claude-code - 💡(How to fix) Fix /ide fails on Windows Server 2019 via RDP: process ancestry check breaks IDE connection after extension reload [1 comments, 2 participants]

Summary

When running Claude Code in a VS Code terminal on Windows Server 2019 via RDP, the /ide command fails with "Failed to connect to Visual Studio Code." after VS Code reloads the extension host (e.g. after Developer: Reload Window or an extension update). The connection cannot be restored without starting a completely new Claude session.

Environment

• OS: Windows Server 2019 Standard (10.0.17763), session via RDP (RDP-Tcp#XX)
• Claude Code CLI: 2.1.119
• VS Code Extension: anthropic.claude-code 2.1.119
• VS Code: 1.117.0

Steps to reproduce

1. Open VS Code on Windows Server 2019 via RDP.
2. Start a Claude Code terminal from VS Code (extension injects CLAUDE_CODE_SSE_PORT=<portA>).
3. Begin a Claude Code session — IDE connection works initially.
4. Reload the VS Code window (Developer: Reload Window) or let the extension update/restart.
5. The extension now starts a new MCP server on a different port <portB> and writes ~/.claude/ide/<portB>.lock.
6. Run /ide in the existing terminal → "Failed to connect to Visual Studio Code."

Root cause

The IDE discovery function in the CLI performs a process-ancestry check when the port in CLAUDE_CODE_SSE_PORT (stale: <portA>) does not match the port in the lock file (<portB>):

// Simplified from CLI source
if (!(K !== null && M.port === K)) {         // port mismatch → enters check
    if (!M.pid || !FpK(M.pid)) continue;
    if (process.ppid !== M.pid) {
        if (!(await z()).has(M.pid)) continue; // ← fails on RDP
    }
}

The check passes only if the lock file's pid (written as process.ppid by the extension host, e.g. 14416) is found in the Claude process's ancestor chain.

On Windows Server via RDP, the ancestor chain is truncated. Debugging shows:

Claude process chain: 9776 → 12340
Lock file pid (14416) in chain: false

The chain stops at 2 levels and never reaches the VS Code process, so the valid lock file is discarded and the function returns [].

The check IS correctly bypassed when K === M.port (i.e. when CLAUDE_CODE_SSE_PORT matches the lock file port). But since process.env is a startup snapshot in Node.js, export CLAUDE_CODE_SSE_PORT=<portB> in the parent shell has no effect on the already-running Claude process.

Expected behavior

/ide should reconnect to the active VS Code instance as long as a valid lock file exists for the current workspace, regardless of whether the Claude process can trace VS Code in its ancestor chain.

Workaround

Start a completely new Claude terminal from VS Code after each extension reload. The extension injects the current port into the new terminal's environment, so the K === M.port path is taken and the ancestry check is skipped.

Suggested fix

Consider one of:

1. Relax the ancestry check on Windows when runningInWindows: true is set in the lock file and the workspace folder matches — RDP sessions commonly break the expected process tree.
2. Re-read CLAUDE_CODE_SSE_PORT from the lock directory at /ide time instead of relying solely on the startup environment, so /ide can discover a new port even in a stale session.
3. Honour CLAUDE_CODE_IDE_SKIP_VALID_CHECK as a full bypass (currently it only sets isValid=true but the ancestry check still runs via the Y block and discards the entry with continue).