feat(producer): surface init telemetry from parallel workers — the band's missing motion axis

The routing surface the short-comp benchmarks validated is (motion x DOM
size x frames). After the baseline release, fleet telemetry carries DOM
size (composition_element_count) and frames on every render — but the
motion proxy, observability_init_tween_count, has 0% coverage on the
exact renders the band routes: parallel workers' console buffers (and so
the [FrameCapture:INIT] line the summary parses) only propagate to the
orchestrator on FAILURE. Single-worker screenshot renders report it;
the multi-worker clamp bucket never does. Verified against 7d of fleet
data: 35k screenshot renders carry tween counts, 0 of 9,600 band renders.

Fix rides the one channel parallel workers already return on success —
the per-worker CapturePerfSummary. Sessions record initTelemetry on
every init path; the perf summary now carries it; the orchestrator
max-merges across workers (same multi-session semantics the console
parser uses) and feeds it to the observability summary as a structured
fallback, console lines still refining when present.

With this, every band render carries full coordinates — (elements,
tweens, frames, path, speed) — which buys two reads: regressing wild DE
speed against element count on the existing 900+ inversions validates
the bench's 0.50ms/element slope BEFORE the routing flip, and any
post-flip misroute can be reproduced locally by feeding its telemetry
row straight into gen-crossover-comp's knobs (--movers ~ tween count,
--static ~ element count) and re-benching.

(Also drops a now-stale fallow suppression in render.ts — the test-only
reset export it guarded gained real test importers, so the issue it
suppressed no longer exists and the gate flags the leftover.)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/producer/src/services/render/observability.test.ts

@@ -407,3 +407,34 @@ describe("RenderObservabilityRecorder", () => {
     );
   });
 });
+
+describe("init observability fallback (parallel workers)", () => {
+  const makeRecorder = () =>
+    new RenderObservabilityRecorder({ renderJobId: "render-par", pipelineStartMs: Date.now() });
+
+  it("uses the structured fallback when the console has no INIT line — the parallel success path", () => {
+    const summary = makeRecorder().summary({
+      lastBrowserConsole: ["[FrameCapture:NAV] page.goto start"],
+      capture: { forceScreenshot: false, captureMode: "screenshot" },
+      initFallback: { initDurationMs: 850, tweenCount: 1200 },
+    });
+    expect(summary.init).toEqual({ initDurationMs: 850, tweenCount: 1200 });
+  });
+
+  it("max-merges console INIT lines over the fallback, matching multi-session semantics", () => {
+    const summary = makeRecorder().summary({
+      lastBrowserConsole: ["[FrameCapture:INIT] complete initDurationMs=1234 tweenCount=42"],
+      capture: { forceScreenshot: false, captureMode: "screenshot" },
+      initFallback: { initDurationMs: 850, tweenCount: 1200 },
+    });
+    expect(summary.init).toEqual({ initDurationMs: 1234, tweenCount: 1200 });
+  });
+
+  it("stays undefined when neither source has anything", () => {
+    const summary = makeRecorder().summary({
+      lastBrowserConsole: [],
+      capture: { forceScreenshot: false, captureMode: "screenshot" },
+    });
+    expect(summary.init).toBeUndefined();
+  });
+});

packages/producer/src/services/render/observability.ts

@@ -270,20 +270,26 @@ function readUnsignedIntAfter(line: string, prefix: string): number | undefined
   return digits > 0 ? value : undefined;
 }
 
-function summarizeInitObservability(lines: string[]): RenderInitObservability | undefined {
-  let initDurationMs: number | undefined;
-  let tweenCount: number | undefined;
+/** Max of two optional readings — multiple worker/session INIT records can appear; keep the worst. */
+function maxReading(current: number | undefined, next: number | undefined): number | undefined {
+  if (next === undefined) return current;
+  return current === undefined ? next : Math.max(current, next);
+}
+
+function summarizeInitObservability(
+  lines: string[],
+  fallback?: RenderInitObservability,
+): RenderInitObservability | undefined {
+  // Console parsing only sees THIS process's session buffer, so parallel
+  // workers' INIT lines never reach it — their init telemetry arrives
+  // structured via the per-worker perf summaries instead. Seed with that and
+  // let the console parse (same max semantics) refine it.
+  let initDurationMs: number | undefined = fallback?.initDurationMs;
+  let tweenCount: number | undefined = fallback?.tweenCount;
   for (const line of lines) {
     if (!line.includes("[FrameCapture:INIT]")) continue;
-    const duration = readUnsignedIntAfter(line, "initDurationMs=");
-    const tweens = readUnsignedIntAfter(line, "tweenCount=");
-    // Multiple worker/session INIT records can appear; keep the worst observed startup cost.
-    if (duration !== undefined) {
-      initDurationMs = initDurationMs === undefined ? duration : Math.max(initDurationMs, duration);
-    }
-    if (tweens !== undefined) {
-      tweenCount = tweenCount === undefined ? tweens : Math.max(tweenCount, tweens);
-    }
+    initDurationMs = maxReading(initDurationMs, readUnsignedIntAfter(line, "initDurationMs="));
+    tweenCount = maxReading(tweenCount, readUnsignedIntAfter(line, "tweenCount="));
   }
   if (initDurationMs === undefined && tweenCount === undefined) return undefined;
   return { initDurationMs, tweenCount };
@@ -402,6 +408,8 @@ export class RenderObservabilityRecorder {
   summary(input: {
     lastBrowserConsole: string[];
     capture: RenderCaptureObservability;
+    /** Structured init telemetry from per-worker perf summaries — the only success-path channel parallel workers have (their console buffers propagate on failure only). */
+    initFallback?: RenderInitObservability;
     extraction?: RenderExtractionObservability;
     compositionHash?: string;
   }): RenderObservabilitySummary {
@@ -416,7 +424,7 @@ export class RenderObservabilityRecorder {
       browserDiagnostics: summarizeBrowserDiagnostics(input.lastBrowserConsole),
       capture: { ...input.capture },
       extraction: input.extraction ? { ...input.extraction } : undefined,
-      init: summarizeInitObservability(input.lastBrowserConsole),
+      init: summarizeInitObservability(input.lastBrowserConsole, input.initFallback),
     };
   }
 

packages/producer/src/services/renderOrchestrator.test.ts

@@ -36,6 +36,7 @@ import {
   shouldRetryViaPinnedFallback,
   countElementTags,
   envInt,
+  mergeWorkerInitObservability,
   shouldPreferParallelDrawElement,
   shouldPreferSingleWorkerDrawElement,
   shouldStreamParallelCapture,
@@ -1761,6 +1762,23 @@ describe("shouldPreferSingleWorkerDrawElement (DE priority inversion)", () => {
     });
   });
 
+  describe("mergeWorkerInitObservability", () => {
+    it("max-merges across workers and ignores workers that reported nothing", () => {
+      expect(
+        mergeWorkerInitObservability([
+          { initDurationMs: 400, initTweenCount: 900 },
+          {},
+          { initDurationMs: 1250, initTweenCount: 880 },
+        ]),
+      ).toEqual({ initDurationMs: 1250, tweenCount: 900 });
+    });
+
+    it("returns undefined when no worker reported — summary.init must stay absent, not zeroed", () => {
+      expect(mergeWorkerInitObservability([])).toBeUndefined();
+      expect(mergeWorkerInitObservability([{}, {}])).toBeUndefined();
+    });
+  });
+
   describe("countElementTags", () => {
     it("counts closing tags", () => {
       expect(countElementTags("<div><span>a</span></div>")).toBe(2);

packages/producer/src/services/renderOrchestrator.ts

@@ -1266,6 +1266,35 @@ export function countElementTags(html: string): number {
   return matches === null ? 0 : matches.length;
 }
 
+/**
+ * Max-merge init telemetry across per-worker capture perf summaries — the
+ * success-path channel for PARALLEL renders, whose worker console buffers
+ * (and so the `[FrameCapture:INIT]` line) only propagate on failure. Max
+ * matches summarizeInitObservability's own multi-session semantics: keep the
+ * worst observed startup cost, and tween count is per-composition so any
+ * worker's reading is the reading.
+ */
+export function mergeWorkerInitObservability(
+  perfs: ReadonlyArray<{ initDurationMs?: number; initTweenCount?: number }>,
+): { initDurationMs?: number; tweenCount?: number } | undefined {
+  let initDurationMs: number | undefined;
+  let tweenCount: number | undefined;
+  for (const perf of perfs) {
+    if (perf.initDurationMs !== undefined) {
+      initDurationMs =
+        initDurationMs === undefined
+          ? perf.initDurationMs
+          : Math.max(initDurationMs, perf.initDurationMs);
+    }
+    if (perf.initTweenCount !== undefined) {
+      tweenCount =
+        tweenCount === undefined ? perf.initTweenCount : Math.max(tweenCount, perf.initTweenCount);
+    }
+  }
+  if (initDurationMs === undefined && tweenCount === undefined) return undefined;
+  return { initDurationMs, tweenCount };
+}
+
 /**
  * DE priority inversion predicate: should an AUTO-resolved multi-worker render
  * drop to single-worker verified drawElement streaming?
@@ -3600,6 +3629,7 @@ async function executeRenderPipeline(input: {
     const observabilitySummary = observability.summary({
       lastBrowserConsole,
       capture: captureObservability,
+      initFallback: mergeWorkerInitObservability(dedupPerfs),
       extraction: extractionObservability,
       compositionHash,
     });
@@ -3761,6 +3791,7 @@ async function executeRenderPipeline(input: {
     const observabilitySummary = observability.summary({
       lastBrowserConsole,
       capture: captureObservability,
+      initFallback: mergeWorkerInitObservability(dedupPerfs),
       extraction: extractionObservability,
       compositionHash,
     });