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

scraper/internal/storage/hybrid.go

@@ -222,6 +222,16 @@ func (h *HybridStore) AudioObjectKey(slug string, n int, voice string, speed flo
 	return AudioObjectKey(slug, n, voice, speed)
 }
 
+// ─── Presigned URLs ───────────────────────────────────────────────────────────
+
+func (h *HybridStore) PresignChapter(ctx context.Context, slug string, n int, expires time.Duration) (string, error) {
+	return h.minio.PresignChapter(ctx, slug, 0, n, expires)
+}
+
+func (h *HybridStore) PresignAudio(ctx context.Context, key string, expires time.Duration) (string, error) {
+	return h.minio.PresignAudio(ctx, key, expires)
+}
+
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
 func recToBookMeta(rec map[string]interface{}) scraper.BookMeta {

scraper/internal/storage/minio.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"strings"
+	"time"
 
 	"github.com/minio/minio-go/v7"
 	"github.com/minio/minio-go/v7/pkg/credentials"
@@ -165,6 +166,29 @@ func (m *MinioClient) AudioExists(ctx context.Context, key string) bool {
 	return err == nil
 }
 
+// ─── Presigned URLs ───────────────────────────────────────────────────────────
+
+// PresignChapter returns a presigned GET URL for a chapter object, valid for
+// the given duration. The URL is signed with the MinIO credentials and can be
+// fetched directly by the browser without authentication.
+func (m *MinioClient) PresignChapter(ctx context.Context, slug string, vol, n int, expires time.Duration) (string, error) {
+	key := chapterKey(slug, vol, n)
+	u, err := m.c.PresignedGetObject(ctx, m.cfg.BucketChapters, key, expires, nil)
+	if err != nil {
+		return "", fmt.Errorf("minio: presign chapter %s: %w", key, err)
+	}
+	return u.String(), nil
+}
+
+// PresignAudio returns a presigned GET URL for an audio object.
+func (m *MinioClient) PresignAudio(ctx context.Context, key string, expires time.Duration) (string, error) {
+	u, err := m.c.PresignedGetObject(ctx, m.cfg.BucketAudio, key, expires, nil)
+	if err != nil {
+		return "", fmt.Errorf("minio: presign audio %s: %w", key, err)
+	}
+	return u.String(), nil
+}
+
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
 // sanitiseVoice converts a voice name to a filename-safe string.

scraper/internal/storage/store.go

@@ -121,4 +121,12 @@ type Store interface {
 
 	// AudioObjectKey returns the MinIO object key for a cached audio file.
 	AudioObjectKey(slug string, n int, voice string, speed float64) string
+
+	// ── Presigned URLs ─────────────────────────────────────────────────────
+
+	// PresignChapter returns a presigned GET URL for a chapter markdown object.
+	PresignChapter(ctx context.Context, slug string, n int, expires time.Duration) (string, error)
+
+	// PresignAudio returns a presigned GET URL for an audio object.
+	PresignAudio(ctx context.Context, key string, expires time.Duration) (string, error)
 }

ui/src/lib/server/minio.ts

@@ -0,0 +1,67 @@
+/**
+ * Server-side MinIO presign helper.
+ * Calls the scraper API to get presigned URLs, then optionally rewrites
+ * the MinIO host to the public-facing URL for browser use.
+ *
+ * Never import this from client-side code.
+ */
+
+import { env } from '$env/dynamic/private';
+import { env as pubEnv } from '$env/dynamic/public';
+
+const SCRAPER_URL = env.SCRAPER_API_URL ?? 'http://localhost:8080';
+// Public MinIO URL — used to rewrite presigned URLs so the browser can reach MinIO directly.
+// In docker-compose this would differ from the internal endpoint.
+const MINIO_PUBLIC_URL = pubEnv.PUBLIC_MINIO_PUBLIC_URL ?? 'http://localhost:9000';
+
+/**
+ * Rewrites the MinIO host in a presigned URL to the public-facing URL.
+ * The presigned URL is signed against the internal endpoint (e.g. minio:9000),
+ * but the browser needs the public URL (e.g. localhost:9000 in dev, or a CDN in prod).
+ * Rewriting the host preserves all query params (signature, expiry, etc).
+ */
+function rewriteHost(presignedUrl: string): string {
+	try {
+		const u = new URL(presignedUrl);
+		const pub = new URL(MINIO_PUBLIC_URL);
+		u.protocol = pub.protocol;
+		u.hostname = pub.hostname;
+		u.port = pub.port;
+		return u.toString();
+	} catch {
+		return presignedUrl;
+	}
+}
+
+/**
+ * Returns a presigned URL for a chapter markdown file.
+ * URL is valid for ~15 minutes (set by the scraper).
+ * The returned URL points to the public MinIO endpoint and can be used
+ * server-side (in a +page.server.ts load function) to fetch the markdown content.
+ */
+export async function presignChapter(slug: string, n: number): Promise<string> {
+	const res = await fetch(`${SCRAPER_URL}/api/presign/chapter/${slug}/${n}`);
+	if (!res.ok) throw new Error(`presign chapter ${slug}/${n}: ${res.status}`);
+	const data = (await res.json()) as { url: string };
+	return rewriteHost(data.url);
+}
+
+/**
+ * Returns a presigned URL for an audio file.
+ * URL is valid for ~1 hour. The URL is returned to the browser for direct streaming.
+ */
+export async function presignAudio(
+	slug: string,
+	n: number,
+	voice?: string,
+	speed?: number
+): Promise<string> {
+	const params = new URLSearchParams();
+	if (voice) params.set('voice', voice);
+	if (speed) params.set('speed', String(speed));
+	const qs = params.toString() ? `?${params.toString()}` : '';
+	const res = await fetch(`${SCRAPER_URL}/api/presign/audio/${slug}/${n}${qs}`);
+	if (!res.ok) throw new Error(`presign audio ${slug}/${n}: ${res.status}`);
+	const data = (await res.json()) as { url: string };
+	return rewriteHost(data.url);
+}