Introduces the state-checksum machinery the replay feature rests on, and a
test that proves the simulation is deterministic for a given seed/binary.
- StateChecksum: FNV-1a Hasher (bit-pattern float hashing, -0 normalization,
length-tagged strings) plus a portable mt19937 state fingerprint.
- BeltSystem/BuildingSystem: appendChecksum(Hasher&) folding transport and
building/site/occupancy state in deterministic (sorted/insertion) order.
- Simulation: rngFingerprint() (cheap, for the future file checksum) and
computeStateChecksum() (full state: RNG, scalars, wave/schematic/unlock
state, subsystems, and ECS position/health/facing/body/scrap/identity).
- DeterminismTest: Hasher unit tests, RNG-fingerprint tests, and a double-run
test asserting identical per-tick full-state checksums from one seed; plus a
different-seed divergence guard.
Exit criteria met: double-run determinism test passes; full suite green
(334 cases / 3346 assertions).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DUsFgd2Ga6pmLz8giS8WUn
Captures the deterministic command-replay design (seed + config hash +
tick-tagged command log, re-simulated on playback), the command-chokepoint
and timing model, determinism/checksum strategy, file format, and a
sequenced Phase 0-4 implementation plan.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DUsFgd2Ga6pmLz8giS8WUn
Fixes a bug where the selected construction site was not drawn with a border.
Reviewed-on: #2
Co-authored-by: Malte Langkabel <malte.langkabel@gmail.com>
Co-committed-by: Malte Langkabel <malte.langkabel@gmail.com>
