Flag removed modules, update dependency files, add a batch-test harness

Three additions to mcp-codemod, closing the gaps a comparison with the
TypeScript codemod surfaced:

Imports of module namespaces v2 deleted outright (the experimental tasks
namespaces, the WebSocket transports, `mcp.shared.progress`) are now
marked with replacement guidance. A new ratchet test freezes the 107
public modules v1 shipped and asserts every one imports on v2, is
renamed, or is in the removed table, so the whole v1 module namespace is
provably accounted for.

The codemod now also updates the `mcp` requirement in `pyproject.toml`
(PEP 621 tables and dependency groups) and `requirements*.txt` to
`>=2,<3` -- only where the current constraint cannot accept any v2
release, and only the version specifier: name, extras, environment
marker, and spacing keep the user's spelling. Poetry tables and the
removed `ws` extra are marked instead of guessed at, under the same
`# mcp-codemod:` contract as source markers.

`scripts/codemod-batch-test/` runs the codemod against pinned real
repositories and audits the marker contract end to end: it type-checks
the pristine clone against the latest v1 and the migrated copy against
this workspace's v2 with identical pyright settings, then requires every
error that exists only on the migrated side to sit next to a marker.
Across the four repos in the manifest every migration-surface error is
covered, and the audit caught two real bugs now fixed here: `Context`
imported from the old `.server` submodule is rehomed to the package (the
submodule holds the name at runtime, but a type checker treats a
non-re-exported name as private), and `request_context` on a receiver
the pre-pass proved holds a lowlevel `Server` is flagged again --
receiver-matched, so the live `ctx.request_context` idiom stays
untouched.

Author: maxisbey

docs/migration.md

@@ -8,7 +8,7 @@ Version 2 of the MCP Python SDK introduces several breaking changes to improve t
 
 ## Automated migration
 
-The `mcp-codemod` tool (published from `src/mcp-codemod` in this repository) rewrites every change in this guide whose meaning is unambiguous from the file alone -- the import moves, the symbol renames, the `MCPError` reshape, and the camelCase to snake_case field renames -- and inserts a `# mcp-codemod:` comment above every site it recognized but would not guess at. Run it on a clean branch first, then work through what it marked:
+The `mcp-codemod` tool (published from `src/mcp-codemod` in this repository) rewrites every change in this guide whose meaning is unambiguous from the file alone -- the import moves, the symbol renames, the `MCPError` reshape, the camelCase to snake_case field renames, and the `mcp` requirement in `pyproject.toml` / `requirements*.txt` -- and inserts a `# mcp-codemod:` comment above every site it recognized but would not guess at. Run it on a clean branch first, then work through what it marked:
 
 ```bash
 uvx mcp-codemod v1-to-v2 ./src

scripts/codemod-batch-test/.gitignore

@@ -0,0 +1 @@
+work/

scripts/codemod-batch-test/README.md

@@ -0,0 +1,42 @@
+# Codemod batch test
+
+Runs the `mcp-codemod` v1 -> v2 migration against real, pinned repositories and
+audits the result with pyright, to find silent misses the unit tests and the
+in-repo example corpus cannot.
+
+## How it works
+
+For each repository in `repos.json`:
+
+1. Clone the pinned commit (shallow).
+2. Run the codemod (sources and dependency files) over a copy.
+3. Type-check the pristine clone against an environment holding the latest v1
+   SDK, and the migrated copy against this workspace's v2 environment, with
+   identical pyright settings.
+4. Diff the two error sets. Errors only on the migrated side are the migration
+   surface; baseline noise (the repo's own issues, missing third-party stubs)
+   appears on both sides and cancels out.
+5. Correlate each new error with the inserted `# mcp-codemod:` markers.
+
+The codemod's contract is that the markers are the complete list of remaining
+manual work, so every new error should sit on or next to a marker. **A new
+error with no nearby marker is a silent miss** -- those are printed, written to
+`work/results/<slug>.json`, and make the run exit 1.
+
+## Usage
+
+From the repository root (the v1 environment is created on first run):
+
+```bash
+uv run --frozen python scripts/codemod-batch-test/run.py            # all repos
+uv run --frozen python scripts/codemod-batch-test/run.py --repo mcp-obsidian
+uv run --frozen python scripts/codemod-batch-test/run.py --fresh    # re-clone
+```
+
+## Adding a repository
+
+Add an entry to `repos.json` with a pinned `sha` (never a branch), an
+`include` list when only part of the repository uses the SDK (empty means the
+whole tree), and a one-line `note`. Prefer repositories that depend on the
+`mcp` package directly; servers built on the external FastMCP library exercise
+that library's surface, not this SDK's.

scripts/codemod-batch-test/repos.json

@@ -0,0 +1,30 @@
+[
+  {
+    "slug": "official-servers",
+    "url": "https://github.com/modelcontextprotocol/servers",
+    "sha": "7b1170d1da1e36bc9f553f51e76e64cbfd652b3e",
+    "include": ["src/fetch", "src/git", "src/time"],
+    "note": "The official reference servers; lowlevel Server and FastMCP usage."
+  },
+  {
+    "slug": "mcp-obsidian",
+    "url": "https://github.com/MarkusPfundstein/mcp-obsidian",
+    "sha": "32285e9ac07049a8a23ea7d7903603a3e48a1bf7",
+    "include": [],
+    "note": "Popular community server; lowlevel Server with mcp.types throughout."
+  },
+  {
+    "slug": "awslabs-aws-documentation",
+    "url": "https://github.com/awslabs/mcp",
+    "sha": "3a5294539de4de3a91d0ee72d5487bc8b8b1fcd7",
+    "include": ["src/aws-documentation-mcp-server"],
+    "note": "One server from the awslabs monorepo; production FastMCP usage."
+  },
+  {
+    "slug": "android-mcp-server",
+    "url": "https://github.com/minhalvp/android-mcp-server",
+    "sha": "451d255a7305e6efef8a1a2b7374a21c512bba45",
+    "include": [],
+    "note": "Small community FastMCP server."
+  }
+]