Count a file as deleted only if the previous snapshot of its name had it (closes #304)

A backup counted as deleted every file in the local index under the
source path that the walk did not find. That took in files the
snapshot excludes but another snapshot backs up, and files removed long
ago, which every later backup, and the first backup of another name
over the same path, reported as deleted again.

The backup now looks up the most recent completed snapshot of the same
name and counts only the files it lists that the walk did not find and
that are not excluded.

The snapshots row stores no deleted figure; only the backup's output
changes.

Model: opus-5-5

ARCHITECTURE.md

@@ -279,8 +279,8 @@ Key methods:
 - `Scan(ctx, path, snapshotID)` → Main scan operation
 
 Scan phases:
-1. **Phase 0**: Detect deleted files from previous snapshots
-2. **Phase 1**: Walk directory, identify files needing processing
+1. **Phase 1**: Walk directory, identify files needing processing
+2. **Phase 1b**: Count as deleted the files that the previous snapshot of the same name lists and the walk did not find; an excluded file is not counted
 3. **Phase 2**: Process files (chunk → pack → upload)
 
 #### SnapshotManager
@@ -320,13 +320,13 @@ CreateSnapshot(opts)
     │       │
     │       ├─► scanner.Scan(ctx, path, snapshotID)
     │       │       │
-    │       │       ├─► Phase 0: detectDeletedFiles()
-    │       │       │
     │       │       ├─► Phase 1: scanPhase()
     │       │       │       Walk directory
     │       │       │       Check file metadata changes
     │       │       │       Build list of files to process
     │       │       │
+    │       │       ├─► Phase 1b: detectDeletedFiles()
+    │       │       │
     │       │       └─► Phase 2: processPhase()
     │       │               For each file:
     │       │                   chunker.ChunkReaderStreaming()

README.md

@@ -349,9 +349,11 @@ the backup destination store. Blobs are NOT touched — deleting blobs
 requires reading every remaining remote manifest (the destination store
 may hold snapshots this host doesn't know about), which is what
 `vaultik prune` does. On success the command prints the exact `vaultik
-prune` invocation to run as a follow-up. Local row cleanup (files,
-chunks, blobs the snapshot was the last referrer for) runs
-automatically. If the destination store is unreachable, the local-DB
+prune` invocation to run as a follow-up. An ID that names no snapshot in
+the local index or on the destination store is an error; with
+`--local-only`, the snapshot must be in the local index. Local row
+cleanup (files, chunks, blobs the snapshot was the last referrer for)
+runs automatically. If the destination store is unreachable, the local-DB
 removal still completes and a warning is emitted; run `vaultik snapshot
 remove <snapshot-id>` again once the store is reachable to remove the
 snapshot's metadata from it (`vaultik prune` does not). To wipe everything
@@ -412,7 +414,8 @@ destination store.
 entirely. Remote storage is unaffected; the next backup will do a full
 scan and re-deduplicate against existing remote blobs, and the local
 index will re-bind to the currently configured storage destination.
-Use this after changing `storage_url` to a different destination.
+Use this after changing `storage_url`, or `s3.endpoint`, `s3.bucket` or
+`s3.prefix`, to a different destination.
 * `--force`: Skip confirmation prompt
 
 ---

TODO.md

@@ -22,6 +22,55 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 2026-10-13: Counted a file as deleted only when the previous snapshot
+  of the same name had it
+  ([issue #304](https://git.eeqj.de/sneak/vaultik/issues/304)). The
+  deleted figure of a backup counted every file in the local index under
+  the source path that the walk did not find. That took in files the
+  snapshot excludes but another snapshot backs up, and files deleted
+  long ago, which every later backup, and the first backup of another
+  name over the same path, reported as deleted again. A file is now
+  counted only when the previous completed snapshot of the same name
+  lists it and the walk did not find it, and an excluded file is never
+  counted.
+
+- 2026-10-13: Made `snapshot remove` fail for a snapshot that does not
+  exist ([issue #293](https://git.eeqj.de/sneak/vaultik/issues/293)).
+  The command never checked the ID: it reported the snapshot removed
+  from the local database and from the destination store and exited 0,
+  under `--json`, `--dry-run` and `--local-only` too. An ID that names
+  no snapshot in the local index or on the destination store is now an
+  error; with `--local-only`, the snapshot must be in the local index.
+  The command now reports a removal from either side only when one
+  happened, and `remote_removed` is true only when metadata was deleted.
+
+- 2026-10-12: Bound the local index to the destination an `s3.*` config
+  names ([issue #298](https://git.eeqj.de/sneak/vaultik/issues/298)).
+  Only `storage_url` was checked, so after `s3.bucket` or `s3.prefix`
+  changed, the next backup treated every chunk as already stored,
+  uploaded nothing, and completed a snapshot that could not be restored.
+  Without `storage_url`, the local index is now bound to `s3.endpoint`,
+  `s3.bucket` and `s3.prefix`, and a change is refused as a changed
+  `storage_url` is.
+
+- 2026-10-12: Rejected a retention duration longer than about 292 years
+  ([issue #289](https://git.eeqj.de/sneak/vaultik/issues/289)). The
+  number given to `--older-than` or `--keep-newer-than` was multiplied
+  by the length of its unit with no limit, so from `293y`, `15251w`,
+  `3559mo` or `106752d`, or a sum of parts such as `200y200y`, the
+  result wrapped to a negative duration. The cutoff then lay in the
+  future, every snapshot of the name was deleted, the one just made
+  included, and the command exited 0. Such a duration is now rejected
+  as invalid and nothing is deleted.
+
+- 2026-10-08: Made a backup cancelled under `--skip-errors` stop at once
+  ([issue #286](https://git.eeqj.de/sneak/vaultik/issues/286)). After
+  Ctrl-C or SIGTERM, phase 2 treated the cancellation error from each
+  remaining file like an unreadable file: it opened the file, printed an
+  error line for it, counted it as failed and went on to the next one.
+  The run now stops at the first file after the cancellation, and no
+  file is counted as failed because of it.
+
 - 2026-10-08: Made `remote nuke` delete the `.partial` files that
   uploads cut off part-way leave on the destination store
   ([issue #281](https://git.eeqj.de/sneak/vaultik/issues/281)). The
@@ -29,6 +78,15 @@ the tag exists and is exercised; what is left is merging `next` to
   place and still reported the store empty. It now removes them under
   `metadata/` and `blobs/` as its last step.
 
+- 2026-10-08: Made a local index error while recording a directory or
+  symlink stop a backup under `--skip-errors`
+  ([issue #284](https://git.eeqj.de/sneak/vaultik/issues/284)). Phase 2
+  only records such an entry in the local index, since it has no data
+  to open or read, but an error doing so was skipped like an unreadable
+  file. The snapshot then completed without the entry, and a restore
+  did not recreate it. The error now stops the backup, as it does
+  without the flag.
+
 - 2026-10-08: Counted a file that a backup could not store as failed
   ([issue #280](https://git.eeqj.de/sneak/vaultik/issues/280)). A file
   that phase 1 counted and phase 2 could not open, because it was

internal/cli/snapshot.go

@@ -255,8 +255,12 @@ manifest (the destination store may hold snapshots this host doesn't
 know about), which is what 'vaultik prune' does. On success the command
 prints the exact 'vaultik prune' invocation to run as a follow-up.
 
+An ID that names no snapshot in the local index or on the destination
+store is an error.
+
 Use --local-only to skip the remote half (e.g. when you want to forget a
-snapshot locally without touching the destination store).
+snapshot locally without touching the destination store); the snapshot
+must then be in the local index.
 
 If the remote is unreachable, the local-database removal still completes
 and a warning is emitted; run 'vaultik snapshot remove <snapshot-id>' again

internal/database/files.go

@@ -277,6 +277,50 @@ func (r *FileRepository) ListUnderPath(
 	return files, rows.Err()
 }
 
+// ListUnderPathInSnapshot returns the files that ListUnderPath returns
+// for path and that the snapshot lists, in no particular order.
+func (r *FileRepository) ListUnderPathInSnapshot(
+	ctx context.Context, path, snapshotID string,
+) ([]*File, error) {
+	path = strings.TrimRight(path, "/")
+	dirPrefix := path + "/"
+
+	query := `
+		SELECT f.id, f.path, f.source_path, f.mtime, f.mtime_nsec, f.size,
+			f.mode, f.uid, f.gid, f.link_target
+		FROM files f
+		JOIN snapshot_files sf ON sf.file_id = f.id
+		WHERE sf.snapshot_id = ?
+		  AND (f.path = ? OR substr(f.path, 1, length(?)) = ?)
+	`
+
+	rows, err := r.db.conn.QueryContext(ctx, query,
+		snapshotID, path, dirPrefix, dirPrefix)
+	if err != nil {
+		return nil, fmt.Errorf("querying files: %w", err)
+	}
+
+	defer func() {
+		err := rows.Close()
+		if err != nil {
+			Fatalf("failed to close rows: %v", err)
+		}
+	}()
+
+	var files []*File
+
+	for rows.Next() {
+		file, err := r.scanFileRows(rows)
+		if err != nil {
+			return nil, fmt.Errorf("scanning file: %w", err)
+		}
+
+		files = append(files, file)
+	}
+
+	return files, rows.Err()
+}
+
 // ListIDsWithChunksNotInUploadedBlobs returns the IDs of the files whose
 // path starts with prefix and that list at least one chunk held by no
 // blob whose upload has completed (uploaded_ts set). A new snapshot

internal/database/files_test.go

@@ -212,6 +212,65 @@ func TestFileRepositoryListUnderPath(t *testing.T) {
 	}
 }
 
+// ListUnderPathInSnapshot leaves out files outside path and files the
+// snapshot does not list, though another snapshot lists them.
+func TestFileRepositoryListUnderPathInSnapshot(t *testing.T) {
+	t.Parallel()
+
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	files := database.NewFileRepository(db)
+	snapshots := database.NewSnapshotRepository(db)
+
+	listed := map[string][]string{
+		"one": {"/src/a.txt", "/src2/c.txt"},
+		"two": {"/src/b.txt"},
+	}
+
+	for snapshotID, paths := range listed {
+		err := snapshots.Create(ctx, nil, &database.Snapshot{
+			ID:        types.SnapshotID(snapshotID),
+			Hostname:  "host",
+			StartedAt: time.Now(),
+		})
+		if err != nil {
+			t.Fatalf("failed to create snapshot %s: %v", snapshotID, err)
+		}
+
+		for _, path := range paths {
+			err := files.Create(ctx, nil, &database.File{
+				Path:  types.FilePath(path),
+				MTime: time.Now().Truncate(time.Second),
+				Mode:  0644,
+			})
+			if err != nil {
+				t.Fatalf("failed to create %s: %v", path, err)
+			}
+
+			err = snapshots.AddFile(ctx, nil, snapshotID, path)
+			if err != nil {
+				t.Fatalf("failed to add %s to %s: %v", path, snapshotID, err)
+			}
+		}
+	}
+
+	found, err := files.ListUnderPathInSnapshot(ctx, "/src", "one")
+	if err != nil {
+		t.Fatalf("failed to list files: %v", err)
+	}
+
+	got := make([]string, 0, len(found))
+	for _, f := range found {
+		got = append(got, f.Path.String())
+	}
+
+	if !slices.Equal(got, []string{"/src/a.txt"}) {
+		t.Errorf("got %q, want only /src/a.txt", got)
+	}
+}
+
 func TestFileRepositorySymlink(t *testing.T) {
 	t.Parallel()
 

internal/snapshot/module.go

@@ -16,6 +16,9 @@ type ScannerParams struct {
 	Fs             afero.Fs
 	Exclude        []string // Exclude patterns (combined global + snapshot-specific)
 	SkipErrors     bool     // Skip file read errors (log loudly but continue)
+	// PreviousSnapshotID is the most recent completed snapshot of the
+	// same name, "" for none.
+	PreviousSnapshotID string
 }
 
 // Module exports backup functionality as an fx module.
@@ -44,17 +47,18 @@ func provideScannerFactory(
 		}
 
 		return NewScanner(ScannerConfig{
-			FS:               params.Fs,
-			ChunkSize:        cfg.ChunkSize.Int64(),
-			Repositories:     repos,
-			Storage:          storer,
-			MaxBlobSize:      cfg.BlobSizeLimit.Int64(),
-			CompressionLevel: cfg.CompressionLevel,
-			AgeRecipients:    cfg.AgeRecipients,
-			EnableProgress:   params.EnableProgress,
-			UI:               params.UI,
-			Exclude:          excludes,
-			SkipErrors:       params.SkipErrors,
+			FS:                 params.Fs,
+			ChunkSize:          cfg.ChunkSize.Int64(),
+			Repositories:       repos,
+			Storage:            storer,
+			MaxBlobSize:        cfg.BlobSizeLimit.Int64(),
+			CompressionLevel:   cfg.CompressionLevel,
+			AgeRecipients:      cfg.AgeRecipients,
+			EnableProgress:     params.EnableProgress,
+			UI:                 params.UI,
+			Exclude:            excludes,
+			SkipErrors:         params.SkipErrors,
+			PreviousSnapshotID: params.PreviousSnapshotID,
 		})
 	}
 }

internal/snapshot/scanner.go

@@ -58,6 +58,10 @@ type Scanner struct {
 	compressionLevel int
 	ageRecipient     string
 	snapshotID       string // Current snapshot being processed
+	// previousSnapshotID is the most recent completed snapshot of the
+	// same name, "" for none. Only a file it lists can be counted as
+	// deleted.
+	previousSnapshotID string
 	// currentSourcePath is the source directory being scanned, stored with
 	// each file record.
 	currentSourcePath string
@@ -129,6 +133,9 @@ type ScannerConfig struct {
 	// SkipErrors skips files that cannot be opened or read (log loudly but
 	// continue); packer, database, encryption, and upload errors still abort.
 	SkipErrors bool
+	// PreviousSnapshotID is the most recent completed snapshot of the
+	// same name, "" for none.
+	PreviousSnapshotID string
 }
 
 // ScanResult contains the results of a scan operation. Files and bytes
@@ -204,6 +211,7 @@ func NewScanner(cfg ScannerConfig) *Scanner {
 		compiledExclude:    compiledExclude,
 		progress:           progress,
 		skipErrors:         cfg.SkipErrors,
+		previousSnapshotID: cfg.PreviousSnapshotID,
 		ui:                 uiw,
 		pendingChunkHashes: make(map[string]struct{}),
 	}
@@ -255,8 +263,9 @@ func (s *Scanner) Scan(
 
 	filesToProcess := scanResult.FilesToProcess
 
-	// Phase 1b: Detect deleted files by comparing DB against scanned files
-	err = s.detectDeletedFilesFromMap(ctx, knownFiles, existingFiles, result)
+	// Phase 1b: Detect deleted files by comparing the previous snapshot
+	// of this name against scanned files
+	err = s.detectDeletedFiles(ctx, path, existingFiles, result)
 	if err != nil {
 		return nil, fmt.Errorf("detecting deleted files: %w", err)
 	}
@@ -436,9 +445,8 @@ func (s *Scanner) summarizeScanPhase(
 }
 
 // loadKnownFiles loads the known files at and beneath path from the
-// database into a map for fast lookup. Every loaded file the scan does
-// not find is counted as deleted. This avoids per-file database queries
-// during the scan phase.
+// database into a map for fast lookup. This avoids per-file database
+// queries during the scan phase.
 func (s *Scanner) loadKnownFiles(
 	ctx context.Context, path string,
 ) (map[string]*database.File, error) {
@@ -1312,6 +1320,13 @@ func (s *Scanner) processPhase(
 
 	// Process each file
 	for _, fileToProcess := range filesToProcess {
+		// Check context cancellation
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
+
 		// Update progress
 		if s.progress != nil {
 			s.progress.GetStats().CurrentFile.Store(fileToProcess.Path)
@@ -1348,13 +1363,32 @@ func (s *Scanner) processPhase(
 	return s.finalizeProcessPhase(ctx, result)
 }
 
-// processFileWithErrorHandling wraps processFileStreaming with error recovery for
-// deleted files and skip-errors mode. Returns (skipped, error).
+// processFileWithErrorHandling records a directory or symlink, or wraps
+// processFileStreaming for a regular file with error recovery for deleted
+// files and skip-errors mode. Returns (skipped, error).
 func (s *Scanner) processFileWithErrorHandling(
 	ctx context.Context, fileToProcess *FileToProcess, result *ScanResult,
 ) (bool, error) {
+	// A directory or symlink has no data to open or read; it is only
+	// recorded in the local index. An error recording it stops the run
+	// even under --skip-errors, or the snapshot would complete without it.
+	mode := os.FileMode(fileToProcess.File.Mode)
+	if mode&os.ModeSymlink != 0 || mode.IsDir() {
+		err := s.recordNonRegularFile(ctx, fileToProcess)
+		if err != nil {
+			return false, fmt.Errorf("processing file %s: %w", fileToProcess.Path, err)
+		}
+
+		return false, nil
+	}
+
 	err := s.processFileStreaming(ctx, fileToProcess, result)
 	if err != nil {
+		// A cancelled run stops here even under --skip-errors, rather than
+		// counting this file as failed and going on to the next one.
+		if ctx.Err() != nil {
+			return false, fmt.Errorf("processing file %s: %w", fileToProcess.Path, err)
+		}
 		// A packer/database/encryption/upload failure means the chunk's data
 		// may not have been stored. Skipping the file would let the snapshot
 		// record a file whose chunk is in no blob and cannot be restored, so
@@ -1392,12 +1426,7 @@ func (s *Scanner) processFileWithErrorHandling(
 
 // countFailedFile counts a file that phase 2 could not store as failed
 // and takes its size back out of BytesScanned, where phase 1 put it.
-// Phase 1 counts no directories, so a directory is not counted here.
 func countFailedFile(fileToProcess *FileToProcess, result *ScanResult) {
-	if fileToProcess.FileInfo.IsDir() {
-		return
-	}
-
 	result.FilesFailed++
 	result.BytesScanned -= fileToProcess.FileInfo.Size()
 }
@@ -1770,16 +1799,11 @@ func (e *packerError) Error() string { return e.err.Error() }
 
 func (e *packerError) Unwrap() error { return e.err }
 
-// processFileStreaming processes a file by streaming chunks directly to the packer
+// processFileStreaming processes a regular file by streaming chunks directly
+// to the packer
 func (s *Scanner) processFileStreaming(
 	ctx context.Context, fileToProcess *FileToProcess, result *ScanResult,
 ) error {
-	// Symlinks and directories have no data to chunk — just record them in the DB.
-	mode := os.FileMode(fileToProcess.File.Mode)
-	if mode&os.ModeSymlink != 0 || mode.IsDir() {
-		return s.recordNonRegularFile(ctx, fileToProcess)
-	}
-
 	file, err := s.fs.Open(fileToProcess.Path)
 	if err != nil {
 		return fmt.Errorf("opening file: %w", wrapPermissionError(fileToProcess.Path, err))
@@ -1917,21 +1941,28 @@ func (s *Scanner) queueFileForBatchInsert(
 	})
 }
 
-// detectDeletedFilesFromMap finds files that existed in previous snapshots
-// but no longer exist. Uses pre-loaded maps to avoid any filesystem or
-// database access.
-func (s *Scanner) detectDeletedFilesFromMap(
+// detectDeletedFiles counts as deleted each file at or beneath path that
+// the previous snapshot of this name lists and the walk did not find.
+// An excluded file is not counted: the walk skips it whether or not it
+// is still on disk.
+func (s *Scanner) detectDeletedFiles(
 	ctx context.Context,
-	knownFiles map[string]*database.File,
+	path string,
 	existingFiles map[string]struct{},
 	result *ScanResult,
 ) error {
-	if len(knownFiles) == 0 {
+	if s.previousSnapshotID == "" {
 		return nil
 	}
 
-	// Check each known file against the enumerated set (no filesystem access needed)
-	for path, file := range knownFiles {
+	previousFiles, err := s.repos.Files.ListUnderPathInSnapshot(
+		ctx, path, s.previousSnapshotID)
+	if err != nil {
+		return fmt.Errorf("listing files of snapshot %s: %w",
+			s.previousSnapshotID, err)
+	}
+
+	for _, file := range previousFiles {
 		// Check context cancellation periodically
 		select {
 		case <-ctx.Done():
@@ -1939,13 +1970,16 @@ func (s *Scanner) detectDeletedFilesFromMap(
 		default:
 		}
 
-		// Check if the file exists in our enumerated set
-		if _, exists := existingFiles[path]; !exists {
-			// File has been deleted
-			result.FilesDeleted++
-			result.BytesDeleted += file.Size
-			log.Debug("Detected deleted file", "path", path, "size", file.Size)
+		filePath := file.Path.String()
+
+		_, exists := existingFiles[filePath]
+		if exists || s.shouldExclude(filePath, path) {
+			continue
 		}
+
+		result.FilesDeleted++
+		result.BytesDeleted += file.Size
+		log.Debug("Detected deleted file", "path", filePath, "size", file.Size)
 	}
 
 	if result.FilesDeleted > 0 {

internal/snapshot/skip_errors_test.go

@@ -82,6 +82,32 @@ func (f *readFailFs) Open(name string) (afero.File, error) {
 	return file, nil
 }
 
+// cancelOnOpenFs cancels the run when the scanner opens the target file to
+// back it up, as Ctrl-C partway through processing would, and records each
+// file opened after that.
+type cancelOnOpenFs struct {
+	afero.Fs
+
+	target            string
+	cancel            context.CancelFunc
+	cancelled         bool
+	openedAfterCancel []string
+}
+
+//nolint:ireturn // afero.Fs.Open is defined to return the interface.
+func (f *cancelOnOpenFs) Open(name string) (afero.File, error) {
+	if f.cancelled {
+		f.openedAfterCancel = append(f.openedAfterCancel, name)
+	}
+
+	if name == f.target {
+		f.cancel()
+		f.cancelled = true
+	}
+
+	return f.Fs.Open(name)
+}
+
 // 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.
@@ -128,15 +154,16 @@ func writeSkipErrorTestFile(t *testing.T, fs afero.Fs, path, content string) {
 	}
 }
 
-// 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.
+// runSkipErrorScan scans source on fs under ctx 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, source string, skipErrors bool, uiw *ui.Writer,
+	ctx context.Context, t *testing.T, fs afero.Fs, source string,
+	skipErrors bool, uiw *ui.Writer,
 ) (*database.Repositories, error) {
 	t.Helper()
 
-	db, err := database.NewTestDB()
+	db, err := database.New(ctx, ":memory:")
 	if err != nil {
 		t.Fatalf("create test db: %v", err)
 	}
@@ -161,7 +188,6 @@ func runSkipErrorScan(
 		SkipErrors:       skipErrors,
 	})
 
-	ctx := context.Background()
 	snapshotID := "test-snapshot-skip-errors"
 	createTestSnapshotRecord(ctx, t, repos, snapshotID)
 
@@ -185,7 +211,7 @@ 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, "/source", true, nil)
+	repos, err := runSkipErrorScan(context.Background(), t, fs, "/source", true, nil)
 	if err == nil {
 		t.Fatal("expected scan to abort on the packer error, got nil")
 	}
@@ -212,7 +238,7 @@ 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, "/source", false, nil)
+	_, err := runSkipErrorScan(context.Background(), t, fs, "/source", false, nil)
 	if err == nil {
 		t.Fatal("expected scan to fail on the read error, got nil")
 	}
@@ -228,7 +254,7 @@ 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, "/source", true, nil)
+	repos, err := runSkipErrorScan(context.Background(), t, fs, "/source", true, nil)
 	if err != nil {
 		t.Fatalf("expected scan to complete with --skip-errors, got %v", err)
 	}
@@ -267,7 +293,7 @@ func TestScannerUnreadableSymlinkAbortsWithoutSkipErrors(t *testing.T) {
 	sourceDir, linkPath := writeSymlinkSource(t)
 	fs := &linkRemovedAfterLstatFs{t: t, target: linkPath}
 
-	_, err := runSkipErrorScan(t, fs, sourceDir, false, nil)
+	_, err := runSkipErrorScan(context.Background(), t, fs, sourceDir, false, nil)
 	if !errors.Is(err, os.ErrNotExist) {
 		t.Fatalf("expected scan to fail on the removed symlink, got %v", err)
 	}
@@ -283,7 +309,7 @@ func TestScannerUnreadableSymlinkSkippedWithSkipErrors(t *testing.T) {
 	fs := &linkRemovedAfterLstatFs{t: t, target: linkPath}
 	uiw := ui.NewWithColor(io.Discard, false)
 
-	repos, err := runSkipErrorScan(t, fs, sourceDir, true, uiw)
+	repos, err := runSkipErrorScan(context.Background(), t, fs, sourceDir, true, uiw)
 	if err != nil {
 		t.Fatalf("expected scan to complete with --skip-errors, got %v", err)
 	}
@@ -302,3 +328,56 @@ func TestScannerUnreadableSymlinkSkippedWithSkipErrors(t *testing.T) {
 		t.Fatalf("expected %s not to be recorded", linkPath)
 	}
 }
+
+// TestScannerCancelStopsSkipErrorsRun checks that a --skip-errors backup
+// cancelled partway through processing returns the cancellation error,
+// opens no further file, and reports no file as failed.
+func TestScannerCancelStopsSkipErrorsRun(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name          string
+		targetContent string
+	}{
+		// The cancellation lands while the target is being read.
+		{name: "while reading a file", targetContent: "first file content"},
+		// An empty target has no chunks, so the cancellation goes unnoticed
+		// until the run moves on to the next file.
+		{name: "between files", targetContent: ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			const target = "/source/a.txt"
+
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			fs := &cancelOnOpenFs{
+				Fs: afero.NewMemMapFs(), target: target, cancel: cancel,
+			}
+			writeSkipErrorTestFile(t, fs, target, tt.targetContent)
+			writeSkipErrorTestFile(t, fs, "/source/b.txt", "second file content")
+			writeSkipErrorTestFile(t, fs, "/source/c.txt", "third file content")
+
+			uiw := ui.NewWithColor(io.Discard, false)
+
+			_, err := runSkipErrorScan(ctx, t, fs, "/source", true, uiw)
+			if !errors.Is(err, context.Canceled) {
+				t.Fatalf("expected the cancellation error, got %v", err)
+			}
+
+			if len(fs.openedAfterCancel) != 0 {
+				t.Fatalf("expected no file opened after the cancellation, got %v",
+					fs.openedAfterCancel)
+			}
+
+			if uiw.ErrorCount() != 0 {
+				t.Fatalf("expected no file reported as failed, got %d error lines",
+					uiw.ErrorCount())
+			}
+		})
+	}
+}

internal/vaultik/fault_injection_test.go

@@ -661,17 +661,18 @@ func faultScannerFactory(
 ) snapshot.ScannerFactory {
 	return func(params snapshot.ScannerParams) *snapshot.Scanner {
 		return snapshot.NewScanner(snapshot.ScannerConfig{
-			FS:               params.Fs,
-			Storage:          storer,
-			ChunkSize:        faultChunkSize,
-			MaxBlobSize:      faultMaxBlobSize,
-			CompressionLevel: cfg.CompressionLevel,
-			AgeRecipients:    cfg.AgeRecipients,
-			Repositories:     repos,
-			EnableProgress:   params.EnableProgress,
-			UI:               params.UI,
-			Exclude:          params.Exclude,
-			SkipErrors:       params.SkipErrors,
+			FS:                 params.Fs,
+			Storage:            storer,
+			ChunkSize:          faultChunkSize,
+			MaxBlobSize:        faultMaxBlobSize,
+			CompressionLevel:   cfg.CompressionLevel,
+			AgeRecipients:      cfg.AgeRecipients,
+			Repositories:       repos,
+			EnableProgress:     params.EnableProgress,
+			UI:                 params.UI,
+			Exclude:            params.Exclude,
+			SkipErrors:         params.SkipErrors,
+			PreviousSnapshotID: params.PreviousSnapshotID,
 		})
 	}
 }

internal/vaultik/helpers.go

@@ -3,6 +3,7 @@ package vaultik
 import (
 	"errors"
 	"fmt"
+	"math"
 	"regexp"
 	"strconv"
 	"strings"
@@ -47,6 +48,10 @@ const (
 	year  = 365 * day
 )
 
+// maxDuration is the largest value a time.Duration can hold, about 292
+// years.
+const maxDuration = time.Duration(math.MaxInt64)
+
 // A snapshot ID split on "_" has at least a hostname and a trailing
 // timestamp.
 const minSnapshotIDParts = 2
@@ -145,10 +150,10 @@ func parseSnapshotName(snapshotID, hostname string) string {
 // parseDuration parses a duration string with support for human-friendly units:
 // d/day/days, w/week/weeks, mo/month/months, y/year/years, plus standard Go
 // duration units. Following Go, m is minutes and mo is months. A bare number,
-// an unknown unit, and a negative value are all rejected. Outside the Go
-// units the input must be whole numbers each followed directly by a unit
-// (2w3d), so 1.0y and 30 days are errors; decimals work only in Go units
-// (1.5h).
+// an unknown unit, a negative value, and a total longer than maxDuration are
+// all rejected. Outside the Go units the input must be whole numbers each
+// followed directly by a unit (2w3d), so 1.0y and 30 days are errors;
+// decimals work only in Go units (1.5h).
 func parseDuration(s string) (time.Duration, error) {
 	if strings.HasPrefix(strings.TrimSpace(s), "-") {
 		return 0, errNegativeDuration
@@ -181,19 +186,30 @@ func parseDuration(s string) (time.Duration, error) {
 			return 0, fmt.Errorf("invalid number %q: %w", match[1], err)
 		}
 
+		var unitLength time.Duration
+
 		unit := strings.ToLower(match[2])
 		switch unit {
 		case "d", "day", "days":
-			total += time.Duration(n) * day
+			unitLength = day
 		case "w", "week", "weeks":
-			total += time.Duration(n) * week
+			unitLength = week
 		case "mo", "month", "months":
-			total += time.Duration(n) * month
+			unitLength = month
 		case "y", "year", "years":
-			total += time.Duration(n) * year
+			unitLength = year
 		default:
 			return 0, fmt.Errorf("%w %q", errUnknownTimeUnit, unit)
 		}
+
+		// Past maxDuration the sum wraps to a negative value, which would
+		// put the purge cutoff in the future.
+		if time.Duration(n) > (maxDuration-total)/unitLength {
+			return 0, fmt.Errorf("%w: %q is longer than about 292 years",
+				errInvalidDuration, s)
+		}
+
+		total += time.Duration(n) * unitLength
 	}
 
 	return total, nil

internal/vaultik/helpers_test.go

@@ -111,6 +111,17 @@ func TestParseDuration(t *testing.T) {
 		{"30 days", 0, true},
 		{"30 days ago", 0, true},
 		{"x7d", 0, true},
+		// The largest time.Duration is about 292 years. A larger value
+		// must be rejected, not wrapped to a negative one, which would
+		// put the cutoff in the future and select every snapshot.
+		{"292y", 292 * 365 * 24 * time.Hour, false},
+		{"293y", 0, true},
+		{"3559mo", 0, true},
+		{"15251w", 0, true},
+		{"106752d", 0, true},
+		{"2562048h", 0, true},
+		{"200y200y", 0, true},
+		{"292y6mo", 0, true},
 	}
 
 	for _, tt := range tests {

internal/vaultik/purge_per_name_test.go

@@ -267,6 +267,29 @@ func TestPurgeOlderThan_WithNameFilter(t *testing.T) {
 	assert.Contains(t, remaining, snapHomeT0)
 }
 
+func TestPurgeOlderThan_TooLargeDeletesNothing(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	snapshotIDs := []string{snapHomeT0, snapHomeT1}
+
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		OlderThan: "1000y",
+		Force:     true,
+	})
+	require.Error(t, err)
+
+	err = v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		OlderThan: "292y",
+		Force:     true,
+	})
+	require.NoError(t, err)
+
+	assert.ElementsMatch(t, snapshotIDs, listRemainingSnapshots(t, v))
+}
+
 func TestPurgeKeepLatest_ThreeNames(t *testing.T) {
 	log.Initialize(log.Config{})
 	t.Parallel()

internal/vaultik/remove_snapshot_test.go

@@ -3,17 +3,21 @@ package vaultik_test
 import (
 	"bytes"
 	"context"
+	"database/sql"
 	"io"
 	"strings"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/klauspost/compress/zstd"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/types"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
 
@@ -214,6 +218,37 @@ func addBlob(t *testing.T, store *testStorer, hash string) {
 	require.NoError(t, err)
 }
 
+// newLocalIndex returns an in-memory local index holding a completed
+// snapshot row for each of ids.
+func newLocalIndex(t *testing.T, ids ...string) *database.Repositories {
+	t.Helper()
+
+	ctx := context.Background()
+
+	db, err := database.New(ctx, ":memory:")
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+
+	for _, id := range ids {
+		completedAt := time.Now().UTC()
+		snap := &database.Snapshot{
+			ID:          types.SnapshotID(id),
+			Hostname:    snapHostname,
+			StartedAt:   completedAt,
+			CompletedAt: &completedAt,
+		}
+
+		err = repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
+			return repos.Snapshots.Create(ctx, tx, snap)
+		})
+		require.NoError(t, err)
+	}
+
+	return repos
+}
+
 // ============================================================================
 // Unit Tests for RemoveSnapshot
 // ============================================================================
@@ -233,6 +268,7 @@ func TestRemoveSnapshot_LocalOnly_PreservesRemote(t *testing.T) {
 	addBlob(t, store, blobA)
 
 	tv := vaultik.NewForTesting(store)
+	tv.Repositories = newLocalIndex(t, "snapshot-001")
 
 	opts := &vaultik.RemoveOptions{Force: true, LocalOnly: true}
 	result, err := tv.RemoveSnapshot("snapshot-001", opts)
@@ -268,6 +304,7 @@ func TestRemoveSnapshot_DefaultRemovesMetadataNotBlobs(t *testing.T) {
 	addBlob(t, store, blobShared)
 
 	tv := vaultik.NewForTesting(store)
+	tv.Repositories = newLocalIndex(t, "snapshot-001", "snapshot-002")
 
 	opts := &vaultik.RemoveOptions{Force: true}
 	result, err := tv.RemoveSnapshot("snapshot-001", opts)
@@ -316,6 +353,84 @@ func TestRemoveSnapshot_DryRun(t *testing.T) {
 	assert.Contains(t, tv.Stdout.String(), "[Dry run - no changes made]")
 }
 
+// TestRemoveSnapshot_UnknownIDIsError checks that an ID naming no
+// snapshot in the local index or on the destination store is an error
+// under every option, and that nothing is reported as removed.
+func TestRemoveSnapshot_UnknownIDIsError(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	for name, opts := range map[string]vaultik.RemoveOptions{
+		"force":      {Force: true},
+		"json":       {JSON: true},
+		"dry-run":    {Force: true, DryRun: true},
+		"local-only": {Force: true, LocalOnly: true},
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			store := newTestStorer()
+			addManifest(t, store, "snapshot-001", nil)
+
+			tv := vaultik.NewForTesting(store)
+			tv.Repositories = newLocalIndex(t, "snapshot-001")
+
+			result, err := tv.RemoveSnapshot("snapshot-999", &opts)
+
+			require.ErrorContains(t, err, "snapshot not found")
+			assert.False(t, result.RemoteRemoved)
+			assert.Empty(t, tv.Stdout.String())
+			assert.True(t, store.hasKey(remoteKeyPath("snapshot-001")))
+		})
+	}
+}
+
+// TestRemoveSnapshot_NoMetadataOnDestination checks that removing a
+// snapshot whose metadata is not on the destination store does not
+// report metadata removed from it.
+func TestRemoveSnapshot_NoMetadataOnDestination(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	tv := vaultik.NewForTesting(newTestStorer())
+	tv.Repositories = newLocalIndex(t, "snapshot-001")
+
+	result, err := tv.RemoveSnapshot("snapshot-001",
+		&vaultik.RemoveOptions{Force: true})
+
+	require.NoError(t, err)
+	assert.False(t, result.RemoteRemoved)
+
+	out := tv.Stdout.String()
+	assert.Contains(t, out, "Removed snapshot 'snapshot-001' from local database")
+	assert.NotContains(t, out, "Removed snapshot metadata from remote storage")
+}
+
+// TestRemoveSnapshot_NotInLocalIndex checks that removing a snapshot
+// only the destination store holds removes its metadata there without
+// reporting a removal from the local database.
+func TestRemoveSnapshot_NotInLocalIndex(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	store := newTestStorer()
+	addManifest(t, store, "snapshot-001", nil)
+
+	tv := vaultik.NewForTesting(store)
+	tv.Repositories = newLocalIndex(t)
+
+	result, err := tv.RemoveSnapshot("snapshot-001",
+		&vaultik.RemoveOptions{Force: true})
+
+	require.NoError(t, err)
+	assert.True(t, result.RemoteRemoved)
+	assert.False(t, store.hasKey(remoteKeyPath("snapshot-001")))
+
+	out := tv.Stdout.String()
+	assert.NotContains(t, out, "from local database")
+	assert.Contains(t, out, "Removed snapshot metadata from remote storage")
+}
+
 func TestRemoveAllSnapshots_RequiresForce(t *testing.T) {
 	log.Initialize(log.Config{})
 	t.Parallel()

internal/vaultik/snapshot.go

@@ -23,6 +23,7 @@ var (
 	errNoSnapshotsInConfig  = errors.New("no snapshots configured")
 	errSnapshotVerifyFailed = errors.New("verification failed")
 	errRemoveAllNeedsForce  = errors.New("--all requires --force")
+	errSnapshotNotFound     = errors.New("snapshot not found")
 	errInvalidTableName     = errors.New("invalid table name")
 	errNoAgeRecipients      = errors.New(
 		"creating a snapshot needs at least one public key in " +
@@ -213,12 +214,18 @@ func (v *Vaultik) createNamedSnapshot(
 		return err
 	}
 
+	previousSnapshotID, err := v.previousSnapshotID(snapName)
+	if err != nil {
+		return err
+	}
+
 	scanner := v.ScannerFactory(snapshot.ScannerParams{
-		EnableProgress: !opts.Cron,
-		UI:             v.UI,
-		Fs:             v.Fs,
-		Exclude:        v.Config.GetExcludes(snapName),
-		SkipErrors:     opts.SkipErrors,
+		EnableProgress:     !opts.Cron,
+		UI:                 v.UI,
+		Fs:                 v.Fs,
+		Exclude:            v.Config.GetExcludes(snapName),
+		SkipErrors:         opts.SkipErrors,
+		PreviousSnapshotID: previousSnapshotID,
 	})
 
 	snapshotID, err := v.SnapshotManager.CreateSnapshotWithName(
@@ -253,6 +260,24 @@ func (v *Vaultik) createNamedSnapshot(
 	return nil
 }
 
+// previousSnapshotID returns the ID of the most recent completed snapshot
+// named snapName in the local index, or "" when there is none.
+func (v *Vaultik) previousSnapshotID(snapName string) (string, error) {
+	snapshots, err := v.Repositories.Snapshots.ListRecent(v.ctx, listRecentLimit)
+	if err != nil {
+		return "", fmt.Errorf("listing snapshots: %w", err)
+	}
+
+	for _, s := range snapshots {
+		if s.CompletedAt != nil &&
+			parseSnapshotName(s.ID.String(), s.Hostname.String()) == snapName {
+			return s.ID.String(), nil
+		}
+	}
+
+	return "", nil
+}
+
 // resolveSnapshotPaths resolves source directories to absolute paths
 // with symlink resolution.
 func (v *Vaultik) resolveSnapshotPaths(snapName string) ([]string, error) {
@@ -643,7 +668,7 @@ func (v *Vaultik) confirmAndExecutePurge(
 				"snapshot_id", snapshotID, "error", err)
 		}
 
-		err = v.deleteRemoteSnapshotByKey(snapshot.RemoteSnapshotKey(snapshotID))
+		_, err = v.deleteRemoteSnapshotByKey(snapshot.RemoteSnapshotKey(snapshotID))
 		if err != nil {
 			return fmt.Errorf("deleting snapshot %s from remote: %w", snapshotID, err)
 		}
@@ -1153,6 +1178,11 @@ func (v *Vaultik) RemoveSnapshot(
 		return result, err
 	}
 
+	inLocalIndex, err := v.findSnapshotToRemove(snapshotID, opts)
+	if err != nil {
+		return result, err
+	}
+
 	if opts.DryRun {
 		return v.removeSnapshotDryRun(result, snapshotID, opts)
 	}
@@ -1161,11 +1191,13 @@ func (v *Vaultik) RemoveSnapshot(
 		return result, nil
 	}
 
-	log.Info("Removing snapshot from local database", "snapshot_id", snapshotID)
+	if inLocalIndex {
+		log.Info("Removing snapshot from local database", "snapshot_id", snapshotID)
 
-	err = v.deleteSnapshotFromLocalDB(snapshotID)
-	if err != nil {
-		return result, fmt.Errorf("removing from local database: %w", err)
+		err = v.deleteSnapshotFromLocalDB(snapshotID)
+		if err != nil {
+			return result, fmt.Errorf("removing from local database: %w", err)
+		}
 	}
 
 	if !opts.LocalOnly {
@@ -1184,9 +1216,11 @@ func (v *Vaultik) RemoveSnapshot(
 		return result, v.outputRemoveJSON(result)
 	}
 
-	v.stdoutf("Removed snapshot '%s' from local database\n", snapshotID)
+	if inLocalIndex {
+		v.stdoutf("Removed snapshot '%s' from local database\n", snapshotID)
+	}
 
-	if !opts.LocalOnly && result.RemoteRemoved {
+	if result.RemoteRemoved {
 		v.printlnStdout("Removed snapshot metadata from remote storage")
 		v.stdoutf("\nNote: The removed snapshot's blobs remain on the remote. "+
 			"Run '%s' to delete any blobs no longer referenced by any "+
@@ -1196,6 +1230,45 @@ func (v *Vaultik) RemoveSnapshot(
 	return result, nil
 }
 
+// findSnapshotToRemove reports whether the local index has a row for
+// snapshotID, and returns errSnapshotNotFound when there is nothing to
+// remove: no row and, unless LocalOnly is set, no metadata on the
+// destination store either. The destination store is consulted only
+// when the local index has no row, so a snapshot in the local index can
+// still be removed from it while the destination store is unreachable.
+func (v *Vaultik) findSnapshotToRemove(
+	snapshotID string, opts *RemoveOptions,
+) (bool, error) {
+	if v.Repositories != nil {
+		snap, err := v.Repositories.Snapshots.GetByID(v.ctx, snapshotID)
+		if err != nil {
+			return false, fmt.Errorf("looking up snapshot in local index: %w", err)
+		}
+
+		if snap != nil {
+			return true, nil
+		}
+	}
+
+	if opts.LocalOnly {
+		return false, fmt.Errorf("%w in the local index: %s",
+			errSnapshotNotFound, snapshotID)
+	}
+
+	objects, err := v.remoteSnapshotObjects(snapshot.RemoteSnapshotKey(snapshotID))
+	if err != nil {
+		return false, fmt.Errorf("looking up snapshot on destination store: %w", err)
+	}
+
+	if len(objects) == 0 {
+		return false, fmt.Errorf(
+			"%w in the local index or on the destination store: %s",
+			errSnapshotNotFound, snapshotID)
+	}
+
+	return false, nil
+}
+
 // removeSnapshotDryRun reports what RemoveSnapshot would do without
 // making changes.
 func (v *Vaultik) removeSnapshotDryRun(
@@ -1255,14 +1328,14 @@ func (v *Vaultik) confirmRemoveSnapshot(snapshotID string, opts *RemoveOptions)
 // didn't finish and to run `vaultik snapshot remove` for the snapshot
 // again once the destination store is reachable (`vaultik prune` never
 // removes snapshot metadata). Returns true when the remote removal
-// succeeded.
+// succeeded and deleted something.
 func (v *Vaultik) removeSnapshotRemote(snapshotID string, opts *RemoveOptions) bool {
 	log.Info("Removing snapshot metadata from remote storage",
 		"snapshot_id", snapshotID)
 
 	remoteKey := snapshot.RemoteSnapshotKey(snapshotID)
 
-	err := v.deleteRemoteSnapshotByKey(remoteKey)
+	deleted, err := v.deleteRemoteSnapshotByKey(remoteKey)
 	if err != nil {
 		log.Warn("Could not remove snapshot metadata from remote storage; "+
 			"run '"+snapshotRemoveCommandHint+"' with the snapshot's ID "+
@@ -1280,7 +1353,7 @@ func (v *Vaultik) removeSnapshotRemote(snapshotID string, opts *RemoveOptions) b
 		return false
 	}
 
-	return true
+	return deleted > 0
 }
 
 // RemoveAllSnapshots removes every snapshot known to the local
@@ -1572,7 +1645,7 @@ func (v *Vaultik) removeAllLocalSnapshots(
 		}
 
 		if !opts.LocalOnly {
-			err = v.deleteRemoteSnapshotByKey(
+			_, err = v.deleteRemoteSnapshotByKey(
 				snapshot.RemoteSnapshotKey(snapshotID))
 			if err != nil {
 				log.Warn("Failed to remove snapshot metadata from remote",
@@ -1598,7 +1671,7 @@ func (v *Vaultik) removeAllOrphanRemotes(
 	for _, key := range orphanRemoteKeys {
 		log.Info("Removing orphan remote snapshot", "remote_key", key)
 
-		err := v.deleteRemoteSnapshotByKey(key)
+		_, err := v.deleteRemoteSnapshotByKey(key)
 		if err != nil {
 			log.Warn("Failed to remove orphan from remote",
 				"remote_key", key, "error", err)
@@ -1645,34 +1718,44 @@ func (v *Vaultik) deleteSnapshotFromLocalDB(snapshotID string) error {
 }
 
 // deleteRemoteSnapshotByKey removes everything under
-// metadata/<remoteKey>/ on the destination store. The argument is a
-// remote key (double-SHA256 derivation), not a human snapshot ID;
-// callers that have a human ID must hash via snapshot.RemoteSnapshotKey
-// first.
-func (v *Vaultik) deleteRemoteSnapshotByKey(remoteKey string) error {
-	prefix := fmt.Sprintf("metadata/%s/", remoteKey)
-	objectCh := v.Storage.ListStream(v.ctx, prefix)
-
-	var objectsToDelete []string
-
-	for object := range objectCh {
-		if object.Err != nil {
-			return fmt.Errorf("listing objects: %w", object.Err)
-		}
-
-		objectsToDelete = append(objectsToDelete, object.Key)
+// metadata/<remoteKey>/ on the destination store and returns how many
+// objects it deleted. The argument is a remote key (double-SHA256
+// derivation), not a human snapshot ID; callers that have a human ID
+// must hash via snapshot.RemoteSnapshotKey first.
+func (v *Vaultik) deleteRemoteSnapshotByKey(remoteKey string) (int, error) {
+	objectsToDelete, err := v.remoteSnapshotObjects(remoteKey)
+	if err != nil {
+		return 0, err
 	}
 
-	for _, key := range objectsToDelete {
-		err := v.Storage.Delete(v.ctx, key)
+	for i, key := range objectsToDelete {
+		err = v.Storage.Delete(v.ctx, key)
 		if err != nil {
-			return fmt.Errorf("removing %s: %w", key, err)
+			return i, fmt.Errorf("removing %s: %w", key, err)
 		}
 
 		log.Debug("Deleted remote object", "key", key)
 	}
 
-	return nil
+	return len(objectsToDelete), nil
+}
+
+// remoteSnapshotObjects lists the keys of every object under
+// metadata/<remoteKey>/ on the destination store.
+func (v *Vaultik) remoteSnapshotObjects(remoteKey string) ([]string, error) {
+	prefix := fmt.Sprintf("metadata/%s/", remoteKey)
+
+	var keys []string
+
+	for object := range v.Storage.ListStream(v.ctx, prefix) {
+		if object.Err != nil {
+			return nil, fmt.Errorf("listing objects: %w", object.Err)
+		}
+
+		keys = append(keys, object.Key)
+	}
+
+	return keys, nil
 }
 
 // outputRemoveJSON outputs the removal result as JSON

internal/vaultik/snapshot_deleted_count_test.go

@@ -0,0 +1,149 @@
+package vaultik_test
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/ui"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// These tests cover https://git.eeqj.de/sneak/vaultik/issues/304: a
+// backup counts a file as deleted only when the previous snapshot of
+// the same name had it and it is gone, and never counts an excluded
+// file.
+
+// deletedCountEnv is a backup setup over the source directory src whose
+// user-facing output is kept in out. Each test configures its snapshots
+// with setSnapshot.
+type deletedCountEnv struct {
+	v   *vaultik.Vaultik
+	out *bytes.Buffer
+	src string
+}
+
+// newDeletedCountEnv writes files, keyed by path relative to src.
+func newDeletedCountEnv(t *testing.T, files map[string][]byte) *deletedCountEnv {
+	t.Helper()
+
+	ctx := context.Background()
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	srcDir := filepath.Join(tempDir, "src")
+
+	for rel, content := range files {
+		path := filepath.Join(srcDir, rel)
+		require.NoError(t, fs.MkdirAll(filepath.Dir(path), 0o755))
+		require.NoError(t, afero.WriteFile(fs, path, content, 0o644))
+	}
+
+	cfg := faultTestConfig()
+	cfg.IndexPath = filepath.Join(tempDir, "index.sqlite")
+	cfg.Snapshots = map[string]config.SnapshotConfig{}
+
+	store, err := storage.NewFileStorer(filepath.Join(tempDir, "remote"))
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, cfg.IndexPath)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+	out := &bytes.Buffer{}
+	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
+	v.UI = ui.NewWithColor(out, false)
+
+	return &deletedCountEnv{v: v, out: out, src: srcDir}
+}
+
+// setSnapshot configures the snapshot name to back up the path rel
+// beneath src, with the given excludes.
+func (e *deletedCountEnv) setSnapshot(name, rel string, exclude ...string) {
+	e.v.Config.Snapshots[name] = config.SnapshotConfig{
+		Paths:   []string{filepath.Join(e.src, rel)},
+		Exclude: exclude,
+	}
+}
+
+// backUp runs a backup of the named snapshot and returns its output.
+func (e *deletedCountEnv) backUp(t *testing.T, name string) string {
+	t.Helper()
+
+	e.out.Reset()
+	require.NoError(t, e.v.CreateSnapshot(&vaultik.SnapshotCreateOptions{
+		Snapshots: []string{name},
+	}))
+
+	return e.out.String()
+}
+
+// A file this snapshot excludes is not counted as deleted: neither one
+// that another snapshot backs up, nor one that the previous snapshot of
+// this name had before the exclude was added.
+func TestBackupDoesNotCountExcludedFileAsDeleted(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	env := newDeletedCountEnv(t, map[string][]byte{
+		"top.txt":       []byte("top"),
+		"cache/tmp.bin": []byte("cache"),
+		"photos/a.jpg":  []byte("photo a"),
+		"photos/b.jpg":  []byte("photo b"),
+		"photos/c.jpg":  []byte("photo c"),
+	})
+	env.setSnapshot("photos", "photos")
+	env.setSnapshot("home", "", "/photos")
+
+	env.backUp(t, "photos")
+	assert.Contains(t, env.backUp(t, "home"), filesLine(2, 2, 0))
+
+	env.setSnapshot("home", "", "/photos", "/cache")
+	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
+}
+
+// A file removed from disk is counted as deleted by the next backup of
+// the snapshot that had it, and not by any later backup of that
+// snapshot, nor by the first backup of another name over the same path.
+func TestBackupCountsDeletedFileOnce(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	aContent := bytes.Repeat([]byte("a"), 1000)
+	bContent := bytes.Repeat([]byte("b"), 2000)
+	keptContent := bytes.Repeat([]byte("k"), 500)
+
+	env := newDeletedCountEnv(t, map[string][]byte{
+		"a.txt":    aContent,
+		"b.txt":    bContent,
+		"kept.txt": keptContent,
+	})
+	env.setSnapshot("home", "")
+	env.setSnapshot("other", "")
+
+	assert.Contains(t, env.backUp(t, "home"), filesLine(3, 3, 0))
+
+	require.NoError(t, os.Remove(filepath.Join(env.src, "a.txt")))
+	require.NoError(t, os.Remove(filepath.Join(env.src, "b.txt")))
+
+	summary := env.backUp(t, "home")
+	assert.Contains(t, summary,
+		"Files: 1 examined, 0 backed up, 1 unchanged, 2 deleted.")
+	assert.Contains(t, summary,
+		fmt.Sprintf("Data: %s total (%s backed up), %s deleted.",
+			env.v.UI.Size(int64(len(keptContent))), env.v.UI.Size(0),
+			env.v.UI.Size(int64(len(aContent)+len(bContent)))))
+
+	assert.Contains(t, env.backUp(t, "home"), filesLine(1, 0, 1))
+	assert.Contains(t, env.backUp(t, "other"), filesLine(1, 0, 1))
+}

internal/vaultik/snapshot_skip_errors_test.go

@@ -0,0 +1,75 @@
+package vaultik_test
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/storage"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// --skip-errors skips only a file that cannot be opened or read. A local
+// index error while a directory is recorded stops the backup, and the
+// snapshot is not recorded as complete. See
+// https://git.eeqj.de/sneak/vaultik/issues/284.
+func TestSkipErrorsBackupStopsOnIndexErrorRecordingDirectory(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	ctx := context.Background()
+
+	// The scan walks the source path with symlinks resolved, so dirPath
+	// must be spelled the same way to match the row the scan inserts.
+	tempDir, err := filepath.EvalSymlinks(t.TempDir())
+	require.NoError(t, err)
+
+	srcDir := filepath.Join(tempDir, "src")
+	dirPath := filepath.Join(srcDir, "dir")
+
+	fs := afero.NewOsFs()
+	require.NoError(t, fs.MkdirAll(dirPath, 0o755))
+	require.NoError(t, afero.WriteFile(fs,
+		filepath.Join(dirPath, "file.txt"), []byte("file content"), 0o644))
+
+	cfg := faultTestConfig()
+	cfg.IndexPath = filepath.Join(tempDir, "index.sqlite")
+	cfg.Snapshots = map[string]config.SnapshotConfig{
+		"tree": {Paths: []string{srcDir}},
+	}
+
+	store, err := storage.NewFileStorer(filepath.Join(tempDir, "remote"))
+	require.NoError(t, err)
+
+	db, err := database.New(ctx, cfg.IndexPath)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	// The local index refuses the directory's files row.
+	_, err = db.Conn().ExecContext(ctx, fmt.Sprintf(`
+		CREATE TRIGGER refuse_directory BEFORE INSERT ON files
+		WHEN NEW.path = '%s'
+		BEGIN SELECT RAISE(ABORT, 'simulated index error'); END`, dirPath))
+	require.NoError(t, err)
+
+	repos := database.NewRepositories(db)
+	v := newBackupVaultik(ctx, cfg, store, repos, db, fs)
+
+	err = v.CreateSnapshot(&vaultik.SnapshotCreateOptions{
+		SkipErrors: true,
+		Snapshots:  []string{"tree"},
+	})
+	require.ErrorContains(t, err, "simulated index error")
+
+	snapshots, err := repos.Snapshots.ListRecent(ctx, listRecentTestLimit)
+	require.NoError(t, err)
+	require.Len(t, snapshots, 1)
+	assert.Nil(t, snapshots[0].CompletedAt)
+}

internal/vaultik/storage_bind.go

@@ -9,7 +9,7 @@ import (
 )
 
 // errStorageBindingMismatch is returned when the local index database is
-// bound to a different destination than the configured storage_url.
+// bound to a different destination than the configured one.
 var errStorageBindingMismatch = errors.New(
 	"local index is bound to a different backup destination")
 
@@ -24,8 +24,9 @@ var errStorageBindingMismatch = errors.New(
 //
 // Behaviour:
 //   - On first use (empty stored value), record the configured
-//     storage_url and log the binding.
-//   - When the stored value matches the configured storage_url, do
+//     destination (storage_url, or the s3.* endpoint, bucket and
+//     prefix) and log the binding.
+//   - When the stored value matches the configured destination, do
 //     nothing and return nil.
 //   - When the two differ, refuse with an error that tells the user
 //     how to recover (revert the config, or run `vaultik database
@@ -46,12 +47,10 @@ func (v *Vaultik) EnsureStorageBinding() error {
 
 	configured := v.Config.StorageURL
 	if configured == "" {
-		// Some legacy configs still use the split s3.* keys instead of
-		// storage_url. Falling back to a synthetic URL for those would
-		// hide the fact that the binding is loose. Instead, treat
-		// unset as "nothing to bind against" — the check is
-		// necessarily best-effort for those configs.
-		return nil
+		// The s3.* form: bind on its endpoint, bucket and prefix,
+		// written the way storage_url would name the same destination.
+		s3 := v.Config.S3
+		configured = "s3://" + s3.Bucket + "/" + s3.Prefix + "?endpoint=" + s3.Endpoint
 	}
 
 	stored, err := v.Repositories.LocalMeta.Get(v.ctx, database.LocalMetaKeyStorageURL)
@@ -96,7 +95,8 @@ func buildBindingMismatchMessage(stored, configured string) string {
 		"future snapshots referencing blobs that don't exist at the new destination.\n" +
 		"\n" +
 		"To proceed, either:\n" +
-		"  - revert storage_url in your config to the bound destination, or\n" +
+		"  - revert storage_url (or the s3.* endpoint, bucket and prefix) in your\n" +
+		"    config to the bound destination, or\n" +
 		"  - run 'vaultik database delete' to discard the local index and rebuild it\n" +
 		"    from a fresh full backup against the new destination"
 }

internal/vaultik/storage_bind_test.go

@@ -76,3 +76,51 @@ func TestEnsureStorageBinding_MismatchRefuses(t *testing.T) {
 	assert.Contains(t, err.Error(), "file:///mnt/backups/new")
 	assert.Contains(t, err.Error(), "vaultik database delete")
 }
+
+// A config with no storage_url names its destination with s3.endpoint,
+// s3.bucket and s3.prefix; a change to any of them must be refused just
+// as a changed storage_url is.
+func TestEnsureStorageBinding_S3FieldsChangeRefuses(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	bound := config.S3Config{
+		Endpoint: "https://s3.example.com",
+		Bucket:   "bucket-a",
+		Prefix:   "backups",
+	}
+
+	tests := []struct {
+		name    string
+		changed config.S3Config
+	}{
+		{"bucket", config.S3Config{
+			Endpoint: bound.Endpoint, Bucket: "bucket-b", Prefix: bound.Prefix,
+		}},
+		{"prefix", config.S3Config{
+			Endpoint: bound.Endpoint, Bucket: bound.Bucket, Prefix: "other",
+		}},
+		{"endpoint", config.S3Config{
+			Endpoint: "https://s3.other.com", Bucket: bound.Bucket, Prefix: bound.Prefix,
+		}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			tv, _ := buildBindTestVaultik(t, "")
+
+			tv.Config.S3 = bound
+			require.NoError(t, tv.EnsureStorageBinding(), "first use binds")
+			require.NoError(t, tv.EnsureStorageBinding(), "same destination passes")
+
+			tv.Config.S3 = tt.changed
+			err := tv.EnsureStorageBinding()
+			require.Error(t, err)
+			assert.Contains(t, err.Error(),
+				"local index is bound to a different backup destination")
+			assert.Contains(t, err.Error(), "vaultik database delete")
+		})
+	}
+}