[BUG] VS Code terminal mode: daemon-hosted session can never hold the IDE connection (front-end keeps reclaiming it), so mcp__ide__* tools are missing

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

In VS Code over Remote-SSH, with the extension in terminal mode (claudeCode.useTerminal: true):

• /ide always fails with "Failed to connect to Visual Studio Code".
• The session's ide MCP server logs "WebSocket is not open. Cannot start transport."
• mcp__ide__getDiagnostics is never available to the model.

This happens in an existing conversation and in a brand-new one.

Interactive sessions are hosted by the background daemon (claude daemon run --origin transient, with each session under bg-pty-host). The claude process in the VS Code integrated terminal is only a front-end attached to that session. Both processes connect to the extension's IDE server for the same window:

• The front-end has CLAUDE_CODE_SSE_PORT and connects first.
• The daemon-hosted session, which owns the ide MCP tools, connects afterwards.

The IDE server keeps only the newest client and closes the previous one with a close frame that has no status code. So the session's connection pushes the front-end out, the front-end reconnects immediately, and the session is pushed out within milliseconds. The session then reports "WebSocket is not open".

What Should Happen?

When the front-end runs in a VS Code terminal, the daemon-hosted session should still get a working IDE connection (getDiagnostics, diffs). For example, the front-end and the session could share one connection, or the server could accept both.

Error Messages/Logs

/ide
  ⎿  Failed to connect to Visual Studio Code.

[DEBUG] MCP server "ide": Starting connection with timeout of 30000ms
[DEBUG] MCP server "ide": Connection failed after 122ms: WebSocket is not open. Cannot start transport.
[ERROR] MCP server "ide" Connection failed: WebSocket is not open. Cannot start transport.

Steps to Reproduce

1. On a macOS host, install Claude Code 2.1.287. Open it in VS Code via Remote-SSH, with extension 2.1.287 and Use Terminal enabled.
2. Open a folder and start Claude from the extension. Two processes result:

• The terminal claude has TERM_PROGRAM=vscode and CLAUDE_CODE_SSE_PORT=<port>.
• The session process's parent chain is claude daemon run, then bg-pty-host, with no CLAUDE_CODE_SSE_PORT.

1. Run /ide. It prints "Failed to connect to Visual Studio Code", and mcp__ide__getDiagnostics is not in the tool list.
2. Run lsof -nP -iTCP:<port>. The only ESTABLISHED client is the terminal front-end.
3. To show the server's behaviour without Claude: open a VS Code window on an empty folder, so that a new ~/.claude/ide/<port>.lock appears.

• Open websocket client A with the lock's token (X-Claude-Code-Ide-Authorization, subprotocol mcp) and send initialize. The server answers.
• Open client B the same way. The server sends A a close frame with no status code.
• A wrong token is closed with code 1008 instead.

1. Against the window from step 2, open one extra connection with the real token. It is closed after about 3 ms, and the front-end's local port changes (observed: 57975 → 59217), which means the front-end was disconnected and reconnected.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.287 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

• VS Code 1.140.0 over Remote-SSH, extension anthropic.claude-code 2.1.287. The remote host is macOS 26.6.2 on Intel.
• getDiagnostics worked in a terminal-mode session on 2026-09-30 with CLI 2.1.286. The same failure now reproduces with 2.1.286, so the CLI version alone is not the trigger. I don't know whether that earlier session was daemon-hosted.
• claude -p --ide never starts the ide server, so it can't reproduce this. An interactive session under a pty can (claude --ide --debug-file <file>).
• Related but different: #96742, where panel sessions never get the IDE server advertised. Here the port is advertised, and the two clients take the connection from each other.