Audit cache and effect float deadline arithmetic

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DISCLOSURE: LLM-GENERATED TEXT

Follow-up to #817's TimedCache correctness work. Other runtime deadlines still add float timestamps and durations before comparison. This audit remainder does not claim these APIs have been reproduced or fixed.

Verified source sites:

• Runtime/Core/DataStructure/Cache.cs: ComputeExpirationTime (941), IsExpired (978), OnAccess (998), Entry.ExpirationTime (1778).
• Runtime/Tags/EffectHandler.cs: TryGetRemainingDuration (476), duration reset (551), initial effect expiration (1076).

Characterize rounding at large finite clocks, finite duration/jitter overflow, strict versus inclusive boundaries, backward clocks, and permanent-duration sentinels. Preserve custom/sliding expiry, effect reset policy, remaining-duration output, and serialized/public contracts.

Acceptance:

1. Add independent arithmetic oracles and deterministic failing controls for affected public operations, with ordinary-clock controls.
2. Fix confirmed sites family-wide while preserving expiry boundaries and permanent entries.
3. Run full native cache/effect fixtures and all threading/Odin/legacy compile variants.
4. Update XML/feature docs and release notes. Keep chore: Production Code Base Sweep #817 open for its wider sweep.

Provenance: session 348 TimedCache audit and new finite-expiry/failed-refresh controls.

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DISCLOSURE: LLM-GENERATED TEXT

Native Unity 6000.4.6f1 controls reproduced the remaining Cache defects through its public API and injected clock:

• With clock 2^24 and TTL 1, write/custom/per-entry deadlines expire on the first read at zero elapsed time. Sliding expiry survives one read, then expires on a second read at the same clock.
• With expiry disabled, a clock of float.MaxValue still expires the entry immediately. Ordinary clock 100 controls remain readable until their deadline.

EffectHandler high-clock collapse, rounding and finite overflow are confirmed arithmetic controls; its public real-clock apply/remaining/refresh/remove controls also characterize finite, Infinity, NaN and Infinite-type behavior. These do not prove high-clock automatic effect removal. Next: add deterministic clock-taking fixture controls for apply, refresh, reapplication and removal, then migrate deadline arithmetic while preserving the existing permanent-effect query contract. No production fix for this remainder has landed.

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DISCLOSURE: LLM-GENERATED TEXT

Implemented in commit 1bb4e4e under PR #933. Cache and EffectHandler now compare finite elapsed time against stored lifetimes. Disabled cache expiry has explicit state; custom lifetime callbacks run before values, storage or evictions change. Sliding precedence, inclusive expiry, reset policies and permanent effects remain covered.

Native Unity 6000.4.6f1 verification passed all 245 cache cases and 87 effect/reentrancy cases, including 71 new regression/control cases. An isolated native probe also confirmed why the nonfinite-clock compatibility path needs explicit float rounding on Mono. Legacy, Odin, SINGLE_THREADED and default compile variants, staged preflight, syntax/output contracts, strict docs and spelling passed.

Keep this issue open until the new PR head passes its full version/threading CI matrix. The earlier head is green, but does not validate this commit.

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DISCLOSURE: LLM-GENERATED TEXT

The final duration sweep found a remaining cancellation boundary in the widened arithmetic. Actual native Unity 6000.4.6f1 calls reproduced:

Consumer	Inputs	Expected	Actual
Cache	start 1, lifetime float.MaxValue, current float.MaxValue	Value retained; age is lifetime minus 1	Value expired
TimedCache	start -1, TTL float.MaxValue, current float.MaxValue	Factory refresh; age is TTL plus 1	Old value retained
EffectHandler	start 1, duration float.MaxValue, current float.MaxValue	Remaining duration 1; handle active	Remaining 0; handle removed

Scalar double subtraction loses the small start value at these boundaries. The same review requires retaining TTL-plus-jitter residuals. The fix will compare compensated elapsed and duration pairs, preserve Cache/Effect's inclusive and TimedCache's strict boundaries, and recover remaining duration before final float conversion. Existing nonfinite, sliding, reset and transactional failure behavior stays in the regression controls.

This disproves full completion of the earlier widening slice. The issue stays open. Deterministic tests and the family correction are in progress; current published head 37b2c09 remains stable while its CI completes.

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DISCLOSURE: LLM-GENERATED TEXT

Commit c9a9de5 in PR #933 fixes the remaining small clock-offset and TTL/jitter loss across Cache, TimedCache and EffectHandler. It also preserves remaining duration at float rounding and overflow boundaries. Public and serialized contracts stay unchanged.

Added 26 regression cases. Native Unity 6000.4.6f1 passed Cache 253/253, TimedCache 65/65, EffectHandler/reentrancy 107/107 and periodic runtime state 30/30: 455 cases, zero failed, skipped or inconclusive. The earlier failing controls are recorded above.

Independent exact arithmetic controls passed 334,513 finite cases; the scalar-double negative control failed 13,877. This is arithmetic evidence, not a performance claim. All host compile variants, strict documentation, spelling and staged gates passed. Independent ownership and compatibility reviews found no remaining blocker.

Keep this issue open until required CI and feedback pass on this final head. Keep #817 open for its wider audit.