fix(physics): widen contact pair key past the 16-bit overflow (A4)#155
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ContactGraph packed collider id pairs as `(a.id << 16) | b.id`, which silently collided once any collider id reached 65536 — JS bitwise operators wrap at 32 bits. Collider ids are allocated monotonically and never recycled, so a long-running world with heavy spawn/destroy churn can hit that ceiling. Switch to multiplication by a 2^26 stride (`pairKeyStride`), keeping pair keys collision-free up to ~67M ids per world within JS's 2^53 safe-integer range. `pairKey` now takes the two ids directly (testable) and is exported `@internal`. Adds a regression test covering ids past 65535 and the old-scheme collision.
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A4 — contact pair-key 16-bit overflow fix (v0.14 wave 1)
ContactGraphpacked collider id pairs as(a.id << 16) | b.id, which silently collided once any collider id reached 65536 — JS bitwise operators wrap at 32 bits. Collider ids are allocated monotonically and never recycled (_nextColliderId++), so a long-running world with heavy spawn/destroy churn can hit that ceiling.pairKeyStride): collision-free up to ~67M ids per world, within JS's 2^53 safe-integer range.pairKeynow takes the two ids directly (testable) and is exported@internal.test/pair-key.test.ts) covering ids past 65535, safe-integer bounds, and the exact old-scheme collision.Verification (local)
physics typecheck · physics test suite (3 new pair-key tests) · lint:packages · format:check