configure crashes on Windows with FileNotFoundError when shelling out to npm-installed CLIs (claude/npm) — bare command name not resolved via PATHEXT

[adrian-tompkins]

Disclaimer: this issue was investigated and drafted with the assistance of an AI coding agent.

Summary

On Windows, ucode configure crashes with FileNotFoundError: [WinError 2] The system cannot find the file specified when it shells out to claude (or npm) via subprocess.run([...]). The subprocess call uses a bare command name ("claude", "npm"), which resolves to claude.cmd / npm.cmd when those tools are installed via npm. Python's subprocess.run (without shell=True) calls CreateProcess, which only appends .exe and does not honor PATHEXT — so .cmd/.ps1 shims are never found, even when where claude / where npm succeed in the shell.

Additionally, _register_web_search_mcp in claude.py only catches RuntimeError around remove_claude_mcp_server, so the FileNotFoundError propagates and crashes the whole configure run instead of being treated as best-effort cleanup.

Environment

• OS: Windows (cmd.exe)
• ucode installed via uv tool install
• Python: uv-managed CPython 3.14.6 (bundled with the ucode tool)
• claude and codex installed via npm install -g (i.e. present as claude.cmd / codex.cmd)
• Databricks CLI >= v1.0.0

Affected call sites

• ucode/mcp.py:140 — subprocess.run(["claude", "mcp", "remove", name, "-s", scope], ...)
• ucode/agents/__init__.py:217 — subprocess.run(["npm", "install", "-g", package], ...)
• ucode/agents/claude.py:277 / 362 — _register_web_search_mcp only guards against RuntimeError, not FileNotFoundError

Repro

1. On Windows, install claude and codex via npm install -g (so they exist as .cmd).
2. Run ucode configure --agents codex,claude.
3. Auth completes, then it crashes at remove_claude_mcp_server with FileNotFoundError: [WinError 2].

(Same class of failure hits the npm install -g path in install_tool_binary when the agent binary isn't already present.)

Traceback

...
File "ucode\mcp.py", line 140, in remove_claude_mcp_server
  subprocess.run(["claude", "mcp", "remove", name, "-s", scope], ...)
...
FileNotFoundError: [WinError 2] The system cannot find the file specified