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Evan
2e6f70c098
## Summary Follow-up to #4230. Two more core-sim optimizations — these are **behavior-affecting in controlled ways** (unlike #4230, which was hash-identical), so both come with dedicated test coverage written before the change. Combined results (`npm run perf:game`, same machine, before → after): | run | mean tick | ticks/sec | p99 | peak heap | |---|---|---|---|---| | default (world, 400 bots, 1800 ticks) | 7.98 → **6.96 ms** | 125 → **144** | 21.2 → **19.0 ms** | 438 → **294 MB** | | giantworldmap, 600 ticks | 17.4 → **15.2 ms** | 58 → **66** | 32.6 → 30.5 ms | | Cumulative with #4230 vs. the original baseline: default run mean 9.04 → 6.96 ms (111 → 144 ticks/sec); giantworldmap 22.5 → 15.2 ms (44 → 66 ticks/sec, max tick 52.8 → 40.1 ms). ### 1. `PseudoRandom`: seedrandom ARC4 → inline sfc32 - ARC4 was ~4% of profiled self time. The new engine is sfc32 with splitmix32 seed expansion and a warmup, using only 32-bit integer ops — sequences are identical across platforms. The class API is unchanged. - This **removes the `seedrandom` dependency entirely**, making `src/core` actually dependency-free (the import was the only violation of that rule). - ⚠️ **The random stream differs, so the deterministic game-state hash changes.** All clients run the same code, so cross-client sync is unaffected; the harness reproduces the same hash on repeated runs per seed. New reference hashes: - `--map world --ticks 200 --bots 100` → `5607618202213430` - default run → `29309648281599524` - `--map giantworldmap --ticks 600` → `39945089450032050` - New `tests/PseudoRandom.test.ts` (15 tests) pins the engine-agnostic contract: per-seed determinism, ranges, uniformity, adjacent-seed decorrelation, and every API method. The tests were verified green against the old engine first, then the swap. - The stream change exposed a test that passed **by RNG luck**: in `AiAttackBehavior.test.ts`, "nation cannot attack allied player" was actually being blocked by the difficulty dice gate in `shouldAttack`, not the alliance check — hiding that the test's `AiAttackBehavior` was constructed without its `NationEmojiBehavior`. The test now supplies one and verifies the real protection layer (`AttackExecution`'s alliance check), robust to any dice outcome. ### 2. `PlayerImpl.toFullUpdate`: allocation-free empty collections - `toFullUpdate` runs for every player every tick and allocated ~10 collections each (allies, embargoes Set, attacks, alliance views, …) even when all were empty — the common case for most of 472 players. Because `lastSentUpdate` retains each snapshot for a full tick, these objects survived minor GC, got promoted, and accumulated as old-space garbage between major GCs — that's the peak-heap drop. - Empty collections now reuse shared **frozen** module-level singletons, so `diffPlayerUpdate`'s existing `a === b` fast paths skip structural comparison entirely. Non-empty collections build in single passes. Freezing makes accidental in-worker mutation throw loudly instead of silently corrupting every player; consumers across the worker boundary get mutable structured clones as before. (`Set` cannot be frozen — `EMPTY_EMBARGOES` is documented as never-mutate.) - Value-identical: the game-state hash is unchanged by this part (verified against the post-PRNG baseline). - New `tests/PlayerUpdateDiff.test.ts` (8 tests): full-snapshot shape, null-when-unchanged, embargo/alliance/target/attack diffs through the real tick pipeline, and the freeze contract. ### Verification - Full suite passes: 124 files / 1408 tests (23 new) + server tests; lint and prettier clean. - Hash reproducibility confirmed: repeated runs with identical args produce identical hashes on all three configs. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Fable 5 <noreply@anthropic.com>