feat: extract video module and add mode-switch fallback

static/player/video.ts

@@ -0,0 +1,36 @@
+import { state } from "./state";
+import { absoluteTimeFromDisplay, displayTimeFromAbsolute, invalidateBounds } from "./timeline";
+
+/**
+ * Force-loads a new video source and preserves playback position.
+ *
+ * Some browsers can be flaky when switching between HLS URLs while playing.
+ * Clearing `src` first ensures the media element fully resets before the new URL is set.
+ */
+export const loadVideoSource = (url: string): void => {
+  if (!url) return;
+
+  const wasPlaying = !state.video.paused;
+  const prevDisplayTime = displayTimeFromAbsolute(state.video.currentTime);
+
+  // Fully reset the element before setting a new source.
+  state.video.pause();
+  state.video.removeAttribute("src");
+  state.video.load();
+
+  state.video.src = url;
+  state.video.load();
+
+  // Try an eager seek; if metadata isn't ready yet, main.ts will restore via pendingSeekTime.
+  state.pendingSeekTime = prevDisplayTime;
+  if (state.video.readyState >= HTMLMediaElement.HAVE_METADATA) {
+    invalidateBounds();
+    state.video.currentTime = absoluteTimeFromDisplay(prevDisplayTime);
+    state.pendingSeekTime = null;
+  }
+
+  if (wasPlaying) {
+    state.video.play().catch(() => undefined);
+  }
+};
+