Use official ACP SDK and support HTTP/SSE based MCP servers

[SteffenDE]

Summary

Closes #12427.

Refactors the Zedintegration code to use the official Agent Client Protocol SDK.

Adds support for using the ACP "Zed Integration" with SSE and HTTP based MCP servers. See https://agentclientprotocol.com/protocol/session-setup#mcp-servers.

Details

In #12427, michalslaski asked for a way to reuse the official ACP schema without copying over the code. I decided to refactor the code to use the official SDK.

Note: I needed to cherrypick a patch from #13795 to make ACP work at all. I can drop that commit once that PR is merged.

Related Issues

#12427

How to Validate

Since Zed doesn't support non-stdio MCPs, I tested this using tidewave.ai's ACP integration. You could also manually send JSON-RPC messages over stdio to verify.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

Summary of Changes

Hello @SteffenDE, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request modernizes the Zed integration by migrating its Agent Client Protocol (ACP) implementation to the official SDK. This change not only simplifies the internal architecture by removing custom protocol handling but also significantly expands the integration's capabilities by enabling communication with HTTP and SSE-based MCP servers. The update ensures broader compatibility and a more robust foundation for agent-client interactions.

Highlights

• Official ACP SDK Adoption: The Zed integration code has been refactored to utilize the official Agent Client Protocol (ACP) SDK, replacing previous custom implementations and schemas.
• HTTP/SSE MCP Server Support: Support has been added for HTTP and Server-Sent Events (SSE) based MCP (Multi-Client Protocol) servers, enhancing the flexibility of agent communication.
• Codebase Simplification: The custom ACP connection logic, schemas, and associated test files have been removed, leading to a more streamlined and maintainable codebase.
• Improved Output Handling: Output listeners have been initialized to ensure proper flushing of buffered output and logs to stderr in non-interactive modes, preventing data loss.

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[gemini-code-assist]

Code Review

This pull request is a significant and valuable refactoring that replaces a custom implementation of the Agent Client Protocol with the official ACP SDK. This greatly improves maintainability and aligns the project with the standard. The PR also successfully adds support for HTTP/SSE based MCP servers. The changes are well-executed, but I've identified one critical issue in the new output handling logic that could disrupt the ACP communication by writing non-protocol data to stdout.

[michalslaski]

Tested the PR with tidewave.ai (see screencast).

Steps:

1. Build gemini-cli from this PR (make build)
2. Generate a sample React+Vite application in Google AI Studio (app.new)
3. Download the sample app and start it (npm run dev)
4. Download Tidewave app for your operating system and configure it for React (see docs)
5. Start Tidewave and visit localhost:9832
6. Configure Gemini CLI as an External Agent of Tidewave (npx /your/path/to/gemini-cli --experimental-acp)
7. Try referencing an element on the web page in the Tidewave Chat prompt

[SteffenDE]

I removed the code from #13795 (fixed in #14159) and rebased!

[jwflicker]

experimental-acp not accepting SSE MCP on session/new #8672

[swissspidy]

@allenhutchison @NTaylorMullen any takers for reviewing this one? Only heard crickets so far when looking for reviewers :)

[michalslaski]

Tested the latest changes and merges by running the steps again. Several rounds of messages and code changes went well.

[allenhutchison]

Overall this looks great. I'm glad that we can move to the standard library from our custom implementation. It looks like there are some merge conflicts with files you've deleted so if you can just clear the conflicts and get this into a mergeable state I'm happy to help you get it in.

[allenhutchison]

Looks like you have some build failures in the current version of the branch. Can you run npm run preflight and address those issues?

[SteffenDE]

@allenhutchison should be good now, sorry!