feat(media): storage for images and audio in notes (M1)

- Table media (migration 5), files in $DATA_DIR/media/<docId>/.
- POST /documents/{id}/media (write access), POST .../media/fetch copies an
  external https image (SSRF-guarded, not in the demo), GET /media/{id}
  with range requests for readers of a note that shows the file.
- Format detected from the content (no SVG); own sandbox CSP on answers.
- Blocks point to files through their content (media:<id>), so the note
  sync needs no change; compaction removes files no block mentions any
  more after a day. Demo reset and demo start clear the folder.
- Limits MEDIA_MAX_IMAGE_MB, MEDIA_MAX_AUDIO_MB, MEDIA_QUOTA_MB,
  MEDIA_DEMO_MAX_MB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/bodylimit.go

@@ -14,6 +14,8 @@ const defaultMaxBody = 2 << 20
 
 func (s *Server) bodyLimitFor(path string) int64 {
 	switch {
+	case strings.HasPrefix(path, "/api/v1/documents/") && strings.HasSuffix(path, "/media"):
+		return s.mediaUploadLimit()
 	case path == "/api/v1/voice/transcribe":
 		return int64(s.cfg.Speech.MaxUploadMB)<<20 + 1<<20
 	case strings.HasPrefix(path, "/api/v1/import/"):

internal/api/demo.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"log/slog"
 	"net/http"
+	"os"
 	"strings"
 	"sync"
 	"time"
@@ -59,6 +60,8 @@ func (s *Server) setDemoNextReset(t time.Time) {
 func (s *Server) resetDemo() {
 	s.demo.gate.Lock()
 	err := s.store.ResetAndSeedDemo()
+	// Uploaded images and recordings belong to the old state; their rows are gone with the tables
+	_ = os.RemoveAll(s.mediaRoot())
 	s.demo.gate.Unlock()
 	if err != nil {
 		slog.Error("Demo-Reset fehlgeschlagen", "error", err)

internal/api/docsync.go

@@ -270,6 +270,7 @@ func (s *Server) startCompaction() {
 
 func (s *Server) compactOnce() {
 	s.leases.Sweep()
+	s.compactMedia(time.Now())
 	st, err := s.store.CompactDocs(time.Now())
 	if err != nil {
 		slog.Error("Verdichtung des Änderungsprotokolls fehlgeschlagen", "error", err)

internal/api/media.go

@@ -0,0 +1,295 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/sandrodach/mindsift/internal/auth"
+	"github.com/sandrodach/mindsift/internal/storage"
+)
+
+// Images and audio in notes. Uploads need write access to the note, reading needs read access to a note
+// that shows the file. Files are served through the API with the normal login (the browser loads them
+// with fetch and shows a blob: URL), never under a public link.
+
+const mediaGrace = 24 * time.Hour // uploads not yet placed in a block are kept this long
+
+// Accepted formats (detected from the content, not from the name): file extension and kind
+var mediaTypes = map[string]struct{ ext, kind string }{
+	"image/jpeg":      {".jpg", "image"},
+	"image/png":       {".png", "image"},
+	"image/gif":       {".gif", "image"},
+	"image/webp":      {".webp", "image"},
+	"audio/webm":      {".webm", "audio"},
+	"video/webm":      {".webm", "audio"}, // Chrome's audio-only recordings are detected as video/webm
+	"audio/ogg":       {".ogg", "audio"},
+	"application/ogg": {".ogg", "audio"},
+	"audio/mpeg":      {".mp3", "audio"},
+	"audio/wave":      {".wav", "audio"},
+	"audio/wav":       {".wav", "audio"},
+	"audio/mp4":       {".m4a", "audio"},
+	"video/mp4":       {".m4a", "audio"}, // Safari records MP4/AAC
+	"audio/aac":       {".aac", "audio"},
+}
+
+func (s *Server) mediaRoot() string {
+	return filepath.Join(filepath.Dir(s.cfg.DatabasePath), "media")
+}
+
+func (s *Server) mediaPath(m *storage.Media) string {
+	ext := ".bin"
+	if t, ok := mediaTypes[m.Mime]; ok {
+		ext = t.ext
+	}
+	return filepath.Join(s.mediaRoot(), filepath.Base(m.DocID), filepath.Base(m.ID)+ext)
+}
+
+// mediaLimit is the largest allowed file of a kind in bytes.
+func (s *Server) mediaLimit(kind string) int64 {
+	mb := s.cfg.Media.MaxImageMB
+	if kind == "audio" {
+		mb = s.cfg.Media.MaxAudioMB
+	}
+	if s.cfg.DemoMode && s.cfg.Media.DemoMaxMB < mb {
+		mb = s.cfg.Media.DemoMaxMB
+	}
+	return int64(mb) << 20
+}
+
+// detectMedia recognises the format from the first bytes. Browsers send audio as e.g.
+// "audio/webm;codecs=opus"; that name is kept when the content looks like a container we accept.
+func detectMedia(data []byte, declared string) (mime, kind string, ok bool) {
+	sniffed := http.DetectContentType(data)
+	if i := strings.IndexByte(sniffed, ';'); i >= 0 {
+		sniffed = sniffed[:i]
+	}
+	// Go does not know WebP and M4A by name; check their signatures directly
+	switch {
+	case len(data) >= 12 && string(data[0:4]) == "RIFF" && string(data[8:12]) == "WEBP":
+		sniffed = "image/webp"
+	case len(data) >= 12 && string(data[4:8]) == "ftyp":
+		sniffed = "video/mp4"
+	}
+	t, ok := mediaTypes[sniffed]
+	if !ok {
+		return "", "", false
+	}
+	if t.kind == "audio" {
+		if d := strings.ToLower(strings.TrimSpace(strings.SplitN(declared, ";", 2)[0])); strings.HasPrefix(d, "audio/") {
+			if dt, known := mediaTypes[d]; known && dt.kind == "audio" {
+				sniffed = d
+			}
+		} else if sniffed == "video/webm" {
+			sniffed = "audio/webm"
+		} else if sniffed == "video/mp4" {
+			sniffed = "audio/mp4"
+		}
+	}
+	return sniffed, t.kind, true
+}
+
+func (s *Server) canEditDoc(userID, docID string) bool {
+	role := s.store.DocRole(userID, docID)
+	return role == "owner" || role == "editor"
+}
+
+// storeMedia checks limits and writes the file; size limits must have been applied while reading.
+func (s *Server) storeMedia(w http.ResponseWriter, userID, docID string, data []byte, declared, sourceURL string) (*storage.Media, bool) {
+	mime, kind, ok := detectMedia(data, declared)
+	if !ok {
+		writeError(w, http.StatusUnsupportedMediaType, "Nicht unterstütztes Format (Bilder: JPEG, PNG, GIF, WebP; Audio: WebM, Ogg, MP3, WAV, M4A)")
+		return nil, false
+	}
+	if limit := s.mediaLimit(kind); int64(len(data)) > limit {
+		writeError(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("Datei zu groß (höchstens %d MB)", limit>>20))
+		return nil, false
+	}
+	if quota := int64(s.cfg.Media.QuotaMB) << 20; quota > 0 {
+		used, _ := s.store.MediaUsage(userID)
+		if used+int64(len(data)) > quota {
+			writeError(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("Speicherplatz für Medien aufgebraucht (%d MB)", s.cfg.Media.QuotaMB))
+			return nil, false
+		}
+	}
+	m, err := s.store.CreateMedia(docID, userID, kind, mime, int64(len(data)), sourceURL)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "Datei konnte nicht gespeichert werden")
+		return nil, false
+	}
+	path := s.mediaPath(m)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err == nil {
+		err = os.WriteFile(path, data, 0o644)
+		if err == nil {
+			return m, true
+		}
+		slog.Error("Mediendatei konnte nicht geschrieben werden", "path", path, "error", err)
+	}
+	_ = s.store.DeleteMediaRow(m.ID)
+	writeError(w, http.StatusInternalServerError, "Datei konnte nicht gespeichert werden")
+	return nil, false
+}
+
+func mediaResponse(m *storage.Media) map[string]interface{} {
+	return map[string]interface{}{"id": m.ID, "kind": m.Kind, "mime": m.Mime, "size": m.Size, "url": "/api/v1/media/" + m.ID}
+}
+
+// handleUploadMedia: POST /documents/{id}/media (multipart, field "file")
+func (s *Server) handleUploadMedia(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	docID := chi.URLParam(r, "id")
+	if !s.canEditDoc(userID, docID) {
+		writeError(w, http.StatusForbidden, "Keine Schreibrechte für diese Notiz")
+		return
+	}
+	allowLongTransfer(w)
+	file, header, err := r.FormFile("file")
+	if err != nil {
+		var tooBig *http.MaxBytesError
+		if errors.As(err, &tooBig) {
+			writeError(w, http.StatusRequestEntityTooLarge, "Datei zu groß")
+			return
+		}
+		writeError(w, http.StatusBadRequest, "Keine Datei im Feld \"file\"")
+		return
+	}
+	defer file.Close()
+	data, err := io.ReadAll(file)
+	if err != nil || len(data) == 0 {
+		writeError(w, http.StatusBadRequest, "Datei konnte nicht gelesen werden")
+		return
+	}
+	if m, ok := s.storeMedia(w, userID, docID, data, header.Header.Get("Content-Type"), ""); ok {
+		writeJSON(w, http.StatusCreated, mediaResponse(m))
+	}
+}
+
+// handleFetchMedia: POST /documents/{id}/media/fetch {url} copies an external image, so readers of the
+// note do not contact the other server and the image stays when it disappears there.
+func (s *Server) handleFetchMedia(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	docID := chi.URLParam(r, "id")
+	if !s.canEditDoc(userID, docID) {
+		writeError(w, http.StatusForbidden, "Keine Schreibrechte für diese Notiz")
+		return
+	}
+	var req struct {
+		URL string `json:"url"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || strings.TrimSpace(req.URL) == "" {
+		writeError(w, http.StatusBadRequest, "Bild-URL erforderlich")
+		return
+	}
+	src := strings.TrimSpace(req.URL)
+	// Same protection as alarm webhooks: https only, no addresses in the server's own network
+	if err := validateWebhookURL(src, false, false); err != nil {
+		writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	limit := s.mediaLimit("image")
+	httpReq, _ := http.NewRequestWithContext(r.Context(), http.MethodGet, src, nil)
+	httpReq.Header.Set("Accept", "image/*")
+	httpReq.Header.Set("User-Agent", "MindSift (image copy)")
+	resp, err := guardedClient(false).Do(httpReq)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, "Bild konnte nicht geladen werden")
+		return
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		writeError(w, http.StatusBadGateway, fmt.Sprintf("Bild konnte nicht geladen werden (HTTP %d)", resp.StatusCode))
+		return
+	}
+	data, err := io.ReadAll(io.LimitReader(resp.Body, limit+1))
+	if err != nil {
+		writeError(w, http.StatusBadGateway, "Bild konnte nicht geladen werden")
+		return
+	}
+	if int64(len(data)) > limit {
+		writeError(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("Bild zu groß (höchstens %d MB)", limit>>20))
+		return
+	}
+	if _, kind, ok := detectMedia(data, ""); !ok || kind != "image" {
+		writeError(w, http.StatusUnsupportedMediaType, "Unter dieser Adresse liegt kein Bild (JPEG, PNG, GIF, WebP)")
+		return
+	}
+	if m, ok := s.storeMedia(w, userID, docID, data, "", src); ok {
+		writeJSON(w, http.StatusCreated, mediaResponse(m))
+	}
+}
+
+// canReadMedia: the user may read the note the file was uploaded to, or a note whose blocks show it
+// (e.g. a block copied into another note).
+func (s *Server) canReadMedia(userID string, m *storage.Media) bool {
+	if s.store.DocRole(userID, m.DocID) != "" {
+		return true
+	}
+	docs, _ := s.store.MediaReferencedIn(m.ID)
+	for _, d := range docs {
+		if s.store.DocRole(userID, d) != "" {
+			return true
+		}
+	}
+	return false
+}
+
+// handleGetMedia: GET /media/{id} with range requests (seeking in audio).
+func (s *Server) handleGetMedia(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	m, err := s.store.GetMedia(chi.URLParam(r, "id"))
+	if err != nil || !s.canReadMedia(userID, m) {
+		writeError(w, http.StatusNotFound, storage.ErrMediaNotFound.Error())
+		return
+	}
+	f, err := os.Open(s.mediaPath(m))
+	if err != nil {
+		writeError(w, http.StatusNotFound, storage.ErrMediaNotFound.Error())
+		return
+	}
+	defer f.Close()
+	allowLongTransfer(w)
+	w.Header().Set("Content-Type", m.Mime)
+	// The content of an ID never changes; the login is checked on every request anyway
+	w.Header().Set("Cache-Control", "private, max-age=31536000, immutable")
+	w.Header().Set("Content-Security-Policy", "default-src 'none'; sandbox")
+	created, _ := time.Parse(time.RFC3339, m.CreatedAt)
+	http.ServeContent(w, r, "", created, f)
+}
+
+// compactMedia deletes files no block mentions any more (after the grace time) and their folders.
+func (s *Server) compactMedia(now time.Time) {
+	orphans, err := s.store.UnreferencedMedia(now.Add(-mediaGrace))
+	if err != nil {
+		slog.Error("Aufräumen der Mediendateien fehlgeschlagen", "error", err)
+		return
+	}
+	for i := range orphans {
+		m := &orphans[i]
+		if err := os.Remove(s.mediaPath(m)); err != nil && !os.IsNotExist(err) {
+			slog.Warn("Mediendatei konnte nicht gelöscht werden", "id", m.ID, "error", err)
+			continue
+		}
+		_ = s.store.DeleteMediaRow(m.ID)
+		_ = os.Remove(filepath.Dir(s.mediaPath(m))) // only succeeds when the folder is empty
+	}
+	if len(orphans) > 0 {
+		slog.Info("Nicht mehr verwendete Mediendateien gelöscht", "count", len(orphans))
+	}
+}
+
+// bodyLimit for uploads: the largest kind plus room for the multipart envelope
+func (s *Server) mediaUploadLimit() int64 {
+	img, audio := s.mediaLimit("image"), s.mediaLimit("audio")
+	if audio > img {
+		return audio + 1<<20
+	}
+	return img + 1<<20
+}

internal/api/media_test.go

@@ -0,0 +1,166 @@
+package api
+
+import (
+	"bytes"
+	"encoding/json"
+	"image"
+	"image/png"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/sandrodach/mindsift/internal/auth"
+	"github.com/sandrodach/mindsift/internal/domain"
+)
+
+func tinyPNG(t *testing.T, extra int) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	if err := png.Encode(&buf, image.NewRGBA(image.Rect(0, 0, 4, 4))); err != nil {
+		t.Fatal(err)
+	}
+	buf.Write(make([]byte, extra)) // padding behind the image data, still detected as PNG
+	return buf.Bytes()
+}
+
+func mediaUpload(t *testing.T, router http.Handler, token, docID string, data []byte, contentType string) *httptest.ResponseRecorder {
+	t.Helper()
+	var body bytes.Buffer
+	mw := multipart.NewWriter(&body)
+	h := make(map[string][]string)
+	h["Content-Disposition"] = []string{`form-data; name="file"; filename="datei"`}
+	h["Content-Type"] = []string{contentType}
+	fw, _ := mw.CreatePart(h)
+	_, _ = fw.Write(data)
+	_ = mw.Close()
+	req := httptest.NewRequest("POST", "/api/v1/documents/"+docID+"/media", &body)
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	return rec
+}
+
+func TestMediaUploadReadAndAccess(t *testing.T) {
+	srv, store, token := setupTestServer(t)
+	srv.cfg.Media.MaxImageMB, srv.cfg.Media.MaxAudioMB = 1, 2
+	router := srv.Router()
+	claims, _ := auth.ValidateToken(testJWTSecret, token)
+	doc, _ := store.CreateDocument(claims.UserID, "", "Bilder", "🖼️", "", nil, nil, false)
+
+	img := tinyPNG(t, 0)
+	rec := mediaUpload(t, router, token, doc.ID, img, "image/png")
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("upload: %d %s", rec.Code, rec.Body.String())
+	}
+	var up struct{ ID, Kind, Mime, URL string }
+	_ = json.Unmarshal(rec.Body.Bytes(), &up)
+	if up.Kind != "image" || up.Mime != "image/png" || up.URL != "/api/v1/media/"+up.ID {
+		t.Fatalf("unexpected upload answer: %+v", up)
+	}
+
+	get := sessionCall(router, "GET", up.URL, token, "", "")
+	if get.Code != http.StatusOK || get.Header().Get("Content-Type") != "image/png" || !bytes.Equal(get.Body.Bytes(), img) {
+		t.Fatalf("read back: %d %s", get.Code, get.Header().Get("Content-Type"))
+	}
+	// Someone without access to the note sees nothing and cannot upload
+	_, strangerToken := newTestUser(t, store, "fremd@example.com")
+	if rec := sessionCall(router, "GET", up.URL, strangerToken, "", ""); rec.Code != http.StatusNotFound {
+		t.Fatalf("stranger read: want 404, got %d", rec.Code)
+	}
+	if rec := mediaUpload(t, router, strangerToken, doc.ID, img, "image/png"); rec.Code != http.StatusForbidden {
+		t.Fatalf("stranger upload: want 403, got %d", rec.Code)
+	}
+	// Only real images and recordings, within the limits
+	if rec := mediaUpload(t, router, token, doc.ID, []byte("<svg onload=alert(1)>"), "image/svg+xml"); rec.Code != http.StatusUnsupportedMediaType {
+		t.Fatalf("svg: want 415, got %d", rec.Code)
+	}
+	if rec := mediaUpload(t, router, token, doc.ID, tinyPNG(t, 1<<20+10), "image/png"); rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("too large: want 413, got %d %s", rec.Code, rec.Body.String())
+	}
+	// External images must not point into the server's own network
+	if rec := sessionCall(router, "POST", "/api/v1/documents/"+doc.ID+"/media/fetch", token, `{"url":"https://127.0.0.1/bild.png"}`, ""); rec.Code != http.StatusBadRequest {
+		t.Fatalf("fetch from localhost: want 400, got %d", rec.Code)
+	}
+}
+
+func TestMediaQuota(t *testing.T) {
+	srv, store, token := setupTestServer(t)
+	srv.cfg.Media.MaxImageMB, srv.cfg.Media.QuotaMB = 2, 1
+	router := srv.Router()
+	claims, _ := auth.ValidateToken(testJWTSecret, token)
+	doc, _ := store.CreateDocument(claims.UserID, "", "Quota", "", "", nil, nil, false)
+	if rec := mediaUpload(t, router, token, doc.ID, tinyPNG(t, 700<<10), "image/png"); rec.Code != http.StatusCreated {
+		t.Fatalf("first upload: %d", rec.Code)
+	}
+	if rec := mediaUpload(t, router, token, doc.ID, tinyPNG(t, 700<<10), "image/png"); rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("over the quota: want 413, got %d", rec.Code)
+	}
+}
+
+func TestMediaCleanupAndCopiedBlocks(t *testing.T) {
+	srv, store, token := setupTestServer(t)
+	srv.cfg.Media.MaxImageMB, srv.cfg.Media.MaxAudioMB = 2, 2
+	router := srv.Router()
+	claims, _ := auth.ValidateToken(testJWTSecret, token)
+	doc, _ := store.CreateDocument(claims.UserID, "", "Quelle", "", "", nil, nil, false)
+	upload := func() string {
+		var up struct{ ID string }
+		_ = json.Unmarshal(mediaUpload(t, router, token, doc.ID, tinyPNG(t, 0), "image/png").Body.Bytes(), &up)
+		return up.ID
+	}
+	used, unused := upload(), upload()
+
+	// A second user's note shows the used image (block copied there); that user may read it
+	other, otherToken := newTestUser(t, store, "kopie@example.com")
+	_, _ = store.CreateDocument(other.ID, "", "Kopie", "", "", []domain.DocumentBlock{{ID: "blk_copy", Type: "image", Content: "![Foto](media:" + used + ")"}}, nil, false)
+	if rec := sessionCall(router, "GET", "/api/v1/media/"+used, otherToken, "", ""); rec.Code != http.StatusOK {
+		t.Fatalf("copied block: want 200, got %d", rec.Code)
+	}
+
+	// Within the grace time nothing is removed, afterwards only the unused file
+	srv.compactMedia(time.Now())
+	if _, err := store.GetMedia(unused); err != nil {
+		t.Fatal("fresh uploads must survive the grace time")
+	}
+	srv.compactMedia(time.Now().Add(2 * mediaGrace))
+	if _, err := store.GetMedia(unused); err == nil {
+		t.Fatal("unused file must be removed")
+	}
+	m, err := store.GetMedia(used)
+	if err != nil {
+		t.Fatal("referenced file must stay")
+	}
+	if _, err := os.Stat(srv.mediaPath(m)); err != nil {
+		t.Fatalf("referenced file missing on disk: %v", err)
+	}
+}
+
+func TestDetectMedia(t *testing.T) {
+	webm := append([]byte{0x1A, 0x45, 0xDF, 0xA3}, make([]byte, 40)...)
+	m4a := append([]byte{0, 0, 0, 0x20}, []byte("ftypM4A ")...)
+	m4a = append(m4a, make([]byte, 40)...)
+	webp := append([]byte("RIFF\x00\x00\x00\x00WEBPVP8 "), make([]byte, 40)...)
+	cases := []struct {
+		data             []byte
+		declared         string
+		wantMime, wantKd string
+	}{
+		{webm, "audio/webm;codecs=opus", "audio/webm", "audio"},
+		{webm, "", "audio/webm", "audio"},
+		{m4a, "audio/mp4", "audio/mp4", "audio"},
+		{webp, "", "image/webp", "image"},
+	}
+	for _, c := range cases {
+		mime, kind, ok := detectMedia(c.data, c.declared)
+		if !ok || mime != c.wantMime || kind != c.wantKd {
+			t.Fatalf("detect(%q): got %s %s %v", c.declared, mime, kind, ok)
+		}
+	}
+	if _, _, ok := detectMedia([]byte("#!/bin/sh\nrm -rf /"), "audio/webm"); ok {
+		t.Fatal("scripts must not pass as audio")
+	}
+}

internal/api/server.go

@@ -132,6 +132,9 @@ func (s *Server) Router() http.Handler {
 		r.Post("/api/v1/events/rooms", s.handleSSERooms)
 		r.Post("/api/v1/auth/stream-ticket", s.handleStreamTicket)
 		r.Post("/api/v1/voice/transcribe", s.handleVoiceTranscribe)
+		r.Post("/api/v1/documents/{id}/media", s.handleUploadMedia)
+		r.Post("/api/v1/documents/{id}/media/fetch", s.notInDemo(s.handleFetchMedia))
+		r.Get("/api/v1/media/{id}", s.handleGetMedia)
 		r.Get("/api/v1/auth/sessions", s.handleListSessions)
 		r.Delete("/api/v1/auth/sessions/{id}", s.notInDemo(s.handleEndSession))
 		r.Post("/api/v1/auth/logout", s.handleLogout)

internal/config/config.go

@@ -46,6 +46,18 @@ type Config struct {
 
 	// Speech recognition, configured only by environment (STT_*)
 	Speech SpeechConfig
+
+	// Images and audio in notes (MEDIA_*)
+	Media MediaConfig
+}
+
+// MediaConfig limits uploads of images and audio recordings in notes. Sizes in MB; QuotaMB 0 = no limit
+// per user. The demo uses DemoMaxMB for every file.
+type MediaConfig struct {
+	MaxImageMB int
+	MaxAudioMB int
+	QuotaMB    int
+	DemoMaxMB  int
 }
 
 // SpeechConfig: with STT_URL set, voice input is transcribed by a self-hosted, OpenAI-compatible
@@ -222,6 +234,12 @@ func Load() *Config {
 			PerUserPerHour: envInt("STT_PER_USER_PER_HOUR", 60, 1, 100000),
 			TimeoutSeconds: envInt("STT_TIMEOUT_SECONDS", 120, 5, 3600),
 		},
+		Media: MediaConfig{
+			MaxImageMB: envInt("MEDIA_MAX_IMAGE_MB", 15, 1, 1000),
+			MaxAudioMB: envInt("MEDIA_MAX_AUDIO_MB", 50, 1, 2000),
+			QuotaMB:    envInt("MEDIA_QUOTA_MB", 0, 0, 10000000),
+			DemoMaxMB:  envInt("MEDIA_DEMO_MAX_MB", 3, 1, 100),
+		},
 		Legal: LegalTexts{
 			ImprintURL:     legalURL("LEGAL_IMPRINT_URL"),
 			ImprintContent: legalContent("LEGAL_IMPRINT_CONTENT"),

internal/storage/media.go

@@ -0,0 +1,119 @@
+package storage
+
+import (
+	"database/sql"
+	"errors"
+	"time"
+
+	"github.com/sandrodach/mindsift/internal/domain"
+)
+
+// Media files of notes (images, audio). The file lies in $DATA_DIR/media/<docID>/<id><ext>; a block
+// points to it through its content, e.g. "![Beschriftung](media:med_…)", so the reference travels with
+// the normal note sync, undo and conflict handling. A file is kept as long as any block (also deleted
+// ones still in the log or a note in the trash) mentions it; CompactMedia removes the rest.
+
+type Media struct {
+	ID        string `json:"id"`
+	DocID     string `json:"docId"`
+	OwnerID   string `json:"ownerId"`
+	Kind      string `json:"kind"` // image | audio
+	Mime      string `json:"mime"`
+	Size      int64  `json:"size"`
+	SourceURL string `json:"sourceUrl,omitempty"` // copied from this address (external image)
+	CreatedAt string `json:"createdAt"`
+}
+
+var ErrMediaNotFound = errors.New("Datei nicht gefunden")
+
+func (s *Store) migrateMedia() error {
+	return s.execInTx(
+		stmt(`CREATE TABLE IF NOT EXISTS media (
+			id TEXT PRIMARY KEY,
+			doc_id TEXT NOT NULL,
+			owner_id TEXT NOT NULL,
+			kind TEXT NOT NULL,
+			mime TEXT NOT NULL,
+			size INTEGER NOT NULL DEFAULT 0,
+			source_url TEXT NOT NULL DEFAULT '',
+			created_at TEXT NOT NULL
+		)`),
+		stmt(`CREATE INDEX IF NOT EXISTS idx_media_doc ON media(doc_id)`),
+		stmt(`CREATE INDEX IF NOT EXISTS idx_media_owner ON media(owner_id)`),
+	)
+}
+
+func (s *Store) CreateMedia(docID, ownerID, kind, mime string, size int64, sourceURL string) (*Media, error) {
+	m := &Media{ID: domain.NewID("med"), DocID: docID, OwnerID: ownerID, Kind: kind, Mime: mime, Size: size,
+		SourceURL: sourceURL, CreatedAt: nowUTC()}
+	_, err := s.db.Exec(`INSERT INTO media (id, doc_id, owner_id, kind, mime, size, source_url, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
+		m.ID, m.DocID, m.OwnerID, m.Kind, m.Mime, m.Size, m.SourceURL, m.CreatedAt)
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+func (s *Store) GetMedia(id string) (*Media, error) {
+	var m Media
+	err := s.db.QueryRow(`SELECT id, doc_id, owner_id, kind, mime, size, source_url, created_at FROM media WHERE id = ?`, id).
+		Scan(&m.ID, &m.DocID, &m.OwnerID, &m.Kind, &m.Mime, &m.Size, &m.SourceURL, &m.CreatedAt)
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, ErrMediaNotFound
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &m, nil
+}
+
+// DeleteMediaRow forgets a file (the caller removes it from disk).
+func (s *Store) DeleteMediaRow(id string) error {
+	_, err := s.db.Exec(`DELETE FROM media WHERE id = ?`, id)
+	return err
+}
+
+// MediaUsage is the stored size of all files the user uploaded.
+func (s *Store) MediaUsage(ownerID string) (int64, error) {
+	var n sql.NullInt64
+	err := s.db.QueryRow(`SELECT SUM(size) FROM media WHERE owner_id = ?`, ownerID).Scan(&n)
+	return n.Int64, err
+}
+
+// MediaReferencedIn lists the notes whose blocks (deleted ones included) point to the file. A block
+// copied into another note keeps working there.
+func (s *Store) MediaReferencedIn(id string) ([]string, error) {
+	rows, err := s.db.Query(`SELECT DISTINCT document_id FROM blocks WHERE instr(content, ?) > 0`, "media:"+id)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var docs []string
+	for rows.Next() {
+		var d string
+		if rows.Scan(&d) == nil {
+			docs = append(docs, d)
+		}
+	}
+	return docs, rows.Err()
+}
+
+// UnreferencedMedia returns files older than the grace time that no block mentions any more. The grace
+// time covers uploads whose block has not reached the server yet (offline, slow sync).
+func (s *Store) UnreferencedMedia(olderThan time.Time) ([]Media, error) {
+	rows, err := s.db.Query(`SELECT id, doc_id, owner_id, kind, mime, size, source_url, created_at FROM media m
+		WHERE created_at < ? AND NOT EXISTS (SELECT 1 FROM blocks b WHERE instr(b.content, 'media:' || m.id) > 0)`,
+		olderThan.UTC().Format(time.RFC3339))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []Media
+	for rows.Next() {
+		var m Media
+		if rows.Scan(&m.ID, &m.DocID, &m.OwnerID, &m.Kind, &m.Mime, &m.Size, &m.SourceURL, &m.CreatedAt) == nil {
+			out = append(out, m)
+		}
+	}
+	return out, rows.Err()
+}

internal/storage/migrations.go

@@ -25,6 +25,7 @@ type migration struct {
 var migrations = []migration{
 	{3, "Basis-Schema v0.4.1", (*Store).migrateBaseline},
 	{4, "Sitzungen", (*Store).migrateSessions},
+	{5, "Medien", (*Store).migrateMedia},
 }
 
 func (s *Store) migrate() error {