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+# Versioning Invariant
+
+Charter uses **unified workspace versioning**: every package under `packages/*/package.json` carries the same version as the release tag.
+
+## Invariant
+
+For any release tag `vX.Y.Z`:
+
+```
+packages/*/package.json  →  "version": "X.Y.Z"
+```
+
+All twelve packages ship together at the same version. There is no per-package version drift.
+
+## Enforcement
+
+`.github/workflows/release.yml` — `publish-npm` job, "Verify tag and workspace versions" step — enforces this at release time. It loops over every `packages/*/package.json` and fails the build if any version does not match the tag.
+
+## Migration note
+
+If Charter ever adopts independent per-package versioning, the enforcement step must be reworked before the first diverging release. Each package would need its own expected version source (e.g. the package's own `package.json` rather than the global tag). See [#122](https://github.com/Stackbilt-dev/charter/issues/122) for the original discussion.