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File content retrieval fails with numeric project IDs but works with string format

Problem Summary

The get_file_contents function fails when using numeric project IDs but works correctly when using the string format for project IDs.

What I was doing

Testing file content retrieval using both numeric and string project ID formats:

  • Numeric: project_id: 2
  • String: project_id: john/melange-mvp-template

Expected behavior

Both numeric and string project ID formats should work according to GitLab API specifications. The GitLab API accepts both formats for project identification.

Actual behavior

  • ✅ String format works: get_file_contents(project_id="john/melange-mvp-template", file_path="README.md") returns file content successfully
  • ❌ Numeric format fails: get_file_contents(project_id=2, file_path="dune") returns "GitLab API error: Not Found"
  • ❌ Same numeric ID works elsewhere: The same numeric ID (2) works fine in other operations like get_issues(project_id="john/melange-mvp-template") which internally resolves to project ID 2

Test cases that demonstrate the issue

// These should both work but only the second one does:

// FAILS - Returns "GitLab API error: Not Found"
mcp_gitlab.get_file_contents({
  project_id: 2,
  file_path: "README.md"
})

// WORKS - Returns file content successfully  
mcp_gitlab.get_file_contents({
  project_id: "john/melange-mvp-template", 
  file_path: "README.md"
})

Error logs

MCP error -32603: GitLab API error: Not Found

Repository tested against

  • Repository: john/melange-mvp-template on git.haley.io
  • Project ID: 2 (confirmed via search_repositories)
  • Files tested: README.md, dune, CLAUDE.md

Reproducibility

100% reproducible. The numeric format consistently fails while the string format consistently works for the exact same files.

Possible root cause

The MCP server may not be properly URL-encoding numeric project IDs when constructing the GitLab API URL, or may be treating numeric vs string project IDs differently in the request construction.

Impact

  • Medium: Users must remember to use string format instead of numeric IDs
  • Consistency: Creates confusion since other operations work with both formats
  • Developer experience: Reduces reliability and predictability of the API

Suggested fix

Ensure that both numeric and string project ID formats are handled consistently across all functions, following GitLab API standards where project ID can be either:

  • Numeric: 123
  • String: namespace/project-name
  • URL-encoded: namespace%2Fproject-name