A new `mcp-codemod` workspace package (`uvx mcp-codemod v1-to-v2 ./src`)
that rewrites every v1 -> v2 change whose meaning is unambiguous from the
file alone, and inserts a `# mcp-codemod:` comment above every site it
recognized but would not guess at. Built on libCST.
Names are resolved through each file's imports, never matched as text, so
an aliased import or an unrelated symbol that shares a name with an SDK
one is never touched. The camelCase to snake_case rename is restricted to
the field names v1's `mcp.types` actually declared. Anything whose correct
rewrite depends on information that is not in the file -- the lowlevel
decorator to `on_*` relocation, the transport keywords on the `MCPServer`
constructor -- is left exactly as written and marked instead, so the
remaining work is one grep. Re-running on the output is a no-op.
The mapping tables are pinned against the installed v2 package by ratchet
tests so they cannot silently drift: every rename target must resolve,
every removed API must be provably absent, and no flagged constructor
keyword may survive on `MCPServer.__init__`. Measured against the example
files that exist on both `v1.x` and `main` (whose diff is the hand-written
migration), the codemod fully reproduces 13 of the 51 with a real
migration diff, improves 35 more, and makes none worse.
Also adds an "Automated migration" section to docs/migration.md, a mention
of the tool in README.v2.md, and the package to the publish workflow's
build step (the PyPI project and its trusted publisher must exist before a
release is tagged with this in it).
Max Isbey
8900f2527c