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Fix server startup issues on Python 3.12+ #1

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Fix server startup issues on Python 3.12+ #1

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@akbad akbad commented Oct 19, 2025 •
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Overview

Hi, I ran into problems trying to start the server after installing it using uv sync.
This PR fixes the 2 issues required to get the server to start on Python 3.12+.

The server now successfully starts using:

  • uv run python -m src.main (as in the README)
  • uv run sourcegraph-mcp also works, of course
  • running as a script via uv run python src/main.py

Fixes

  • Import path mismatch (fixed in f39dd6d)

    • Commit ebbf4bc changed imports to use relative paths (e.g. from server import ...)
    • However, based on the existing package structure, to run the server as a module the imports must be package-qualified (i.e. from sourcegraph_mcp.server import ...)

  • FastMCP issues (fixed in 5fe47fe)

    • Upgraded fastmcp dep from ==2.4.0 to >=2.11.2 (to integrate upstream fix for Python 3.12+ "default vs default_factory" bug)
    • Refactored tool registration to use @server.tool() decorators (as needed by new
      FastMCP API)
    • Migrated SSE endpoint configuration to new env variables (FASTMCP_SSE_PATH,
      FASTMCP_MESSAGE_PATH) and updated Dockerfile, .env.sample, and README accordingly

akbad added 2 commits October 19, 2025 01:31
@akbad
fix(imports)!: use package-qualified imports for sourcegraph_mcp
f39dd6d
@akbad
fix(deps)!: upgrade FastMCP to 2.11.2+ (required for Python 3.12+ com…
5fe47fe 
…patibility) and adapt to new API

- Upgrade FastMCP from 2.4.0 to >=2.11.2 (fixes Pydantic field bug)
- Refactor tool registration to use `@server.tool()` decorators (required by new FastMCP version)
- Migrate SSE path config to use env variables (since prev method is now deprecated by FastMCP)

All changes are interdependent to maintain the server in a working state
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@akbad