fix(producer): open a fresh segmented session when the probe has risk frames (#6434)

* fix(producer): open a fresh segmented session when the probe has risk frames

Since #6318 the gate-check probe is planned with deFrameFallback: true, so
it can carry deRiskFrames. The segmented stage reuses that probe for its
first session and captures every frame with captureFrameToBuffer, which
cannot hand a risk frame to a screenshot session: the first one throws
"frame needs screenshot capture, which this capture path cannot hand over"
and the segmented route has no drawElement catch, so the render fails.

Close such a probe and open a fresh segmented session instead; those are
created with deFrameFallback: false and keep the whole-render screenshot
fallback.

— Via

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* refactor(producer): name the risk-frame probe condition instead of commenting it

The comment ratchet does not allow a file's comment share to rise.

— Via

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

packages/producer/src/services/render/stages/captureSegmentedStage.test.ts

@@ -315,6 +315,37 @@ describe("runCaptureSegmentedStage", () => {
     });
   });
 
+  it("does not capture on a probe that left frames to a screenshot session", async () => {
+    closeCaptureSession.mockClear();
+    const probeSession = {
+      ...fakeStageInput({ totalFrames: 1 }).probeSession,
+      captureMode: "drawelement" as const,
+      workerEncodeEnabled: true,
+      deRiskFrames: new Set([2]),
+    };
+    const capturedOn = new Set<unknown>();
+    const captureFrame = mock(async (session: unknown) => {
+      capturedOn.add(session);
+      return { buffer: Buffer.alloc(1) };
+    });
+    const result = await runCaptureSegmentedStage({
+      ...fakeStageInput({ totalFrames: 6 }),
+      probeSession: probeSession as never,
+      segmentFrames: 3,
+      segmentDir: join(fixtureRoot, "risk-probe"),
+      deps: {
+        spawnEncoder: mock(async () => okEncoder()),
+        captureFrame,
+        concat: mock(async () => ({ success: true as const })),
+        closeSession: mock(async () => {}),
+        removeFile: () => {},
+      },
+    });
+    expect(result.success).toBe(true);
+    expect(capturedOn.has(probeSession)).toBe(false);
+    expect(closeCaptureSession.mock.calls.map((c) => c[0])).toContain(probeSession);
+  });
+
   it("skips completed segments and still concats all of them in order", async () => {
     const stableDir = join(fixtureRoot, "stable");
     const spawned: string[] = [];

packages/producer/src/services/render/stages/captureSegmentedStage.ts

@@ -291,6 +291,11 @@ function defaultSessionFactory(input: CaptureSegmentedStageInput): SessionFactor
   let probeSession = input.probeSession;
   return {
     create: async () => {
+      const probeCannotCaptureEveryFrame = Boolean(probeSession?.deRiskFrames?.size);
+      if (probeSession && probeCannotCaptureEveryFrame) {
+        await closeCaptureSession(probeSession).catch(() => {});
+        probeSession = null;
+      }
       const session = probeSession ?? (await openSegmentedSession(input));
       if (probeSession) {
         openSegmentedSessionReuse(input, probeSession);