@remotion/gsap: Fix delayed fromTo leaving from-values behind on remount

[Fats403]

useGsapTimeline() primed the timeline inside its gsap.context(). Seeking a fromTo with immediateRender: false makes GSAP create that tween's start state lazily, so the context recorded it. On cleanup, context.revert() undid the start state first, then the owning tween, whose revert puts its from-values back on the element. Nothing removes them after that. The next mount on the same element (Strict Mode, or a rebuild from dependencies) reads them as the element's own style.

What it looked like for us: an end title animated with

timeline.fromTo(
	selector('[data-title]'),
	{yPercent: 60, opacity: 0},
	{yPercent: 0, opacity: 1, duration: 0.25, ease: 'expo.out', immediateRender: false},
	'slam+=0.5',
);

sat 60% lower in the Player, cut off by its overflow: hidden mask (transform: translate(0px, 66px) at the end of the timeline), and the offset compounded with every remount. Exports were fine since nothing remounts there.

The fix primes and seeks outside the context. The context still records everything the builder creates, and each tween reverts its own start state in the right order.

Minimal repro with GSAP 3.15.0 alone, no React:

const ctx = gsap.context(() => {
	const tl = gsap.timeline({paused: true});
	tl.fromTo(el, {yPercent: 60}, {yPercent: 0, duration: 0.25, immediateRender: false}, 0.7);
	tl.totalTime(1.2, true);
});
ctx.revert();
el.style.transform; // "translate(0%, 60%)", expected ""

timeline.revert() restores it correctly, as does a fromTo with the default immediateRender or a from() with immediateRender: false. Happy to report the context ordering to GreenSock too if that's useful.

Testing:

• Two new tests in packages/gsap: a Strict Mode mount, and a rebuild from dependencies. Both fail on main (opacity 0.2, the from-value, instead of the element's 0.25) and pass with the fix.
• bun test src/test: 48 pass. tsgo clean, lint unchanged.

[vercel]

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Project	Deployment	Actions	Updated
bugs	Ready	Preview	Oct 12, 2026 8:36am UTC
remotion	Ready	Preview	Oct 12, 2026 8:36am UTC

[pullfrog]

✅ No new issues found.

Reviewed changes

• packages/gsap/src/use-gsap-timeline.ts — Closes the context.add() callback after state.controls.pause() and runs the initial playhead sweep outside the context. The _startAt tween that GSAP lazily creates for a fromTo/from with immediateRender: false is no longer captured by context.revert(), so it is no longer reverted ahead of its owning tween. The owner reverts its own start state, which restores the element's React style rather than leaving the from-values behind on the element for the next mount.
• packages/gsap/src/test/use-gsap-timeline.test.tsx — Adds two regression tests (Strict Mode setup-cleanup-setup, and a rebuild from dependencies) asserting the element's own opacity: 0.25 survives a delayed fromTo. I confirmed both fail against 32af7e8f and pass with this change.

  ^{｜ View workflow run ｜ Using deepseek-v4.1-flash ｜ 𝕏}