a loose dependency outside the repository lock.

  The test ran:

  uvx mcp-server-fetch

  uvx creates a separate environment, so the SDK's uv.lock does not apply. Inside that environment, mcp-server-fetch declared:

  mcp>=1.1.3

  with no <2 upper bound.

  13:22 UTC  PR CI:   mcp>=1.1.3 resolves to MCP 1.x → green
  13:45 UTC           MCP 2.0 appears on PyPI
  16:51 UTC  main CI: mcp>=1.1.3 resolves to MCP 2.0 → red

  The PR was legitimately green when approved and merged. The dependency universe changed between its PR run and the post-merge run—even though the repository code and lockfile did not.

  That is the underlying test bug: it was not hermetic. PR #4301 removes the floating external environment and runs a local server using the repository's locked Python environment.