fix(lab): make recorded replay seek-safe

apps/control-station/test/recordedCameraBuffering.test.mjs

@@ -9,6 +9,8 @@ let fetchRecordedMediaArchive;
 let recordedMediaPresentationState;
 let recordedMediaSeekableCoverage;
 let recordedMediaFragmentUrl;
+let recordedMediaDecodeStartSequence;
+let recordedMediaSegmentAppendOrder;
 
 before(async () => {
   server = await createServer({
@@ -21,6 +23,8 @@ before(async () => {
     recordedMediaPresentationState,
     recordedMediaSeekableCoverage,
     recordedMediaFragmentUrl,
+    recordedMediaDecodeStartSequence,
+    recordedMediaSegmentAppendOrder,
   } = await server.ssrLoadModule("/src/components/RecordedFmp4Player.tsx"));
 });
 
@@ -29,6 +33,7 @@ after(async () => {
 });
 
 function fixture({ byteLength = 36_000_000_000 } = {}) {
+  const segmentCount = 1_501;
   const manifestUrl = "/api/v1/observation-sessions/session-1/media/camera-1/manifest";
   const generation = "a".repeat(64);
   const streamUrl = manifestUrl.replace(
@@ -36,7 +41,7 @@ function fixture({ byteLength = 36_000_000_000 } = {}) {
     `/epochs/1/recording.mp4?generation=${generation}`,
   );
   const manifest = {
-    schema_version: "missioncore.observation-recorded-media/v3",
+    schema_version: "missioncore.observation-recorded-media/v4",
     source_id: "recorded.camera.camera-1",
     generation_sha256: generation,
     byte_length: byteLength,
@@ -50,6 +55,12 @@ function fixture({ byteLength = 36_000_000_000 } = {}) {
       media_type: 'video/mp4; codecs="avc1.640028"',
       byte_length: byteLength,
       stream_url: streamUrl,
+      segment_count: segmentCount,
+      random_access_sequences: [1, 1491, 1501],
+      segment_end_times_seconds: Array.from(
+        { length: segmentCount },
+        (_value, index) => ((index + 1) * 36_000) / segmentCount,
+      ),
     }],
   };
   const source = {
@@ -92,6 +103,8 @@ test("multi-hour camera admission fetches only its compact generation-bound mani
   assert.deepEqual(requested, [source.manifestUrl]);
   assert.equal(archive.byteLength, 36_000_000_000);
   assert.equal(archive.manifest.epochs[0].streamUrl, streamUrl);
+  assert.equal(archive.manifest.epochs[0].segmentCount, 1_501);
+  assert.deepEqual(archive.manifest.epochs[0].randomAccessSequences, [1, 1491, 1501]);
 });
 
 test("first camera manifest request rejects a replaced generation", async () => {
@@ -154,8 +167,16 @@ test("recorded player keeps full-archive range fallback and uses bounded generat
   assert.match(source, /video\.src\s*=\s*descriptor\.streamUrl/);
   assert.doesNotMatch(source, /new Blob\(/);
   assert.match(source, /new MediaSource\(\)/);
-  assert.match(source, /segmentSequence \+ 36/);
+  assert.match(source, /RECORDED_MEDIA_SEGMENTS_AHEAD = 36/);
   assert.match(source, /pumpRecordedSegmentWindow/);
+  assert.match(source, /waitForRecordedVideoTarget/);
+  assert.match(source, /removeRecordedMediaRange/);
+
+  assert.equal(recordedMediaDecodeStartSequence([1, 1491, 1501], 1500), 1491);
+  assert.deepEqual(
+    recordedMediaSegmentAppendOrder(new Set([1491, 1492]), 1491, 1500),
+    [1493, 1494, 1495, 1496, 1497, 1498, 1499, 1500],
+  );
 
   const { manifest, generation } = fixture();
   const epoch = {
@@ -165,6 +186,9 @@ test("recorded player keeps full-archive range fallback and uses bounded generat
     mediaType: manifest.epochs[0].media_type,
     byteLength: manifest.epochs[0].byte_length,
     streamUrl: manifest.epochs[0].stream_url,
+    segmentCount: manifest.epochs[0].segment_count,
+    randomAccessSequences: manifest.epochs[0].random_access_sequences,
+    segmentEndTimesSeconds: manifest.epochs[0].segment_end_times_seconds,
   };
   assert.equal(
     recordedMediaFragmentUrl(epoch, generation, "init"),