Pass headers to SSE (fixes #2705)

[mrubens]

Related GitHub Issue

Closes: #2705

Description

Fixes the issue where headers aren't correctly passed through SSE with an approach similar to modelcontextprotocol/typescript-sdk#436 (comment)

Test Procedure

I set up a SSE server locally following https://glama.ai/mcp/servers/@anisirji/mcp-server-remote-setup-with-jwt-auth and confirmed that this change sent the header through correctly with config like this:

{
  "mcpServers": {
    "test-server": {
      "type": "sse",
      "url": "http://localhost:3001/sse",
      "headers": {
        "Authorization": "Bearer ey..."
      }
    }
  }
}

Type of Change

• 🐛 Bug Fix: Non-breaking change that fixes an issue.
• ✨ New Feature: Non-breaking change that adds functionality.
• 💥 Breaking Change: Fix or feature that would cause existing functionality to not work as expected.
• ♻️ Refactor: Code change that neither fixes a bug nor adds a feature.
• 💅 Style: Changes that do not affect the meaning of the code (white-space, formatting, etc.).
• 📚 Documentation: Updates to documentation files.
• ⚙️ Build/CI: Changes to the build process or CI configuration.
• 🧹 Chore: Other changes that don't modify src or test files.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Code Quality:
  • My code adheres to the project's style guidelines.
  • There are no new linting errors or warnings (npm run lint).
  • All debug code (e.g., console.log) has been removed.
• Testing:
  • New and/or updated tests have been added to cover my changes.
  • All tests pass locally (npm test).
  • The application builds successfully with my changes.
• Branch Hygiene: My branch is up-to-date (rebased) with the main branch.
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Changeset: A changeset has been created using npm run changeset if this PR includes user-facing changes or dependency updates.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

Headers are already documented - this just makes them work: https://docs.roocode.com/features/mcp/using-mcp-in-roo#understanding-transport-types

---

Important

Fixes header passing in SSE connections in McpHub.ts by modifying the fetch function to include headers.

• Behavior:
  • Fixes header passing in SSE connections in McpHub.ts by modifying the fetch function to include headers from configInjected.
• Misc:
  • Adds a changeset file nine-windows-read.md to document the patch.

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[fabriciojoc]

Just tested and it works!! @cte or who else needs to review this, please do it asap to add it to the next release!! This is awesome, thanks @mrubens !