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| 1 | +# Versioning Policy |
| 2 | + |
| 3 | +## Versioning Scheme |
| 4 | + |
| 5 | +The MCP Python SDK follows [Semantic Versioning 2.0.0](https://semver.org/): |
| 6 | + |
| 7 | +- **Major** (X.0.0): Breaking changes to the public API |
| 8 | +- **Minor** (0.X.0): New features, backward-compatible additions |
| 9 | +- **Patch** (0.0.X): Bug fixes, backward-compatible corrections |
| 10 | + |
| 11 | +## What Constitutes a Breaking Change |
| 12 | + |
| 13 | +The following are considered breaking changes and require a major version bump: |
| 14 | + |
| 15 | +- Removing or renaming a public function, class, method, or module |
| 16 | +- Changing the signature of a public function or method in a non-backward-compatible way (removing parameters, changing required parameters, changing return types) |
| 17 | +- Changing the behavior of a public API in a way that existing callers would not expect |
| 18 | +- Dropping support for a Python version |
| 19 | +- Changing the minimum required version of a dependency in a way that is incompatible with previously supported ranges |
| 20 | +- Removing or renaming protocol message types or fields from the public schema |
| 21 | + |
| 22 | +The following are **not** considered breaking changes: |
| 23 | + |
| 24 | +- Adding new optional parameters with default values |
| 25 | +- Adding new public functions, classes, or methods |
| 26 | +- Adding new fields to response types |
| 27 | +- Deprecating (but not removing) existing APIs |
| 28 | +- Changes to private/internal APIs (prefixed with `_`) |
| 29 | +- Bug fixes that correct behavior to match documented intent |
| 30 | +- Adding support for new protocol versions while maintaining backward compatibility |
| 31 | + |
| 32 | +## How Breaking Changes Are Communicated |
| 33 | + |
| 34 | +1. **Deprecation warnings**: Before removal, public APIs are deprecated for at least one minor release with `DeprecationWarning` and migration guidance. |
| 35 | +2. **Release notes**: All breaking changes are documented in GitHub Release notes with migration instructions. |
| 36 | +3. **PR labels**: Pull requests containing breaking changes are labeled accordingly. |
| 37 | + |
| 38 | +## Release Branches |
| 39 | + |
| 40 | +- **`main`**: Development branch for the next major version |
| 41 | +- **`v1.x`**: Stable release branch for the 1.x series; receives bug fixes and backward-compatible features |
| 42 | +- **`v1.Y.x`** (e.g., `v1.7.x`): Patch release branches for specific minor versions when needed |
| 43 | + |
| 44 | +Bug fixes target the latest release branch and are forward-merged into `main`. New features target `main` and may be backported to the release branch if appropriate. |
| 45 | + |
| 46 | +## Protocol Version Tracking |
| 47 | + |
| 48 | +The SDK tracks the MCP specification. When a new spec version is released, the SDK targets a corresponding release within 30 days. Protocol version support is documented in the README. |
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