fix: use playback selector in MediaPanel

apps/web/app/components/MediaPanel.tsx

@@ -2,6 +2,8 @@
 
 import { useEffect, useMemo, useState } from "react";
 
+import { pickVideoPlaybackVariant } from "../lib/playback";
+
 type Asset = {
   id: string;
   media_type: "image" | "video";
@@ -25,6 +27,7 @@ type SignedUrlResponse = {
 
 type PreviewUrlState = Record<string, string | undefined>;
 type VideoPlaybackVariant = { kind: "original" } | { kind: "video_mp4"; size: 720 };
+type VariantsResponse = Array<{ kind: string; size: number; key: string }>;
 
 function startOfDayUtc(iso: string) {
   const d = new Date(iso);
@@ -125,12 +128,32 @@ export function MediaPanel(props: { selectedDayIso: string | null }) {
     assetId: string,
   ): Promise<{ url: string; variant: VideoPlaybackVariant }> {
     try {
-      const url = await loadSignedUrl(assetId, "video_mp4_720");
-      return { url, variant: { kind: "video_mp4", size: 720 } };
+      const res = await fetch(`/api/assets/${assetId}/variants`, {
+        cache: "no-store",
+      });
+      if (!res.ok) throw new Error(`variants_fetch_failed:${res.status}`);
+      const variants = (await res.json()) as VariantsResponse;
+      const picked = pickVideoPlaybackVariant({
+        originalMimeType: null,
+        variants: variants
+          .filter((variant) => variant.kind === "video_mp4")
+          .map((variant) => ({
+            kind: "video_mp4",
+            size: variant.size,
+            key: variant.key,
+          })),
+      });
+
+      if (picked?.kind === "video_mp4") {
+        const url = await loadSignedUrl(assetId, "video_mp4_720");
+        return { url, variant: { kind: "video_mp4", size: 720 } };
+      }
     } catch {
-      const url = await loadSignedUrl(assetId, "original");
-      return { url, variant: { kind: "original" } };
+      // fall through to original
     }
+
+    const url = await loadSignedUrl(assetId, "original");
+    return { url, variant: { kind: "original" } };
   }
 
   async function openViewer(asset: Asset) {

apps/web/app/lib/playback.ts

@@ -9,14 +9,14 @@ type PlaybackInput = {
   variants: Variant[];
 };
 
-export function pickVideoPlaybackVariant(input: PlaybackInput):
-  | { kind: "video_mp4"; size: number }
-  | { kind: "original" } {
+export function pickVideoPlaybackVariant(
+  input: PlaybackInput,
+): { kind: "video_mp4"; size: number } | null {
   const mp4Variant = input.variants.find(
     (variant) => variant.kind === "video_mp4" && variant.size === 720,
   );
   if (mp4Variant) {
     return { kind: "video_mp4", size: mp4Variant.size };
   }
-  return { kind: "original" };
+  return null;
 }

apps/web/src/__tests__/prefer-derived.test.ts

@@ -9,10 +9,10 @@ test("prefer mp4 derived over original", () => {
   expect(picked).toEqual({ kind: "video_mp4", size: 720 });
 });
 
-test("falls back to original when no derived", () => {
+test("returns null when no mp4 variants", () => {
   const picked = pickVideoPlaybackVariant({
     originalMimeType: "video/x-matroska",
     variants: [],
   });
-  expect(picked).toEqual({ kind: "original" });
+  expect(picked).toBeNull();
 });