Store and compare file mtimes to the nanosecond (closes #226)

The files table held mtime in whole seconds and the scanner compared
whole seconds. A file rewritten with its size unchanged and a new mtime
in the same second as the indexed one was treated as unchanged, and
every later snapshot restored the old content. A new mtime_nsec column
now holds the nanoseconds within the second that mtime holds, and the
scanner compares the full mtime.

A local index created before this change lacks the column and is
rebuilt with `vaultik database delete` and a full backup. A snapshot
made before it cannot be restored by this version.

Model: opus-5-5

README.md

@@ -352,8 +352,9 @@ may hold snapshots this host doesn't know about), which is what
 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
-removal still completes and a warning is emitted; rerun `vaultik prune`
-once the store is reachable to finish remote cleanup. To wipe everything
+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
 on the destination in one go, use `vaultik remote nuke --force`.
 * `--local-only`: Skip remote cleanup; only touch the local index
 * `--dry-run`: Show what would be deleted without deleting

TODO.md

@@ -22,6 +22,27 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 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.
+
+- 2026-10-06: 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
+  warning that the snapshot's metadata was left on the destination store
+  went to stdout ahead of the document, breaking `| jq` on a command that
+  exited 0. Under `--json` the warning now reaches stderr only, through
+  the logger. The warning, the README and the command's help said
+  `vaultik prune` would finish the cleanup, but `prune` never removes
+  snapshot metadata; they now say to run `vaultik snapshot remove` for the
+  snapshot again once the destination store is reachable.
+
 - 2026-10-06: Made the backup summary and the `snapshots` row count each
   file, byte and upload once
   ([issue #225](https://git.eeqj.de/sneak/vaultik/issues/225)). The

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

internal/cli/entry_stdout_stderr_test.go

@@ -2,7 +2,9 @@ package cli //nolint:testpackage // shares hermeticConfig and the capture helper
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"log/slog"
 	"os"
 	"path/filepath"
 	"strings"
@@ -87,12 +89,45 @@ func TestEntryJSONFailureIsReportedOnStderr(t *testing.T) {
 	}
 }
 
-// writeUnusableDestinationConfig builds a config whose destination
-// directory does not exist, which fails `remote info`, and whose local
-// index is bound to another destination, which fails `prune` and
-// `snapshot remove` (a missing destination alone only makes `snapshot
-// remove` warn). Returns the config path.
-func writeUnusableDestinationConfig(t *testing.T) string {
+// TestEntrySnapshotRemoveJSONWarningIsOnStderr runs `snapshot remove
+// --json` on a snapshot in the local index, against a destination
+// directory that does not exist. The command removes the snapshot from
+// the local index and still exits 0. Its stdout must hold the document
+// alone, with the warning about the destination store on stderr: the
+// command to run again once it is reachable, and the snapshot's ID in
+// the record's snapshot_id field.
+//
+//nolint:paralleltest // replaces os.Args, os.Stdout, os.Stderr and the xdg globals
+func TestEntrySnapshotRemoveJSONWarningIsOnStderr(t *testing.T) {
+	configPath, indexPath := writeMissingDestinationConfig(t)
+	seedStaleSnapshotRecord(t, indexPath)
+
+	code, stdout, stderr := runEntry(t, flagConfig, configPath,
+		cmdSnapshot, cmdRemove, stalePruneSnapshotID, flagJSON)
+
+	require.Equal(t, 0, code)
+	requireExactlyOneJSONDocument(t, stdout)
+
+	// stderr is a pipe here, so the logger writes one JSON record a line.
+	var warning map[string]any
+
+	for line := range strings.Lines(stderr) {
+		if strings.Contains(line,
+			"Could not remove snapshot metadata from remote storage") {
+			require.NoError(t, json.Unmarshal([]byte(line), &warning))
+		}
+	}
+
+	require.NotNil(t, warning, "the warning must reach stderr")
+	assert.Contains(t, warning[slog.MessageKey],
+		"run 'vaultik snapshot remove' with the snapshot's ID again")
+	assert.Equal(t, stalePruneSnapshotID, warning["snapshot_id"])
+}
+
+// writeMissingDestinationConfig builds a config whose destination
+// directory does not exist. Returns the config path and the path of
+// its local index, which is not created here.
+func writeMissingDestinationConfig(t *testing.T) (string, string) {
 	t.Helper()
 
 	dir := t.TempDir()
@@ -114,6 +149,19 @@ func writeUnusableDestinationConfig(t *testing.T) string {
 	xdg.Reload()
 	t.Cleanup(xdg.Reload)
 
+	return configPath, indexPath
+}
+
+// writeUnusableDestinationConfig builds a config whose destination
+// directory does not exist, which fails `remote info`, and whose local
+// index is bound to another destination, which fails `prune` and
+// `snapshot remove` (a missing destination alone only makes `snapshot
+// remove` warn). Returns the config path.
+func writeUnusableDestinationConfig(t *testing.T) string {
+	t.Helper()
+
+	configPath, indexPath := writeMissingDestinationConfig(t)
+
 	ctx := context.Background()
 
 	db, err := database.New(ctx, indexPath)
@@ -122,7 +170,7 @@ func writeUnusableDestinationConfig(t *testing.T) string {
 	defer func() { require.NoError(t, db.Close()) }()
 
 	require.NoError(t, database.NewRepositories(db).LocalMeta.Set(ctx,
-		database.LocalMetaKeyStorageURL, "file://"+filepath.Join(dir, "other")))
+		database.LocalMetaKeyStorageURL, "file://"+t.TempDir()))
 
 	return configPath
 }

internal/cli/snapshot.go

@@ -258,8 +258,9 @@ Use --local-only to skip the remote half (e.g. when you want to forget a
 snapshot locally without touching the destination store).
 
 If the remote is unreachable, the local-database removal still completes
-and a warning is emitted; rerun 'vaultik prune' once the destination store
-is reachable to finish remote cleanup.
+and a warning is emitted; run 'vaultik snapshot remove <snapshot-id>' again
+once the destination store is reachable to remove the snapshot's metadata
+from it ('vaultik prune' does not).
 
 To wipe the entire destination store and start over, use 'vaultik remote
 nuke --force' — it is the single supported entry point for that.`,

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 +252,58 @@ 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)
+			}
+		}
+	}
+}
+
 func TestFileRepositoryTransaction(t *testing.T) {
 	t.Parallel()
 

internal/database/repository_edge_cases_test.go

@@ -606,8 +606,7 @@ 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

@@ -6,7 +6,8 @@ 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,
+    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/snapshot/scanner.go

@@ -1221,7 +1221,7 @@ 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/vaultik/same_second_rewrite_test.go

@@ -0,0 +1,73 @@
+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.
+//
+//nolint:paralleltest // installs the global logger via log.Initialize
+func TestBackupOfSameSecondRewriteRestoresNewContent(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	fs := afero.NewOsFs()
+	tempDir := t.TempDir()
+	dataDir := filepath.Join(tempDir, "src")
+	storeDir := filepath.Join(tempDir, "remote")
+	restoreDir := filepath.Join(tempDir, "restored")
+	dbPath := filepath.Join(tempDir, "index.sqlite")
+	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

@@ -1110,6 +1110,12 @@ type RemoveResult struct {
 // just-removed snapshot left behind on the destination store.
 const pruneCommandHint = "vaultik prune"
 
+// snapshotRemoveCommandHint is the command suggested, with the
+// snapshot's ID, when a remove could not reach the destination store:
+// running it again removes the snapshot's metadata there, which
+// `vaultik prune` never does.
+const snapshotRemoveCommandHint = "vaultik snapshot remove"
+
 // RemoveSnapshot removes a snapshot from the local index database and,
 // unless LocalOnly is set, also strips the snapshot's metadata from the
 // destination store. Blobs are NOT touched: removing a snapshot's
@@ -1146,7 +1152,7 @@ func (v *Vaultik) RemoveSnapshot(
 	}
 
 	if !opts.LocalOnly {
-		result.RemoteRemoved = v.removeSnapshotRemote(snapshotID)
+		result.RemoteRemoved = v.removeSnapshotRemote(snapshotID, opts)
 	}
 
 	if v.SnapshotManager != nil {
@@ -1229,9 +1235,11 @@ func (v *Vaultik) confirmRemoveSnapshot(snapshotID string, opts *RemoveOptions)
 // removeSnapshotRemote strips the snapshot's metadata from the
 // destination store, warning and proceeding on failure: the local-DB
 // removal has already happened, so the user is told the remote half
-// didn't finish and can retry with `vaultik prune` once the destination
-// store is reachable. Returns true when the remote removal succeeded.
-func (v *Vaultik) removeSnapshotRemote(snapshotID string) bool {
+// 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.
+func (v *Vaultik) removeSnapshotRemote(snapshotID string, opts *RemoveOptions) bool {
 	log.Info("Removing snapshot metadata from remote storage",
 		"snapshot_id", snapshotID)
 
@@ -1239,13 +1247,17 @@ func (v *Vaultik) removeSnapshotRemote(snapshotID string) bool {
 
 	err := v.deleteRemoteSnapshotByKey(remoteKey)
 	if err != nil {
-		log.Warn("Could not remove snapshot metadata from remote storage",
-			"error", err)
+		log.Warn("Could not remove snapshot metadata from remote storage; "+
+			"run '"+snapshotRemoveCommandHint+"' with the snapshot's ID "+
+			"again once the remote is reachable",
+			"snapshot_id", snapshotID, "error", err)
 
-		if v.UI != nil {
+		// The UI writes to stdout, which under --json holds only the
+		// document; the log record above is the warning on stderr.
+		if v.UI != nil && !opts.JSON {
 			v.UI.Warningf("Could not remove snapshot metadata from remote: "+
-				"%v. Run '%s' once the remote is reachable to finish cleanup.",
-				err, pruneCommandHint)
+				"%v. Run '%s %s' again once the remote is reachable.",
+				err, snapshotRemoveCommandHint, snapshotID)
 		}
 
 		return false