[audit] motion-dom/stats: dedupe summarise calls, inline helpers

[mattgperry]

Directory

packages/motion-dom/src/stats/ — debug-mode runtime stats collection.
Exports recordStats (called from framer-motion/src/debug.ts and
projection.ts) plus the internal statsBuffer and activeAnimations
that hot-path code (JSAnimation, WAAPI start, projection node)
increments/decrements and conditionally reads from. recordStats is the
only public entry: it allocates buffer arrays, schedules record() on
every postRender frame, and returns a reportStats() closure that
summarises the buffer into a StatsSummary.

Both lenses applied.

Performance

No changes. The per-frame work inside record() is gated on
statsBuffer.value, so it's only active during an explicit
recordStats() profiling session. All hot-path call sites elsewhere
already short-circuit on if (statsBuffer.value) / if (statsBuffer.addProjectionMetrics)
before touching the buffer, so there is no idle-cost to trim. The
reportStats() work (Math.min(...values) / Math.max(...values) /
reduce) runs once when the user ends a session — not a hot path.

Filesize

Measured per-file gzipped deltas after yarn build:

Output	Before	After	Δ
motion-dom/dist/motion-dom.js	38921	38799	−122
motion-dom/dist/motion-dom.dev.js	90813	90655	−158
motion-dom/dist/cjs/index.js	89109	88989	−120
motion-dom/dist/es/stats/index.mjs	997	910	−87
framer-motion/dist/framer-motion.js	60694	60568	−126
framer-motion/dist/dom.js	44678	44568	−110
framer-motion/dist/dom-mini.js	4979	4979	0 (no stats)
motion-dom/dist/es/index.mjs	3094	3094	0 (barrel only)

User-facing bundles drop ~110–126 gzipped bytes each.

Changes (all in reportStats / summarise):

1. Collapse 15× summarise(value.X.Y) into a generic summariseAll
   helper that iterates each sub-object's keys. The summary object
   shrinks from three nested literals (~700 chars pre-min) to three
   helper calls. This is the bulk of the win.
2. Inline single-use mean() — the calcAverage default
   parameter was never overridden by any caller. Replaced with an
   inline reduce inside summarise.
3. Inline single-use msToFps() — three call sites become
   Math.round(1000 / x) directly; the explicit array-destructuring
   swap becomes a single temp, which compresses slightly better.
4. Drop the defensive cancelFrame(record) inside record() —
   reportStats() already calls cancelFrame(record) before clearing
   the buffer, so the null branch was unreachable. Replaced with a
   simple if (!value) return.

No public API changed; recordStats / statsBuffer / activeAnimations
signatures are identical.

Verification

• yarn build clean.
• yarn test — all stats tests pass (3/3 in motion-dom/src/stats/__tests__/index.test.ts).
  One unrelated AnimatePresence test was flaky on the first run and
  passed on re-run.

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR refactors the debug-mode stats collection module (motion-dom/src/stats/index.ts) to reduce bundle size without any behavioral changes. The public API (recordStats, statsBuffer, activeAnimations) and the StatsSummary shape are untouched.

• summariseAll helper: replaces 15 explicit summarise(value.X.Y) calls with a generic for...in loop helper, correctly inferring the key-set from the shape of each sub-object passed at the three call sites.
• Inlined mean and msToFps: the two single-use helpers are folded into their call sites as inline reduce and Math.round(1000/x) expressions; the FPS min/max swap is preserved — the new two-step temp-variable pattern is mathematically equivalent to the old destructuring swap.
• Removed unreachable cancelFrame in record(): reportStats() already calls cancelFrame(record) synchronously before nulling the buffer, so the null-guard branch inside record() could never fire; replaced with a simple falsy early-return.

Confidence Score: 5/5

Safe to merge — purely mechanical refactoring with no behavioral changes and full test coverage.

Every changed behavior was verified: the FPS min/max swap is mathematically identical to the old destructuring swap, summariseAll iterates the same fixed keys on plain objects, the inlined expressions match their extracted helpers exactly, and the dropped defensive cancelFrame was genuinely unreachable. All three existing tests pass.

No files require special attention.

Important Files Changed

Filename	Overview
packages/motion-dom/src/stats/index.ts	Clean refactor: collapsed 15× explicit summarise() calls into a summariseAll helper, inlined single-use mean/msToFps helpers, and dropped a provably unreachable defensive cancelFrame branch — logic is preserved and tests pass

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