fix: revert flattenInnerRoot, use host-level authored-id + count-based rebind

Three changes to fix regression failures without breaking baselines:

1. Revert flattenInnerRoot in producer — use the original innerHTML
   inlining that preserves the existing DOM structure. Instead, set
   data-hf-authored-id on the HOST element so the scoped proxy can
   still rewrite #id selectors for sub-composition scripts.

2. Revert compiled.html baselines to main (no DOM structure changes).

3. Use timeline-count comparison instead of poll duration to decide
   whether to call __hfForceTimelineRebind. Compare timeline count
   before vs after the poll — rebind only when new timelines appeared
   during polling. This correctly identifies async compositions
   regardless of fetch speed, while leaving sync compositions
   untouched.

packages/engine/src/services/frameCapture.ts

@@ -365,10 +365,14 @@ async function pollSubCompositionTimelines(
     }
     return true;
   })()`;
-  const beforePoll = Date.now();
+  const timelinesBeforePoll = Number(
+    await page.evaluate(`Object.keys(window.__timelines || {}).length`),
+  );
   const ready = await pollPageExpression(page, expression, timeoutMs, intervalMs);
-  const pollDurationMs = Date.now() - beforePoll;
-  if (ready && pollDurationMs > intervalMs * 2) {
+  const timelinesAfterPoll = Number(
+    await page.evaluate(`Object.keys(window.__timelines || {}).length`),
+  );
+  if (ready && timelinesAfterPoll > timelinesBeforePoll) {
     await page.evaluate(`(function() {
       if (typeof window.__hfForceTimelineRebind === "function") {
         window.__hfForceTimelineRebind();

packages/producer/src/services/htmlCompiler.ts

@@ -21,10 +21,7 @@ import {
   type ResolvedDuration,
   type UnresolvedElement,
 } from "@hyperframes/core";
-import {
-  inlineSubCompositions as inlineSubCompositionsShared,
-  prepareFlattenedInnerRoot,
-} from "@hyperframes/core/compiler";
+import { inlineSubCompositions as inlineSubCompositionsShared } from "@hyperframes/core/compiler";
 import { extractMediaMetadata, extractAudioMetadata } from "../utils/ffprobe.js";
 import { isPathInside, toExternalAssetKey } from "../utils/paths.js";
 import {
@@ -577,11 +574,22 @@ function inlineSubCompositions(
         return compHtml;
       },
       parseHtml: (htmlStr: string) => parseHTML(htmlStr).document as unknown as Document,
-      flattenInnerRoot: prepareFlattenedInnerRoot as (innerRoot: Element) => Element,
       scriptErrorLabel: "[Compiler] Composition script failed",
     },
   );
 
+  // Set data-hf-authored-id on host elements so the scoped script proxy
+  // can rewrite #id selectors (e.g. #us-map → [data-hf-authored-id="us-map"]).
+  // Unlike flattenInnerRoot (which changes DOM structure and breaks baselines),
+  // this preserves the existing innerHTML-based inlining while enabling the
+  // authored-id selector contract.
+  for (const hostEl of hosts) {
+    const compId = hostEl.getAttribute("data-composition-id");
+    if (compId && !hostEl.getAttribute("data-hf-authored-id")) {
+      hostEl.setAttribute("data-hf-authored-id", compId);
+    }
+  }
+
   // Producer-specific: set explicit pixel dimensions on host elements so
   // children using width/height: 100% resolve correctly. The runtime does
   // this automatically but compiled HTML needs it inline.