Keep real old saves
Commit small, synthetic or redacted fixtures from every supported public version.
ENGINE-AGNOSTIC · ZERO RUNTIME DEPENDENCIES
CI for the save files
your players already have.
Weave every historical JSON save through declarative migrations, validate each version, and prove the result is deterministic before the release reaches players.
node bin/saveweaver.js matrix --project examples/space-rangerOLD SAVEv1
OLD SAVEv2
CURRENTv3
releaseschema · hash · receipt
GENERATED FROM REPOSITORY FIXTURES
A compatibility claim you can inspect.
Loading matrix…
| Fixture | Source | Target | Migration chain | Proof |
|---|---|---|---|---|
| Loading generated matrix data… | ||||
Each passing row validates source and target schemas, runs twice for deterministic SHA-256 output, then runs once more to prove current-save idempotency.
RELEASE WORKFLOW
Guard the data contract, not just today's serializer.
Migrate as data
Use ten deterministic operations. No eval, scripts, network, or hidden coercion.
Prove the path
CI validates each contract, migration lock, replay hash, and final idempotency.
Write with evidence
Explicit output, content-addressed backup, atomic replacement, and SHA-256 receipt.