[valeriangalliat]

🤖 AI agent: Arcade fork patch. Do not merge.

This draft shows patch/jump-seek-css-settle against main, the upstream mirror, so the patch has one page for its diff, its revisions and its reason. Arcade's /hyperframes-update rebases the branch onto main and cherry-picks it onto arcade; this PR is not part of that flow. When a rebuild changes the patch, its git range-diff against the previous sync/<date>/jump-seek-css-settle tag is posted as a comment.

Why

A chunk worker starts with a jump seek. Class swaps on that seek spawn CSS transitions, and the worker then replays those fades in its first frames. The patch calls finish() on transitions spawned by a jump seek; swaps that land on the seam snap. Static-frame verification folds the settle into its single seek call, because upstream tests (staticDedupVerifyDensity) count page.evaluate calls.

Upstream

Kept local. Carried before as ArcadeHQ/hyperframes#33.

Drop when

Not recorded yet.

Arcade

ARC-14274 · ARC-14435

[valeriangalliat]

🤖 AI agent: sync/2026-10-24 (tags moved the same day): rebased onto upstream 2e397dba5 (v0.8.194). Replayed clean.

First pass on this date, onto 722481214 (0.8.193): Sits beside upstream beginFrameSeekPresented (heygen-com#5812) and captureStep (heygen-com#5450). Iframe loop reads win.frames?.length ?? 0: upstream motion-blur tests run the page function on a stub window without frames.

The range-diff below is against sync/2026-10-05.

git range-diff sync/2026-10-05/base..sync/2026-10-05/jump-seek-css-settle sync/2026-10-24/base..sync/2026-10-24/jump-seek-css-settle

1:  56d8fbcc5 ! 1:  4c51242c1 fix(engine): settle CSS transitions spawned by jump seeks
    @@ packages/engine/src/services/frameCapture-jumpSeek.test.ts (new)
     
      ## packages/engine/src/services/frameCapture.ts ##
     @@ packages/engine/src/services/frameCapture.ts: export interface CaptureSession {
    -   beginFrameIntervalMs: number;
        beginFrameHasDamageCount: number;
        beginFrameNoDamageCount: number;
    +   beginFrameSeekPresented?: boolean;
     +  lastSeekTime?: number;
        /** Optional producer config — when set, overrides module-level env var constants. */
        config?: Partial<EngineConfig>;
    @@ packages/engine/src/services/frameCapture.ts: async function seekPageTimeline(
     +      try {
     +        settleDocument(win.document);
     +      } catch {}
    -+      for (let i = 0; i < win.frames.length; i++) {
    ++      for (let i = 0; i < (win.frames?.length ?? 0); i++) {
     +        const child = win.frames[i];
     +        if (child && child !== win) settleWindow(child);
     +      }
    @@ packages/engine/src/services/frameCapture.ts: async function seekPageTimeline(
        session: CaptureSession,
        frameIndex: number,
     @@ packages/engine/src/services/frameCapture.ts: async function prepareFrameForCapture(
    -   );
      
        const seekStart = Date.now();
    +   session.captureStep = "seeking the timeline";
     -  const hasPendingComposite = await seekPageTimeline(page, quantizedTime, seekOptions);
     +  const { hasPendingComposite } = await seekPageWithJumpSettle(
     +    session,
    @@ packages/engine/src/services/frameCapture.ts: async function prepareFrameForCapt
     +    seekOptions,
     +  );
      
    +   session.captureStep = "decoding CSS background images";
        await decodeDynamicCssBackgroundImages(page);
    - 
     @@ packages/engine/src/services/frameCapture.ts: export async function verifyStaticFramesSafe(
        const seekToFrame = async (frameIdx: number): Promise<void> => {
          stats.seeks++;
    @@ packages/engine/src/services/frameCapture.ts: export async function verifyStatic
     +              }
     +            }
     +          } catch {}
    -+          for (let i = 0; i < win.frames.length; i++) {
    ++          for (let i = 0; i < (win.frames?.length ?? 0); i++) {
     +            const child = win.frames[i];
     +            if (child && child !== win) settleWindow(child);
     +          }

[github-actions]

Edit accuracy: accurate 271 (base branch 271), smooth 156 of those

The gate passes.
Smoothness is reported in the artifact, not gated. A case fails only if it fails 2 of 3 runs.

Quarantined, measured but not gated (0)

Unstable (1)

• seqplainkeys-none-pct-r0-root-z100: tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true