After making major changes (new language features, bug fixes, backend additions, refactors), ensure the following docs are up to date before committing:
- CHANGELOG.md — add an entry for the change
- README.md — update usage, feature lists, or examples if affected
- docs/SPEC.md — update if language semantics or syntax changed
- MISSING_FEATURES.md — mark completed gaps or document new ones
- TODO.md — check off completed items or add newly discovered work