merged from gramsrv upstream

internal/app/files/blobcache_test.go

@@ -69,7 +69,7 @@ func TestGetFileCachesMetadataAndSmallBlobBytes(t *testing.T) {
 		t.Fatalf("put: %v", err)
 	}
 	media := newFakeMediaStore()
-	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:42", ObjectKey: objectKey, Size: 10, MimeType: "application/octet-stream"}); err != nil {
+	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:42", Backend: domain.MediaBackendLocalFS, ObjectKey: objectKey, Size: 10, MimeType: "application/octet-stream"}); err != nil {
 		t.Fatalf("put blob: %v", err)
 	}
 	counting := &countingMediaStore{fakeMediaStore: media}
@@ -121,7 +121,7 @@ func TestGetFileLogsCacheHitMiss(t *testing.T) {
 		t.Fatalf("put: %v", err)
 	}
 	media := newFakeMediaStore()
-	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:log", ObjectKey: objectKey, Size: 10, MimeType: "application/octet-stream"}); err != nil {
+	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:log", Backend: domain.MediaBackendLocalFS, ObjectKey: objectKey, Size: 10, MimeType: "application/octet-stream"}); err != nil {
 		t.Fatalf("put blob: %v", err)
 	}
 	blobs := &countingBlobBackend{BlobBackend: local}
@@ -176,6 +176,7 @@ func TestGetFileDoesNotByteCacheLargeBlob(t *testing.T) {
 	media := newFakeMediaStore()
 	if err := media.PutFileBlob(ctx, domain.FileBlob{
 		LocationKey: "doc:large",
+		Backend:     domain.MediaBackendLocalFS,
 		ObjectKey:   objectKey,
 		Size:        int64(len(content)),
 		MimeType:    "application/octet-stream",
@@ -199,6 +200,33 @@ func TestGetFileDoesNotByteCacheLargeBlob(t *testing.T) {
 	}
 }
 
+func TestGetFileRejectsStoredBackendMismatch(t *testing.T) {
+	ctx := context.Background()
+	local, err := NewLocalFS(t.TempDir())
+	if err != nil {
+		t.Fatalf("local fs: %v", err)
+	}
+	objectKey, err := local.Put(ctx, []byte("must-not-fallback"))
+	if err != nil {
+		t.Fatalf("put: %v", err)
+	}
+	media := newFakeMediaStore()
+	if err := media.PutFileBlob(ctx, domain.FileBlob{
+		LocationKey: "doc:mismatch",
+		Backend:     domain.MediaBackendS3,
+		ObjectKey:   objectKey,
+		Size:        int64(len("must-not-fallback")),
+	}); err != nil {
+		t.Fatalf("put blob: %v", err)
+	}
+	svc := NewService(media, local, 2)
+	if _, found, err := svc.GetFile(ctx, domain.FileDownloadRequest{
+		LocationKey: "doc:mismatch", Limit: 128 << 10,
+	}); err == nil || found {
+		t.Fatalf("mismatched backend found=%v err=%v", found, err)
+	}
+}
+
 func TestWarmCachesPreloadsStickerSetAndSmallBlobs(t *testing.T) {
 	ctx := context.Background()
 	local, err := NewLocalFS(t.TempDir())
@@ -227,10 +255,10 @@ func TestWarmCachesPreloadsStickerSetAndSmallBlobs(t *testing.T) {
 	if err := media.PutDocument(ctx, doc); err != nil {
 		t.Fatalf("put doc: %v", err)
 	}
-	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:100", ObjectKey: mainKey, Size: 7, MimeType: doc.MimeType}); err != nil {
+	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:100", Backend: domain.MediaBackendLocalFS, ObjectKey: mainKey, Size: 7, MimeType: doc.MimeType}); err != nil {
 		t.Fatalf("put main blob: %v", err)
 	}
-	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:100:m", ObjectKey: thumbKey, Size: 5, MimeType: "image/jpeg"}); err != nil {
+	if err := media.PutFileBlob(ctx, domain.FileBlob{LocationKey: "doc:100:m", Backend: domain.MediaBackendLocalFS, ObjectKey: thumbKey, Size: 5, MimeType: "image/jpeg"}); err != nil {
 		t.Fatalf("put thumb blob: %v", err)
 	}
 	set := domain.StickerSet{

internal/app/files/photos_test.go

@@ -549,7 +549,7 @@ func TestCreateAvatarVideoMarkupFallsBackToVideoFirstFrame(t *testing.T) {
 	assertAvatarImageSize(t, svc, photo.ID, "a", 160, 160, "image/jpeg")
 }
 
-func TestCreateAvatarVideoMarkupRejectsSyntheticPreviewAndFallsBackToVideo(t *testing.T) {
+func TestCreateAvatarVideoMarkupRejectsDegeneratePreviewAndFallsBackToVideo(t *testing.T) {
 	ctx := context.Background()
 	media := newFakeMediaStore()
 	blobs, err := NewLocalFS(t.TempDir())
@@ -562,7 +562,7 @@ func TestCreateAvatarVideoMarkupRejectsSyntheticPreviewAndFallsBackToVideo(t *te
 		MimeType: "application/x-tgsticker",
 		Thumbs: []domain.PhotoSize{{
 			Kind: domain.PhotoSizeKindCached, Type: "m", W: 1, H: 1,
-			Bytes: append([]byte(nil), seedSyntheticTGStickerPreviewThumbPNG...),
+			Bytes: testJPEG(t, 1, 1),
 		}},
 	}); err != nil {
 		t.Fatalf("PutDocument: %v", err)
@@ -581,14 +581,14 @@ func TestCreateAvatarVideoMarkupRejectsSyntheticPreviewAndFallsBackToVideo(t *te
 		t.Fatalf("CreateAvatarVideoMarkupFromUpload: %v", err)
 	}
 	if thumbnailer.calls != 1 {
-		t.Fatalf("thumbnailer calls = %d, want synthetic preview rejected and video fallback used", thumbnailer.calls)
+		t.Fatalf("thumbnailer calls = %d, want degenerate preview rejected and video fallback used", thumbnailer.calls)
 	}
 	chunk, found, err := svc.GetFile(ctx, domain.FileDownloadRequest{LocationKey: fmt.Sprintf("photo:%d:c", photo.ID), Limit: 1 << 20})
 	if err != nil || !found {
 		t.Fatalf("avatar c blob found=%v err=%v", found, err)
 	}
 	if !bytes.Equal(chunk.Bytes, frame) {
-		t.Fatal("avatar still did not use extracted video frame after rejecting synthetic preview")
+		t.Fatal("avatar still did not use extracted video frame after rejecting degenerate preview")
 	}
 }
 

internal/app/files/seed.go

@@ -1,14 +1,10 @@
 package files
 
 import (
-	"bytes"
 	"context"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
-	"image"
-	"image/color"
-	"image/png"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -485,6 +481,9 @@ func (s *Service) importDocument(ctx context.Context, dj seedDocumentJSON, binDi
 		thumbs = append(thumbs, ps)
 	}
 	doc.Thumbs = thumbs
+	if data, ok := seedBundledDocumentPreview(doc.ID); ok {
+		doc.Thumbs = appendSeedBundledDocumentPreview(doc.Thumbs, data)
+	}
 	if existingFound {
 		doc.Thumbs = mergeSeedDocumentThumbs(existing.Thumbs, doc.Thumbs)
 	}
@@ -492,10 +491,6 @@ func (s *Service) importDocument(ctx context.Context, dj seedDocumentJSON, binDi
 		return domain.Document{}, err
 	}
 
-	if err := s.ensureTGStickerPreviewThumb(ctx, &doc, stats); err != nil {
-		return domain.Document{}, err
-	}
-
 	if err := s.media.PutDocument(ctx, doc); err != nil {
 		return domain.Document{}, err
 	}
@@ -503,6 +498,27 @@ func (s *Service) importDocument(ctx context.Context, dj seedDocumentJSON, binDi
 	return doc, nil
 }
 
+func appendSeedBundledDocumentPreview(thumbs []domain.PhotoSize, data []byte) []domain.PhotoSize {
+	for _, thumb := range thumbs {
+		if thumb.Type == seedBundledDocumentThumbType && seedPhotoSizePreviewTier(thumb) >= 4 {
+			return thumbs
+		}
+	}
+	out := thumbs[:0]
+	for _, thumb := range thumbs {
+		if thumb.Type != seedBundledDocumentThumbType {
+			out = append(out, thumb)
+		}
+	}
+	return append(out, domain.PhotoSize{
+		Kind:  domain.PhotoSizeKindCached,
+		Type:  seedBundledDocumentThumbType,
+		W:     128,
+		H:     128,
+		Bytes: append([]byte(nil), data...),
+	})
+}
+
 func (s *Service) prewarmSmallBlob(objectKey string, data []byte) {
 	if len(data) > 0 && len(data) <= blobBytesCacheMaxEntryBytes {
 		s.byteCache.put(objectKey, data)
@@ -520,10 +536,8 @@ var seedTrailingDigits = regexp.MustCompile(`(\d{6,})`)
 var seedThumbMarker = regexp.MustCompile(`_thumb\d+_`)
 
 const seedInlineCachedDocumentThumbMaxBytes = 32 * 1024
-const seedSyntheticDocumentThumbType = "m"
 
 var seedThumbType = regexp.MustCompile(`PhotoSize_type([a-z])`)
-var seedSyntheticTGStickerPreviewThumbPNG = makeSeedSyntheticTGStickerPreviewThumbPNG()
 
 func scanSeedDir(dir string) (seedDirIndex, error) {
 	idx := seedDirIndex{main: map[int64]string{}, thumb: map[int64]map[string]string{}}
@@ -758,23 +772,7 @@ func mergeSeedDocumentThumbs(existing, incoming []domain.PhotoSize) []domain.Pho
 		out = append(out, thumb)
 	}
 
-	hasRealPreview := false
-	for _, thumb := range out {
-		if !seedSyntheticTGStickerPreviewThumb(thumb) && seedPhotoSizePreviewTier(thumb) > 1 {
-			hasRealPreview = true
-			break
-		}
-	}
-	if !hasRealPreview {
-		return out
-	}
-	filtered := out[:0]
-	for _, thumb := range out {
-		if !seedSyntheticTGStickerPreviewThumb(thumb) {
-			filtered = append(filtered, thumb)
-		}
-	}
-	return filtered
+	return out
 }
 
 func seedDocumentThumbByType(thumbs []domain.PhotoSize, typ string) (domain.PhotoSize, bool) {
@@ -800,9 +798,6 @@ func seedPhotoSizeBetter(a, b domain.PhotoSize) bool {
 }
 
 func seedPhotoSizePreviewTier(thumb domain.PhotoSize) int {
-	if seedSyntheticTGStickerPreviewThumb(thumb) {
-		return 0
-	}
 	switch thumb.Kind {
 	case domain.PhotoSizeKindCached:
 		if len(thumb.Bytes) > 0 && thumb.W > 0 && thumb.H > 0 {
@@ -820,13 +815,6 @@ func seedPhotoSizePreviewTier(thumb domain.PhotoSize) int {
 	return 1
 }
 
-func seedSyntheticTGStickerPreviewThumb(thumb domain.PhotoSize) bool {
-	return thumb.Kind == domain.PhotoSizeKindCached &&
-		thumb.Type == seedSyntheticDocumentThumbType &&
-		thumb.W == 1 && thumb.H == 1 &&
-		bytes.Equal(thumb.Bytes, seedSyntheticTGStickerPreviewThumbPNG)
-}
-
 // ensureSeedCachedThumbBlobs keeps the RPC conversion invariant: document cached
 // previews are exposed as downloadable PhotoSize entries, so every advertised type
 // must have a matching blob even when the source JSON carried the bytes inline.
@@ -866,43 +854,6 @@ func (s *Service) ensureSeedCachedThumbBlobs(ctx context.Context, doc domain.Doc
 	return nil
 }
 
-func (s *Service) ensureTGStickerPreviewThumb(ctx context.Context, doc *domain.Document, stats *SeedStats) error {
-	if !seedDocumentNeedsSyntheticTGStickerPreviewThumb(*doc) {
-		return nil
-	}
-	if s.blobs == nil {
-		return fmt.Errorf("blob backend not configured for synthetic sticker preview thumb")
-	}
-	data := seedSyntheticTGStickerPreviewThumbPNG
-	objectKey, err := s.blobs.Put(ctx, data)
-	if err != nil {
-		return err
-	}
-	if err := s.media.PutFileBlob(ctx, domain.FileBlob{
-		LocationKey: fmt.Sprintf("doc:%d:%s", doc.ID, seedSyntheticDocumentThumbType),
-		Backend:     domain.MediaBackend(s.blobs.Name()),
-		ObjectKey:   objectKey,
-		Size:        int64(len(data)),
-		MimeType:    "image/png",
-	}); err != nil {
-		return err
-	}
-	doc.Thumbs = append(doc.Thumbs, domain.PhotoSize{
-		Kind:  domain.PhotoSizeKindCached,
-		Type:  seedSyntheticDocumentThumbType,
-		W:     1,
-		H:     1,
-		Bytes: append([]byte(nil), data...),
-	})
-	s.prewarmSmallBlob(objectKey, data)
-	stats.Blobs++
-	return nil
-}
-
-func seedDocumentNeedsSyntheticTGStickerPreviewThumb(doc domain.Document) bool {
-	return doc.MimeType == "application/x-tgsticker" && len(doc.Thumbs) == 0
-}
-
 func seedDocumentHasAttribute(attrs []domain.DocumentAttribute, kind domain.DocumentAttributeKind) bool {
 	for _, attr := range attrs {
 		if attr.Kind == kind {
@@ -912,14 +863,6 @@ func seedDocumentHasAttribute(attrs []domain.DocumentAttribute, kind domain.Docu
 	return false
 }
 
-func makeSeedSyntheticTGStickerPreviewThumbPNG() []byte {
-	var buf bytes.Buffer
-	img := image.NewNRGBA(image.Rect(0, 0, 1, 1))
-	img.Set(0, 0, color.NRGBA{})
-	_ = png.Encode(&buf, img)
-	return buf.Bytes()
-}
-
 func seedThumbMimeType(data []byte) string {
 	switch {
 	case len(data) >= 12 && data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F' &&
@@ -980,9 +923,6 @@ func (s *Service) documentsNeedSeedRepair(ctx context.Context, ids []int64) (boo
 		return false, err
 	}
 	for _, doc := range docs {
-		if seedDocumentNeedsSyntheticTGStickerPreviewThumb(doc) {
-			return true, nil
-		}
 		for _, thumb := range doc.Thumbs {
 			if thumb.Kind == domain.PhotoSizeKindDefault && thumb.Size > 0 && thumb.Size <= seedInlineCachedDocumentThumbMaxBytes {
 				return true, nil

internal/app/files/seed_state.go

@@ -106,13 +106,12 @@ func seedDocumentJSONLocationKeys(dj seedDocumentJSON, index seedDirIndex) []str
 			keys = append(keys, fmt.Sprintf("doc:%d:%s", dj.ID, ps.Type))
 		}
 	}
+	if _, ok := seedBundledDocumentPreview(dj.ID); ok {
+		keys = append(keys, fmt.Sprintf("doc:%d:%s", dj.ID, seedBundledDocumentThumbType))
+	}
 	return keys
 }
 
-func seedDocumentJSONNeedsSyntheticTGStickerPreviewThumb(dj seedDocumentJSON) bool {
-	return dj.MimeType == "application/x-tgsticker" && len(dj.Thumbs) == 0
-}
-
 func (s *Service) seedDocumentJSONsReady(ctx context.Context, docs []seedDocumentJSON, index seedDirIndex) (bool, error) {
 	expected := make(map[int64]seedDocumentJSON, len(docs))
 	ids := make([]int64, 0, len(docs))
@@ -152,27 +151,11 @@ func (s *Service) seedDocumentJSONsReady(ctx context.Context, docs []seedDocumen
 		if doc.DCID != s.dc || doc.MimeType != dj.MimeType || doc.Size != dj.Size {
 			return false, nil
 		}
-		// A catalog without its own thumbnail may share this document with a richer
-		// catalog. Readiness follows the preview that is actually stored instead of
-		// demanding the synthetic "m" key and repeatedly downgrading that richer
-		// document on every import.
-		if seedDocumentJSONNeedsSyntheticTGStickerPreviewThumb(dj) {
-			if len(doc.Thumbs) == 0 {
+		if _, bundled := seedBundledDocumentPreview(dj.ID); bundled {
+			thumb, ok := seedDocumentThumbByType(doc.Thumbs, seedBundledDocumentThumbType)
+			if !ok || seedPhotoSizePreviewTier(thumb) < 4 {
 				return false, nil
 			}
-			for _, thumb := range doc.Thumbs {
-				switch thumb.Kind {
-				case domain.PhotoSizeKindDefault, domain.PhotoSizeKindProgressive, domain.PhotoSizeKindCached:
-					if thumb.Type == "" {
-						return false, nil
-					}
-					key := fmt.Sprintf("doc:%d:%s", doc.ID, thumb.Type)
-					if _, seen := seenLocationKeys[key]; !seen {
-						seenLocationKeys[key] = struct{}{}
-						locationKeys = append(locationKeys, key)
-					}
-				}
-			}
 		}
 		delete(expected, doc.ID)
 	}

internal/app/files/seed_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"image/png"
 	"os"
 	"path/filepath"
 	"sort"
@@ -463,8 +464,8 @@ func TestSeedMediaRepairsPartialReactionBlobs(t *testing.T) {
 	svc := NewService(media, blobs, 2)
 	if stats, err := svc.SeedMedia(context.Background(), seedDir, 0); err != nil {
 		t.Fatalf("initial seed: %v", err)
-	} else if stats.Reactions != 1 || stats.Blobs != 3 {
-		t.Fatalf("initial stats = %+v, want one reaction and three blobs", stats)
+	} else if stats.Reactions != 1 || stats.Blobs != 2 {
+		t.Fatalf("initial stats = %+v, want one reaction and two document blobs", stats)
 	}
 	chunk, ok, err := svc.GetFile(context.Background(), domain.FileDownloadRequest{LocationKey: "doc:2222222", Offset: 0, Limit: 4})
 	if err != nil || !ok {
@@ -486,7 +487,7 @@ func TestSeedMediaRepairsPartialReactionBlobs(t *testing.T) {
 		t.Fatalf("repair seed: %v", err)
 	}
 	if stats.Reactions != 1 || stats.Blobs != 2 || stats.Skipped {
-		t.Fatalf("repair stats = %+v, want two missing/revalidated main blobs without rewriting intact preview", stats)
+		t.Fatalf("repair stats = %+v, want two revalidated main document blobs", stats)
 	}
 	if _, ok, _ := media.GetFileBlob(context.Background(), "doc:2222222"); !ok {
 		t.Fatal("missing reaction blob was not repaired")
@@ -496,10 +497,10 @@ func TestSeedMediaRepairsPartialReactionBlobs(t *testing.T) {
 	}
 }
 
-func TestSeedCustomEmojiTGSWithoutThumbGetsSyntheticPreview(t *testing.T) {
+func TestSeedStatusPackTGSWithoutExportedThumbUsesBundledPreview(t *testing.T) {
 	ctx := context.Background()
 	seedDir := t.TempDir()
-	const sourceID int64 = 4444444
+	const sourceID int64 = 5247133031235329609
 	writeStatusPackWithoutThumbSeed(t, seedDir, sourceID, 17)
 
 	media := newFakeMediaStore()
@@ -513,7 +514,7 @@ func TestSeedCustomEmojiTGSWithoutThumbGetsSyntheticPreview(t *testing.T) {
 		t.Fatalf("seed media: %v", err)
 	}
 	if stats.StickerSets != 1 || stats.Documents != 1 || stats.Blobs != 2 || stats.Skipped {
-		t.Fatalf("stats = %+v, want one set, one doc, main blob plus synthetic preview", stats)
+		t.Fatalf("stats = %+v, want one set, one doc, main blob plus bundled preview", stats)
 	}
 
 	set, ok, err := media.GetStickerSetByShortName(ctx, "StatusPack")
@@ -529,21 +530,52 @@ func TestSeedCustomEmojiTGSWithoutThumbGetsSyntheticPreview(t *testing.T) {
 	}
 	thumb, ok := findCachedThumb(doc.Thumbs)
 	if !ok {
-		t.Fatalf("document thumbs = %+v, want synthetic cached preview", doc.Thumbs)
+		t.Fatalf("document thumbs = %+v, want bundled cached preview", doc.Thumbs)
 	}
-	if thumb.Type != seedSyntheticDocumentThumbType || thumb.W != 1 || thumb.H != 1 || len(thumb.Bytes) == 0 {
-		t.Fatalf("synthetic thumb = %+v, want 1x1 cached %q thumb", thumb, seedSyntheticDocumentThumbType)
+	want, ok := seedBundledDocumentPreview(sourceID)
+	if !ok {
+		t.Fatal("bundled StatusPack preview missing")
+	}
+	if thumb.Type != seedBundledDocumentThumbType || thumb.W != 128 || thumb.H != 128 || !bytes.Equal(thumb.Bytes, want) {
+		t.Fatalf("bundled thumb = %+v, want visible 128x128 cached %q preview", thumb, seedBundledDocumentThumbType)
 	}
 	blob, ok, err := media.GetFileBlob(ctx, fmt.Sprintf("doc:%d:%s", doc.ID, thumb.Type))
 	if err != nil || !ok {
-		t.Fatalf("synthetic thumb blob ok=%v err=%v", ok, err)
+		t.Fatalf("bundled thumb blob ok=%v err=%v", ok, err)
 	}
 	if blob.MimeType != "image/png" {
-		t.Fatalf("synthetic thumb blob mime = %q, want image/png", blob.MimeType)
+		t.Fatalf("bundled thumb blob mime = %q, want image/png", blob.MimeType)
 	}
 }
 
-func TestSeedMediaRepairsCustomEmojiTGSWithoutThumb(t *testing.T) {
+func TestBundledStatusPackPreviewsAreVisibleTransparentPNGs(t *testing.T) {
+	if len(seedBundledDocumentPreviews) != 11 {
+		t.Fatalf("bundled StatusPack previews = %d, want 11", len(seedBundledDocumentPreviews))
+	}
+	for documentID, data := range seedBundledDocumentPreviews {
+		img, err := png.Decode(bytes.NewReader(data))
+		if err != nil {
+			t.Fatalf("decode bundled preview %d: %v", documentID, err)
+		}
+		if bounds := img.Bounds(); bounds.Dx() != 128 || bounds.Dy() != 128 {
+			t.Fatalf("bundled preview %d bounds = %v, want 128x128", documentID, bounds)
+		}
+		visible := false
+		transparent := false
+		for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ {
+			for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ {
+				_, _, _, alpha := img.At(x, y).RGBA()
+				visible = visible || alpha != 0
+				transparent = transparent || alpha != 0xffff
+			}
+		}
+		if !visible || !transparent {
+			t.Fatalf("bundled preview %d visible=%v transparent=%v", documentID, visible, transparent)
+		}
+	}
+}
+
+func TestSeedMediaDoesNotInventPreviewForUnknownTGS(t *testing.T) {
 	ctx := context.Background()
 	seedDir := t.TempDir()
 	const sourceID int64 = 5555555
@@ -586,15 +618,15 @@ func TestSeedMediaRepairsCustomEmojiTGSWithoutThumb(t *testing.T) {
 	if err != nil {
 		t.Fatalf("repair seed: %v", err)
 	}
-	if stats.StickerSets != 1 || stats.Documents != 1 || stats.Blobs != 2 || stats.Skipped {
-		t.Fatalf("repair stats = %+v, want forced reimport", stats)
+	if stats.StickerSets != 1 || stats.Documents != 1 || stats.Blobs != 1 || stats.Skipped {
+		t.Fatalf("reimport stats = %+v, want main document blob only", stats)
 	}
 	doc, ok, err := media.GetDocument(ctx, sourceID)
 	if err != nil || !ok {
 		t.Fatalf("repaired document ok=%v err=%v", ok, err)
 	}
-	if _, ok := findCachedThumb(doc.Thumbs); !ok {
-		t.Fatalf("repaired document thumbs = %+v, want synthetic cached preview", doc.Thumbs)
+	if len(doc.Thumbs) != 0 {
+		t.Fatalf("document thumbs = %+v, want no invented preview for unknown TGS", doc.Thumbs)
 	}
 }
 
@@ -614,8 +646,8 @@ func TestSeedMediaSkipsUnchangedEffectsDocuments(t *testing.T) {
 	if err != nil {
 		t.Fatalf("first seed: %v", err)
 	}
-	if first.Effects != 1 || first.Documents != 1 || first.Blobs != 2 {
-		t.Fatalf("first stats = %+v, want one imported effect document with main plus synthetic preview blobs", first)
+	if first.Effects != 1 || first.Documents != 1 || first.Blobs != 1 {
+		t.Fatalf("first stats = %+v, want one imported effect document with its main blob", first)
 	}
 
 	second, err := svc.SeedMedia(ctx, seedDir, 0)
@@ -665,7 +697,7 @@ func TestSeedEffectsDoesNotDowngradeSharedStickerPreview(t *testing.T) {
 	if !ok {
 		t.Fatalf("shared document thumbs = %+v, want real cached preview", doc.Thumbs)
 	}
-	if thumb.W != 128 || thumb.H != 128 || !bytes.Equal(thumb.Bytes, realThumb) || seedSyntheticTGStickerPreviewThumb(thumb) {
+	if thumb.W != 128 || thumb.H != 128 || !bytes.Equal(thumb.Bytes, realThumb) {
 		t.Fatalf("shared preview = %+v, want original 128x128 catalog thumbnail", thumb)
 	}
 	blob, ok, err := media.GetFileBlob(ctx, fmt.Sprintf("doc:%d:m", sourceID))
@@ -692,55 +724,6 @@ func TestSeedEffectsDoesNotDowngradeSharedStickerPreview(t *testing.T) {
 	}
 }
 
-func TestSeedMediaMigratesSyntheticStickerPreviewToExportedThumbnail(t *testing.T) {
-	ctx := context.Background()
-	seedDir := t.TempDir()
-	const sourceID int64 = 8888888
-	realThumb := writeStatusPackWithThumbSeed(t, seedDir, sourceID, 31)
-
-	media := newFakeMediaStore()
-	if err := media.PutDocument(ctx, domain.Document{
-		ID:       sourceID,
-		MimeType: "application/x-tgsticker",
-		Thumbs: []domain.PhotoSize{{
-			Kind: domain.PhotoSizeKindCached, Type: seedSyntheticDocumentThumbType,
-			W: 1, H: 1, Bytes: append([]byte(nil), seedSyntheticTGStickerPreviewThumbPNG...),
-		}},
-	}); err != nil {
-		t.Fatalf("put stale document: %v", err)
-	}
-	if err := media.PutStickerSet(ctx, domain.StickerSet{
-		ID: 773947703670341676, AccessHash: 1, ShortName: "StatusPack", Title: "Status Pack",
-		Hash: 31, Kind: domain.StickerSetKindEmoji, Emojis: true, DocumentIDs: []int64{sourceID},
-	}); err != nil {
-		t.Fatalf("put stale sticker set: %v", err)
-	}
-
-	blobs, err := NewLocalFS(t.TempDir())
-	if err != nil {
-		t.Fatalf("local fs: %v", err)
-	}
-	svc := NewService(media, blobs, 2)
-	stats, err := svc.SeedMedia(ctx, seedDir, 0)
-	if err != nil {
-		t.Fatalf("migration seed: %v", err)
-	}
-	if stats.StickerSets != 1 || stats.Documents != 1 {
-		t.Fatalf("migration stats = %+v, want forced sticker document rebuild", stats)
-	}
-	doc, ok, err := media.GetDocument(ctx, sourceID)
-	if err != nil || !ok {
-		t.Fatalf("migrated document ok=%v err=%v", ok, err)
-	}
-	thumb, ok := findCachedThumb(doc.Thumbs)
-	if !ok || thumb.W != 128 || thumb.H != 128 || !bytes.Equal(thumb.Bytes, realThumb) {
-		t.Fatalf("migrated thumbs = %+v, want exported 128x128 preview", doc.Thumbs)
-	}
-	if state, ok, err := media.GetSeedState(ctx, seedStickerPreviewStateKey); err != nil || !ok || state == "" {
-		t.Fatalf("preview migration state = %q ok=%v err=%v", state, ok, err)
-	}
-}
-
 func TestSeedMediaFromRealExport(t *testing.T) {
 	seedDir := os.Getenv("TELESRV_REAL_STICKER_SEED_DIR")
 	if seedDir == "" {
@@ -841,7 +824,7 @@ func TestSeedMediaFromRealExport(t *testing.T) {
 			t.Fatalf("sample sticker thumb mime = %q, want %q", blob.MimeType, want)
 		}
 		if !hasPathThumb(doc.Thumbs) {
-			t.Logf("sample sticker document has no exported PhotoPathSize placeholder; synthetic cached preview is present: %+v", doc.Thumbs)
+			t.Logf("sample sticker document has no exported PhotoPathSize placeholder; cached preview is present: %+v", doc.Thumbs)
 		}
 	}
 }

internal/app/files/statuspack_previews.go

@@ -0,0 +1,46 @@
+package files
+
+import (
+	"embed"
+	"fmt"
+)
+
+const seedBundledDocumentThumbType = "m"
+
+// StatusPack is exported without document thumbnails, while Android uses a
+// non-empty thumbs vector to recognize application/x-tgsticker documents as
+// animated custom emoji. Keep real, visible first-frame previews with the
+// server's default media assets instead of inventing transparent metadata.
+//
+//go:embed statuspack_previews/*.png
+var statusPackPreviewFS embed.FS
+
+var seedBundledDocumentPreviews = map[int64][]byte{
+	5244508282231465075: mustReadStatusPackPreview(5244508282231465075),
+	5246743378917334735: mustReadStatusPackPreview(5246743378917334735),
+	5246772116543512028: mustReadStatusPackPreview(5246772116543512028),
+	5246828303305678732: mustReadStatusPackPreview(5246828303305678732),
+	5246842176050046092: mustReadStatusPackPreview(5246842176050046092),
+	5246960163096632543: mustReadStatusPackPreview(5246960163096632543),
+	5247100325059370738: mustReadStatusPackPreview(5247100325059370738),
+	5247133031235329609: mustReadStatusPackPreview(5247133031235329609),
+	5247176827016847212: mustReadStatusPackPreview(5247176827016847212),
+	5247209275494769660: mustReadStatusPackPreview(5247209275494769660),
+	5249273776079640466: mustReadStatusPackPreview(5249273776079640466),
+}
+
+func mustReadStatusPackPreview(documentID int64) []byte {
+	data, err := statusPackPreviewFS.ReadFile(fmt.Sprintf("statuspack_previews/%d.png", documentID))
+	if err != nil {
+		panic(fmt.Sprintf("read bundled StatusPack preview %d: %v", documentID, err))
+	}
+	return data
+}
+
+func seedBundledDocumentPreview(documentID int64) ([]byte, bool) {
+	data, ok := seedBundledDocumentPreviews[documentID]
+	if !ok {
+		return nil, false
+	}
+	return append([]byte(nil), data...), true
+}

internal/app/files/sticker_admin.go

@@ -94,6 +94,47 @@ func isWebPData(data []byte) bool {
 	return len(data) >= 12 && string(data[0:4]) == "RIFF" && string(data[8:12]) == "WEBP"
 }
 
+// ValidateAdminAddStickerToSet is a pure check (no store writes), used by a
+// dry-run preview before AdminAddStickerToSet actually mutates the pack.
+func (s *Service) ValidateAdminAddStickerToSet(ctx context.Context, setID int64, emoji string) error {
+	set, _, found, err := s.ResolveStickerSet(ctx, domain.StickerSetRef{Kind: domain.StickerSetRefByID, ID: setID})
+	if err != nil {
+		return err
+	}
+	if !found || set.ID == 0 || set.Deleted || set.Kind == domain.StickerSetKindSystem {
+		return domain.ErrStickerSetInvalid
+	}
+	if len(set.DocumentIDs) >= domain.MaxStickerSetItems {
+		return domain.ErrStickerSetTooMuch
+	}
+	return validateStickerEmoji(strings.TrimSpace(emoji))
+}
+
+// ValidateAdminCreateStickerSet is a pure check (no store writes), used by a
+// dry-run preview before AdminCreateStickerSet actually creates the pack.
+func (s *Service) ValidateAdminCreateStickerSet(ctx context.Context, title, shortName, emoji string, kind domain.StickerSetKind) error {
+	if err := validateStickerSetTitle(strings.TrimSpace(title)); err != nil {
+		return err
+	}
+	if kind != domain.StickerSetKindEmoji && kind != domain.StickerSetKindMasks && kind != "" {
+		return domain.ErrStickerSetTypeInvalid
+	}
+	normalizedShortName := normalizeStickerSetShortName(shortName)
+	if normalizedShortName != "" {
+		if err := validateStickerSetShortName(normalizedShortName); err != nil {
+			return err
+		}
+		available, err := s.media.StickerSetShortNameAvailable(ctx, normalizedShortName)
+		if err != nil {
+			return err
+		}
+		if !available {
+			return domain.ErrStickerSetShortNameOccupied
+		}
+	}
+	return validateStickerEmoji(strings.TrimSpace(emoji))
+}
+
 // AdminAddStickerToSet appends an already-materialized document (from
 // AdminUploadStickerMaterial) to an existing pack with no ownership check —
 // same convention as AdminSetStickerSetArchived and friends.

internal/app/files/sticker_management.go

@@ -142,7 +142,7 @@ func (s *Service) AdminSetStickerSetArchived(ctx context.Context, setID int64, a
 	if err != nil {
 		return false, err
 	}
-	if !found {
+	if !found || set.Deleted {
 		return false, domain.ErrStickerSetInvalid
 	}
 	if set.Archived == archived {
@@ -163,7 +163,7 @@ func (s *Service) AdminSetStickerSetSortOrder(ctx context.Context, setID int64,
 	if err != nil {
 		return false, err
 	}
-	if !found {
+	if !found || set.Deleted {
 		return false, domain.ErrStickerSetInvalid
 	}
 	if set.SortOrder == order {
@@ -188,7 +188,7 @@ func (s *Service) AdminRenameStickerSet(ctx context.Context, setID int64, title
 	if err != nil {
 		return domain.StickerSet{}, err
 	}
-	if !found {
+	if !found || set.Deleted {
 		return domain.StickerSet{}, domain.ErrStickerSetInvalid
 	}
 	set.Title = title
@@ -203,15 +203,15 @@ func (s *Service) AdminRenameStickerSet(ctx context.Context, setID int64, title
 // AdminDeleteStickerSet deletes (soft-delete) a set with no ownership check;
 // see AdminSetStickerSetArchived for why that's needed here. Safe to bypass
 // ownership for: sticker_sets has no incoming foreign keys, so there's no
-// cascade to worry about (unlike star gifts, which have ~15 dependent
-// tables). Seed-imported sets will reappear on next restart if their source
-// files are still under data/sticker-seed — this only removes the DB row.
+// cascade to worry about. Seed-imported sets will reappear on next restart
+// if their source files are still under data/sticker-seed — this only
+// removes the DB row.
 func (s *Service) AdminDeleteStickerSet(ctx context.Context, setID int64) (domain.StickerSetKind, error) {
 	set, found, err := s.media.GetStickerSetByID(ctx, setID)
 	if err != nil {
 		return "", err
 	}
-	if !found {
+	if !found || set.Deleted {
 		return "", domain.ErrStickerSetInvalid
 	}
 	if err := s.media.AdminDeleteStickerSet(ctx, setID); err != nil {

internal/app/files/sticker_management_test.go

@@ -138,6 +138,50 @@ func TestManageStickerSetRejectsNonCreator(t *testing.T) {
 	}
 }
 
+func TestValidateAdminStickerSetUploadPreconditions(t *testing.T) {
+	ctx := context.Background()
+	fullIDs := make([]int64, domain.MaxStickerSetItems)
+	for i := range fullIDs {
+		fullIDs[i] = int64(i + 1)
+	}
+	media := &fakeMediaStore{
+		docs: map[int64]domain.Document{},
+		sets: map[int64]domain.StickerSet{
+			10: {ID: 10, Kind: domain.StickerSetKindEmoji, DocumentIDs: fullIDs},
+			20: {ID: 20, Kind: domain.StickerSetKindSystem, DocumentIDs: []int64{1}},
+			30: {ID: 30, Kind: domain.StickerSetKindEmoji, DocumentIDs: []int64{1}},
+			40: {ID: 40, Kind: domain.StickerSetKindEmoji, Deleted: true, DocumentIDs: []int64{1}},
+		},
+	}
+	svc := NewService(media, nil, 2)
+
+	if err := svc.ValidateAdminAddStickerToSet(ctx, 10, "🙂"); !errors.Is(err, domain.ErrStickerSetTooMuch) {
+		t.Fatalf("full pack validation err = %v, want ErrStickerSetTooMuch", err)
+	}
+	for _, setID := range []int64{20, 40, 999} {
+		if err := svc.ValidateAdminAddStickerToSet(ctx, setID, "🙂"); !errors.Is(err, domain.ErrStickerSetInvalid) {
+			t.Fatalf("set %d validation err = %v, want ErrStickerSetInvalid", setID, err)
+		}
+	}
+	if err := svc.ValidateAdminAddStickerToSet(ctx, 30, ""); !errors.Is(err, domain.ErrStickerSetEmojiInvalid) {
+		t.Fatalf("empty emoji validation err = %v, want ErrStickerSetEmojiInvalid", err)
+	}
+	if err := svc.ValidateAdminAddStickerToSet(ctx, 30, "🙂"); err != nil {
+		t.Fatalf("editable pack validation: %v", err)
+	}
+
+	if err := svc.ValidateAdminCreateStickerSet(ctx, "New Emoji", "new_emoji", "🙂", domain.StickerSetKindEmoji); err != nil {
+		t.Fatalf("create validation: %v", err)
+	}
+	if err := svc.ValidateAdminCreateStickerSet(ctx, "New Emoji", "new_emoji", "🙂", domain.StickerSetKindSystem); !errors.Is(err, domain.ErrStickerSetTypeInvalid) {
+		t.Fatalf("system create validation err = %v, want ErrStickerSetTypeInvalid", err)
+	}
+	media.sets[50] = domain.StickerSet{ID: 50, ShortName: "occupied_name"}
+	if err := svc.ValidateAdminCreateStickerSet(ctx, "New Emoji", "occupied_name", "🙂", domain.StickerSetKindEmoji); !errors.Is(err, domain.ErrStickerSetShortNameOccupied) {
+		t.Fatalf("occupied name validation err = %v, want ErrStickerSetShortNameOccupied", err)
+	}
+}
+
 func TestAddStickerToSetAcceptsUploadedMaterial(t *testing.T) {
 	ctx := context.Background()
 	media := &fakeMediaStore{

internal/app/files/webpage.go

@@ -176,7 +176,7 @@ func (f *webpageFetcher) fetch(ctx context.Context, rawURL, accept string) ([]by
 	if err != nil {
 		// SSRF 拦截（dial Control 返回的 terminal）经 url.Error 传上来，errors.Is 仍能识别；
 		// 其余 dial/超时错误是瞬时。
-		return nil, "", fmt.Errorf("%w: %v", ErrWebPagePreviewInvalid, err)
+		return nil, "", fmt.Errorf("%w: %w", ErrWebPagePreviewInvalid, err)
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
@@ -293,7 +293,7 @@ func (f *webpageFetcher) resolve(ctx context.Context, s *Service, normalizedURL
 	if err != nil {
 		// 终态失败（SSRF/4xx/非法 URL）→ 负缓存为空预览，避免重复按键/发送重打 PG+外网。
 		// 瞬时失败（5xx/超时/dial/限速）→ 上抛 error，GetOrLoad 不缓存、可重试。
-		if errors.Is(err, errWebPageTerminal) {
+		if isTerminalWebPageFetchError(err) {
 			return emptyWebPage(normalizedURL, urlHash), nil
 		}
 		return domain.MessageWebPage{}, err
@@ -316,6 +316,14 @@ func (f *webpageFetcher) resolve(ctx context.Context, s *Service, normalizedURL
 	return page, nil
 }
 
+func isTerminalWebPageFetchError(err error) bool {
+	if errors.Is(err, errWebPageTerminal) {
+		return true
+	}
+	var dnsErr *net.DNSError
+	return errors.As(err, &dnsErr) && dnsErr.IsNotFound
+}
+
 // fetchImage 抓取并铸造预览图（best-effort）。解码前按尺寸拦截解压炸弹；非图片/失败丢弃。
 func (f *webpageFetcher) fetchImage(ctx context.Context, s *Service, imageURL string) (domain.Photo, bool) {
 	data, _, err := f.fetch(ctx, imageURL, acceptImage)

internal/app/files/webpage_test.go

@@ -201,7 +201,8 @@ func TestResolveWebPageNonHTMLIsEmpty(t *testing.T) {
 	}
 }
 
-// TestResolveWebPageSSRFBlocksLoopback 验证生产配置（allowPrivate=false）拦截指向 loopback 的 URL。
+// TestResolveWebPageSSRFBlocksLoopback 验证生产配置（allowPrivate=false）拦截指向 loopback 的 URL，
+// 并把该确定性失败收敛为空预览。
 func TestResolveWebPageSSRFBlocksLoopback(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		w.Header().Set("Content-Type", "text/html")
@@ -210,8 +211,12 @@ func TestResolveWebPageSSRFBlocksLoopback(t *testing.T) {
 	defer srv.Close()
 
 	svc := newWebpageTestService(t, false) // 生产口径：禁 loopback
-	if _, err := svc.ResolveWebPage(context.Background(), srv.URL+"/x"); err == nil {
-		t.Fatalf("expected SSRF guard to block loopback fetch")
+	page, err := svc.ResolveWebPage(context.Background(), srv.URL+"/x")
+	if err != nil {
+		t.Fatalf("SSRF guard should resolve as terminal-empty: %v", err)
+	}
+	if page.State != domain.MessageWebPageStateEmpty {
+		t.Fatalf("state = %q, want empty", page.State)
 	}
 }