feat: seek media particles and speed playback

Closes #79
Closes #80

js/src/features/particles/media-particle-view.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useRef, useState } from "react";
+import { forwardRef, useEffect, useImperativeHandle, useRef, useState } from "react";
 import type { Particle } from "@/api/types";
 import type { ParticlePath } from "@/lib/particle-path";
 import { useDownloadUrl } from "@/hooks/use-download-url";
@@ -12,6 +12,12 @@ import { ParticleAttachments } from "@/features/particles/particle-attachments";
 
 type MediaParticle = Extract<Particle, { type: "media" }>;
 
+export interface MediaParticleHandle {
+  /** Seek by delta. Returns true if seeked, false if at boundary (should navigate). */
+  seek: (deltaSec: number) => boolean;
+  setPlaybackRate: (rate: number) => void;
+}
+
 interface MediaParticleViewProps {
   particle: MediaParticle;
   streamPath: ParticlePath;
@@ -20,19 +26,34 @@ interface MediaParticleViewProps {
   onProgress?: (ratio: number) => void;
 }
 
-export function MediaParticleView({
+export const MediaParticleView = forwardRef<MediaParticleHandle, MediaParticleViewProps>(function MediaParticleView({
   particle,
   streamPath,
   paused,
   onEnded,
   onProgress,
-}: MediaParticleViewProps) {
+}, ref) {
   const { data: url, error } = useDownloadUrl(particle.properties.object_id);
   const { attachments } = useParticleAttachments(streamPath, particle.id);
 
   const videoRef = useRef<HTMLVideoElement>(null);
   const audioRef = useRef<HTMLAudioElement>(null);
   const isAudio = particle.properties.mime_type?.startsWith("audio/");
+
+  useImperativeHandle(ref, () => ({
+    seek(deltaSec: number) {
+      const el = isAudio ? audioRef.current : videoRef.current;
+      if (!el) return false;
+      if (deltaSec < 0 && el.currentTime < Math.abs(deltaSec)) return false;
+      if (deltaSec > 0 && el.duration - el.currentTime < deltaSec) return false;
+      el.currentTime = Math.max(0, Math.min(el.duration, el.currentTime + deltaSec));
+      return true;
+    },
+    setPlaybackRate(rate: number) {
+      const el = isAudio ? audioRef.current : videoRef.current;
+      if (el) el.playbackRate = rate;
+    },
+  }), [isAudio]);
   const [currentTime, setCurrentTime] = useState(0);
 
   const transcript = particle.properties.transcript;
@@ -140,4 +161,4 @@ export function MediaParticleView({
       {attachmentOverlay}
     </div>
   );
-}
+});

js/src/features/particles/stream-view.tsx

@@ -6,7 +6,7 @@ import type { Particle } from "@/api/types";
 import { parseParticlePath, particlePath, toFirestoreDocPath, type ParticlePath } from "@/lib/particle-path";
 import { ComposeOverlay } from "@/features/compose/compose-overlay";
 import { PlaybackPageIndicator } from "@/features/particles/playback-page-indicator";
-import { MediaParticleView } from "@/features/particles/media-particle-view";
+import { MediaParticleView, type MediaParticleHandle } from "@/features/particles/media-particle-view";
 import { TextParticleView } from "@/features/particles/text-particle-view";
 import { FallbackParticleView } from "@/features/particles/fallback-particle-view";
 import { Avatar, AvatarFallback, AvatarGroup } from "@/components/ui/avatar";
@@ -140,8 +140,11 @@ export function StreamView({ path, streamParticle }: StreamViewProps) {
     authedUser?.id,
   );
 
+  const mediaRef = useRef<MediaParticleHandle>(null);
+
   const [composeActive, setComposeActive] = useState(false);
   const [progress, setProgress] = useState(0);
+  const [fastPlayback, setFastPlayback] = useState(false);
 
   // Show/hide chrome on mouse activity (YouTube-style)
   const [showControls, setShowControls] = useState(true);
@@ -196,17 +199,23 @@ export function StreamView({ path, streamParticle }: StreamViewProps) {
         case "ArrowRight":
         case "ArrowDown":
           e.preventDefault();
-          next();
+          if (!mediaRef.current?.seek(10)) next();
           break;
         case "ArrowLeft":
         case "ArrowUp":
           e.preventDefault();
-          prev();
+          if (!mediaRef.current?.seek(-10)) prev();
           break;
         case " ":
           e.preventDefault();
           if (!e.repeat) pause();
           break;
+        case "Shift":
+          if (!e.repeat) {
+            mediaRef.current?.setPlaybackRate(1.5);
+            setFastPlayback(true);
+          }
+          break;
         case "Escape":
           e.preventDefault();
           navigate(`/${networkId}`);
@@ -230,6 +239,10 @@ export function StreamView({ path, streamParticle }: StreamViewProps) {
         e.preventDefault();
         resume();
       }
+      if (e.key === "Shift") {
+        mediaRef.current?.setPlaybackRate(1);
+        setFastPlayback(false);
+      }
     };
 
     window.addEventListener("keydown", handleKeyDown);
@@ -287,6 +300,7 @@ export function StreamView({ path, streamParticle }: StreamViewProps) {
       case "media":
         return (
           <MediaParticleView
+            ref={mediaRef}
             key={particle.id}
             particle={particle}
             streamPath={path}
@@ -333,6 +347,12 @@ export function StreamView({ path, streamParticle }: StreamViewProps) {
             onClick={handlePlaybackClick}
           >
             {renderParticle(currentParticle)}
+
+            {fastPlayback && (
+              <div className="pointer-events-none absolute right-4 top-14 z-20 rounded-full bg-black/50 px-2.5 py-1 text-xs font-medium text-white backdrop-blur-sm">
+                1.5x
+              </div>
+            )}
           </div>
         )}
       </div>