yamlStringTag is YAML's tag for a string scalar.
+const yamlStringTag = "!!str"
+
 var (
 	errConfigExists     = errors.New("config file already exists")
 	errEmptyConfig      = errors.New("empty config file")
@@ -199,7 +205,7 @@ storage_url: ""
 #   access_key_id: YOUR_ACCESS_KEY
 #   secret_access_key: YOUR_SECRET_KEY
 #   # region: us-east-1        # Default: us-east-1
-#   # part_size: 5MB           # Multipart upload part size. Default: 5MB
+#   # part_size: 5MiB          # Upload part size, 5MiB to 5GiB. Default: 5MiB
 #   # For the s3:// form, disable TLS with ?ssl=false in the URL, not use_ssl.
 
 # ─── OPTIONAL ────────────────────────────────────────────────────────────────
@@ -583,9 +589,58 @@ func yamlPathSet(root *yaml.Node, keys []string, value string) error {
 		}
 	}
 
+	// config.Load reads the file through untyped YAML, which turns an
+	// unquoted 00112233 into the number 38043 and 1e5 into 100000. Tagging
+	// a string setting as a string makes the encoder quote such a value.
+	// Other settings stay unquoted, so compression_level 9 is a number.
+	// The encoder refuses to write a value that is not valid UTF-8 as a
+	// string. Left untagged, such a value is written as base64 !!binary and
+	// loads back unchanged.
+	if configKeyIsString(keys) && utf8.ValidString(value) {
+		node.Tag = yamlStringTag
+	}
+
 	return nil
 }
 
+// configKeyIsString reports whether the dotted key names a string in
+// config.Config, following the fields' yaml tags, as s3.access_key_id and
+// snapshots.home.exclude.0 do.
+func configKeyIsString(keys []string) bool {
+	typ := reflect.TypeFor[config.Config]()
+
+	for _, key := range keys {
+		switch {
+		case typ.Kind() == reflect.Map || typ.Kind() == reflect.Slice:
+			// The key is a snapshot name or a list index.
+			typ = typ.Elem()
+		case typ.Kind() == reflect.Struct:
+			field, ok := yamlField(typ, key)
+			if !ok {
+				return false
+			}
+
+			typ = field.Type
+		default:
+			return false
+		}
+	}
+
+	return typ.Kind() == reflect.String
+}
+
+// yamlField returns the field of struct type typ whose yaml tag names key.
+func yamlField(typ reflect.Type, key string) (reflect.StructField, bool) {
+	for field := range typ.Fields() {
+		name, _, _ := strings.Cut(field.Tag.Get("yaml"), ",")
+		if name == key {
+			return field, true
+		}
+	}
+
+	return reflect.StructField{}, false
+}
+
 // yamlSetInMapping resolves (creating if needed) the value node for key
 // within a mapping node, setting it to value when it is the final path
 // element, and returns the node to descend into.

internal/cli/config_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -94,6 +95,110 @@ func TestConfigSetRecipientOnFreshConfig(t *testing.T) {
 	}
 }
 
+// TestConfigSetStringLooksLikeNumber sets string settings to values that
+// YAML reads as numbers or booleans when they are unquoted, and checks that
+// config.Load returns each one unchanged.
+func TestConfigSetStringLooksLikeNumber(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		key   string
+		value string
+		field func(cfg *config.Config) string
+	}{
+		{"s3.access_key_id", "00112233",
+			func(cfg *config.Config) string { return cfg.S3.AccessKeyID }},
+		{"s3.secret_access_key", "12345678901234567890123456789012",
+			func(cfg *config.Config) string { return cfg.S3.SecretAccessKey }},
+		{"hostname", "007",
+			func(cfg *config.Config) string { return cfg.Hostname }},
+		{"s3.prefix", "1e5",
+			func(cfg *config.Config) string { return cfg.S3.Prefix }},
+		{"s3.bucket", "true",
+			func(cfg *config.Config) string { return cfg.S3.Bucket }},
+		{"s3.region", "FALSE",
+			func(cfg *config.Config) string { return cfg.S3.Region }},
+		{"snapshots.home.exclude.0", "1.10",
+			func(cfg *config.Config) string { return cfg.Snapshots["home"].Exclude[0] }},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.key+"="+tt.value, func(t *testing.T) {
+			t.Parallel()
+
+			cfg := loadAfterConfigSet(t, tt.key, tt.value)
+
+			got := tt.field(cfg)
+			if got != tt.value {
+				t.Errorf("%s = %q after config set %q", tt.key, got, tt.value)
+			}
+		})
+	}
+}
+
+// TestConfigSetNonUTF8Path checks that config set still accepts a value that
+// is not valid UTF-8, such as a path with a Latin-1 file name, and that
+// config.Load returns it unchanged.
+func TestConfigSetNonUTF8Path(t *testing.T) {
+	t.Parallel()
+
+	const dir = "/srv/caf\xe9"
+
+	cfg := loadAfterConfigSet(t, "snapshots.home.paths.0", dir)
+
+	got := cfg.Snapshots["home"].Paths[0]
+	if got != dir {
+		t.Errorf("snapshots.home.paths.0 = %q, want %q", got, dir)
+	}
+}
+
+// TestConfigSetNumberStaysNumber checks that a number set for an integer
+// setting is still read as a number, not as a quoted string.
+func TestConfigSetNumberStaysNumber(t *testing.T) {
+	t.Parallel()
+
+	const level = 9
+
+	cfg := loadAfterConfigSet(t, "compression_level", strconv.Itoa(level))
+
+	if cfg.CompressionLevel != level {
+		t.Errorf("compression_level = %d, want %d", cfg.CompressionLevel, level)
+	}
+}
+
+// loadAfterConfigSet writes the file `config init` writes, sets storage_url
+// to a local directory so that the file passes validation, applies
+// `config set key value` and returns what config.Load reads back.
+func loadAfterConfigSet(t *testing.T, key, value string) *config.Config {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "config.yml")
+
+	err := os.WriteFile(path, []byte(defaultConfigTemplate), configFileMode)
+	if err != nil {
+		t.Fatalf("write config: %v", err)
+	}
+
+	out := ui.NewWithColor(&bytes.Buffer{}, false)
+
+	err = writeConfigSet(out, path, "storage_url", "file:///mnt/backups")
+	if err != nil {
+		t.Fatalf("config set storage_url: %v", err)
+	}
+
+	err = writeConfigSet(out, path, key, value)
+	if err != nil {
+		t.Fatalf("config set %s: %v", key, err)
+	}
+
+	cfg, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("config.Load: %v", err)
+	}
+
+	return cfg
+}
+
 const testYAML = `# top comment
 compression_level: 3
 age_recipients:

internal/cli/entry.go

@@ -15,6 +15,11 @@ import (
 // the startup banner.
 const shortCommitLen = 12
 
+// exitCodeInterrupted is the exit status of a command that SIGINT or
+// SIGTERM stopped. It is 128 plus SIGINT's number, 2, which is what a
+// shell reports for a command stopped by Ctrl-C.
+const exitCodeInterrupted = 130
+
 // Entry is the main entry point for the CLI application.
 // It prints the startup banner to stderr (unless a banner-suppressing
 // flag is present in os.Args — see bannerSuppressedInArgs), executes the
@@ -23,9 +28,10 @@ const shortCommitLen = 12
 // The banner goes to stderr because stdout carries only the output the
 // user asked for, such as a completion script or a `config get` value.
 //
-// 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.
+// It returns the process exit code (0 on success, 130 when interrupted,
+// 1 on any other 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.Stderr)
 
@@ -39,11 +45,16 @@ func Entry() int {
 		// document instead); 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.
+		// load, an interrupt — reaches Entry unreported, so it is shown
+		// here.
 		if !errors.Is(err, errReported) {
 			ReportErrorf("%s", err.Error())
 		}
 
+		if errors.Is(err, errInterrupted) {
+			return exitCodeInterrupted
+		}
+
 		return 1
 	}
 

internal/cli/entry_interrupt_test.go

@@ -0,0 +1,203 @@
+package cli //nolint:testpackage // shares runEntry and the argument constants
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/adrg/xdg"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// stalledStoreConfig is hermeticConfig with an s3:// destination store
+// in place of the file:// one. The server behind it accepts any
+// credentials.
+const stalledStoreConfig = `age_recipients:
+  - age1278m9q7dp3chsh2dcy82qk27v047zywyvtxwnj4cvt0z65jw6a7q5dqhfj
+snapshots:
+  test:
+    paths:
+      - %s
+storage_url: s3://bucket?endpoint=%s&ssl=false
+s3:
+  access_key_id: key
+  secret_access_key: secret
+index_path: %s
+hostname: test-host
+`
+
+// interruptRepeat is how often interruptOnFirstRequest sends SIGINT.
+const interruptRepeat = 50 * time.Millisecond
+
+// TestEntryInterruptedRun sends SIGINT to the test process while a
+// command waits on the destination store, and checks that Entry returns
+// 130 and prints one line on stderr saying the run was interrupted. The
+// store is a local HTTP server that holds every request open, so the
+// command is always mid-operation when the signal arrives. The two
+// cases cover --cron and --json, which silence other output.
+//
+// Not parallel: it signals the process and replaces os.Args, os.Stdout,
+// os.Stderr and the xdg globals.
+//
+//nolint:paralleltest // signals the process and replaces process globals
+func TestEntryInterruptedRun(t *testing.T) {
+	for _, testCase := range []struct {
+		name string
+		args []string
+	}{
+		{
+			name: "snapshot create --cron",
+			args: []string{cmdSnapshot, cmdCreate, "--cron"},
+		},
+		{
+			name: "snapshot verify --json",
+			args: []string{cmdSnapshot, cmdVerify, someSnapshotID, flagJSON},
+		},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			endpoint, requestArrived := startStalledStore(t)
+			configPath := writeStalledStoreConfig(t, endpoint)
+			interruptOnFirstRequest(t, requestArrived)
+
+			code, _, stderr := runEntry(t,
+				append([]string{flagConfig, configPath}, testCase.args...)...)
+
+			assert.Equal(t, 130, code)
+			assert.Equal(t, 1,
+				strings.Count(stderr, errInterrupted.Error()), stderr)
+		})
+	}
+}
+
+// interruptOnFirstRequest sends SIGINT to the test process every
+// interruptRepeat, from the first request to the destination store until
+// the test ends. One signal is not enough: the command can reach the
+// store before fx has started catching signals. The test catches SIGINT
+// too, so that a signal fx is not catching does not kill the test
+// binary.
+func interruptOnFirstRequest(t *testing.T, requestArrived <-chan struct{}) {
+	t.Helper()
+
+	self, err := os.FindProcess(os.Getpid())
+	require.NoError(t, err)
+
+	caught := make(chan os.Signal, 1)
+	signal.Notify(caught, os.Interrupt)
+
+	testEnded := make(chan struct{})
+	senderDone := make(chan struct{})
+
+	// Stop catching SIGINT only after the sender has returned. The sender
+	// waits for each SIGINT it sends to arrive on caught; one still on
+	// its way after signal.Stop would kill the test binary.
+	t.Cleanup(func() {
+		close(testEnded)
+		<-senderDone
+		signal.Stop(caught)
+	})
+
+	go func() {
+		defer close(senderDone)
+
+		select {
+		case <-requestArrived:
+		case <-testEnded:
+			return
+		}
+
+		ticker := time.NewTicker(interruptRepeat)
+		defer ticker.Stop()
+
+		for {
+			// Empty caught, so that the receive below waits for this
+			// SIGINT rather than an earlier one.
+			select {
+			case <-caught:
+			default:
+			}
+
+			sendErr := self.Signal(os.Interrupt)
+			if sendErr != nil {
+				t.Errorf("sending SIGINT: %v", sendErr)
+
+				return
+			}
+
+			<-caught
+
+			select {
+			case <-testEnded:
+				return
+			case <-ticker.C:
+			}
+		}
+	}()
+}
+
+// startStalledStore starts an HTTP server that never answers: each
+// request is held until the client gives up on it or the test ends.
+// It returns the server's host:port and a channel that receives a value
+// when the first request arrives.
+func startStalledStore(t *testing.T) (string, <-chan struct{}) {
+	t.Helper()
+
+	requestArrived := make(chan struct{}, 1)
+	release := make(chan struct{})
+
+	server := httptest.NewServer(http.HandlerFunc(
+		func(_ http.ResponseWriter, r *http.Request) {
+			select {
+			case requestArrived <- struct{}{}:
+			default:
+			}
+
+			select {
+			case <-r.Context().Done():
+			case <-release:
+			}
+		}))
+
+	// Cleanups run last-registered first, so release lets any held
+	// request return before Close waits for it.
+	t.Cleanup(server.Close)
+	t.Cleanup(func() { close(release) })
+
+	return server.Listener.Addr().String(), requestArrived
+}
+
+// writeStalledStoreConfig writes a config whose destination store is the
+// server at endpoint and whose snapshot source holds one small file, so
+// that `snapshot create` has a blob to upload. Returns the config path.
+func writeStalledStoreConfig(t *testing.T, endpoint string) string {
+	t.Helper()
+
+	dir := t.TempDir()
+	configPath := filepath.Join(dir, "config.yml")
+	sourceDir := filepath.Join(dir, "source")
+
+	require.NoError(t, os.Mkdir(sourceDir, 0o750))
+	require.NoError(t, os.WriteFile(filepath.Join(sourceDir, "file.txt"),
+		[]byte("contents"), 0o600))
+
+	contents := fmt.Sprintf(stalledStoreConfig,
+		sourceDir, endpoint, filepath.Join(dir, "index.sqlite"))
+
+	require.NoError(t,
+		os.WriteFile(configPath, []byte(contents), configFileMode))
+
+	// The PID lock lives under xdg.DataHome, which xdg resolves at
+	// package init; point it at the temp dir so the test neither
+	// touches nor collides with the real one.
+	t.Setenv("XDG_DATA_HOME", filepath.Join(dir, "data"))
+	xdg.Reload()
+	t.Cleanup(xdg.Reload)
+
+	return configPath
+}

internal/cli/prune.go

@@ -22,9 +22,11 @@ scans every snapshot manifest in the destination store, builds the
 set of still-referenced blob hashes, and deletes any blob not in that
 set.
 
-Snapshot create --prune and snapshot remove run the same cleanup
-automatically; this command is the manual entry point for the same
-work (e.g. after a crashed backup or to reclaim storage).`,
+Snapshot create --prune runs the same cleanup automatically; this
+command is the manual entry point for the same work (e.g. after a
+crashed backup or to reclaim storage). Snapshot remove leaves blobs in
+place; run this command afterwards to delete the ones no longer
+referenced.`,
 		Args: cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, _ []string) error {
 			// Use unified config resolution

internal/cli/snapshot.go

@@ -66,8 +66,9 @@ func newSnapshotCreateCommand() *cobra.Command {
 If snapshot names are provided, only those snapshots are created.
 If no names are provided, all configured snapshots are created.
 
-Config is located at /etc/vaultik/config.yml by default, but can be overridden by
-specifying a path using --config or by setting VAULTIK_CONFIG to a path.`,
+The config is read from the path given by --config or VAULTIK_CONFIG;
+otherwise from the platform config directory (~/.config/vaultik/config.yml
+on Linux), then /etc/vaultik/config.yml.`,
 		Args: cobra.ArbitraryArgs,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			// Pass snapshot names from args

internal/config/config.go

@@ -33,11 +33,14 @@ const secretKeyPrefix = "AGE-SECRET-KEY-"
 const (
 	defaultBlobSizeLimit    = Size(10 * 1024 * 1024 * 1024) // 10GB
 	defaultChunkSize        = Size(10 * 1024 * 1024)        // 10MB
-	defaultS3PartSize       = Size(5 * 1024 * 1024)         // 5MB
+	defaultS3PartSize       = Size(5 * 1024 * 1024)         // 5MiB
 	defaultCompressionLevel = 3
 	minChunkSize            = 1024 * 1024 // 1MB
 	minCompressionLevel     = 1
 	maxCompressionLevel     = 19
+	// S3 accepts a multipart upload part from 5MiB to 5GiB.
+	minS3PartSize = 5 * 1024 * 1024
+	maxS3PartSize = 5 * 1024 * 1024 * 1024
 )
 
 // Sentinel validation errors.
@@ -55,6 +58,7 @@ var (
 		"blob_size_limit must be at least the largest chunk the chunker can " +
 			"emit (chunk_size times the FastCDC size spread)")
 	errBadCompression   = errors.New("compression_level must be between 1 and 19")
+	errBadS3PartSize    = errors.New("s3.part_size must be between 5MiB and 5GiB")
 	errBadStorageScheme = errors.New(
 		"storage_url must start with s3://, file://, or rclone://")
 	errStorageNotConfigured = errors.New(
@@ -244,6 +248,7 @@ func Load(path string) (*Config, error) {
 		ChunkSize:        defaultChunkSize,
 		IndexPath:        filepath.Join(xdg.DataHome, appName, "index.sqlite"),
 		CompressionLevel: defaultCompressionLevel,
+		S3:               S3Config{PartSize: defaultS3PartSize},
 	}
 
 	// Convert smartconfig data to YAML then unmarshal
@@ -294,17 +299,13 @@ func Load(path string) (*Config, error) {
 		cfg.S3.Region = "us-east-1"
 	}
 
-	if cfg.S3.PartSize == 0 {
-		cfg.S3.PartSize = defaultS3PartSize
-	}
-
 	// Check config file permissions (warn if world or group readable)
 	//nolint:gosec // G703: config path is operator-supplied by design
 	info, statErr := os.Stat(path)
 	if statErr == nil {
 		mode := info.Mode().Perm()
 		if mode&0044 != 0 { // group or world readable
-			log.Warn("Config file has insecure permissions (contains S3 credentials)",
+			log.Warn(cfg.readableByOthersWarning(),
 				"path", path,
 				"mode", fmt.Sprintf("%04o", mode),
 				"recommendation", "chmod 600 "+path)
@@ -332,6 +333,7 @@ func Load(path string) (*Config, error) {
 //     (chunk_size times chunker.ChunkSizeSpread), so a single-chunk blob never
 //     exceeds the configured limit
 //   - Compression level must be between 1 and 19
+//   - S3 part size must be between 5MiB and 5GiB, the part sizes S3 accepts
 //
 // Returns an error describing the first validation failure encountered.
 func (c *Config) Validate() error {
@@ -376,6 +378,11 @@ func (c *Config) Validate() error {
 		return errBadCompression
 	}
 
+	if c.S3.PartSize.Int64() < minS3PartSize ||
+		c.S3.PartSize.Int64() > maxS3PartSize {
+		return errBadS3PartSize
+	}
+
 	return nil
 }
 
@@ -411,6 +418,18 @@ func (c *Config) setAgeSecretKey() {
 	}
 }
 
+// readableByOthersWarning is the warning Load logs when others can read
+// the config file. It says "may contain" because the S3 credentials are
+// seen only after smartconfig has replaced any ${...} reference in the
+// file with its value, so a set credential need not be in the file.
+func (c *Config) readableByOthersWarning() string {
+	if c.S3.AccessKeyID != "" || c.S3.SecretAccessKey != "" {
+		return "Config file is readable by others and may contain S3 credentials"
+	}
+
+	return "Config file is readable by others"
+}
+
 // validateStorage validates storage configuration.
 // If StorageURL is set, it takes precedence. S3 URLs require credentials.
 // File URLs don't require any S3 configuration.

internal/config/config_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"sneak.berlin/go/vaultik/internal/chunker"
+	"sneak.berlin/go/vaultik/internal/log"
 )
 
 const (
@@ -166,6 +167,7 @@ func TestValidateBlobSizeLimit(t *testing.T) {
 			ChunkSize:        chunkSize,
 			BlobSizeLimit:    blobLimit,
 			CompressionLevel: 3,
+			S3:               S3Config{PartSize: defaultS3PartSize},
 		}
 	}
 
@@ -221,6 +223,120 @@ func TestValidateBlobSizeLimit(t *testing.T) {
 	}
 }
 
+// TestValidateS3PartSize checks that s3.part_size is held to the part sizes
+// S3 accepts, 5MiB to 5GiB, by changing only the part size of the test
+// config. "5MB" in the config file is 5,000,000 bytes, below the minimum.
+func TestValidateS3PartSize(t *testing.T) {
+	t.Parallel()
+
+	base, err := Load(os.Getenv("VAULTIK_CONFIG"))
+	if err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+
+	tests := []struct {
+		name     string
+		partSize Size
+		wantErr  bool
+	}{
+		{
+			name:     "5MB is rejected",
+			partSize: 5_000_000,
+			wantErr:  true,
+		},
+		{
+			name:     "one byte below 5MiB is rejected",
+			partSize: minS3PartSize - 1,
+			wantErr:  true,
+		},
+		{
+			name:     "5MiB is accepted",
+			partSize: minS3PartSize,
+			wantErr:  false,
+		},
+		{
+			name:     "5GiB is accepted",
+			partSize: maxS3PartSize,
+			wantErr:  false,
+		},
+		{
+			name:     "one byte above 5GiB is rejected",
+			partSize: maxS3PartSize + 1,
+			wantErr:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			cfg := *base
+			cfg.S3.PartSize = tt.partSize
+
+			err := cfg.Validate()
+			if tt.wantErr {
+				if !errors.Is(err, errBadS3PartSize) {
+					t.Fatalf("Validate() error = %v, want errBadS3PartSize", err)
+				}
+
+				return
+			}
+
+			if err != nil {
+				t.Fatalf("Validate() unexpected error: %v", err)
+			}
+		})
+	}
+}
+
+// TestLoadS3PartSize checks that a config file without s3.part_size loads
+// with the 5MiB default, and that an explicit 0 fails at load like any other
+// part size S3 refuses.
+func TestLoadS3PartSize(t *testing.T) {
+	t.Parallel()
+
+	const withoutPartSize = "snapshots:\n" +
+		"  test:\n" +
+		"    paths: [/tmp/vaultik-test-source]\n" +
+		"storage_url: file:///tmp/vaultik-test-storage\n"
+
+	writeConfig := func(t *testing.T, text string) string {
+		t.Helper()
+
+		path := filepath.Join(t.TempDir(), "config.yml")
+
+		err := os.WriteFile(path, []byte(text), 0o600)
+		if err != nil {
+			t.Fatalf("write config: %v", err)
+		}
+
+		return path
+	}
+
+	t.Run("absent loads as 5MiB", func(t *testing.T) {
+		t.Parallel()
+
+		cfg, err := Load(writeConfig(t, withoutPartSize))
+		if err != nil {
+			t.Fatalf("Load() unexpected error: %v", err)
+		}
+
+		if cfg.S3.PartSize != defaultS3PartSize {
+			t.Errorf("s3.part_size = %d, want %d",
+				cfg.S3.PartSize, defaultS3PartSize)
+		}
+	})
+
+	t.Run("0 is rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := Load(writeConfig(t, withoutPartSize+"s3:\n  part_size: 0\n"))
+		if !errors.Is(err, errBadS3PartSize) {
+			t.Fatalf("Load() error = %v, want errBadS3PartSize", 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. An empty list
@@ -236,6 +352,7 @@ func TestValidateAgeRecipients(t *testing.T) {
 			ChunkSize:        Size(10 * 1024 * 1024),
 			BlobSizeLimit:    Size(10 * 1024 * 1024 * 1024),
 			CompressionLevel: 3,
+			S3:               S3Config{PartSize: defaultS3PartSize},
 		}
 	}
 
@@ -343,3 +460,125 @@ func TestAgeSecretKeySourceName(t *testing.T) {
 		})
 	}
 }
+
+// loadReadableConfig writes configYAML to a file that others can read,
+// loads it, and returns what the logger wrote to stderr meanwhile. The
+// logger writes to the os.Stderr it finds when it is initialized, so
+// os.Stderr is pointed at a file first. Not parallel-safe: os.Stderr and
+// the logger are process-global.
+func loadReadableConfig(t *testing.T, configYAML string) string {
+	t.Helper()
+
+	dir := t.TempDir()
+	configPath := filepath.Join(dir, "config.yml")
+	stderrPath := filepath.Join(dir, "stderr")
+
+	err := os.WriteFile(configPath, []byte(configYAML), 0o600)
+	if err != nil {
+		t.Fatalf("writing config: %v", err)
+	}
+
+	//nolint:gosec // G302: the test needs a config file others can read
+	err = os.Chmod(configPath, 0o644)
+	if err != nil {
+		t.Fatalf("chmod config: %v", err)
+	}
+
+	stderrFile, err := os.Create(stderrPath) //nolint:gosec // G304: test temp path
+	if err != nil {
+		t.Fatalf("creating stderr file: %v", err)
+	}
+
+	previous := os.Stderr
+	os.Stderr = stderrFile
+
+	log.Initialize(log.Config{})
+
+	_, loadErr := Load(configPath)
+
+	os.Stderr = previous
+
+	log.Initialize(log.Config{})
+
+	_ = stderrFile.Close()
+
+	if loadErr != nil {
+		t.Fatalf("Load() error = %v", loadErr)
+	}
+
+	captured, err := os.ReadFile(stderrPath) //nolint:gosec // G304: test temp path
+	if err != nil {
+		t.Fatalf("reading stderr file: %v", err)
+	}
+
+	return string(captured)
+}
+
+// TestLoadWarnsReadableConfigWithoutS3Credentials checks that a config
+// file others can read, holding no S3 credentials, is warned about
+// without a claim that it holds them.
+//
+//nolint:paralleltest // loadReadableConfig replaces os.Stderr
+func TestLoadWarnsReadableConfigWithoutS3Credentials(t *testing.T) {
+	stderr := loadReadableConfig(t, `
+storage_url: file:///var/backups/vaultik
+snapshots:
+  home:
+    paths:
+      - /home
+`)
+
+	if !strings.Contains(stderr, "Config file is readable by others") {
+		t.Errorf("expected a warning that the file is readable by others, got %q",
+			stderr)
+	}
+
+	if strings.Contains(stderr, "S3 credentials") {
+		t.Errorf("warning names S3 credentials the file does not set: %q", stderr)
+	}
+}
+
+// TestLoadWarnsReadableConfigWithS3Credentials checks that a config file
+// others can read and that sets S3 credentials, as values or as ${ENV:...}
+// references, is warned about as one that may contain them.
+//
+//nolint:paralleltest // loadReadableConfig replaces os.Stderr
+func TestLoadWarnsReadableConfigWithS3Credentials(t *testing.T) {
+	t.Setenv("VAULTIK_TEST_ACCESS_KEY_ID", "test-access-key")
+	t.Setenv("VAULTIK_TEST_SECRET_ACCESS_KEY", "test-secret-key")
+
+	configs := map[string]string{
+		"values": `
+storage_url: s3://bucket/prefix?endpoint=s3.example.com
+s3:
+  access_key_id: test-access-key
+  secret_access_key: test-secret-key
+snapshots:
+  home:
+    paths:
+      - /home
+`,
+		"references": `
+storage_url: s3://bucket/prefix?endpoint=s3.example.com
+s3:
+  access_key_id: ${ENV:VAULTIK_TEST_ACCESS_KEY_ID}
+  secret_access_key: ${ENV:VAULTIK_TEST_SECRET_ACCESS_KEY}
+snapshots:
+  home:
+    paths:
+      - /home
+`,
+	}
+
+	for name, configYAML := range configs {
+		t.Run(name, func(t *testing.T) {
+			stderr := loadReadableConfig(t, configYAML)
+
+			if !strings.Contains(stderr,
+				"Config file is readable by others and may contain S3 credentials") {
+				t.Errorf("expected a warning naming the S3 credentials, got %q",
+					stderr)
+			}
+		})
+	}
+}

internal/database/files.go

@@ -33,11 +33,13 @@ func (r *FileRepository) Create(ctx context.Context, tx *sql.Tx, file *File) err
 	}
 
 	query := `
-		INSERT INTO files (id, path, source_path, mtime, size, mode, uid, gid, link_target)
-		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+		INSERT INTO files
+			(id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
 		ON CONFLICT(path) DO UPDATE SET
 			source_path = excluded.source_path,
 			mtime = excluded.mtime,
+			mtime_nsec = excluded.mtime_nsec,
 			size = excluded.size,
 			mode = excluded.mode,
 			uid = excluded.uid,
@@ -54,16 +56,19 @@ func (r *FileRepository) Create(ctx context.Context, tx *sql.Tx, file *File) err
 	if tx != nil {
 		LogSQL("Execute", query,
 			file.ID.String(), file.Path.String(), file.SourcePath.String(),
-			file.MTime.Unix(), file.Size, file.Mode, file.UID, file.GID,
+			file.MTime.Unix(), file.MTime.Nanosecond(),
+			file.Size, file.Mode, file.UID, file.GID,
 			file.LinkTarget.String())
 		err = tx.QueryRowContext(ctx, query,
 			file.ID.String(), file.Path.String(), file.SourcePath.String(),
-			file.MTime.Unix(), file.Size, file.Mode, file.UID, file.GID,
+			file.MTime.Unix(), file.MTime.Nanosecond(),
+			file.Size, file.Mode, file.UID, file.GID,
 			file.LinkTarget.String()).Scan(&idStr)
 	} else {
 		err = r.db.QueryRowWithLog(ctx, query,
 			file.ID.String(), file.Path.String(), file.SourcePath.String(),
-			file.MTime.Unix(), file.Size, file.Mode, file.UID, file.GID,
+			file.MTime.Unix(), file.MTime.Nanosecond(),
+			file.Size, file.Mode, file.UID, file.GID,
 			file.LinkTarget.String()).Scan(&idStr)
 	}
 
@@ -84,7 +89,7 @@ func (r *FileRepository) Create(ctx context.Context, tx *sql.Tx, file *File) err
 // in the index.
 func (r *FileRepository) GetByPath(ctx context.Context, path string) (*File, error) {
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
 		WHERE path = ?
 	`
@@ -104,7 +109,7 @@ func (r *FileRepository) GetByPath(ctx context.Context, path string) (*File, err
 // GetByID retrieves a file by its UUID
 func (r *FileRepository) GetByID(ctx context.Context, id types.FileID) (*File, error) {
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
 		WHERE id = ?
 	`
@@ -127,7 +132,7 @@ func (r *FileRepository) GetByPathTx(
 	ctx context.Context, tx *sql.Tx, path string,
 ) (*File, error) {
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
 		WHERE path = ?
 	`
@@ -158,13 +163,14 @@ func (r *FileRepository) ListModifiedSince(
 	ctx context.Context, since time.Time,
 ) ([]*File, error) {
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
-		WHERE mtime >= ?
+		WHERE (mtime, mtime_nsec) >= (?, ?)
 		ORDER BY path
 	`
 
-	rows, err := r.db.conn.QueryContext(ctx, query, since.Unix())
+	rows, err := r.db.conn.QueryContext(ctx, query,
+		since.Unix(), since.Nanosecond())
 	if err != nil {
 		return nil, fmt.Errorf("querying files: %w", err)
 	}
@@ -239,7 +245,7 @@ func (r *FileRepository) ListUnderPath(
 
 	// LIKE would ignore ASCII case and treat _ and % in path as wildcards.
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
 		WHERE path = ? OR substr(path, 1, length(?)) = ?
 		ORDER BY path
@@ -324,7 +330,7 @@ func (r *FileRepository) ListIDsWithChunksNotInUploadedBlobs(
 // ListAll returns all files in the database
 func (r *FileRepository) ListAll(ctx context.Context) ([]*File, error) {
 	query := `
-		SELECT id, path, source_path, mtime, size, mode, uid, gid, link_target
+		SELECT id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target
 		FROM files
 		ORDER BY path
 	`
@@ -365,7 +371,7 @@ func (r *FileRepository) CreateBatch(
 	}
 
 	// Each files row binds this many SQL variables.
-	const fileCols = 9
+	const fileCols = 10
 
 	// Batch at 100 rows to be safe with SQLite's variable limit.
 	const batchSize = 100
@@ -376,7 +382,7 @@ func (r *FileRepository) CreateBatch(
 		batch := files[i:end]
 
 		query := `INSERT INTO files
-			(id, path, source_path, mtime, size, mode, uid, gid, link_target)
+			(id, path, source_path, mtime, mtime_nsec, size, mode, uid, gid, link_target)
 			VALUES `
 
 		args := make([]any, 0, len(batch)*fileCols)
@@ -388,11 +394,12 @@ func (r *FileRepository) CreateBatch(
 				querySb325.WriteString(", ")
 			}
 
-			querySb325.WriteString("(?, ?, ?, ?, ?, ?, ?, ?, ?)")
+			querySb325.WriteString("(?, ?, ?, ?, ?, ?, ?, ?, ?, ?)")
 
 			args = append(args,
 				f.ID.String(), f.Path.String(), f.SourcePath.String(),
-				f.MTime.Unix(), f.Size, f.Mode, f.UID, f.GID,
+				f.MTime.Unix(), f.MTime.Nanosecond(),
+				f.Size, f.Mode, f.UID, f.GID,
 				f.LinkTarget.String())
 		}
 
@@ -401,6 +408,7 @@ func (r *FileRepository) CreateBatch(
 		query += ` ON CONFLICT(path) DO UPDATE SET
 			source_path = excluded.source_path,
 			mtime = excluded.mtime,
+			mtime_nsec = excluded.mtime_nsec,
 			size = excluded.size,
 			mode = excluded.mode,
 			uid = excluded.uid,
@@ -460,7 +468,7 @@ func (r *FileRepository) scanFileFrom(row fileRowScanner) (*File, error) {
 	var (
 		file                          File
 		idStr, pathStr, sourcePathStr string
-		mtimeUnix                     int64
+		mtimeUnix, mtimeNsec          int64
 		linkTarget                    sql.NullString
 	)
 
@@ -469,6 +477,7 @@ func (r *FileRepository) scanFileFrom(row fileRowScanner) (*File, error) {
 		&pathStr,
 		&sourcePathStr,
 		&mtimeUnix,
+		&mtimeNsec,
 		&file.Size,
 		&file.Mode,
 		&file.UID,
@@ -487,7 +496,7 @@ func (r *FileRepository) scanFileFrom(row fileRowScanner) (*File, error) {
 	file.Path = types.FilePath(pathStr)
 	file.SourcePath = types.SourcePath(sourcePathStr)
 
-	file.MTime = time.Unix(mtimeUnix, 0).UTC()
+	file.MTime = time.Unix(mtimeUnix, mtimeNsec).UTC()
 	if linkTarget.Valid {
 		file.LinkTarget = types.FilePath(linkTarget.String)
 	}

internal/database/files_test.go

@@ -252,6 +252,115 @@ func TestFileRepositorySymlink(t *testing.T) {
 	}
 }
 
+// An mtime after 2262 or before 1678 does not fit in int64 nanoseconds
+// since the epoch, and must still come back from the database unchanged.
+func TestFileRepositoryMTimeOutsideInt64NanosecondRange(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	repo := database.NewFileRepository(db)
+
+	mtimes := []time.Time{
+		time.Date(2300, time.January, 1, 0, 0, 0, 123456789, time.UTC),
+		time.Date(1601, time.January, 1, 0, 0, 0, 987654321, time.UTC),
+	}
+
+	for _, mtime := range mtimes {
+		created := &database.File{
+			Path:  types.FilePath("/created-" + mtime.Format(time.RFC3339Nano)),
+			MTime: mtime,
+		}
+
+		err := repo.Create(ctx, nil, created)
+		if err != nil {
+			t.Fatalf("failed to create file: %v", err)
+		}
+
+		batched := &database.File{
+			ID:    types.NewFileID(),
+			Path:  types.FilePath("/batched-" + mtime.Format(time.RFC3339Nano)),
+			MTime: mtime,
+		}
+
+		err = repo.CreateBatch(ctx, nil, []*database.File{batched})
+		if err != nil {
+			t.Fatalf("failed to batch create file: %v", err)
+		}
+
+		for _, path := range []types.FilePath{created.Path, batched.Path} {
+			retrieved, err := repo.GetByPath(ctx, path.String())
+			if err != nil {
+				t.Fatalf("failed to get file: %v", err)
+			}
+
+			if !retrieved.MTime.Equal(mtime) {
+				t.Errorf("%s: mtime got %v, want %v",
+					path, retrieved.MTime, mtime)
+			}
+		}
+	}
+}
+
+// A file already in the index and rewritten within the same second must get
+// its new nanoseconds stored, through both Create and CreateBatch.
+func TestFileRepositoryUpsertMTimeInSameSecond(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	repo := database.NewFileRepository(db)
+
+	indexed := time.Date(2026, time.October, 7, 12, 0, 0, 100000000, time.UTC)
+	rewritten := indexed.Add(800 * time.Millisecond)
+
+	tests := []struct {
+		name   string
+		upsert func(file *database.File) error
+	}{
+		{"Create", func(file *database.File) error {
+			return repo.Create(ctx, nil, file)
+		}},
+		{"CreateBatch", func(file *database.File) error {
+			return repo.CreateBatch(ctx, nil, []*database.File{file})
+		}},
+	}
+
+	for _, tt := range tests {
+		file := &database.File{
+			ID:    types.NewFileID(),
+			Path:  types.FilePath("/" + tt.name),
+			MTime: indexed,
+		}
+
+		err := tt.upsert(file)
+		if err != nil {
+			t.Fatalf("%s: failed to create file: %v", tt.name, err)
+		}
+
+		file.MTime = rewritten
+
+		err = tt.upsert(file)
+		if err != nil {
+			t.Fatalf("%s: failed to update file: %v", tt.name, err)
+		}
+
+		retrieved, err := repo.GetByPath(ctx, file.Path.String())
+		if err != nil {
+			t.Fatalf("%s: failed to get file: %v", tt.name, err)
+		}
+
+		if !retrieved.MTime.Equal(rewritten) {
+			t.Errorf("%s: mtime got %v, want %v",
+				tt.name, retrieved.MTime, rewritten)
+		}
+	}
+}
+
 func TestFileRepositoryTransaction(t *testing.T) {
 	t.Parallel()
 

internal/database/models.go

@@ -14,8 +14,7 @@ type File struct {
 	ID   types.FileID   // UUID primary key
 	Path types.FilePath // Absolute path of the file
 
-	// SourcePath is the source directory this file came from (used for
-	// restore path stripping).
+	// SourcePath is the source directory this file came from.
 	SourcePath types.SourcePath
 	MTime      time.Time
 	Size       int64

internal/database/repository_edge_cases_test.go

@@ -3,6 +3,7 @@ package database
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 	"strings"
 	"testing"
@@ -367,7 +368,7 @@ func verifyBlobNullUploadTS(
 }
 
 // createLargeDatasetFiles creates fileCount files and adds every other
-// one to the snapshot.
+// one to the snapshot, in one transaction as a backup writes them.
 func createLargeDatasetFiles(
 	t *testing.T,
 	repos *Repositories,
@@ -376,31 +377,38 @@ func createLargeDatasetFiles(
 ) {
 	t.Helper()
 
-	ctx := context.Background()
 	start := time.Now()
 
-	for i := range fileCount {
-		file := &File{
-			Path:  types.FilePath(fmt.Sprintf("/large/file%05d.txt", i)),
-			MTime: time.Now(),
-			Size:  int64(i * 1024),
-			Mode:  0644,
-			UID:   uint32(1000 + (i % 10)),
-			GID:   uint32(1000 + (i % 10)),
-		}
+	err := repos.WithTx(context.Background(),
+		func(ctx context.Context, tx *sql.Tx) error {
+			for i := range fileCount {
+				file := &File{
+					Path:  types.FilePath(fmt.Sprintf("/large/file%05d.txt", i)),
+					MTime: time.Now(),
+					Size:  int64(i * 1024),
+					Mode:  0644,
+					UID:   uint32(1000 + (i % 10)),
+					GID:   uint32(1000 + (i % 10)),
+				}
 
-		err := repos.Files.Create(ctx, nil, file)
-		if err != nil {
-			t.Fatalf("failed to create file %d: %v", i, err)
-		}
+				err := repos.Files.Create(ctx, tx, file)
+				if err != nil {
+					return fmt.Errorf("creating file %d: %w", i, err)
+				}
 
-		// Add half to snapshot
-		if i%2 == 0 {
-			err = repos.Snapshots.AddFileByID(ctx, nil, snapshotID, file.ID)
-			if err != nil {
-				t.Fatal(err)
+				// Add half to snapshot
+				if i%2 == 0 {
+					err = repos.Snapshots.AddFileByID(ctx, tx, snapshotID, file.ID)
+					if err != nil {
+						return err
+					}
+				}
 			}
-		}
+
+			return nil
+		})
+	if err != nil {
+		t.Fatal(err)
 	}
 
 	t.Logf("Created %d files in %v", fileCount, time.Since(start))
@@ -606,8 +614,7 @@ func TestTimezoneHandling(t *testing.T) {
 		t.Skip("timezone not available")
 	}
 
-	// Use Truncate to remove sub-second precision since we store as Unix timestamps
-	nyTime := time.Now().In(loc).Truncate(time.Second)
+	nyTime := time.Now().In(loc)
 	file := &File{
 		Path:  "/timezone-test.txt",
 		MTime: nyTime,

internal/database/schema/001.sql

@@ -5,8 +5,9 @@
 CREATE TABLE IF NOT EXISTS files (
     id TEXT PRIMARY KEY,  -- UUID
     path TEXT NOT NULL UNIQUE,
-    source_path TEXT NOT NULL DEFAULT '',  -- The source directory this file came from (for restore path stripping)
-    mtime INTEGER NOT NULL,
+    source_path TEXT NOT NULL DEFAULT '',  -- The source directory this file came from
+    mtime INTEGER NOT NULL,  -- whole seconds since the Unix epoch
+    mtime_nsec INTEGER NOT NULL,  -- nanoseconds within that second, 0 to 999999999
     size INTEGER NOT NULL,
     mode INTEGER NOT NULL,
     uid INTEGER NOT NULL,

internal/pidlock/pidlock.go

@@ -10,15 +10,18 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
-	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 // ErrAlreadyRunning indicates another vaultik instance is running.
 var ErrAlreadyRunning = errors.New("another vaultik instance is already running")
 
-// Lock represents an acquired PID lock.
+// Lock represents an acquired PID lock: an flock(2) on the PID file,
+// held while the file stays open. The kernel drops it when the process
+// exits, however it exits, so a crashed run never leaves the lock held.
 type Lock struct {
-	path string
+	file *os.File
 }
 
 const (
@@ -29,10 +32,9 @@ const (
 )
 
 // Acquire attempts to acquire a PID lock in the specified directory.
-// If the lock file exists and the process is still running, it returns
-// ErrAlreadyRunning with details about the existing process.
-// On success, it writes the current PID to the lock file and returns
-// a Lock that must be released with Release().
+// If another process holds the lock, it returns ErrAlreadyRunning with
+// that process's PID. On success, it writes the current PID to the lock
+// file and returns a Lock that must be released with Release().
 func Acquire(lockDir string) (*Lock, error) {
 	// Ensure lock directory exists
 	err := os.MkdirAll(lockDir, lockDirPerm)
@@ -42,56 +44,82 @@ func Acquire(lockDir string) (*Lock, error) {
 
 	lockPath := filepath.Join(lockDir, "vaultik.pid")
 
-	// Check for existing lock
-	existingPID, err := readPIDFile(lockPath)
-	if err == nil {
-		// Lock file exists, check if process is running
-		if isProcessRunning(existingPID) {
-			return nil, fmt.Errorf("%w (PID %d)", ErrAlreadyRunning, existingPID)
-		}
-		// Process is not running, stale lock file - we can take over
-	}
-
-	// Write our PID
-	pid := os.Getpid()
-
-	err = os.WriteFile(lockPath, []byte(strconv.Itoa(pid)), pidFilePerm)
+	// No O_TRUNC: the file may hold the PID of the process that has the
+	// lock, which the error below reports.
+	file, err := os.OpenFile( //nolint:gosec // G304: path is our own lock file
+		lockPath, os.O_RDWR|os.O_CREATE, pidFilePerm)
 	if err != nil {
-		return nil, fmt.Errorf("writing PID file: %w", err)
+		return nil, fmt.Errorf("opening PID file: %w", err)
 	}
 
-	return &Lock{path: lockPath}, nil
+	err = unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB)
+	if err != nil {
+		_ = file.Close()
+
+		if errors.Is(err, unix.EWOULDBLOCK) {
+			return nil, alreadyRunningError(lockPath)
+		}
+
+		return nil, fmt.Errorf("locking PID file: %w", err)
+	}
+
+	err = writePID(file)
+	if err != nil {
+		_ = file.Close()
+
+		return nil, err
+	}
+
+	return &Lock{file: file}, nil
 }
 
-// Release removes the PID lock file.
+// Release empties the PID file and closes it, which drops the lock.
 // It is safe to call Release multiple times.
 func (l *Lock) Release() error {
-	if l == nil || l.path == "" {
+	if l == nil || l.file == nil {
 		return nil
 	}
 
-	// Verify we still own the lock (our PID is in the file)
-	existingPID, err := readPIDFile(l.path)
+	file := l.file
+	l.file = nil
+
+	// Do not remove the file here. A process that opened it a moment
+	// earlier could then lock the removed file while another creates and
+	// locks a new one, and both would run.
+	truncateErr := file.Truncate(0)
+	closeErr := file.Close()
+
+	return errors.Join(truncateErr, closeErr)
+}
+
+// writePID replaces the contents of the locked PID file with the current
+// PID.
+func writePID(file *os.File) error {
+	err := file.Truncate(0)
 	if err != nil {
-		// File already gone or unreadable - that's fine
-		return nil //nolint:nilerr // unreadable lock file means nothing to release
+		return fmt.Errorf("truncating PID file: %w", err)
 	}
 
-	if existingPID != os.Getpid() {
-		// Someone else wrote to our lock file - don't remove it
-		return nil
+	_, err = file.WriteAt([]byte(strconv.Itoa(os.Getpid())), 0)
+	if err != nil {
+		return fmt.Errorf("writing PID file: %w", err)
 	}
 
-	err = os.Remove(l.path)
-	if err != nil && !os.IsNotExist(err) {
-		return fmt.Errorf("removing PID file: %w", err)
-	}
-
-	l.path = "" // Prevent double-release
-
 	return nil
 }
 
+// alreadyRunningError reports that another process holds the lock,
+// naming its PID when the file holds one. The holder writes its PID just
+// after it locks, so the file can briefly be empty.
+func alreadyRunningError(lockPath string) error {
+	pid, err := readPIDFile(lockPath)
+	if err != nil {
+		return ErrAlreadyRunning
+	}
+
+	return fmt.Errorf("%w (PID %d)", ErrAlreadyRunning, pid)
+}
+
 // readPIDFile reads and parses the PID from a lock file.
 func readPIDFile(path string) (int, error) {
 	data, err := os.ReadFile(path) //nolint:gosec // G304: path is our own lock file
@@ -106,16 +134,3 @@ func readPIDFile(path string) (int, error) {
 
 	return pid, nil
 }
-
-// isProcessRunning checks if a process with the given PID is running.
-func isProcessRunning(pid int) bool {
-	process, err := os.FindProcess(pid)
-	if err != nil {
-		return false
-	}
-
-	// On Unix, FindProcess always succeeds. We need to send signal 0 to check.
-	err = process.Signal(syscall.Signal(0))
-
-	return err == nil
-}

internal/pidlock/pidlock_test.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -33,9 +34,10 @@ func TestAcquireAndRelease(t *testing.T) {
 	err = lock.Release()
 	require.NoError(t, err)
 
-	// Verify PID file is gone
-	_, err = os.Stat(pidPath)
-	assert.True(t, os.IsNotExist(err))
+	// Verify PID file is empty
+	data, err = os.ReadFile(pidPath) //nolint:gosec // G304: test's own temp file
+	require.NoError(t, err)
+	assert.Empty(t, data)
 }
 
 func TestAcquireBlocksSecondInstance(t *testing.T) {
@@ -55,6 +57,64 @@ func TestAcquireBlocksSecondInstance(t *testing.T) {
 	lock2, err := pidlock.Acquire(tmpDir)
 	require.ErrorIs(t, err, pidlock.ErrAlreadyRunning)
 	assert.Nil(t, lock2)
+
+	// Once the first lock is released, the next Acquire succeeds
+	require.NoError(t, lock1.Release())
+
+	lock3, err := pidlock.Acquire(tmpDir)
+	require.NoError(t, err)
+	require.NoError(t, lock3.Release())
+}
+
+// TestConcurrentAcquireAdmitsOne starts many Acquire calls at the same
+// moment, as two cron entries firing together would, and checks that
+// exactly one of them gets the lock.
+func TestConcurrentAcquireAdmitsOne(t *testing.T) {
+	t.Parallel()
+
+	const callers = 50
+
+	tmpDir := t.TempDir()
+	start := make(chan struct{})
+
+	var (
+		mu       sync.Mutex
+		acquired []*pidlock.Lock
+		failures []error
+		wg       sync.WaitGroup
+	)
+
+	for range callers {
+		wg.Go(func() {
+			<-start
+
+			lock, err := pidlock.Acquire(tmpDir)
+
+			mu.Lock()
+			defer mu.Unlock()
+
+			if err != nil {
+				failures = append(failures, err)
+
+				return
+			}
+
+			acquired = append(acquired, lock)
+		})
+	}
+
+	close(start)
+	wg.Wait()
+
+	for _, lock := range acquired {
+		require.NoError(t, lock.Release())
+	}
+
+	assert.Len(t, acquired, 1, "exactly one caller should hold the lock")
+
+	for _, err := range failures {
+		require.ErrorIs(t, err, pidlock.ErrAlreadyRunning)
+	}
 }
 
 func TestAcquireWithStaleLock(t *testing.T) {

internal/s3/client.go

@@ -27,10 +27,12 @@ type Client struct {
 	bucket   string
 	prefix   string
 	endpoint string
+	partSize int64
 }
 
 // Config contains S3 client configuration.
-// All fields are required except Prefix, which defaults to an empty string.
+// All fields are required except Prefix, which defaults to an empty string,
+// and PartSize, where zero means the SDK default of 5 MiB.
 // A non-empty Prefix is joined to every key with one "/", whether or not
 // it ends with one.
 // The Endpoint field should include the protocol (http:// or https://).
@@ -41,6 +43,9 @@ type Config struct {
 	AccessKeyID     string
 	SecretAccessKey string
 	Region          string
+	// PartSize is the size in bytes of each part of a multipart upload.
+	// An upload too large for S3's limit of 10,000 parts gets larger parts.
+	PartSize int64
 }
 
 // nopLogger is a logger that discards all output.
@@ -90,6 +95,7 @@ func NewClient(ctx context.Context, cfg Config) (*Client, error) {
 		bucket:   cfg.Bucket,
 		prefix:   prefix,
 		endpoint: cfg.Endpoint,
+		partSize: cfg.PartSize,
 	}, nil
 }
 
@@ -123,12 +129,9 @@ func (c *Client) PutObjectWithProgress(
 ) error {
 	fullKey := c.prefix + key
 
-	// uploadPartSize is 10MB for better progress granularity.
-	const uploadPartSize = 10 * 1024 * 1024
-
 	// Create an uploader with the S3 client
 	uploader := manager.NewUploader(c.s3Client, func(u *manager.Uploader) {
-		u.PartSize = uploadPartSize
+		u.PartSize = uploadPartSize(c.partSize, size)
 	})
 
 	// Create a progress reader that tracks upload progress
@@ -149,6 +152,21 @@ func (c *Client) PutObjectWithProgress(
 	return err
 }
 
+// uploadPartSize returns the part size for an upload of size bytes: the
+// configured part size (the SDK default when zero), raised where needed so
+// the upload fits in S3's limit of 10,000 parts. The uploader cannot raise
+// it itself, because it cannot seek the progress reader to learn its size.
+func uploadPartSize(configured, size int64) int64 {
+	if configured == 0 {
+		configured = manager.DefaultUploadPartSize
+	}
+
+	maxParts := int64(manager.MaxUploadParts)
+	smallestThatFits := (size + maxParts - 1) / maxParts // rounded up
+
+	return max(configured, smallestThatFits)
+}
+
 // GetObject downloads an object from S3 with the specified key.
 // The key is automatically prefixed with the configured prefix.
 // Returns a ReadCloser containing the object data. The caller must

internal/s3/client_internal_test.go

@@ -0,0 +1,55 @@
+package s3
+
+import "testing"
+
+// TestUploadPartSize checks that an upload too large for 10,000 parts of the
+// configured size gets parts just large enough to fit in 10,000.
+func TestUploadPartSize(t *testing.T) {
+	t.Parallel()
+
+	const mib = 1024 * 1024
+
+	tests := []struct {
+		name       string
+		configured int64
+		size       int64
+		want       int64
+	}{
+		{
+			name:       "an upload that fits keeps the configured size",
+			configured: 5 * mib,
+			size:       10 * 1024 * mib,
+			want:       5 * mib,
+		},
+		{
+			name:       "exactly 10,000 parts keeps the configured size",
+			configured: 6 * mib,
+			size:       10_000 * 6 * mib,
+			want:       6 * mib,
+		},
+		{
+			name:       "one byte more than 10,000 parts adds a byte to each",
+			configured: 6 * mib,
+			size:       10_000*6*mib + 1,
+			want:       6*mib + 1,
+		},
+		{
+			name:       "zero means the SDK default of 5MiB",
+			configured: 0,
+			size:       1,
+			want:       5 * mib,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := uploadPartSize(tt.configured, tt.size)
+			if got != tt.want {
+				t.Errorf("uploadPartSize(%d, %d) = %d, want %d",
+					tt.configured, tt.size, got, tt.want)
+			}
+		})
+	}
+}

internal/s3/module.go

@@ -28,6 +28,7 @@ func provideClient(lc fx.Lifecycle, cfg *config.Config) (*Client, error) {
 		AccessKeyID:     cfg.S3.AccessKeyID,
 		SecretAccessKey: cfg.S3.SecretAccessKey,
 		Region:          cfg.S3.Region,
+		PartSize:        cfg.S3.PartSize.Int64(),
 	})
 	if err != nil {
 		return nil, err

internal/snapshot/scanner.go

@@ -58,8 +58,8 @@ type Scanner struct {
 	compressionLevel int
 	ageRecipient     string
 	snapshotID       string // Current snapshot being processed
-	// currentSourcePath is the source directory being scanned (used for
-	// restore path stripping).
+	// currentSourcePath is the source directory being scanned, stored with
+	// each file record.
 	currentSourcePath string
 	exclude           []string          // Glob patterns for files/directories to exclude
 	compiledExclude   []compiledPattern // Compiled glob patterns
@@ -211,7 +211,6 @@ func (s *Scanner) Scan(
 	ctx context.Context, path string, snapshotID string,
 ) (*ScanResult, error) {
 	s.snapshotID = snapshotID
-	// Store source path for file records (used during restore)
 	s.currentSourcePath = path
 	result := &ScanResult{
 		StartTime: time.Now().UTC(),
@@ -890,9 +889,10 @@ func (s *Scanner) scanPhase(
 		}
 
 		// Handle symlinks and directories
-		if handled := s.recordSpecialEntry(
-			filePath, info, existingFiles, collector, result); handled {
-			return nil
+		handled, err := s.recordSpecialEntry(
+			filePath, info, existingFiles, collector, result)
+		if handled {
+			return err
 		}
 
 		// Skip other non-regular files (devices, sockets, etc.)
@@ -934,22 +934,25 @@ func (s *Scanner) scanPhase(
 }
 
 // recordSpecialEntry records symlinks and directories (which have no
-// data to chunk) and reports whether it handled the entry.
+// data to chunk) and reports whether it handled the entry. For a symlink
+// whose target cannot be read it returns handleWalkError's result.
 func (s *Scanner) recordSpecialEntry(
 	filePath string, info os.FileInfo,
 	existingFiles map[string]struct{},
 	collector *scanCollector, result *ScanResult,
-) bool {
+) (bool, error) {
 	// Handle symlinks
 	if info.Mode()&os.ModeSymlink != 0 {
-		file := s.buildSymlinkEntry(filePath, info)
-		if file != nil {
-			existingFiles[filePath] = struct{}{}
-			collector.addToProcess(filePath, info, file)
-			s.updateScanEntryStats(result, true, info)
+		file, err := s.buildSymlinkEntry(filePath, info)
+		if err != nil {
+			return true, s.handleWalkError(filePath, err)
 		}
 
-		return true
+		existingFiles[filePath] = struct{}{}
+		collector.addToProcess(filePath, info, file)
+		s.updateScanEntryStats(result, true, info)
+
+		return true, nil
 	}
 
 	// Handle directories (record for permission/ownership preservation
@@ -959,10 +962,10 @@ func (s *Scanner) recordSpecialEntry(
 		existingFiles[filePath] = struct{}{}
 		collector.addToProcess(filePath, info, file)
 
-		return true
+		return true, nil
 	}
 
-	return false
+	return false, nil
 }
 
 // handleWalkError deals with a filesystem error surfaced by the walk:
@@ -1112,13 +1115,12 @@ func (s *Scanner) printScanProgressLine(
 }
 
 // buildSymlinkEntry creates a File record for a symlink.
-// Returns nil if the link target cannot be read.
-func (s *Scanner) buildSymlinkEntry(path string, info os.FileInfo) *database.File {
+func (s *Scanner) buildSymlinkEntry(
+	path string, info os.FileInfo,
+) (*database.File, error) {
 	target, err := os.Readlink(path)
 	if err != nil {
-		log.Debug("Cannot read symlink target", "path", path, "error", err)
-
-		return nil
+		return nil, err
 	}
 
 	var uid, gid uint32
@@ -1137,7 +1139,7 @@ func (s *Scanner) buildSymlinkEntry(path string, info os.FileInfo) *database.Fil
 		UID:        uid,
 		GID:        gid,
 		LinkTarget: types.FilePath(target),
-	}
+	}, nil
 }
 
 // buildDirectoryEntry creates a File record for a directory.
@@ -1198,9 +1200,8 @@ func (s *Scanner) checkFileInMemory(
 	}
 
 	file := &database.File{
-		ID:   fileID,
-		Path: types.FilePath(path),
-		// Store source directory for restore path stripping
+		ID:         fileID,
+		Path:       types.FilePath(path),
 		SourcePath: types.SourcePath(s.currentSourcePath),
 		MTime:      info.ModTime(),
 		Size:       info.Size(),
@@ -1221,7 +1222,7 @@ func (s *Scanner) checkFileInMemory(
 
 	// Check if file has changed
 	if existingFile.Size != file.Size ||
-		existingFile.MTime.Unix() != file.MTime.Unix() ||
+		!existingFile.MTime.Equal(file.MTime) ||
 		existingFile.Mode != file.Mode ||
 		existingFile.UID != file.UID ||
 		existingFile.GID != file.GID {

internal/snapshot/skip_errors_test.go

@@ -3,6 +3,7 @@ package snapshot_test
 import (
 	"context"
 	"errors"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -13,6 +14,7 @@ import (
 	"github.com/spf13/afero"
 	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/ui"
 )
 
 // errSimTempFail is the one-time temp-file creation failure blobTempFailFs
@@ -80,6 +82,30 @@ func (f *readFailFs) Open(name string) (afero.File, error) {
 	return file, nil
 }
 
+// linkRemovedAfterLstatFs is the real filesystem, except that the symlink at
+// target is removed right after the walk lstats it, as happens when a link is
+// deleted during a backup. The scanner's readlink of it then fails.
+type linkRemovedAfterLstatFs struct {
+	afero.OsFs
+
+	t      *testing.T
+	target string
+}
+
+func (f *linkRemovedAfterLstatFs) LstatIfPossible(
+	name string,
+) (os.FileInfo, bool, error) {
+	info, lstatCalled, err := f.OsFs.LstatIfPossible(name)
+	if err == nil && name == f.target {
+		rmErr := os.Remove(name)
+		if rmErr != nil {
+			f.t.Errorf("removing %s: %v", name, rmErr)
+		}
+	}
+
+	return info, lstatCalled, err
+}
+
 // writeSkipErrorTestFile writes one file into fs with a fixed mtime.
 func writeSkipErrorTestFile(t *testing.T, fs afero.Fs, path, content string) {
 	t.Helper()
@@ -102,10 +128,11 @@ func writeSkipErrorTestFile(t *testing.T, fs afero.Fs, path, content string) {
 	}
 }
 
-// runSkipErrorScan scans /source on fs with the given skip-errors setting and
-// returns the repositories (for inspection) and the scan error.
+// runSkipErrorScan scans source on fs with the given skip-errors setting,
+// printing user-facing messages to uiw (nil discards them), and returns the
+// repositories (for inspection) and the scan error.
 func runSkipErrorScan(
-	t *testing.T, fs afero.Fs, skipErrors bool,
+	t *testing.T, fs afero.Fs, source string, skipErrors bool, uiw *ui.Writer,
 ) (*database.Repositories, error) {
 	t.Helper()
 
@@ -130,6 +157,7 @@ func runSkipErrorScan(
 		MaxBlobSize:      int64(1024 * 1024),
 		CompressionLevel: 3,
 		AgeRecipients:    []string{testAgePublicKey},
+		UI:               uiw,
 		SkipErrors:       skipErrors,
 	})
 
@@ -137,7 +165,7 @@ func runSkipErrorScan(
 	snapshotID := "test-snapshot-skip-errors"
 	createTestSnapshotRecord(ctx, t, repos, snapshotID)
 
-	_, err = scanner.Scan(ctx, "/source", snapshotID)
+	_, err = scanner.Scan(ctx, source, snapshotID)
 
 	return repos, err
 }
@@ -157,7 +185,7 @@ func TestScannerPackingFailureAbortsUnderSkipErrors(t *testing.T) {
 	writeSkipErrorTestFile(t, fs, "/source/file1.txt", "first file content")
 	writeSkipErrorTestFile(t, fs, "/source/file2.txt", "second file content")
 
-	repos, err := runSkipErrorScan(t, fs, true)
+	repos, err := runSkipErrorScan(t, fs, "/source", true, nil)
 	if err == nil {
 		t.Fatal("expected scan to abort on the packer error, got nil")
 	}
@@ -184,7 +212,7 @@ func TestScannerReadErrorAbortsWithoutSkipErrors(t *testing.T) {
 	fs := &readFailFs{Fs: afero.NewMemMapFs(), target: target}
 	writeSkipErrorTestFile(t, fs, target, "content that cannot be read")
 
-	_, err := runSkipErrorScan(t, fs, false)
+	_, err := runSkipErrorScan(t, fs, "/source", false, nil)
 	if err == nil {
 		t.Fatal("expected scan to fail on the read error, got nil")
 	}
@@ -200,7 +228,7 @@ func TestScannerReadErrorSkippedWithSkipErrors(t *testing.T) {
 	fs := &readFailFs{Fs: afero.NewMemMapFs(), target: target}
 	writeSkipErrorTestFile(t, fs, target, "content that cannot be read")
 
-	repos, err := runSkipErrorScan(t, fs, true)
+	repos, err := runSkipErrorScan(t, fs, "/source", true, nil)
 	if err != nil {
 		t.Fatalf("expected scan to complete with --skip-errors, got %v", err)
 	}
@@ -214,3 +242,63 @@ func TestScannerReadErrorSkippedWithSkipErrors(t *testing.T) {
 		t.Fatalf("expected unreadable file skipped, got %d chunks", len(chunks))
 	}
 }
+
+// writeSymlinkSource creates a source directory on disk holding one symlink
+// and returns the directory and the symlink's path.
+func writeSymlinkSource(t *testing.T) (string, string) {
+	t.Helper()
+
+	sourceDir := t.TempDir()
+	linkPath := filepath.Join(sourceDir, "link")
+
+	err := os.Symlink("target.txt", linkPath)
+	if err != nil {
+		t.Fatalf("creating symlink: %v", err)
+	}
+
+	return sourceDir, linkPath
+}
+
+// TestScannerUnreadableSymlinkAbortsWithoutSkipErrors checks that a symlink
+// whose target cannot be read aborts the run when --skip-errors is not set.
+func TestScannerUnreadableSymlinkAbortsWithoutSkipErrors(t *testing.T) {
+	t.Parallel()
+
+	sourceDir, linkPath := writeSymlinkSource(t)
+	fs := &linkRemovedAfterLstatFs{t: t, target: linkPath}
+
+	_, err := runSkipErrorScan(t, fs, sourceDir, false, nil)
+	if !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("expected scan to fail on the removed symlink, got %v", err)
+	}
+}
+
+// TestScannerUnreadableSymlinkSkippedWithSkipErrors checks that a symlink
+// whose target cannot be read is skipped with an error line, and the run
+// completes, when --skip-errors is set.
+func TestScannerUnreadableSymlinkSkippedWithSkipErrors(t *testing.T) {
+	t.Parallel()
+
+	sourceDir, linkPath := writeSymlinkSource(t)
+	fs := &linkRemovedAfterLstatFs{t: t, target: linkPath}
+	uiw := ui.NewWithColor(io.Discard, false)
+
+	repos, err := runSkipErrorScan(t, fs, sourceDir, true, uiw)
+	if err != nil {
+		t.Fatalf("expected scan to complete with --skip-errors, got %v", err)
+	}
+
+	if uiw.ErrorCount() != 1 {
+		t.Fatalf("expected one error line for the symlink, got %d",
+			uiw.ErrorCount())
+	}
+
+	file, err := repos.Files.GetByPath(context.Background(), linkPath)
+	if err != nil {
+		t.Fatalf("getting %s: %v", linkPath, err)
+	}
+
+	if file != nil {
+		t.Fatalf("expected %s not to be recorded", linkPath)
+	}
+}

internal/snapshot/snapshot.go

@@ -105,17 +105,21 @@ func (sm *SnapshotManager) CreateSnapshot(
 	return sm.CreateSnapshotWithName(ctx, hostname, "", version, gitRevision)
 }
 
+// ShortHostname returns hostname up to its first dot. A snapshot ID starts
+// with this form, while the snapshots table stores the full hostname.
+func ShortHostname(hostname string) string {
+	short, _, _ := strings.Cut(hostname, ".")
+
+	return short
+}
+
 // CreateSnapshotWithName creates a new snapshot record with an optional
 // snapshot name. The snapshot ID format is: hostname_name_timestamp or
 // hostname_timestamp if name is empty.
 func (sm *SnapshotManager) CreateSnapshotWithName(
 	ctx context.Context, hostname, name, version, gitRevision string,
 ) (string, error) {
-	// Use short hostname (strip domain if present)
-	shortHostname := hostname
-	if before, _, ok := strings.Cut(hostname, "."); ok {
-		shortHostname = before
-	}
+	shortHostname := ShortHostname(hostname)
 
 	// Build snapshot ID with optional name
 	timestamp := time.Now().UTC().Format("2006-01-02T15:04:05Z")

internal/storage/module.go

@@ -99,6 +99,7 @@ func storerFromParsedS3URL(parsed *URL, cfg *config.Config) (Storer, error) {
 		AccessKeyID:     cfg.S3.AccessKeyID,
 		SecretAccessKey: cfg.S3.SecretAccessKey,
 		Region:          region,
+		PartSize:        cfg.S3.PartSize.Int64(),
 	})
 	if err != nil {
 		return nil, fmt.Errorf("creating S3 client: %w", err)
@@ -134,6 +135,7 @@ func storerFromLegacyS3Config(cfg *config.Config) (Storer, error) {
 		AccessKeyID:     cfg.S3.AccessKeyID,
 		SecretAccessKey: cfg.S3.SecretAccessKey,
 		Region:          region,
+		PartSize:        cfg.S3.PartSize.Int64(),
 	})
 	if err != nil {
 		return nil, fmt.Errorf("creating S3 client: %w", err)

internal/storage/s3_test.go

@@ -1,11 +1,14 @@
 package storage_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"net/http"
 	"net/http/httptest"
 	"slices"
 	"strings"
+	"sync/atomic"
 	"testing"
 
 	"github.com/johannesboyne/gofakes3"
@@ -19,6 +22,13 @@ import (
 // s3TestBucket is the bucket created for each in-process S3 server.
 const s3TestBucket = "test-bucket"
 
+// Credentials for the tests that build a storer from a config.Config. The
+// in-process S3 server accepts any.
+const (
+	s3TestAccessKeyID     = "key"
+	s3TestSecretAccessKey = "secret"
+)
+
 // 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,
@@ -128,8 +138,8 @@ func TestS3URLPrefixKeyLayout(t *testing.T) {
 			storer, err := storage.NewStorer(&config.Config{
 				StorageURL: storageURL + "?endpoint=" + srv.URL,
 				S3: config.S3Config{
-					AccessKeyID:     "key",
-					SecretAccessKey: "secret",
+					AccessKeyID:     s3TestAccessKeyID,
+					SecretAccessKey: s3TestSecretAccessKey,
 				},
 			})
 			if err != nil {
@@ -171,6 +181,90 @@ func TestS3URLPrefixKeyLayout(t *testing.T) {
 	}
 }
 
+// TestS3UploadUsesConfiguredPartSize checks that s3.part_size reaches the
+// multipart uploader, through storage_url and through the s3.* fields. An
+// object three parts long must arrive as three parts; at the SDK's default
+// of 5 MiB it would arrive as four.
+func TestS3UploadUsesConfiguredPartSize(t *testing.T) {
+	t.Parallel()
+
+	const (
+		partSize  = 6 * 1024 * 1024
+		wantParts = 3
+	)
+
+	backend := s3mem.New()
+
+	err := backend.CreateBucket(s3TestBucket)
+	if err != nil {
+		t.Fatalf("create bucket: %v", err)
+	}
+
+	// Every part of a multipart upload is one request with a partNumber.
+	var parts atomic.Int32
+
+	fake := gofakes3.New(backend).Server()
+	srv := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Query().Has("partNumber") {
+				parts.Add(1)
+			}
+
+			fake.ServeHTTP(w, r)
+		}))
+	t.Cleanup(srv.Close)
+
+	cases := []struct {
+		name string
+		cfg  *config.Config
+	}{
+		{
+			name: "storage_url",
+			cfg: &config.Config{
+				StorageURL: "s3://" + s3TestBucket + "?endpoint=" + srv.URL,
+				S3: config.S3Config{
+					AccessKeyID:     s3TestAccessKeyID,
+					SecretAccessKey: s3TestSecretAccessKey,
+					PartSize:        partSize,
+				},
+			},
+		},
+		{
+			name: "s3.endpoint",
+			cfg: &config.Config{
+				S3: config.S3Config{
+					Endpoint:        srv.URL,
+					Bucket:          s3TestBucket,
+					AccessKeyID:     s3TestAccessKeyID,
+					SecretAccessKey: s3TestSecretAccessKey,
+					PartSize:        partSize,
+				},
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		parts.Store(0)
+
+		storer, err := storage.NewStorer(tc.cfg)
+		if err != nil {
+			t.Fatalf("%s: NewStorer: %v", tc.name, err)
+		}
+
+		data := bytes.NewReader(make([]byte, wantParts*partSize))
+
+		err = storer.PutWithProgress(
+			context.Background(), "blob", data, data.Size(), nil)
+		if err != nil {
+			t.Fatalf("%s: PutWithProgress: %v", tc.name, err)
+		}
+
+		if got := parts.Load(); got != wantParts {
+			t.Errorf("%s: uploaded in %d parts, want %d", tc.name, got, wantParts)
+		}
+	}
+}
+
 // listStreamKeys returns the keys ListStream yields under a prefix, and
 // fails the test on a listing error.
 func listStreamKeys(t *testing.T, s storage.Storer, prefix string) []string {

internal/types/types.go

@@ -155,8 +155,8 @@ type BlobHash string
 // FilePath represents an absolute path to a file or directory.
 type FilePath string
 
-// SourcePath represents the root directory from which files are backed up.
-// Used during restore to strip the source prefix from paths.
+// SourcePath is the source directory a scan found a file under, made
+// absolute and with symlinks resolved.
 type SourcePath string
 
 // Hostname identifies a host machine.

internal/vaultik/changed_file_restore_test.go

@@ -130,10 +130,9 @@ func assertThirdSnapshotRestores(
 // up, and that snapshot is removed. The first snapshot keeps the file row,
 // which now lists the appended content's chunks, while removal drops the
 // blob that held them.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestBackupAfterRemovingNewestSnapshotRestoresChangedFile(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -178,10 +177,9 @@ func TestBackupAfterRemovingNewestSnapshotRestoresChangedFile(t *testing.T) {
 // The next run's prune drops that incomplete snapshot and its blob, while
 // the first snapshot keeps the file row, which now lists the appended
 // content's chunks.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestBackupAfterInterruptedRunRestoresChangedFile(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()

internal/vaultik/fault_injection_test.go

@@ -38,11 +38,9 @@ import (
 // (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.
+// log.Initialize replaces the package-global logger that a running
+// backup or restore reads, so each test calls it before t.Parallel,
+// while no parallel test is running yet.
 
 const (
 	faultChunkSize   = int64(64 * 1024)
@@ -165,17 +163,19 @@ func newReaderVaultik(
 // 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) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	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) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	assertRestoreRejectsDamagedBlob(t, faultstore.GetTruncate, "truncated")
 }
 
@@ -188,7 +188,6 @@ func assertRestoreRejectsDamagedBlob(
 	t *testing.T, fault faultstore.GetFault, name string,
 ) {
 	t.Helper()
-	log.Initialize(log.Config{})
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -232,10 +231,9 @@ func assertRestoreRejectsDamagedBlob(
 
 // 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{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -285,10 +283,9 @@ func TestDeepVerifyCatchesLyingBackend(t *testing.T) {
 // 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{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -361,10 +358,9 @@ func TestInterruptedBlobUploadRecordsNoUploadedBlob(t *testing.T) {
 // 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{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -426,10 +422,9 @@ func TestBackupRetryAfterInterruptedUploadIsRestorable(t *testing.T) {
 // covered by TestBackupCompletesOnlyAfterMetadataExport
 // (https://git.eeqj.de/sneak/vaultik/issues/177); this test exercises the
 // lower-level export path in isolation.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestBackupSurvivesMetadataExportInterruption(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -509,10 +504,9 @@ func TestBackupSurvivesMetadataExportInterruption(t *testing.T) {
 // destination. Rerunning the backup must then prune the incomplete
 // snapshot, produce a snapshot whose destination metadata and local index
 // agree, and restore. See https://git.eeqj.de/sneak/vaultik/issues/177.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestBackupCompletesOnlyAfterMetadataExport(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
@@ -685,10 +679,9 @@ func faultScannerFactory(
 // 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.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestRestoreReportsDiskFull(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	osFS := afero.NewOsFs()
 	tempDir := t.TempDir()

internal/vaultik/helpers.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/dustin/go-humanize"
+	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
@@ -46,12 +47,9 @@ const (
 	year  = 365 * day
 )
 
-// Snapshot IDs split on "_" into hostname, optional name parts, and a
-// trailing timestamp.
-const (
-	minSnapshotIDParts     = 2
-	minSnapshotIDNameParts = 3
-)
+// A snapshot ID split on "_" has at least a hostname and a trailing
+// timestamp.
+const minSnapshotIDParts = 2
 
 // SnapshotInfo contains information about a snapshot.
 //
@@ -121,20 +119,27 @@ func parseSnapshotTimestamp(snapshotID string) (time.Time, error) {
 	return timestamp.UTC(), nil
 }
 
-// parseSnapshotName extracts the snapshot name from a snapshot ID.
-// Format: hostname_snapshotname_timestamp — the middle part(s) between hostname
-// and the RFC3339 timestamp are the snapshot name (may contain underscores).
-// Returns the snapshot name, or empty string if the ID is malformed.
-func parseSnapshotName(snapshotID string) string {
-	parts := strings.Split(snapshotID, "_")
-	if len(parts) < minSnapshotIDNameParts {
-		// Format: hostname_timestamp — no snapshot name
+// parseSnapshotName extracts the snapshot name from a snapshot ID of the
+// form hostname_name_timestamp, given the hostname stored with that
+// snapshot. The hostname and the name may both contain underscores, so the
+// name is what is left after removing the short hostname and its "_" from
+// the front and the last "_" and the timestamp from the end. Returns "" for
+// an ID with no name (hostname_timestamp), and for an ID that does not start
+// with that hostname, which CreateSnapshotWithName never writes.
+func parseSnapshotName(snapshotID, hostname string) string {
+	prefix := snapshot.ShortHostname(hostname) + "_"
+
+	rest, ok := strings.CutPrefix(snapshotID, prefix)
+	if !ok {
 		return ""
 	}
-	// Format: hostname_name_timestamp — middle parts are the name.
-	// The last part is the RFC3339 timestamp, the first part is the hostname,
-	// everything in between is the snapshot name (which may itself contain underscores).
-	return strings.Join(parts[1:len(parts)-1], "_")
+
+	end := strings.LastIndex(rest, "_")
+	if end < 0 {
+		return ""
+	}
+
+	return rest[:end]
 }
 
 // parseDuration parses a duration string with support for human-friendly units:

internal/vaultik/helpers_test.go

@@ -11,33 +11,55 @@ func TestParseSnapshotName(t *testing.T) {
 	tests := []struct {
 		name       string
 		snapshotID string
+		hostname   string
 		want       string
 	}{
 		{
 			name:       "standard format with name",
 			snapshotID: "myhost_home_2026-01-12T14:41:15Z",
+			hostname:   "myhost",
 			want:       "home",
 		},
 		{
 			name:       "standard format with different name",
 			snapshotID: "server1_system_2026-02-15T09:30:00Z",
+			hostname:   "server1",
 			want:       "system",
 		},
 		{
 			name:       "name with underscores",
 			snapshotID: "myhost_my_special_backup_2026-03-01T00:00:00Z",
+			hostname:   "myhost",
 			want:       "my_special_backup",
 		},
+		{
+			name:       "hostname with underscores",
+			snapshotID: "my_host_docs_2026-03-01T00:00:00Z",
+			hostname:   "my_host",
+			want:       "docs",
+		},
+		{
+			name:       "stored hostname with domain",
+			snapshotID: "my_host_mail_2026-03-01T00:00:00Z",
+			hostname:   "my_host.example.com",
+			want:       "mail",
+		},
+		{
+			name:       "no name",
+			snapshotID: "my_host_2026-03-01T00:00:00Z",
+			hostname:   "my_host",
+			want:       "",
+		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			got := parseSnapshotName(tt.snapshotID)
+			got := parseSnapshotName(tt.snapshotID, tt.hostname)
 			if got != tt.want {
-				t.Errorf("parseSnapshotName(%q) = %q, want %q",
-					tt.snapshotID, got, tt.want)
+				t.Errorf("parseSnapshotName(%q, %q) = %q, want %q",
+					tt.snapshotID, tt.hostname, got, tt.want)
 			}
 		})
 	}

internal/vaultik/info.go

@@ -183,6 +183,11 @@ type SnapshotMetadataInfo struct {
 	TotalSize    int64  `json:"total_size"`
 	BlobCount    int    `json:"blob_count"`
 	BlobsSize    int64  `json:"blobs_size"`
+
+	// Set when the listing holds this snapshot's manifest.json.zst. A
+	// backup interrupted before its manifest upload leaves a directory
+	// without one, which prune does not treat as a snapshot.
+	hasManifest bool
 }
 
 // RemoteInfoResult contains all remote storage information
@@ -206,9 +211,20 @@ type RemoteInfoResult struct {
 	ReferencedBlobCount int   `json:"referenced_blob_count"`
 	ReferencedBlobSize  int64 `json:"referenced_blob_size"`
 
-	// Orphaned blobs
-	OrphanedBlobCount int   `json:"orphaned_blob_count"`
-	OrphanedBlobSize  int64 `json:"orphaned_blob_size"`
+	// Orphaned blobs. Both stay nil (null in the JSON) when a manifest
+	// was listed but not read, since that snapshot's blobs would be
+	// counted as orphaned.
+	OrphanedBlobCount *int   `json:"orphaned_blob_count"`
+	OrphanedBlobSize  *int64 `json:"orphaned_blob_size"`
+
+	// Remote key of each snapshot whose manifest could not be read
+	UnreadableManifests []string `json:"unreadable_manifests,omitempty"`
+
+	// Number of manifests not read because the name above them under
+	// metadata/ is not a remote key. The names themselves are not
+	// reported: they come from the destination store and may hold
+	// control characters.
+	SkippedManifestCount int `json:"skipped_manifest_count,omitempty"`
 }
 
 // RemoteInfo displays information about remote storage
@@ -234,16 +250,28 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 		v.stdoutf("Scanning snapshot metadata...\n")
 	}
 
-	snapshotMetadata, snapshotIDs, err := v.collectSnapshotMetadata()
+	snapshotMetadata, snapshotIDs, skippedManifestCount, err := v.collectSnapshotMetadata()
 	if err != nil {
 		return err
 	}
 
+	result.SkippedManifestCount = skippedManifestCount
+
 	if showText {
-		v.stdoutf("Downloading %d manifest(s)...\n", len(snapshotIDs))
+		manifestCount := 0
+
+		for _, info := range snapshotMetadata {
+			if info.hasManifest {
+				manifestCount++
+			}
+		}
+
+		v.stdoutf("Downloading %d manifest(s)...\n", manifestCount)
 	}
 
-	referencedBlobs := v.collectReferencedBlobsFromManifests(snapshotIDs, snapshotMetadata)
+	referencedBlobs, unreadableManifests := v.collectReferencedBlobsFromManifests(
+		snapshotIDs, snapshotMetadata)
+	result.UnreadableManifests = unreadableManifests
 
 	v.populateRemoteInfoResult(result, snapshotMetadata, snapshotIDs, referencedBlobs)
 
@@ -256,7 +284,7 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 		"snapshots", result.TotalMetadataCount,
 		"total_blobs", result.TotalBlobCount,
 		"referenced_blobs", result.ReferencedBlobCount,
-		"orphaned_blobs", result.OrphanedBlobCount)
+		"unreadable_manifests", len(result.UnreadableManifests))
 
 	if jsonOutput {
 		enc := json.NewEncoder(v.Stdout)
@@ -273,16 +301,18 @@ func (v *Vaultik) RemoteInfo(jsonOutput bool) error {
 }
 
 // collectSnapshotMetadata scans remote metadata and returns
-// per-snapshot info and sorted IDs.
+// per-snapshot info, sorted IDs and the number of manifests it skipped
+// because the name above them is not a remote key.
 func (v *Vaultik) collectSnapshotMetadata() (
-	map[string]*SnapshotMetadataInfo, []string, error,
+	map[string]*SnapshotMetadataInfo, []string, int, error,
 ) {
 	snapshotMetadata := make(map[string]*SnapshotMetadataInfo)
+	skippedManifestCount := 0
 
 	metadataCh := v.Storage.ListStream(v.ctx, "metadata/")
 	for obj := range metadataCh {
 		if obj.Err != nil {
-			return nil, nil, fmt.Errorf("listing metadata: %w", obj.Err)
+			return nil, nil, 0, fmt.Errorf("listing metadata: %w", obj.Err)
 		}
 
 		parts := strings.Split(obj.Key, "/")
@@ -291,6 +321,22 @@ func (v *Vaultik) collectSnapshotMetadata() (
 		}
 
 		snapshotID := parts[1]
+		filename := parts[2]
+		isManifest := filename == "manifest.json.zst"
+
+		// The name comes from the destination store, which is not
+		// trusted, and is printed in the report. Accept it only in the
+		// form of a remote key.
+		if !isBlobHash(snapshotID) {
+			log.Warn("Skipping non-conforming key under metadata/",
+				"key", obj.Key)
+
+			if isManifest {
+				skippedManifestCount++
+			}
+
+			continue
+		}
 
 		if _, exists := snapshotMetadata[snapshotID]; !exists {
 			snapshotMetadata[snapshotID] = &SnapshotMetadataInfo{SnapshotID: snapshotID}
@@ -298,7 +344,10 @@ func (v *Vaultik) collectSnapshotMetadata() (
 
 		info := snapshotMetadata[snapshotID]
 
-		filename := parts[2]
+		if isManifest {
+			info.hasManifest = true
+		}
+
 		if strings.HasPrefix(filename, "manifest") {
 			info.ManifestSize = obj.Size
 		} else if strings.HasPrefix(filename, "db") {
@@ -315,17 +364,25 @@ func (v *Vaultik) collectSnapshotMetadata() (
 
 	sort.Strings(snapshotIDs)
 
-	return snapshotMetadata, snapshotIDs, nil
+	return snapshotMetadata, snapshotIDs, skippedManifestCount, nil
 }
 
-// collectReferencedBlobsFromManifests downloads manifests and returns
-// referenced blob hashes with sizes.
+// collectReferencedBlobsFromManifests downloads the listed manifests
+// and returns referenced blob hashes with sizes, and the remote keys
+// of the manifests it could not read.
 func (v *Vaultik) collectReferencedBlobsFromManifests(
 	snapshotIDs []string, snapshotMetadata map[string]*SnapshotMetadataInfo,
-) map[string]int64 {
+) (map[string]int64, []string) {
 	referencedBlobs := make(map[string]int64)
 
+	var unreadable []string
+
 	for _, snapshotID := range snapshotIDs {
+		info := snapshotMetadata[snapshotID]
+		if !info.hasManifest {
+			continue
+		}
+
 		// snapshotIDs here are remote keys, taken straight from the
 		// metadata/ listing. downloadManifestByKey is the single reader
 		// for remote manifests; see its doc comment.
@@ -333,10 +390,11 @@ func (v *Vaultik) collectReferencedBlobsFromManifests(
 		if err != nil {
 			log.Warn("Failed to read manifest", "snapshot", snapshotID, "error", err)
 
+			unreadable = append(unreadable, snapshotID)
+
 			continue
 		}
 
-		info := snapshotMetadata[snapshotID]
 		info.BlobCount = manifest.BlobCount
 
 		var blobsSize int64
@@ -349,7 +407,7 @@ func (v *Vaultik) collectReferencedBlobsFromManifests(
 		info.BlobsSize = blobsSize
 	}
 
-	return referencedBlobs
+	return referencedBlobs, unreadable
 }
 
 // populateRemoteInfoResult fills in the result's snapshot and
@@ -378,8 +436,9 @@ func (v *Vaultik) populateRemoteInfoResult(
 }
 
 // scanRemoteBlobStorage lists all blobs on remote and computes orphan
-// stats. showText is true only when the human report is being printed
-// (not --json, not --quiet), gating the progress line.
+// stats when every listed manifest was read. showText is true only
+// when the human report is being printed (not --json, not --quiet),
+// gating the progress line.
 func (v *Vaultik) scanRemoteBlobStorage(
 	result *RemoteInfoResult, referencedBlobs map[string]int64, showText bool,
 ) error {
@@ -406,13 +465,28 @@ func (v *Vaultik) scanRemoteBlobStorage(
 		result.TotalBlobSize += obj.Size
 	}
 
+	// A blob named only by a manifest that could not be read, or by one
+	// under a skipped name, would be counted as orphaned, so the orphan
+	// figures stay unknown.
+	if len(result.UnreadableManifests) > 0 || result.SkippedManifestCount > 0 {
+		return nil
+	}
+
+	var (
+		orphanedCount int
+		orphanedSize  int64
+	)
+
 	for hash, size := range allBlobs {
 		if _, referenced := referencedBlobs[hash]; !referenced {
-			result.OrphanedBlobCount++
-			result.OrphanedBlobSize += size
+			orphanedCount++
+			orphanedSize += size
 		}
 	}
 
+	result.OrphanedBlobCount = &orphanedCount
+	result.OrphanedBlobSize = &orphanedSize
+
 	return nil
 }
 
@@ -465,11 +539,21 @@ func (v *Vaultik) printRemoteInfoTable(result *RemoteInfoResult) {
 	v.stdoutf("Referenced by snapshots:    %s (%s)\n",
 		humanize.Comma(int64(result.ReferencedBlobCount)),
 		ubytes(result.ReferencedBlobSize))
-	v.stdoutf("Orphaned (unreferenced):    %s (%s)\n",
-		humanize.Comma(int64(result.OrphanedBlobCount)),
-		ubytes(result.OrphanedBlobSize))
 
-	if result.OrphanedBlobCount > 0 {
+	if result.OrphanedBlobCount == nil {
+		v.stdoutf("Orphaned (unreferenced):    unknown "+
+			"(%d manifest(s) could not be read, "+
+			"%d manifest(s) under a non-conforming name skipped)\n",
+			len(result.UnreadableManifests), result.SkippedManifestCount)
+
+		return
+	}
+
+	v.stdoutf("Orphaned (unreferenced):    %s (%s)\n",
+		humanize.Comma(int64(*result.OrphanedBlobCount)),
+		ubytes(*result.OrphanedBlobSize))
+
+	if *result.OrphanedBlobCount > 0 {
 		v.stdoutf("\nRun 'vaultik prune' to remove orphaned blobs.\n")
 	}
 }

internal/vaultik/integration_test.go

@@ -928,17 +928,17 @@ func setupDedupBackupEnv(
 	}
 }
 
-// runDedupSnapshot creates a "dedup" snapshot, scans dataDir into it,
-// completes it, and exports its metadata, returning the snapshot ID and
-// scan result.
+// runDedupSnapshot creates a snapshot with the given name, scans dataDir
+// into it, completes it, and exports its metadata, returning the snapshot
+// ID and scan result.
 func runDedupSnapshot(
 	ctx context.Context, t *testing.T,
 	sm *snapshot.SnapshotManager, scanner *snapshot.Scanner,
-	hostname, dataDir, dbPath string,
+	hostname, name, dataDir, dbPath string,
 ) (string, *snapshot.ScanResult) {
 	t.Helper()
 
-	id, err := sm.CreateSnapshotWithName(ctx, hostname, "dedup", "v", "g")
+	id, err := sm.CreateSnapshotWithName(ctx, hostname, name, "v", "g")
 	require.NoError(t, err)
 
 	result, err := scanner.Scan(ctx, dataDir, id)
@@ -980,16 +980,15 @@ func TestDedupOnlySnapshotRestores(t *testing.T) {
 
 	// First snapshot — uploads all blobs.
 	_, r1 := runDedupSnapshot(ctx, t, sm, makeScanner(),
-		cfg.Hostname, dataDir, dbPath)
+		cfg.Hostname, "first", dataDir, dbPath)
 	require.Positive(t, r1.BlobsCreated,
 		"first snapshot should upload at least one blob")
 
-	// Second snapshot — same data, every chunk dedups. Sleep past the
-	// second-precision timestamp so the snapshot IDs differ.
-	time.Sleep(1100 * time.Millisecond)
-
+	// Second snapshot — same data, every chunk dedups. Its own name gives
+	// it a different snapshot ID without waiting for the one-second
+	// timestamp in the ID to tick over.
 	id2, r2 := runDedupSnapshot(ctx, t, sm, makeScanner(),
-		cfg.Hostname, dataDir, dbPath)
+		cfg.Hostname, "second", dataDir, dbPath)
 	require.Equal(t, 0, r2.BlobsCreated,
 		"second snapshot should upload zero new blobs (fully dedup'd)")
 

internal/vaultik/missing_destination_test.go

@@ -6,6 +6,7 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/spf13/afero"
@@ -77,10 +78,9 @@ func backUpThenUnplug(
 // TestFirstBackupCreatesDestinationDirectory checks that a first backup
 // to a destination directory that does not exist yet creates it, and
 // that the destination can be listed afterwards.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestFirstBackupCreatesDestinationDirectory(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	storeDir := filepath.Join(t.TempDir(), "volume", "backup")
@@ -95,10 +95,9 @@ func TestFirstBackupCreatesDestinationDirectory(t *testing.T) {
 // TestListSnapshotsWarnsWhenDestinationMissing checks that snapshot list
 // warns and shows the local index alone, without reporting the local
 // snapshot as missing from the destination.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestListSnapshotsWarnsWhenDestinationMissing(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	v, repos, out := backUpThenUnplug(ctx, t)
@@ -115,10 +114,9 @@ func TestListSnapshotsWarnsWhenDestinationMissing(t *testing.T) {
 // TestRemoveSnapshotWarnsWhenDestinationMissing checks that snapshot
 // remove warns that the metadata could not be removed from the
 // destination, instead of reporting that it was.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestRemoveSnapshotWarnsWhenDestinationMissing(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	v, repos, out := backUpThenUnplug(ctx, t)
@@ -137,10 +135,9 @@ func TestRemoveSnapshotWarnsWhenDestinationMissing(t *testing.T) {
 // TestPruneKeepsLocalRecordsWhenDestinationMissing checks that prune
 // fails on a destination it cannot list and deletes no local snapshot
 // record.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestPruneKeepsLocalRecordsWhenDestinationMissing(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	v, repos, _ := backUpThenUnplug(ctx, t)
@@ -153,3 +150,22 @@ func TestPruneKeepsLocalRecordsWhenDestinationMissing(t *testing.T) {
 	require.NoError(t, err)
 	assert.Len(t, snapshots, 1, "prune must delete no local snapshot record")
 }
+
+// TestPurgeSaysListingFailedOnceWhenDestinationMissing checks that
+// snapshot purge fails on a destination it cannot list, with an error
+// that says "listing remote snapshots" once.
+func TestPurgeSaysListingFailedOnceWhenDestinationMissing(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ctx := context.Background()
+	v, _, _ := backUpThenUnplug(ctx, t)
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		KeepLatest: true,
+		Force:      true,
+	})
+	require.ErrorIs(t, err, fs.ErrNotExist)
+	assert.Equal(t, 1, strings.Count(err.Error(), "listing remote snapshots"),
+		err.Error())
+}

internal/vaultik/prune_count_test.go

@@ -14,10 +14,9 @@ import (
 // the discarded-error bug: getTableCount for a table its query cannot
 // resolve must not silently become 0. A count that could not be read is
 // reported as unknown, which a reader can tell apart from an empty table.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestTableCountForReportSurfacesReadFailure(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 

internal/vaultik/purge_local_remote_consistency_test.go

@@ -42,7 +42,7 @@ func setupConsistencyTest(
 		completedAt := startedAt.Add(5 * time.Minute)
 		snap := &database.Snapshot{
 			ID:             types.SnapshotID(id),
-			Hostname:       testHostname,
+			Hostname:       snapHostname,
 			VaultikVersion: testLabel,
 			StartedAt:      startedAt,
 			CompletedAt:    &completedAt,

internal/vaultik/purge_per_name_test.go

@@ -17,8 +17,10 @@ import (
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
 
-// Snapshot IDs reused across the purge tests.
+// Snapshot IDs reused across the purge tests, and the hostname they were
+// taken on.
 const (
+	snapHostname = "testhost"
 	snapSystemT0 = "testhost_system_2026-01-01T00:00:00Z"
 	snapHomeT0   = "testhost_home_2026-01-01T00:00:00Z"
 	snapHomeT1   = "testhost_home_2026-01-01T01:00:00Z"
@@ -26,9 +28,12 @@ const (
 )
 
 // setupPurgeTest creates a Vaultik instance with an in-memory database and mock
-// storage pre-populated with the given snapshot IDs. Each snapshot is marked as
-// completed. Remote metadata stubs are created so syncWithRemote keeps them.
-func setupPurgeTest(t *testing.T, snapshotIDs []string) *vaultik.Vaultik {
+// storage pre-populated with the given snapshot IDs, all taken on hostname.
+// Each snapshot is marked as completed. Remote metadata stubs are created so
+// syncWithRemote keeps them.
+func setupPurgeTest(
+	t *testing.T, hostname string, snapshotIDs []string,
+) *vaultik.Vaultik {
 	t.Helper()
 
 	ctx := context.Background()
@@ -51,7 +56,7 @@ func setupPurgeTest(t *testing.T, snapshotIDs []string) *vaultik.Vaultik {
 		completedAt := startedAt.Add(5 * time.Minute)
 		snap := &database.Snapshot{
 			ID:             types.SnapshotID(id),
-			Hostname:       "testhost",
+			Hostname:       types.Hostname(hostname),
 			VaultikVersion: testLabel,
 			StartedAt:      startedAt,
 			CompletedAt:    &completedAt,
@@ -120,7 +125,7 @@ func TestPurgeKeepLatest_PerName(t *testing.T) {
 		"testhost_system_2026-01-01T04:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -148,7 +153,7 @@ func TestPurgeKeepLatest_SingleName(t *testing.T) {
 		"testhost_home_2026-01-01T02:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -176,7 +181,7 @@ func TestPurgeKeepLatest_WithNameFilter(t *testing.T) {
 		"testhost_home_2026-01-01T04:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -198,7 +203,7 @@ func TestPurgeKeepLatest_NoSnapshots(t *testing.T) {
 	log.Initialize(log.Config{})
 	t.Parallel()
 
-	v := setupPurgeTest(t, nil)
+	v := setupPurgeTest(t, snapHostname, nil)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -216,7 +221,7 @@ func TestPurgeKeepLatest_NameFilterNoMatch(t *testing.T) {
 		"testhost_system_2026-01-01T01:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -243,7 +248,7 @@ func TestPurgeOlderThan_WithNameFilter(t *testing.T) {
 		snapHomeT0,
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	// Purge only "home" snapshots older than 365 days
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
@@ -277,7 +282,7 @@ func TestPurgeKeepLatest_ThreeNames(t *testing.T) {
 		"testhost_home_2026-01-01T06:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -291,3 +296,28 @@ func TestPurgeKeepLatest_ThreeNames(t *testing.T) {
 	assert.Contains(t, remaining, "testhost_system_2026-01-01T04:00:00Z")
 	assert.Contains(t, remaining, "testhost_media_2026-01-01T05:00:00Z")
 }
+
+// A hostname may contain underscores, so the snapshot name cannot be found
+// by splitting the ID at them. A purge by name must still select "docs".
+func TestPurgeKeepLatest_HostnameWithUnderscore(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	const (
+		system = "my_host_system_2026-01-01T00:00:00Z"
+		docsT1 = "my_host_docs_2026-01-01T01:00:00Z"
+		docsT2 = "my_host_docs_2026-01-01T02:00:00Z"
+	)
+
+	v := setupPurgeTest(t, "my_host", []string{system, docsT1, docsT2})
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		KeepLatest: true,
+		Force:      true,
+		Names:      []string{"docs"},
+	})
+	require.NoError(t, err)
+
+	assert.ElementsMatch(t, []string{system, docsT2},
+		listRemainingSnapshots(t, v))
+}

internal/vaultik/remote_info_test.go

@@ -0,0 +1,159 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/snapshot"
+)
+
+// testBlobHashB is a blob that the manifest written by addRemote does
+// not reference.
+const testBlobHashB = "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb" +
+	"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
+
+// TestRemoteInfo_UnreadableManifestLeavesOrphansUnknown checks that a
+// manifest remote info cannot read makes the orphan figures unknown. A
+// blob referenced only by that snapshot would otherwise be counted as
+// orphaned, and the report would advise running prune.
+func TestRemoteInfo_UnreadableManifestLeavesOrphansUnknown(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newListEnv(t)
+
+	// The readable manifest references blob A only.
+	env.addRemote(t, listRemoteID, time.Date(2026, 3, 2, 0, 0, 0, 0, time.UTC))
+	addBlob(t, env.store.testStorer, testBlobHashA)
+	addBlob(t, env.store.testStorer, testBlobHashB)
+
+	// With every manifest readable, blob B is orphaned.
+	require.NoError(t, env.v.RemoteInfo(true))
+
+	var doc map[string]any
+
+	require.NoError(t, json.Unmarshal(env.stdout.Bytes(), &doc))
+	assert.InDelta(t, 1, doc["orphaned_blob_count"], 0)
+
+	// A second snapshot whose manifest cannot be decoded. Blob B may be
+	// one of its blobs.
+	unreadableKey := snapshot.RemoteSnapshotKey(listLocalID)
+	require.NoError(t, env.store.Put(context.Background(),
+		"metadata/"+unreadableKey+"/manifest.json.zst",
+		bytes.NewReader([]byte("not a valid manifest"))))
+
+	env.stdout.Reset()
+	require.NoError(t, env.v.RemoteInfo(false))
+
+	text := env.stdout.String()
+	assert.Contains(t, text, "Orphaned (unreferenced):    unknown "+
+		"(1 manifest(s) could not be read, "+
+		"0 manifest(s) under a non-conforming name skipped)")
+	assert.NotContains(t, text, "vaultik prune")
+
+	env.stdout.Reset()
+	require.NoError(t, env.v.RemoteInfo(true))
+
+	doc = nil
+	require.NoError(t, json.Unmarshal(env.stdout.Bytes(), &doc))
+	assert.Contains(t, doc, "orphaned_blob_count")
+	assert.Nil(t, doc["orphaned_blob_count"])
+	assert.Contains(t, doc, "orphaned_blob_size")
+	assert.Nil(t, doc["orphaned_blob_size"])
+	assert.Equal(t, []any{unreadableKey}, doc["unreadable_manifests"])
+}
+
+// TestRemoteInfo_SkipsNonConformingMetadataName checks that a directory
+// under metadata/ whose name is not a remote key is left out of the
+// report, and that the orphan figures are unknown when it holds a
+// manifest. The name comes from the destination store; printed raw, its
+// control characters would reach the terminal. Its manifest is not
+// read, so a blob only it references would otherwise be counted as
+// orphaned.
+func TestRemoteInfo_SkipsNonConformingMetadataName(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newListEnv(t)
+	env.addRemote(t, listRemoteID, time.Date(2026, 3, 2, 0, 0, 0, 0, time.UTC))
+	addBlob(t, env.store.testStorer, testBlobHashA)
+	addBlob(t, env.store.testStorer, testBlobHashB)
+	require.NoError(t, env.store.Put(context.Background(),
+		"metadata/\x1b[31mred/manifest.json.zst",
+		bytes.NewReader([]byte("not a valid manifest"))))
+
+	require.NoError(t, env.v.RemoteInfo(false))
+
+	text := env.stdout.String()
+	assert.NotContains(t, text, "\x1b")
+	assert.NotContains(t, text, "31mred")
+	assert.Contains(t, text, "Total (1 snapshots)")
+	assert.Contains(t, text, "Orphaned (unreferenced):    unknown "+
+		"(0 manifest(s) could not be read, "+
+		"1 manifest(s) under a non-conforming name skipped)")
+	assert.NotContains(t, text, "vaultik prune")
+
+	env.stdout.Reset()
+	require.NoError(t, env.v.RemoteInfo(true))
+
+	out := env.stdout.String()
+	assert.NotContains(t, out, "31mred")
+
+	var doc map[string]any
+
+	require.NoError(t, json.Unmarshal([]byte(out), &doc))
+	assert.Contains(t, doc, "orphaned_blob_count")
+	assert.Nil(t, doc["orphaned_blob_count"])
+	assert.Contains(t, doc, "orphaned_blob_size")
+	assert.Nil(t, doc["orphaned_blob_size"])
+	assert.InDelta(t, 1, doc["skipped_manifest_count"], 0)
+	assert.NotContains(t, doc, "unreadable_manifests")
+}
+
+// TestRemoteInfo_DirectoryWithoutManifestLeavesOrphansKnown checks that
+// a directory under metadata/ holding no manifest.json.zst, such as one
+// left by a backup interrupted before its manifest upload, leaves the
+// orphan figures known. prune does not treat such a directory as a
+// snapshot and deletes the blobs the report lists as orphaned.
+func TestRemoteInfo_DirectoryWithoutManifestLeavesOrphansKnown(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newListEnv(t)
+	env.addRemote(t, listRemoteID, time.Date(2026, 3, 2, 0, 0, 0, 0, time.UTC))
+	addBlob(t, env.store.testStorer, testBlobHashA)
+	addBlob(t, env.store.testStorer, testBlobHashB)
+
+	// One directory under a remote key and one under a non-conforming
+	// name, each holding only a database.
+	names := []string{snapshot.RemoteSnapshotKey(listLocalID), "\x1b[31mred"}
+	for _, name := range names {
+		require.NoError(t, env.store.Put(context.Background(),
+			"metadata/"+name+"/db.zst.age",
+			bytes.NewReader([]byte("not a valid database"))))
+	}
+
+	require.NoError(t, env.v.RemoteInfo(false))
+
+	text := env.stdout.String()
+	assert.NotContains(t, text, "\x1b")
+	assert.Contains(t, text, "Downloading 1 manifest(s)...")
+	assert.Contains(t, text, "Orphaned (unreferenced):    1 (")
+	assert.Contains(t, text, "Run 'vaultik prune' to remove orphaned blobs.")
+
+	env.stdout.Reset()
+	require.NoError(t, env.v.RemoteInfo(true))
+
+	var doc map[string]any
+
+	require.NoError(t, json.Unmarshal(env.stdout.Bytes(), &doc))
+	assert.InDelta(t, 1, doc["orphaned_blob_count"], 0)
+	assert.NotContains(t, doc, "unreadable_manifests")
+	assert.NotContains(t, doc, "skipped_manifest_count")
+}

internal/vaultik/restore_interrupt_test.go

@@ -164,10 +164,9 @@ func scratchEntries(t *testing.T, dir string) []string {
 // restore while a blob download is in progress. The download fails only
 // because of the cancel, so Restore must return context.Canceled without
 // reporting the file that needs the blob as failed.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestRestoreSkipErrorsCancelDuringBlobDownload(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()

internal/vaultik/restore_skip_errors_test.go

@@ -45,9 +45,10 @@ type missingBlobBackup struct {
 // after one blob of a two-blob snapshot was deleted. Every file stored in
 // that blob must be reported as failed and left absent, every other file
 // must be restored intact, and Restore must still return an error.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestRestoreSkipErrorsSkipsFilesOfMissingBlob(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	ctx := context.Background()
 	backup := backupThenDeleteOneBlob(ctx, t)
 
@@ -85,9 +86,10 @@ func TestRestoreSkipErrorsSkipsFilesOfMissingBlob(t *testing.T) {
 
 // TestRestoreMissingBlobAbortsWithoutSkipErrors checks that a deleted blob
 // still ends the restore with an error when SkipErrors is not set.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestRestoreMissingBlobAbortsWithoutSkipErrors(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	ctx := context.Background()
 	backup := backupThenDeleteOneBlob(ctx, t)
 
@@ -107,7 +109,6 @@ func backupThenDeleteOneBlob(
 	ctx context.Context, t *testing.T,
 ) *missingBlobBackup {
 	t.Helper()
-	log.Initialize(log.Config{})
 
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()

internal/vaultik/same_second_rewrite_test.go

@@ -0,0 +1,72 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// A file rewritten with its size unchanged and a new mtime in the same
+// second as the mtime the index holds must still be backed up. See
+// https://git.eeqj.de/sneak/vaultik/issues/226.
+func TestBackupOfSameSecondRewriteRestoresNewContent(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	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")
+	rewrittenPath := filepath.Join(dataDir, "small.txt")
+
+	ctx := context.Background()
+	files := writeFaultSourceTree(t, fs, dataDir)
+	cfg := changedFileConfig(dataDir, dbPath)
+
+	firstMTime := time.Date(2026, time.January, 2, 3, 4, 5, 0, time.UTC).
+		Add(100 * time.Millisecond)
+	secondMTime := firstMTime.Add(800 * time.Millisecond)
+
+	require.NoError(t, fs.Chtimes(rewrittenPath, firstMTime, firstMTime))
+
+	store, err := storage.NewFileStorer(storeDir)
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, dbPath)
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
+
+	require.NoError(t, backUp(v, "first"))
+
+	// Upper-casing ASCII text keeps its size.
+	files[rewrittenPath] = bytes.ToUpper(files[rewrittenPath])
+	require.NoError(t, afero.WriteFile(fs, rewrittenPath, files[rewrittenPath], 0o644))
+	require.NoError(t, fs.Chtimes(rewrittenPath, secondMTime, secondMTime))
+
+	require.NoError(t, backUp(v, "second"))
+
+	id := localSnapshotID(ctx, t, repos, "second")
+	require.NoError(t, db.Close())
+
+	reader := newReaderVaultik(ctx, cfg, store, nil, fs)
+	require.NoError(t, reader.Restore(&vaultik.RestoreOptions{
+		SnapshotID: id,
+		TargetDir:  restoreDir,
+		Verify:     true,
+	}))
+
+	assertRestoredTree(t, fs, restoreDir, files)
+}

internal/vaultik/snapshot.go

@@ -14,6 +14,7 @@ import (
 
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/types"
 )
 
 // Sentinel errors for snapshot management.
@@ -495,19 +496,23 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 		nameFilter[n] = struct{}{}
 	}
 
-	// Collect completed snapshots, applying the name filter.
+	// Collect completed snapshots and their names, applying the name filter.
 	snapshots := make([]SnapshotInfo, 0, len(dbSnapshots))
+	names := make(map[types.SnapshotID]string, len(dbSnapshots))
+
 	for _, s := range dbSnapshots {
 		if s.CompletedAt == nil {
 			continue
 		}
 
+		name := parseSnapshotName(s.ID.String(), s.Hostname.String())
 		if len(nameFilter) > 0 {
-			if _, ok := nameFilter[parseSnapshotName(s.ID.String())]; !ok {
+			if _, ok := nameFilter[name]; !ok {
 				continue
 			}
 		}
 
+		names[s.ID] = name
 		snapshots = append(snapshots, SnapshotInfo{
 			ID:             s.ID,
 			Timestamp:      s.StartedAt,
@@ -520,7 +525,7 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 		return snapshots[i].Timestamp.After(snapshots[j].Timestamp)
 	})
 
-	toDelete, err := selectSnapshotsToPurge(snapshots, opts)
+	toDelete, err := selectSnapshotsToPurge(snapshots, names, opts)
 	if err != nil {
 		return err
 	}
@@ -538,9 +543,11 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 
 // selectSnapshotsToPurge applies the purge retention criteria to the
 // newest-first sorted snapshot list and returns the deletion
-// candidates.
+// candidates. names maps each snapshot's ID to its snapshot name.
 func selectSnapshotsToPurge(
-	snapshots []SnapshotInfo, opts *SnapshotPurgeOptions,
+	snapshots []SnapshotInfo,
+	names map[types.SnapshotID]string,
+	opts *SnapshotPurgeOptions,
 ) ([]SnapshotInfo, error) {
 	var toDelete []SnapshotInfo
 
@@ -551,7 +558,7 @@ func selectSnapshotsToPurge(
 		seen := make(map[string]bool)
 
 		for _, snap := range snapshots {
-			name := parseSnapshotName(snap.ID.String())
+			name := names[snap.ID]
 			if seen[name] {
 				toDelete = append(toDelete, snap)
 
@@ -1045,7 +1052,7 @@ func (v *Vaultik) syncWithRemote() error {
 	// every local snapshot record (issue #160).
 	remoteKeys, err := v.listAllRemoteSnapshotKeys()
 	if err != nil {
-		return fmt.Errorf("listing remote snapshots: %w", err)
+		return err
 	}
 
 	remoteKeySet := make(map[string]bool, len(remoteKeys))

internal/vaultik/snapshot_summary_test.go

@@ -54,8 +54,6 @@ type summaryEnv struct {
 func newSummaryEnv(t *testing.T) *summaryEnv {
 	t.Helper()
 
-	log.Initialize(log.Config{})
-
 	fs := afero.NewOsFs()
 	tempDir := t.TempDir()
 	srcDir := filepath.Join(tempDir, "src")
@@ -193,9 +191,10 @@ func (e *summaryEnv) dataLine(total, backedUp int64) string {
 // A first backup stores copy.bin's chunks while backing up a.bin, so
 // copy.bin's chunks are deduplicated within the run. Each file and byte
 // is still counted once.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestSnapshotSummaryFirstRun(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	env := newSummaryEnv(t)
 
 	summary := env.backUp(t, "first", false)
@@ -219,9 +218,10 @@ func TestSnapshotSummaryFirstRun(t *testing.T) {
 // An incremental backup where a.bin's mtime changed but its content did
 // not: a.bin is backed up again and every one of its chunks is already
 // stored.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestSnapshotSummaryIncrementalRunWithDeduplicatedChunks(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	env := newSummaryEnv(t)
 
 	env.backUp(t, "first", false)
@@ -251,9 +251,10 @@ func TestSnapshotSummaryIncrementalRunWithDeduplicatedChunks(t *testing.T) {
 // Under --cron the progress reporter is off; the upload figures must
 // still reach the summary and the snapshots row. The snapshot has two
 // paths, each backed up by its own scan.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestSnapshotSummaryCronRunRecordsUploads(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
 	env := newSummaryEnv(t)
 
 	summary := env.backUp(t, "split", true)

internal/vaultik/two_path_snapshot_test.go

@@ -18,10 +18,9 @@ import (
 // A backup without --cron runs the progress reporter while one scanner
 // scans each path of the snapshot in turn. See
 // https://git.eeqj.de/sneak/vaultik/issues/253.
-//
-//nolint:paralleltest // installs the global logger via log.Initialize
 func TestBackupWithoutCronOfTwoPathSnapshotRestoresBothPaths(t *testing.T) {
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	const snapshotName = "data"
 

script/fmt-check

@@ -1,6 +1,9 @@
 #!/bin/sh
-# script/fmt-check: check formatting (read-only). Same scope as
-# script/fmt, but fails instead of writing.
+# script/fmt-check: check formatting (read-only). Fails instead of
+# writing. It checks every Go file outside .tool, which is more than
+# script/fmt formats: `go fmt ./...` skips `testdata` directories and
+# files and directories whose names start with `.` or `_`. Fix a file
+# only this reports with `gofmt -w`.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"

script/release

@@ -21,10 +21,9 @@ goreleaser_version() {
         head -n 1
 }
 
-# Resolve the goreleaser to run, on the same rule script/lint uses for
-# golangci-lint: a binary on PATH is accepted only when it is exactly
-# the pinned version, because a differently versioned tool would
-# produce a differently built release from the same tag. Anything else
+# Resolve the goreleaser to run. A binary on PATH is accepted only when
+# it is exactly the pinned version, because a differently versioned tool
+# would produce a differently built release from the same tag. Anything else
 # comes from .tool/bin, and a missing one is a loud failure naming the
 # script that installs it rather than a silent fallback.
 resolve_goreleaser() {

test/config.yaml

@@ -19,7 +19,7 @@ s3:
   secret_access_key: test-secret-key
   region: us-east-1
   use_ssl: true
-  part_size: 5242880  # 5MB
+  part_size: 5242880  # 5MiB
 index_path: /tmp/vaultik-test.sqlite
 chunk_size: 10MB
 blob_size_limit: 10GB