feat(engine,producer,cli): verify video comps via deferred DE init + capture p50 (#2015)

* feat(engine,producer,cli): verify video comps via deferred DE init + capture p50

Closes the two biggest gaps in the first day of v0.7.38 wild data: 88% of
drawElement renders (video comps initialized via probe sessions) ran with
self-verification unarmed, and speedup was measurable on only 3 of 76 renders.

- Deferred drawElement init: probe sessions initialize before video
  extraction, so they have no frame injector — ground-truth screenshots
  would capture black <video> boxes, and verification skipped the whole
  comp. DE init now stops after the gates for injector-less video comps
  (deInitDeferred; autoAlpha flag retracted in case no path completes it)
  and completeDeferredDrawElementInit finishes verification + canvas
  injection + worker-encode at capture time, once
  prepareCaptureSessionForReuse has attached the injector. Validated
  end-to-end: a probe-path video comp now arms 4 ground-truth frames with
  real video pixels (3x inf + 64.7dB) and renders drawElement verified.
- capture_p50_ms: per-frame capture durations are sampled
  (capturePerf.frameMs; batch frames get the batch mean) and the median
  ships as CapturePerfSummary.p50TotalMs -> RenderPerfSummary.captureP50Ms
  -> render_complete capture_p50_ms. Unlike capture_avg_ms it is immune
  to first-frame warmup and stage-setup amortization — smoke: avg 15ms vs
  p50 8ms on the same render, p50 matching the measured steady-state
  floor. Dashboard speedup tiles can drop their frame-count floor once
  this ships.
- video_count on render_complete: segments speedup by video-injection
  comps (whose per-frame gain is legitimately lower) vs pure-graphics.

Canary suite 7/7; engine suite 905 passed (1 pre-existing upstream
failure); tsc/oxlint/oxfmt clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(producer): complete deferred drawElement init on the disk capture path

Review (miga): a probe-initialized video comp falling back to the disk path
kept deInitDeferred and silently stayed in screenshot mode — a regression
for PRODUCER_EXPERIMENTAL_FAST_CAPTURE=true renders that previously ran
drawElement there. Complete the deferred init on the sequential disk path
under the same explicit-opt-in test the orchestrator clamp uses; default-on
renders stay on the screenshot baseline (this path has no drain-time
self-verification, per the #1998 confinement rule).

Validated: video comp + PRODUCER_ENABLE_STREAMING_ENCODE=false + explicit
opt-in logs "(deferred drawElement init)" completion on capture_disk and
renders correct video pixels.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/cli/src/commands/render.ts

@@ -1684,6 +1684,8 @@ function trackRenderMetrics(
     totalFrames: perf?.totalFrames,
     speedRatio,
     captureAvgMs: perf?.captureAvgMs,
+    captureP50Ms: perf?.captureP50Ms,
+    videoCount: perf?.videoCount,
     capturePeakMs: perf?.capturePeakMs,
     tmpPeakBytes: perf?.tmpPeakBytes,
     stageCompileMs: stages.compileMs,

packages/cli/src/telemetry/events.ts

@@ -143,6 +143,10 @@ export function trackRenderComplete(
     // Processing efficiency
     speedRatio?: number;
     captureAvgMs?: number;
+    /** Warmup-robust per-frame capture median (basis for speedup estimates). */
+    captureP50Ms?: number;
+    /** <video> element count (speedup segmentation: injection comps read lower). */
+    videoCount?: number;
     capturePeakMs?: number;
     // Resource usage
     peakMemoryMb?: number;
@@ -211,6 +215,8 @@ export function trackRenderComplete(
       total_frames: props.totalFrames,
       speed_ratio: props.speedRatio,
       capture_avg_ms: props.captureAvgMs,
+      capture_p50_ms: props.captureP50Ms,
+      video_count: props.videoCount,
       capture_peak_ms: props.capturePeakMs,
       peak_memory_mb: props.peakMemoryMb,
       memory_free_mb: props.memoryFreeMb,