fix: migrate to mcp 2.x SDK (FastMCP -> MCPServer)

[shenxianpeng]

Summary

Fixes the CI failure on #25 (ModuleNotFoundError: No module named 'mcp.server.fastmcp').

Root cause: dependabot PR #25 relaxes the mcp constraint to allow 2.x, and mcp 2.0.0 removes mcp.server.fastmcp — the module this server imports. All four test jobs (3.10–3.13) fail at collection.

Fix: migrate to the v2 API. mcp 2.0.0 replaced FastMCP with mcp.server.mcpserver.MCPServer, whose API is identical for this project's usage:

# before
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("commit-check-mcp", instructions=...)

# after
from mcp.server.mcpserver import MCPServer
mcp = MCPServer("commit-check-mcp", instructions=...)

Verified MCPServer.tool(), MCPServer.run(transport="stdio") and the instructions kwarg have the same signatures in 1.x/2.x.

Changes

• src/commit_check_mcp/server.py — import + instantiate MCPServer (2 lines)
• pyproject.toml — require mcp>=2,<3 (the code now uses a v2-only module; keeping >=1.27 would let pip resolve 1.x and break imports)
• uv.lock — regenerated

Validation

• Clean install from the new constraint resolves mcp 2.0.0; all 67 tests pass
• All 8 MCP tools register on the v2 server (server_health, validate_commit_message, validate_branch_name, validate_author_info, validate_push_safety, validate_commit_context, validate_repository_state, describe_validation_rules)
• CI failure reproduced locally before the fix (same traceback as GitHub Actions)

Supersedes #25 (close #25 after merging this).

Summary by CodeRabbit

• New Features

  • Updated compatibility with MCP version 2.
  • Continued support for existing server configuration and registered tools.

• Bug Fixes

  • Improved server startup compatibility following the MCP framework update.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: bfc73e28-c69c-4873-81af-fdf6981c5427

📥 Commits

Reviewing files that changed from the base of the PR and between c4be16d and e150df6.

⛔ Files ignored due to path filters (1)

• uv.lock is excluded by !**/*.lock

📒 Files selected for processing (2)

• pyproject.toml
• src/commit_check_mcp/server.py

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📝 Walkthrough

Walkthrough

The project now requires MCP v2. The server imports and instantiates MCPServer instead of FastMCP.

Changes

MCP v2 migration

Layer / File(s)	Summary
Update MCP dependency and server initialization pyproject.toml, src/commit_check_mcp/server.py	The mcp requirement now targets version 2. The server uses MCPServer while retaining its existing configuration and tool registrations.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Linked Issues check	❓ Inconclusive	The source migration and dependency constraint satisfy the visible issue requirements, but uv.lock regeneration cannot be verified because uv.lock was excluded by !**/*.lock.	Include uv.lock in the review or provide evidence that it resolves mcp to version 2.0.0 or later.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the MCP 2.x migration and the FastMCP to MCPServer API change.
Out of Scope Changes check	✅ Passed	The reviewed changes are limited to the MCP dependency update and required server API migration.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/mcp-2-migration

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (c4be16d) to head (e150df6).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #27   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          203       203           
=========================================
  Hits           203       203           

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