Zig replay verifier status (`crimson-zig/`)¶

Last reviewed: 2026-02-26

Scope target: fast, headless, deterministic verification with a native fast-path for latest-ruleset 1-4 player Survival/Rush/Quest replays (preserve_bugs=false), with explicit hard-fail behavior for unsupported native paths.

Ported in Zig (current)¶

Replay ingestion from .crd bytes (msgpack decode path in-tree).
Deterministic Survival/Rush/Quest sim scaffold + runtime loops for:
player/weapon runtime (reload/fire/ammo counters, level/XP progression),
survival/quest spawn systems,
creature updates,
primary/secondary projectile runtime,
bonus/perk runtime integration,
run-result assembly (ticks, elapsed_ms, score_xp, kills, weapon usage, RNG state).
Verification is fully self-contained from replay bytes (no checkpoint/high-score sidecars).
Deterministic Rush spawn runtime path (tick_rush_mode_spawns) ported in Zig.
Deterministic Quest spawn tables and runtime progression hooks ported in Zig.
Quest spawn builder logic is full-version-only in Zig (no shareware-gated branch path).
Multiplayer gameplay logic and perk gating parity achieved.
CLI surface: crimson-zig replay verify <replay> with human/json outputs, intrinsic replay-header claimed-stats checking, plus replay SHA-256 reporting.
Wasm target build + export ABI for worker-side integration.
Unsupported/not-yet-ported native paths hard-fail instead of silently accepting.

Runtime ownership model (Zig rewrite)¶

Internal gameplay runtime uses a typed owner union (OwnerRef) instead of raw magic owner IDs.
OwnerRef.player{index, local_host}
OwnerRef.creature{index}
OwnerRef.none
Legacy owner-id encoding (-100, -1-n, >=0) is treated as an interop format only, not the internal simulation representation.
Any required legacy serialization/trace surface is emitted by explicit conversion (OwnerRef.toLegacy()) at boundaries.

Not fully ported / known parity gaps¶

Native fast path is still scoped to 1-4 player Survival/Rush/Quest:
no native preserve_bugs=true compatibility layer.
Replay compatibility is still under active expansion using differential captures; parity is strong on the current working set but not yet claimed for all unseen Survival captures.
Mode/scope limits still apply to the native path:
latest ruleset only (preserve_bugs=false).

Current replay parity snapshot (2026-02-25)¶

Older-version captures are no longer used as acceptance inputs for the latest ruleset verifier status.
survival_20260224_113737_score4032.crd
Python and Zig both ok with exact summary match:
- ticks=34808 elapsed_ms=532112 score_xp=4032 kills=1498 most_used_weapon_id=20 shots_fired=10241 shots_hit=3035 rng_state=2592828730
survival_20260224_223838_score134360.crd
Python and Zig both ok with exact summary match:
- ticks=32213 elapsed_ms=448469 score_xp=134360 kills=1231 most_used_weapon_id=20 shots_fired=1718 shots_hit=1030 rng_state=4205621066
Differential harness (--skip-build) reports exact tick parity:
- match: ticks=32213

Performance snapshot (2026-02-25)¶

hyperfine './crimson-zig/zig-out/bin/crimson-zig replay verify survival_20260224_223838_score134360.crd' 'uv run crimson replay verify survival_20260224_223838_score134360.crd'

Benchmark 1: ./crimson-zig/zig-out/bin/crimson-zig replay verify survival_20260224_223838_score134360.crd
  Time (mean ± σ):     564.1 ms ±  10.0 ms    [User: 555.5 ms, System: 2.5 ms]
  Range (min … max):   555.0 ms … 588.7 ms    10 runs

Benchmark 2: uv run crimson replay verify survival_20260224_223838_score134360.crd
  Time (mean ± σ):     31.599 s ±  0.550 s    [User: 31.268 s, System: 0.115 s]
  Range (min … max):   30.912 s … 32.871 s    10 runs

Summary
  ./crimson-zig/zig-out/bin/crimson-zig replay verify survival_20260224_223838_score134360.crd ran
   56.02 ± 1.39 times faster than uv run crimson replay verify survival_20260224_223838_score134360.crd

Zig replay verifier status (crimson-zig/)¶