From a51db37fdb5a8a0225498dfea0a868cc645bba85 Mon Sep 17 00:00:00 2001
From: Ein Anderssono <einand@3gdev.com>
Date: Mon, 15 Jun 2026 01:48:32 +0200
Subject: [PATCH] v0.8.2: add metadata-only sidecars

---
 CHANGELOG.md               |  10 ++++
 Makefile                   |   2 +-
 README.md                  |   8 +++
 RELEASE_NOTES.md           |  17 +++---
 USERGUIDE.md               |   8 +++
 cmd/photoscli/main.go      | 117 ++++++++++++++++++++++++++++++++++--
 cmd/photoscli/main_test.go | 120 +++++++++++++++++++++++++++++++++++++
 7 files changed, 266 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 46c05db..23675fe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,16 @@
 
 This changelog is maintained from git history plus the published Gitea release series. Future releases should update this file and publish matching release notes on the release page.
 
+## v0.8.2
+
+Metadata-only XMP refresh release.
+
+- Add `--metadata-only` for manifest-based XMP sidecar generation without re-exporting media files.
+- Support metadata-only refresh for both `export` and `backup-all` when used with `--sidecar xmp`.
+- Require a manifest for metadata-only mode so existing media paths are resolved safely.
+- Keep media files untouched while overwriting/regenerating generated XMP sidecars.
+- Support `--reverse-geocode` during metadata-only sidecar refresh.
+
 ## v0.8.1
 
 XMP standards and sidecar verification release.
diff --git a/Makefile b/Makefile
index bfba1ed..e9bc806 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 BINARY     := ./bin/photoscli
 MODULE     := gitea.k3s.k0.nu/tools/photocli
-VERSION    := 0.8.1
+VERSION    := 0.8.2
 RELEASE_ZIP := ./bin/photoscli-$(VERSION)-macos-arm64.zip
 RELEASE_NOTES := RELEASE_NOTES.md
 BRIDGE_DIR := bridge
diff --git a/README.md b/README.md
index d2b4f18..39fcf3d 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,7 @@ For a practical step-by-step manual with recommended backup workflows, recovery
 - Deduplicated failure management with `failures list`, `failures clear`, and `retry-failed --clear-on-success`.
 - Verification, reporting, and diff commands for backup integrity.
 - Optional XMP sidecar verification with `verify --sidecar`.
+- Metadata-only XMP refresh for manifest-backed exports with `--metadata-only`.
 - Status command for quick backup summaries.
 - Opt-in rich XMP sidecar metadata with `--sidecar xmp`.
 - Optional Apple MapKit reverse geocoding for GPS assets on macOS 26+ with `--reverse-geocode`.
@@ -283,6 +284,7 @@ Common flags for `export` and `backup-all`:
 - `--max-size <n>`: filter by estimated pixel count.
 - `--format jpeg|heic|png`: preview format hint. Current bridge output is still the existing preview path; non-JPEG bridge output is future work.
 - `--sidecar none|xmp`: write opt-in XMP metadata sidecars next to exported files.
+- `--metadata-only`: with `--sidecar xmp`, refresh XMP sidecars for manifest-backed files without exporting media.
 - `--reverse-geocode`: with `--sidecar xmp`, add cached Apple MapKit address metadata for GPS assets on macOS 26+.
 - `--date-template <template>`: append date folders based on creation date, for example `YYYY/MM/DD`.
 
@@ -361,6 +363,12 @@ Verify generated sidecars with:
 photoscli verify --out ./backup --sidecar
 ```
 
+Refresh sidecars for files already present in a manifest-backed export without rewriting media files:
+
+```bash
+photoscli backup-all --out ./backup --sidecar xmp --metadata-only
+```
+
 ## Failure Tracking
 
 Failed exports are deduplicated by asset ID and stored in:
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 1d14fb5..8caa030 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,20 +1,19 @@
-# v0.8.1
+# v0.8.2
 
-This release improves XMP sidecar standards compatibility and adds sidecar verification.
+This release adds metadata-only XMP sidecar refresh for existing manifest-backed exports.
 
 ## Highlights
 
-- Add `photoscli:xmpSchemaVersion="2"` to generated XMP sidecars.
-- Add standard XMP mappings for favorite rating, metadata date, Photoshop date created, and EXIF GPS coordinates.
-- Add `dc:subject` keywords from album/folder context.
-- Add sidecar generator and generated timestamp metadata.
-- Add `verify --sidecar` for missing, zero-byte, unreadable, and asset-ID mismatched XMP sidecars.
-- Keep Vision/Core ML people, animal, object, and scene analysis out of this release.
+- Add `--metadata-only` for `export` and `backup-all`.
+- Use manifest paths to find existing media files and write or refresh `.xmp` sidecars without re-exporting media.
+- Require `--sidecar xmp` and an enabled manifest for metadata-only mode.
+- Leave media files untouched; only generated XMP sidecars are written.
+- Support `--reverse-geocode` during metadata-only refresh.
 
 ## Assets
 
 - `photoscli`: Apple Silicon macOS binary (`darwin/arm64`).
-- `photoscli-0.8.1-macos-arm64.zip`: Apple Silicon binary plus README, USERGUIDE, and CHANGELOG.
+- `photoscli-0.8.2-macos-arm64.zip`: Apple Silicon binary plus README, USERGUIDE, and CHANGELOG.
 - `USERGUIDE.md`: standalone user guide.
 
 Intel Macs are not currently a supported release target.
diff --git a/USERGUIDE.md b/USERGUIDE.md
index 8d18cb0..f3af7c0 100644
--- a/USERGUIDE.md
+++ b/USERGUIDE.md
@@ -573,6 +573,14 @@ Verify sidecars after an export:
 
 This reports missing, zero-byte, unreadable, or asset-ID mismatched `.xmp` files.
 
+Refresh metadata only for an existing manifest-backed backup:
+
+```bash
+./bin/photoscli backup-all --out ./PhotosBackup --sidecar xmp --metadata-only
+```
+
+Metadata-only mode does not re-export media files. It uses manifest paths to find existing files and rewrites generated `.xmp` sidecars next to them. It requires `--sidecar xmp` and an enabled manifest.
+
 If you explicitly request `--sidecar xmp` and the XMP file cannot be written, the asset is counted as failed.
 
 ## Configuration File
diff --git a/cmd/photoscli/main.go b/cmd/photoscli/main.go
index e649cb8..5d45a57 100644
--- a/cmd/photoscli/main.go
+++ b/cmd/photoscli/main.go
@@ -41,6 +41,7 @@ type exportOptions struct {
 	verify         bool
 	format         string
 	sidecar        string
+	metadataOnly   bool
 	reverseGeocode bool
 	minSize        int64
 	maxSize        int64
@@ -220,6 +221,10 @@ COMMON EXPORT FLAGS
       Write opt-in XMP sidecar metadata next to each exported file. Default:
       none. If XMP writing fails, the asset is counted as failed.
 
+  --metadata-only
+      With --sidecar xmp, write or refresh XMP sidecars for files already in
+      the manifest without exporting media files. Requires a manifest.
+
   --reverse-geocode
       With --sidecar xmp, use Apple MapKit on macOS 26+ to add address metadata
       for assets with GPS coordinates. Results are cached under .photoscli.
@@ -444,6 +449,10 @@ func cmdExport(args []string, stdout, stderr io.Writer, bridge photos.Bridge) in
 		fmt.Fprintln(stderr, "error: --out is required")
 		return exitErr
 	}
+	if opts.metadataOnly && noManifest {
+		fmt.Fprintln(stderr, "error: --metadata-only requires a manifest")
+		return exitErr
+	}
 
 	mf, mfErr := manifest.ParseFormat(manifestFmt)
 	if mfErr != nil {
@@ -546,8 +555,17 @@ func cmdExport(args []string, stdout, stderr io.Writer, bridge photos.Bridge) in
 		fmt.Fprintf(stderr, "dry-run: %d assets would be exported to %s\n", total, outDir)
 		return exitOK
 	}
-	fmt.Fprintf(stderr, "exporting %d assets (%s) to %s...\n", total, exportMode(originals), outDir)
-	exported, failed := exportAssets(assets, outDir, size, quality, concurrency, originals, total, stderr, bridge, "", noManifest, mf, enableLog, opts)
+	var exported, failed int
+	if opts.metadataOnly {
+		m, _ := manifest.Open(outDir, mf)
+		defer m.Close()
+		entries := manifestEntries(m)
+		fmt.Fprintf(stderr, "writing metadata for %d assets to %s...\n", total, outDir)
+		exported, failed = metadataOnlyAssets(assets, outDir, originals, "", entries, opts, bridge)
+	} else {
+		fmt.Fprintf(stderr, "exporting %d assets (%s) to %s...\n", total, exportMode(originals), outDir)
+		exported, failed = exportAssets(assets, outDir, size, quality, concurrency, originals, total, stderr, bridge, "", noManifest, mf, enableLog, opts)
+	}
 	if opts.jsonOut {
 		writeJSONSummary(stdout, commandSummary{Exported: exported, Failed: failed, Total: total})
 	}
@@ -562,7 +580,9 @@ func cmdExport(args []string, stdout, stderr io.Writer, bridge photos.Bridge) in
 		return exitErr
 	}
 
-	if originals {
+	if opts.metadataOnly {
+		fmt.Fprintf(stderr, "\nwrote %d metadata sidecars to %s", exported, outDir)
+	} else if originals {
 		fmt.Fprintf(stderr, "\nexported %d original files to %s", exported, outDir)
 	} else {
 		fmt.Fprintf(stderr, "\nexported %d photos to %s", exported, outDir)
@@ -602,6 +622,10 @@ func cmdBackupAll(args []string, stdout, stderr io.Writer, bridge photos.Bridge)
 		fmt.Fprintln(stderr, "error: --out is required")
 		return exitErr
 	}
+	if opts.metadataOnly && noManifest {
+		fmt.Fprintln(stderr, "error: --metadata-only requires a manifest")
+		return exitErr
+	}
 
 	mf, mfErr := manifest.ParseFormat(manifestFmt)
 	if mfErr != nil {
@@ -675,13 +699,25 @@ func cmdBackupAll(args []string, stdout, stderr io.Writer, bridge photos.Bridge)
 		fmt.Fprintf(stderr, "dry-run: %d assets would be exported (%d skipped)\n", len(pending), skipped)
 		return exitOK
 	}
-	totalAssets, failed, err := backupTree(nodes, outDir, size, quality, concurrency, originals, skipVideos, stderr, bridge, noManifest, mf, sortNewest, excludeAlbums, sinceTime, enableLog, opts)
+	var totalAssets, failed int
+	if opts.metadataOnly {
+		m, _ := manifest.Open(outDir, mf)
+		entries := manifestEntries(m)
+		m.Close()
+		pending, skipped := collectPendingAssets(nodes, outDir, bridge, skipVideos, originals, nil, nil, sortNewest, excludeAlbums, sinceTime, opts)
+		fmt.Fprintf(stderr, "  indexed %d metadata entries (%d skipped), writing sidecars to %s...\n", len(pending), skipped, outDir)
+		totalAssets, failed = metadataOnlyPending(pending, entries, originals, opts, bridge)
+	} else {
+		totalAssets, failed, err = backupTree(nodes, outDir, size, quality, concurrency, originals, skipVideos, stderr, bridge, noManifest, mf, sortNewest, excludeAlbums, sinceTime, enableLog, opts)
+	}
 	if err != nil {
 		fmt.Fprintf(stderr, "error: %v\n", err)
 		return exitErr
 	}
 
-	if originals {
+	if opts.metadataOnly {
+		fmt.Fprintf(stderr, "\nwrote %d metadata sidecars across %d albums to %s", totalAssets, albumCount, outDir)
+	} else if originals {
 		fmt.Fprintf(stderr, "\nexported %d original files across %d albums to %s", totalAssets, albumCount, outDir)
 	} else {
 		fmt.Fprintf(stderr, "\nexported %d preview files across %d albums to %s", totalAssets, albumCount, outDir)
@@ -1086,6 +1122,46 @@ func writeSidecarIfNeeded(pa pendingAsset, result photos.ExportResult, originals
 	})
 }
 
+func writeMetadataOnlySidecar(pa pendingAsset, entry manifest.Entry, originals bool, opts exportOptions, cache *geocodeCache, bridge photos.Bridge) error {
+	checkPath := entry.Path
+	if checkPath == "" {
+		checkPath = entry.Filename
+	}
+	if checkPath == "" {
+		return fmt.Errorf("manifest entry has no path")
+	}
+	root := pa.root
+	if root == "" {
+		root = pa.path
+	}
+	fullPath := filepath.Join(root, checkPath)
+	info, err := statFunc(fullPath)
+	if err != nil {
+		return fmt.Errorf("metadata target missing: %s", checkPath)
+	}
+	if info.Size() == 0 {
+		return fmt.Errorf("metadata target zero-byte: %s", checkPath)
+	}
+	pa.path = filepath.Dir(fullPath)
+	result := photos.ExportResult{Filename: filepath.Base(fullPath), Size: info.Size(), Cloud: entry.Cloud}
+	return writeSidecarIfNeeded(pa, result, originals, opts, cache, bridge)
+}
+
+func manifestEntries(m manifest.Manifest) map[string]manifest.Entry {
+	if r, ok := m.(manifest.EntryReader); ok {
+		return r.Entries()
+	}
+	return nil
+}
+
+func metadataOnlyAssets(assets []photos.Asset, outDir string, originals bool, dirPrefix string, entries map[string]manifest.Entry, opts exportOptions, bridge photos.Bridge) (int, int) {
+	pending := make([]pendingAsset, 0, len(assets))
+	for _, a := range assets {
+		pending = append(pending, pendingAsset{asset: a, root: outDir, path: outDir, album: dirPrefix})
+	}
+	return metadataOnlyPending(pending, entries, originals, opts, bridge)
+}
+
 func collectPendingAssets(nodes []photos.CollectionNode, outDir string, bridge photos.Bridge, skipVideos bool, originals bool, onProgress func(collectProgress), m manifest.Manifest, sortNewest bool, exclude []string, since time.Time, opts exportOptions) ([]pendingAsset, int) {
 	var items []pendingAsset
 	var skipped int
@@ -1123,6 +1199,30 @@ func collectPendingAssets(nodes []photos.CollectionNode, outDir string, bridge p
 	return items, skipped
 }
 
+func metadataOnlyPending(pending []pendingAsset, entries map[string]manifest.Entry, originals bool, opts exportOptions, bridge photos.Bridge) (int, int) {
+	var cache *geocodeCache
+	if opts.reverseGeocode && len(pending) > 0 {
+		root := pending[0].root
+		if root == "" {
+			root = pending[0].path
+		}
+		cache = newGeocodeCache(root)
+	}
+	written, failed := 0, 0
+	for _, pa := range pending {
+		entry, ok := entries[pa.asset.ID]
+		if !ok {
+			continue
+		}
+		if err := writeMetadataOnlySidecar(pa, entry, originals, opts, cache, bridge); err != nil {
+			failed++
+			continue
+		}
+		written++
+	}
+	return written, failed
+}
+
 func collectNodes(nodes []photos.CollectionNode, outDir string, bridge photos.Bridge, skipVideos bool, originals bool, items *[]pendingAsset, skipped *int, onProgress func(collectProgress), m manifest.Manifest, exclude []string, opts exportOptions) {
 	names := make(map[string]int)
 	for _, node := range nodes {
@@ -1160,7 +1260,7 @@ func collectNodes(nodes []photos.CollectionNode, outDir string, bridge photos.Br
 			}
 			assets = applyAssetFilters(assets, opts)
 			for _, a := range assets {
-				if m != nil && m.Has(a.ID) {
+				if m != nil && m.Has(a.ID) && !opts.metadataOnly {
 					*skipped++
 					continue
 				}
@@ -1767,6 +1867,7 @@ func parseExportOptions(args []string, stderr io.Writer) (exportOptions, bool) {
 		verify:         hasFlag(args, "--verify"),
 		format:         flagValWithDefault(args, "--format", "jpeg"),
 		sidecar:        flagValWithDefault(args, "--sidecar", "none"),
+		metadataOnly:   hasFlag(args, "--metadata-only"),
 		reverseGeocode: hasFlag(args, "--reverse-geocode"),
 		dateTemplate:   flagVal(args, "--date-template"),
 	}
@@ -1782,6 +1883,10 @@ func parseExportOptions(args []string, stderr io.Writer) (exportOptions, bool) {
 		fmt.Fprintf(stderr, "error: --sidecar must be none or xmp, got %q\n", opts.sidecar)
 		return opts, false
 	}
+	if opts.metadataOnly && opts.sidecar != "xmp" {
+		fmt.Fprintln(stderr, "error: --metadata-only requires --sidecar xmp")
+		return opts, false
+	}
 	if v := flagVal(args, "--retry"); v != "" {
 		n, err := strconv.Atoi(v)
 		if err != nil || n < 0 {
diff --git a/cmd/photoscli/main_test.go b/cmd/photoscli/main_test.go
index 8e8b0e1..8f094fe 100644
--- a/cmd/photoscli/main_test.go
+++ b/cmd/photoscli/main_test.go
@@ -35,6 +35,15 @@ type mockBridge struct {
 	cancelled        atomic.Bool
 }
 
+type noEntryManifest struct{}
+
+func (noEntryManifest) Has(string) bool                   { return false }
+func (noEntryManifest) Add(string, string, int64, string) {}
+func (noEntryManifest) AddEntry(manifest.Entry)           {}
+func (noEntryManifest) Save() error                       { return nil }
+func (noEntryManifest) Close()                            {}
+func (noEntryManifest) OpenAppend() error                 { return nil }
+
 func (m *mockBridge) RequestAccess() error                { return m.accessErr }
 func (m *mockBridge) ListAlbums() ([]photos.Album, error) { return m.albums, m.albumsErr }
 func (m *mockBridge) ListAssets(albumID string) ([]photos.Asset, int, error) {
@@ -4505,6 +4514,117 @@ func TestSidecarConfigAndErrors(t *testing.T) {
 	}
 }
 
+func TestMetadataOnlyExport(t *testing.T) {
+	dir := t.TempDir()
+	m := manifest.LoadJSONL(dir)
+	if err := m.OpenAppend(); err != nil {
+		t.Fatal(err)
+	}
+	m.AddEntry(manifest.Entry{ID: "x1", Filename: "photo.jpg", Path: "photo.jpg", Size: 4, Cloud: "local", Exported: time.Now().Unix()})
+	m.Close()
+	if err := os.WriteFile(filepath.Join(dir, "photo.jpg"), []byte("data"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	b := &mockBridge{assets: []photos.Asset{{ID: "x1", Filename: "orig.heic", MediaType: "image", IsFavorite: true}}}
+	b.exportPreviewFn = func(string, string, int, int, int) (photos.ExportResult, error) {
+		t.Fatal("metadata-only must not export media")
+		return photos.ExportResult{}, nil
+	}
+	out, stderr, rc := runWith([]string{"export", "--album-id", "x", "--out", dir, "--sidecar", "xmp", "--metadata-only"}, b)
+	if rc != exitOK || out != "" || !strings.Contains(stderr, "wrote 1 metadata sidecars") {
+		t.Fatalf("metadata-only rc=%d out=%q stderr=%q", rc, out, stderr)
+	}
+	data, err := os.ReadFile(filepath.Join(dir, "photo.xmp"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(data), "photoscli:assetID=\"x1\"") || !strings.Contains(string(data), "xmp:Rating=\"5\"") {
+		t.Fatalf("unexpected metadata sidecar: %s", string(data))
+	}
+}
+
+func TestMetadataOnlyExportErrors(t *testing.T) {
+	dir := t.TempDir()
+	b := &mockBridge{assets: []photos.Asset{{ID: "x1", Filename: "photo.jpg"}}}
+	_, stderr, rc := runWith([]string{"export", "--album-id", "x", "--out", dir, "--metadata-only"}, b)
+	if rc != exitErr || !strings.Contains(stderr, "--metadata-only requires --sidecar xmp") {
+		t.Fatalf("expected sidecar requirement rc=%d stderr=%q", rc, stderr)
+	}
+	_, stderr, rc = runWith([]string{"export", "--album-id", "x", "--out", dir, "--sidecar", "xmp", "--metadata-only", "--no-manifest"}, b)
+	if rc != exitErr || !strings.Contains(stderr, "requires a manifest") {
+		t.Fatalf("expected manifest requirement rc=%d stderr=%q", rc, stderr)
+	}
+	_, stderr, rc = runWith([]string{"backup-all", "--out", dir, "--sidecar", "xmp", "--metadata-only", "--no-manifest"}, &mockBridge{})
+	if rc != exitErr || !strings.Contains(stderr, "requires a manifest") {
+		t.Fatalf("expected backup manifest requirement rc=%d stderr=%q", rc, stderr)
+	}
+}
+
+func TestMetadataOnlyHelperBranches(t *testing.T) {
+	dir := t.TempDir()
+	pa := pendingAsset{asset: photos.Asset{ID: "x1", Filename: "photo.jpg"}, path: dir}
+	if err := writeMetadataOnlySidecar(pa, manifest.Entry{ID: "x1"}, false, exportOptions{sidecar: "xmp"}, nil, &mockBridge{}); err == nil || !strings.Contains(err.Error(), "no path") {
+		t.Fatalf("expected no path error, got %v", err)
+	}
+	if err := writeMetadataOnlySidecar(pa, manifest.Entry{ID: "x1", Path: "missing.jpg"}, false, exportOptions{sidecar: "xmp"}, nil, &mockBridge{}); err == nil || !strings.Contains(err.Error(), "missing") {
+		t.Fatalf("expected missing error, got %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "zero.jpg"), nil, 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := writeMetadataOnlySidecar(pa, manifest.Entry{ID: "x1", Path: "zero.jpg"}, false, exportOptions{sidecar: "xmp"}, nil, &mockBridge{}); err == nil || !strings.Contains(err.Error(), "zero-byte") {
+		t.Fatalf("expected zero-byte error, got %v", err)
+	}
+	if entries := manifestEntries(noEntryManifest{}); entries != nil {
+		t.Fatalf("expected nil entries, got %#v", entries)
+	}
+	written, failed := metadataOnlyPending([]pendingAsset{{asset: photos.Asset{ID: "x1"}, path: dir}}, map[string]manifest.Entry{"x1": {ID: "x1", Path: "missing.jpg"}}, false, exportOptions{sidecar: "xmp"}, &mockBridge{})
+	if written != 0 || failed != 1 {
+		t.Fatalf("expected failed metadata pending, written=%d failed=%d", written, failed)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "photo.jpg"), []byte("data"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	written, failed = metadataOnlyPending([]pendingAsset{{asset: photos.Asset{ID: "x2", Location: &photos.AssetLocation{Latitude: 1, Longitude: 2}}, path: dir}}, map[string]manifest.Entry{"x2": {ID: "x2", Path: "photo.jpg"}}, false, exportOptions{sidecar: "xmp", reverseGeocode: true}, &mockBridge{reverseGeocodeFn: func(float64, float64) (photos.Placemark, error) {
+		return photos.Placemark{Country: "Sweden"}, nil
+	}})
+	if written != 1 || failed != 0 {
+		t.Fatalf("expected reverse geocode metadata success, written=%d failed=%d", written, failed)
+	}
+}
+
+func TestMetadataOnlyBackupAll(t *testing.T) {
+	dir := t.TempDir()
+	m := manifest.LoadJSONL(dir)
+	if err := m.OpenAppend(); err != nil {
+		t.Fatal(err)
+	}
+	m.AddEntry(manifest.Entry{ID: "x1", Filename: "photo.jpg", Path: "Album/photo.jpg", Size: 4, Cloud: "local", Exported: time.Now().Unix()})
+	m.Close()
+	albumDir := filepath.Join(dir, "Album")
+	if err := os.Mkdir(albumDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(albumDir, "photo.jpg"), []byte("data"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	b := &mockBridge{
+		tree:          []photos.CollectionNode{{ID: "a1", Name: "Album", Kind: "album"}},
+		assetsByAlbum: map[string][]photos.Asset{"a1": {{ID: "x1", Filename: "orig.heic", MediaType: "image"}, {ID: "x2", Filename: "missing.heic", MediaType: "image"}}},
+	}
+	b.exportPreviewFn = func(string, string, int, int, int) (photos.ExportResult, error) {
+		t.Fatal("metadata-only backup-all must not export media")
+		return photos.ExportResult{}, nil
+	}
+	_, stderr, rc := runWith([]string{"backup-all", "--out", dir, "--sidecar", "xmp", "--metadata-only"}, b)
+	if rc != exitOK || !strings.Contains(stderr, "wrote 1 metadata sidecars") {
+		t.Fatalf("metadata-only backup rc=%d stderr=%q", rc, stderr)
+	}
+	if _, err := os.Stat(filepath.Join(albumDir, "photo.xmp")); err != nil {
+		t.Fatalf("expected metadata-only sidecar: %v", err)
+	}
+}
+
 func TestSidecarAdditionalBranches(t *testing.T) {
 	dir := t.TempDir()
 	oldCreateTemp := createTempFunc