Function postTimeline

packages/core/src/runtime/init.ts:1809–1852

()

    return sig;
  };
  const postTimeline = () => {
    sanitizeCompositionDurationAttributes();
    applyCompositionSizing();
    applyClipLayout();
    // Post resolved stage size so the parent can scale the iframe container
    const stageSizeRootEl = resolveRootCompositionElement();
    if (stageSizeRootEl) {
      const w = parseDimensionPx(stageSizeRootEl.getAttribute("data-width"));
      const h = parseDimensionPx(stageSizeRootEl.getAttribute("data-height"));
      const width = w ? parseInt(w, 10) : 0;
      const height = h ? parseInt(h, 10) : 0;
      if (width > 0 && height > 0) {
        postRuntimeMessage({ source: "hf-preview", type: "stage-size", width, height });
      }
    }
    bindRootTimelineIfAvailable();
    const payload = collectRuntimeTimelinePayload({
      canonicalFps: state.canonicalFps,
    });
    window.__clipManifest = payload;

    const currentSignature = computeClipTreeSignature();
    if (clipTreeSignature !== currentSignature) {
      // The timed-element set changed — leaf/in-flow caches may be stale.
      invalidateTimedClipCaches();
    }
    if (!window.__clipTree || clipTreeSignature !== currentSignature) {
      const runtimeWindow = window as Window & {
        __timelines?: Record<string, RuntimeTimelineLike | undefined>;
      };
      window.__clipTree = createClipTree({
        startResolver: createRuntimeStartTimeResolver({
          timelineRegistry: runtimeWindow.__timelines ?? {},
          includeAuthoredTimingAttrs: true,
        }),
        timelineRegistry: runtimeWindow.__timelines ?? {},
        rootDuration: payload.durationInFrames / state.canonicalFps,
      });
      clipTreeSignature = currentSignature;
    }

    postRuntimeMessage(payload);
    scheduleRootStageLayoutDiagnostics();
  };

  const runAdapters = (method: "discover" | "pause" | "play", timeSeconds = 0) => {
    for (const adapter of state.deterministicAdapters) {