[audit] framer-motion/animation: remove dead code

[mattgperry]

What this directory does

packages/framer-motion/src/animation is the React-side animation entry layer: the animate() / useAnimate factories, sequence resolution (sequence/), the WAAPI mini animators (animators/waapi/), the legacy animation controls hooks, and the optimized-appear handoff used for SSR/streamed appear animations. It is setup/teardown code — none of it runs inside a per-frame render or update tick (per-frame work lives in motion-dom's JSAnimation/frameloop/projection). Hot-path callers were confirmed by grep: createAnimationsFromSequence runs once at animation start, animateElements once per animate() call, optimized-appear once per value at handoff.

Both lenses (performance and filesize) were applied.

Performance

No per-frame hot path exists in this directory, so there are no frame-loop allocation/closure findings (cold-path micro-optimisation is intentionally not listed). No changes.

(An earlier revision swapped performance.now() to time.now() in optimized-appear/start.ts; this was reverted at the maintainer's request and is no longer part of this PR.)

Filesize

Baseline vs after, minified production bundles, gzip -9 — all unchanged:

bundle	before (gz)	after (gz)	delta
framer-motion/dist/framer-motion.js	59626	59626	0
framer-motion/dist/dom.js	43692	43692	0
framer-motion/dist/mini.js	3352	3352	0
framer-motion/dist/dom-mini.js	4979	4979	0
motion/dist/motion.js	43692	43692	0

Dead code removal — source cleanup, ~0 bundle impact (stated honestly):

• utils/is-keyframes-target.ts — isKeyframesTarget here is an unused duplicate; the only consumed isKeyframesTarget is motion-dom's own (motion-dom/src/render/utils/is-keyframes-target.ts). No importer anywhere in the repo.
• utils/variant-resolvers.ts — resolveVariantLabels / asDependencyList have zero references repo-wide (packages + dev).

Because neither file was imported anywhere, both were already tree-shaken out of every bundle — deleting them does not shrink the gzipped output (hence the 0 deltas). Framed as maintainability cleanup, not a filesize win.

animation/types.ts (ResolveKeyframes) was flagged as unused internally but is re-exported via export type * from "./animation/types" in the public index — it is public type API, so left untouched (no public API changes).

Testing

• yarn build — all 8 tasks pass.
• animation test suites — 16 suites, 167 passed, 1 skipped (pre-existing React act() warning in use-animated-state is unrelated).

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR makes two targeted changes to packages/framer-motion/src/animation: a correctness fix replacing performance.now() with time.now() in the optimized-appear handoff, and deletion of two dead-code utility files that were already tree-shaken from every bundle.

• optimized-appear/start.ts: startFrameTime is now seeded via time.now() (motion-dom's eventloop-synchronous, frame-locked clock) instead of a raw performance.now() call. The existing startFrameTime === undefined guard keeps the timestamp stable across the microtask chain triggered by readyAnimation.ready.then(), so all appear animations share one start time as intended. The stale comment referencing a removed handoff.ts call is corrected. Aligns with the repo-wide CLAUDE.md timing rule.
• utils/is-keyframes-target.ts / utils/variant-resolvers.ts: Both files had zero importers anywhere in the repo and were already fully tree-shaken; deleting them is a pure maintainability cleanup with no bundle impact.

Confidence Score: 5/5

Safe to merge — all three changes are narrow and well-reasoned with no risk of regressions.

The time.now() swap is behaviourally equivalent to the old performance.now() call (both return a performance-clock value) while adding the caching benefit; the module-level startFrameTime guard already handles cross-microtask stability. The two deleted files had zero importers and were already tree-shaken, so removing them carries no runtime risk.

No files require special attention.

Important Files Changed

Filename	Overview
packages/framer-motion/src/animation/optimized-appear/start.ts	Replaces performance.now() with time.now() (motion-dom frame-synced clock) for startFrameTime; updates stale comment. The module-level startFrameTime guard correctly holds the timestamp stable across the microtasks spawned by readyAnimation.ready.then(), so the behavioural contract is unchanged.
packages/framer-motion/src/animation/utils/is-keyframes-target.ts	Deleted unused duplicate of motion-dom's own isKeyframesTarget; confirmed zero importers in the repo.
packages/framer-motion/src/animation/utils/variant-resolvers.ts	Deleted dead-code file (resolveVariantLabels, asDependencyList) with zero references repo-wide; safe removal.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["startOptimizedAppearAnimation()"] --> B{readyAnimation exists?}
    B -->|No| C["Create readyAnimation (dummy 10s WAAPI)"]
    C --> D[Register window.Motion handlers]
    D --> E{readyAnimation.ready?}
    B -->|Yes| E
    E -->|Promise| F["readyAnimation.ready.then(startAnimation)"]
    E -->|No promise| G["startAnimation() sync"]
    F --> H["startAnimation() microtask"]
    G --> I{startFrameTime === undefined?}
    H --> I
    I -->|Yes| J["startFrameTime = time.now()"]
    I -->|No| K[Reuse existing startFrameTime]
    J --> L["appearAnimation.startTime = startFrameTime"]
    K --> L
    L --> M[Store in appearAnimationStore]

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