feat: add MinIO presign endpoints to scraper API and SvelteKit presign helper

scraper/internal/server/server.go

@@ -115,6 +115,9 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 	mux.HandleFunc("GET /api/progress", s.handleGetProgress)
 	mux.HandleFunc("POST /api/progress/{slug}", s.handleSetProgress)
 	mux.HandleFunc("DELETE /api/progress/{slug}", s.handleDeleteProgress)
+	// Presigned URL API (for SvelteKit UI)
+	mux.HandleFunc("GET /api/presign/chapter/{slug}/{n}", s.handlePresignChapter)
+	mux.HandleFunc("GET /api/presign/audio/{slug}/{n}", s.handlePresignAudio)
 	// UI routes
 	mux.HandleFunc("GET /", s.handleHome)
 	mux.HandleFunc("GET /scrape", s.handleScrape)
@@ -526,6 +529,64 @@ func (s *Server) handleAudioProxy(w http.ResponseWriter, r *http.Request) {
 	_, _ = io.Copy(w, resp.Body)
 }
 
+// ─── Presigned URL handlers ───────────────────────────────────────────────────
+
+// handlePresignChapter handles GET /api/presign/chapter/{slug}/{n}.
+// Returns a short-lived presigned MinIO URL for the chapter markdown object.
+// The SvelteKit server uses this to fetch chapter content server-side.
+func (s *Server) handlePresignChapter(w http.ResponseWriter, r *http.Request) {
+	slug := r.PathValue("slug")
+	n, err := strconv.Atoi(r.PathValue("n"))
+	if err != nil || n < 1 || slug == "" {
+		http.Error(w, `{"error":"invalid params"}`, http.StatusBadRequest)
+		return
+	}
+
+	url, err := s.store.PresignChapter(r.Context(), slug, n, 15*time.Minute)
+	if err != nil {
+		s.log.Error("presign chapter failed", "slug", slug, "n", n, "err", err)
+		http.Error(w, `{"error":"presign failed"}`, http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]string{"url": url})
+}
+
+// handlePresignAudio handles GET /api/presign/audio/{slug}/{n}.
+// Returns a presigned MinIO URL for the audio object (if it has been generated).
+// Query params: voice, speed (optional, defaults to server defaults).
+func (s *Server) handlePresignAudio(w http.ResponseWriter, r *http.Request) {
+	slug := r.PathValue("slug")
+	n, err := strconv.Atoi(r.PathValue("n"))
+	if err != nil || n < 1 || slug == "" {
+		http.Error(w, `{"error":"invalid params"}`, http.StatusBadRequest)
+		return
+	}
+
+	voice := r.URL.Query().Get("voice")
+	if voice == "" {
+		voice = s.kokoroVoice
+	}
+	speed := 1.0
+	if sv := r.URL.Query().Get("speed"); sv != "" {
+		if v, err := strconv.ParseFloat(sv, 64); err == nil && v > 0 {
+			speed = v
+		}
+	}
+
+	key := s.store.AudioObjectKey(slug, n, voice, speed)
+	url, err := s.store.PresignAudio(r.Context(), key, 1*time.Hour)
+	if err != nil {
+		s.log.Error("presign audio failed", "slug", slug, "n", n, "err", err)
+		http.Error(w, `{"error":"presign failed"}`, http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]string{"url": url})
+}
+
 func (s *Server) handleScrapeCatalogue(w http.ResponseWriter, r *http.Request) {
 	cfg := s.oCfg
 	cfg.SingleBookURL = "" // full catalogue