diff --git a/packages/engine/src/services/frameCapture.ts b/packages/engine/src/services/frameCapture.ts
index 693565d056..9b367979f1 100644
--- a/packages/engine/src/services/frameCapture.ts
+++ b/packages/engine/src/services/frameCapture.ts
@@ -1309,6 +1309,7 @@ async function cssEffectRiskFrames(
       fps,
       totalFrames,
       totalFrames * MAX_RISK_FRAME_FRACTION,
+      { onProgress: session.options.onEffectScanProgress },
     );
     return live && withFramesAfterCallback(live, scan.callbackFrom, fps, totalFrames);
   } catch (error) {
diff --git a/packages/engine/src/services/riskFrames.test.ts b/packages/engine/src/services/riskFrames.test.ts
index d9856aef1c..5536098528 100644
--- a/packages/engine/src/services/riskFrames.test.ts
+++ b/packages/engine/src/services/riskFrames.test.ts
@@ -102,6 +102,52 @@ const frames = (live: Set<number> | null) => [...(live ?? [])].sort((a, b) => a
 const range = (from: number, count: number) => Array.from({ length: count }, (_, i) => from + i);
 
 describe("scanCssEffectLiveFrames", () => {
+  it("stops after one chunk when the whole scan would hold back the first frame too long", async () => {
+    const seeks: number[] = [];
+    const page = makePage(between(0, 0));
+    const evaluate = page.evaluate.bind(page);
+    page.evaluate = (async (...args: Parameters<Page["evaluate"]>) => {
+      seeks.push((args[1] as number[]).length);
+      return evaluate(...args);
+    }) as Page["evaluate"];
+    let clock = 0;
+    // 24 ms a frame, what a heavy page costs: 40,219 frames would take 16 minutes.
+    const now = () => (clock += 240 * 24);
+
+    expect(
+      await scanCssEffectLiveFrames(page, 60, 40_219, 40_219, { budgetMs: 60_000, now }),
+    ).toBeNull();
+    expect(seeks).toEqual([240]);
+  });
+
+  it("reports the frames scanned after each chunk", async () => {
+    const seen: Array<[number, number]> = [];
+
+    await scanCssEffectLiveFrames(makePage(between(0, 0)), 10, 500, 500, {
+      onProgress: (scanned, total) => seen.push([scanned, total]),
+    });
+    expect(seen).toEqual([
+      [240, 500],
+      [480, 500],
+      [500, 500],
+    ]);
+  });
+
+  it("scans to the end when the whole scan fits the budget", async () => {
+    let clock = 0;
+    const now = () => (clock += 240);
+
+    const live = await scanCssEffectLiveFrames(
+      makePage(between(2, 4)),
+      10,
+      1000,
+      1000,
+      60_000,
+      now,
+    );
+    expect(frames(live)).toEqual(range(20, 20));
+  });
+
   it("returns the frames where the effect element shows", async () => {
     const live = await scanCssEffectLiveFrames(makePage(between(2, 4)), 10, 100, 100);
     expect(frames(live)).toEqual(range(20, 20));
diff --git a/packages/engine/src/services/riskFrames.ts b/packages/engine/src/services/riskFrames.ts
index 87d127753f..90e089b311 100644
--- a/packages/engine/src/services/riskFrames.ts
+++ b/packages/engine/src/services/riskFrames.ts
@@ -9,6 +9,9 @@ import { quantizeTimeToFrame } from "@hyperframes/core";
 /** Frames per page round trip while scanning; a scan is one in-page loop per chunk. */
 const SCAN_CHUNK_FRAMES = 240;
 
+/** Longest the scan may hold back the first frame; above it the whole render captures by screenshot. */
+const SCAN_BUDGET_MS = 120_000;
+
 /**
  * Above this share of risk frames the second browser and the switching cost outweigh the fast
  * frames, so the whole render captures by screenshot as it always has.
@@ -26,53 +29,71 @@ const PIXELS_1080P = 1920 * 1080;
 /** Risk ranges closer than this many frames are joined, so capture never alternates modes. */
 export const RISK_RANGE_HYSTERESIS_FRAMES = 12;
 
+async function scanChunk(page: Page, times: number[]): Promise<number[]> {
+  return page.evaluate(async (ts: number[]): Promise<number[]> => {
+    type HfWindow = Window & {
+      __hf?: { seek?: (t: number) => void };
+      __hfWaitForSeekCompletion?: () => Promise<void>;
+      __hfCssFxTargets?: Element[];
+    };
+    const w = window as HfWindow;
+    const targets = w.__hfCssFxTargets ?? [];
+    // A hidden element still shows a descendant that sets `visibility: visible` itself.
+    const paints = (el: Element): boolean =>
+      getComputedStyle(el).visibility !== "hidden" ||
+      Array.from(el.querySelectorAll("*")).some(
+        (d) => getComputedStyle(d).visibility === "visible",
+      );
+    const shows = (el: Element): boolean => {
+      for (let n: Element | null = el; n; n = n.parentElement) {
+        const cs = getComputedStyle(n);
+        if (cs.display === "none" || Number(cs.opacity) === 0) return false;
+      }
+      return paints(el);
+    };
+    const out: number[] = [];
+    for (let i = 0; i < ts.length; i++) {
+      w.__hf?.seek?.(ts[i] as number);
+      await w.__hfWaitForSeekCompletion?.();
+      if (targets.some(shows)) out.push(i);
+    }
+    return out;
+  }, times);
+}
+
+interface ScanOptions {
+  budgetMs?: number;
+  now?: () => number;
+  onProgress?: (scannedFrames: number, totalFrames: number) => void;
+}
+
 /**
  * Frames where a recorded effect element shows. Seeks the page forward, so use a throwaway one.
- * Null once more than `maxFrames` frames qualify.
+ * Null once more than `maxFrames` frames qualify, or once the whole scan would take over `budgetMs`.
  */
 export async function scanCssEffectLiveFrames(
   page: Page,
   fps: number,
   totalFrames: number,
   maxFrames: number,
+  { budgetMs = SCAN_BUDGET_MS, now = () => performance.now(), onProgress }: ScanOptions = {},
 ): Promise<Set<number> | null> {
   const live = new Set<number>();
-  for (let from = 0; from < totalFrames; from += SCAN_CHUNK_FRAMES) {
+  const started = now();
+  for (let from = 0; from < totalFrames && live.size <= maxFrames; from += SCAN_CHUNK_FRAMES) {
+    const to = Math.min(totalFrames, from + SCAN_CHUNK_FRAMES);
     const times: number[] = [];
-    for (let f = from; f < Math.min(totalFrames, from + SCAN_CHUNK_FRAMES); f++) {
-      times.push(quantizeTimeToFrame(f / fps, fps));
+    for (let f = from; f < to; f++) times.push(quantizeTimeToFrame(f / fps, fps));
+    for (const i of await scanChunk(page, times)) live.add(from + i);
+    onProgress?.(to, totalFrames);
+    const projectedMs = ((now() - started) / to) * totalFrames;
+    if (to < totalFrames && projectedMs > budgetMs) {
+      console.error(
+        `[engine] fast capture: the effect scan of ${totalFrames} frames would take ` +
+          `${Math.round(projectedMs / 1000)} s, over its ${budgetMs / 1000} s budget`,
+      );
+      return null;
     }
-    const hits = await page.evaluate(async (ts: number[]): Promise<number[]> => {
-      type HfWindow = Window & {
-        __hf?: { seek?: (t: number) => void };
-        __hfWaitForSeekCompletion?: () => Promise<void>;
-        __hfCssFxTargets?: Element[];
-      };
-      const w = window as HfWindow;
-      const targets = w.__hfCssFxTargets ?? [];
-      // A hidden element still shows a descendant that sets `visibility: visible` itself.
-      const paints = (el: Element): boolean =>
-        getComputedStyle(el).visibility !== "hidden" ||
-        Array.from(el.querySelectorAll("*")).some(
-          (d) => getComputedStyle(d).visibility === "visible",
-        );
-      const shows = (el: Element): boolean => {
-        for (let n: Element | null = el; n; n = n.parentElement) {
-          const cs = getComputedStyle(n);
-          if (cs.display === "none" || Number(cs.opacity) === 0) return false;
-        }
-        return paints(el);
-      };
-      const out: number[] = [];
-      for (let i = 0; i < ts.length; i++) {
-        w.__hf?.seek?.(ts[i] as number);
-        await w.__hfWaitForSeekCompletion?.();
-        if (targets.some(shows)) out.push(i);
-      }
-      return out;
-    }, times);
-    for (const i of hits) live.add(from + i);
-    if (live.size > maxFrames) break;
   }
   return live.size > maxFrames ? null : live;
 }
diff --git a/packages/engine/src/types.ts b/packages/engine/src/types.ts
index 606f2bbec9..a4b2436744 100644
--- a/packages/engine/src/types.ts
+++ b/packages/engine/src/types.ts
@@ -246,6 +246,7 @@ export interface CaptureOptions {
    */
   deVerifySamples?: number;
   deFrameFallback?: boolean;
+  onEffectScanProgress?: (scannedFrames: number, totalFrames: number) => void;
 }
 
 export interface CaptureVideoMetadataHint {
diff --git a/packages/producer/src/services/renderOrchestrator.ts b/packages/producer/src/services/renderOrchestrator.ts
index 9d4abc0ba1..2b815a120a 100644
--- a/packages/producer/src/services/renderOrchestrator.ts
+++ b/packages/producer/src/services/renderOrchestrator.ts
@@ -3683,6 +3683,15 @@ async function executeRenderPipeline(input: {
       // sample frame indices from this so they land inside the drained range.
       compositionDurationSeconds: job.duration,
       deFrameFallback: true,
+      // A line per scanned chunk, so a long effect scan reads as preparing, not as a stall.
+      onEffectScanProgress: (scanned, total) =>
+        updateJobStatus(
+          job,
+          "rendering",
+          `Checking effects, ${scanned} of ${total} frames`,
+          25,
+          onProgress,
+        ),
       requiresWebGpu: compositionRequiresWebGpu(compiled.html),
       // Live route for Chrome memory (spec §5 Phase −1). The aggregate route
       // through CapturePerfSummary only exists on success; a mid-capture