fix(engine): bucket gpu_renderer + cover the failure cohort (review)

Three review findings on the win32 drawElement PR:

1. gpu_renderer shipped the raw UNMASKED_RENDERER_WEBGL string — unbounded,
   driver-authored, GPU-model-specific, and |-joined across parallel
   sessions, i.e. high cardinality by construction, against this file's own
   convention of sanitizing engine-sourced strings (deGateReason is a
   bucket; error messages go through redactTelemetryString). Now bucketed at
   the source by classifyGpuRenderer to <backend>/<vendor>
   (metal/apple, d3d11/nvidia, swiftshader/other, ...), which is the whole
   analytic signal the win32 rollout needs and nothing else. The raw string
   never leaves the engine.

2. gpu_renderer reached render_complete only, so a crashed render — the
   cohort the field exists to attribute — carried no backend. It now rides
   RenderCaptureObservability (deGpuRenderer, sourced from the live probe
   session like the de_* counters), so both render_complete and
   render_error carry it and a hard failure still reports its GPU backend.
   On render_complete the perfSummary value still wins by spread order.

3. Restore the fallow-ignore-next-line suppression above
   __resetDeParallelRouterTrialStateForTests: CLI test files are not fallow
   entry points, so removing it fails the CI dead-code audit (local
   pre-commit passed only because of its changed-file scope).

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

packages/cli/src/telemetry/events.ts

@@ -51,6 +51,7 @@ export interface RenderObservabilityTelemetryPayload {
   captureDeWorkerInversion?: string;
   captureDePreInversionWorkers?: number;
   captureDeParallelRouter?: string;
+  captureDeGpuRenderer?: string;
   captureDePreRouterWorkers?: number;
   captureDeSelfVerifyFallback?: boolean;
   captureDeFallbackReason?: string;
@@ -108,6 +109,7 @@ function renderObservabilityEventProperties(props: RenderObservabilityTelemetryP
     de_worker_inversion: props.captureDeWorkerInversion,
     de_pre_inversion_workers: props.captureDePreInversionWorkers,
     de_parallel_router: props.captureDeParallelRouter,
+    gpu_renderer: props.captureDeGpuRenderer,
     de_pre_router_workers: props.captureDePreRouterWorkers,
     de_self_verify_fallback: props.captureDeSelfVerifyFallback,
     de_fallback_reason: props.captureDeFallbackReason,
@@ -183,7 +185,7 @@ export function trackRenderComplete(
     deParallelRouter?: string;
     dePreRouterWorkers?: number;
     deGateReason?: string;
-    /** Raw WebGL renderer string from DE session init (ANGLE backend + GPU vendor). */
+    /** Low-cardinality GPU bucket from DE session init (`<backend>/<vendor>`, e.g. `d3d11/nvidia`). */
     gpuRenderer?: string;
     deWorkerEncode?: boolean;
     deVerifyArmed?: number;
@@ -377,6 +379,10 @@ export function trackRenderError(
       elapsed_ms: props.elapsedMs,
       peak_memory_mb: props.peakMemoryMb,
       memory_free_mb: props.memoryFreeMb,
+      // gpu_renderer arrives via renderObservabilityEventProperties below:
+      // on the failure path perfSummary is never built, so live capture
+      // observability is the only source. Backend attribution matters MOST
+      // here — a win32 D3D11 crash is what the rollout is watching for.
       ...renderObservabilityEventProperties(props),
     },
     props.distinctId,

packages/cli/src/telemetry/renderObservability.ts

@@ -43,6 +43,7 @@ export function renderObservabilityTelemetryPayload(
     captureDeWorkerInversion: capture.deWorkerInversion,
     captureDePreInversionWorkers: capture.dePreInversionWorkers,
     captureDeParallelRouter: capture.deParallelRouter,
+    captureDeGpuRenderer: capture.deGpuRenderer,
     captureDePreRouterWorkers: capture.dePreRouterWorkers,
     captureDeSelfVerifyFallback: capture.deSelfVerifyFallback,
     captureDeFallbackReason: capture.deFallbackReason,