perf(producer): skip wasted Chrome media work + injector page.evaluates during render

packages/core/src/runtime/media.ts

@@ -290,18 +290,33 @@ export function syncRuntimeMedia(params: {
       }
       const forceSync = !isPlayingVideo && params.forceSync && drift > 0.02;
       if (hardSync || strictSync || forceSync) {
-        try {
-          el.currentTime = relTime;
-        } catch (err) {
-          swallow("runtime.media.site2", err);
-        }
-        if (Math.abs(el.currentTime - relTime) > 0.5 && !seekLoadRetried.has(el)) {
-          seekLoadRetried.add(el);
-          el.load();
+        // Skip the per-tick seek (and the `el.load()` drift-recovery retry
+        // below) for `<video>` elements that have a sibling
+        // `<img id="__render_frame_<id>__">`. The sibling is created only
+        // by the producer's frame-injection pipeline during render — its
+        // presence means the visual is painted from the `<img>` and the
+        // `<video>` is `visibility: hidden`. Audio is mixed by ffmpeg from
+        // source files in `runAudioStage`, never via Chrome's in-browser
+        // audio path. So the `<video>`'s `currentTime` has no observable
+        // effect during render, and the per-tick set just kicks Chrome's
+        // media pipeline for nothing. Preview is unaffected (the sibling
+        // only exists during render).
+        const skipForInjectedVideo =
+          el.tagName === "VIDEO" && el.id && !!document.getElementById(`__render_frame_${el.id}__`);
+        if (!skipForInjectedVideo) {
           try {
             el.currentTime = relTime;
           } catch (err) {
-            swallow("runtime.media.site3", err);
+            swallow("runtime.media.site2", err);
+          }
+          if (Math.abs(el.currentTime - relTime) > 0.5 && !seekLoadRetried.has(el)) {
+            seekLoadRetried.add(el);
+            el.load();
+            try {
+              el.currentTime = relTime;
+            } catch (err) {
+              swallow("runtime.media.site3", err);
+            }
           }
         }
         playRequested.delete(el);