## Versioning

Two version axes — the API itself, and individual processes — evolve independently.

### API version

The wire format is identified by the top-level `opensop:` field on every process YAML. The engine refuses to register YAML whose major version it does not understand.

| Version | Status | Notes |
|---------|--------|-------|
| 0.1 | CURRENT | Initial public release. |
| 0.2 | PREVIEW | Configurable metrics window, parallel step blocks. |

### Process versions

Every process has its own semver-style `version` string. Re-publishing under a new version does not affect in-flight instances — they continue running against the version they started under.

When you call `GET /sop/:name/schema` without `?version=`, you get the latest published version. To pin, pass it explicitly.