Windows: agent steps fail with "claude returned no result event" — claude.cmd shim doesn't stream stdout to the daemon

Summary

On Windows, every agent-driven pipeline step (review, test, document, lint) fails immediately with:

step review failed: agent review: claude returned no result event

…even though the Claude Code CLI works perfectly when invoked directly with the exact same flags.

Environment

• no-mistakes v1.27.3 (daemon also seen after update-check to v1.28.0)
• Windows 10 (19044), daemon running unsandboxed from %LOCALAPPDATA%\no-mistakes\no-mistakes.exe
• Claude Code CLI v2.1.143 (@anthropic-ai/claude-code), npm-global install — claude.cmd shim → node_modules\@anthropic-ai\claude-code\bin\claude.exe
• agent: auto (resolves to claude); no-mistakes doctor reports claude ✓
• Not sandbox / MAX_PATH / rate-limit related (all ruled out; the test step later ran a full project suite for 4.5 min and passed once the agent call worked)

Root cause

no-mistakes invokes the agent through the claude.cmd shim, which on Windows runs via cmd.exe. In that path claude.exe's stdout (the --output-format stream-json stream) is not streamed back to the no-mistakes daemon, so the daemon never receives a result event and reports "claude returned no result event".

Proof

• The exact pipeline invocation run directly in a shell returns a clean {"type":"result","subtype":"success",...} event: claude -p "<prompt>" --verbose --output-format stream-json --json-schema <schema> --dangerously-skip-permissions
• Routing the daemon's agent call through a thin Node wrapper that spawns bin\claude.exe directly (identical argv/stdin) makes the whole pipeline pass: review -> test -> document -> lint -> outcome: passed.

Workaround

Point the agent override at the real exe so no-mistakes bypasses the .cmd shim:

# ~/.no-mistakes/config.yaml
agent_path_override:
  claude: 'C:\Users\<you>\AppData\Roaming\npm\node_modules\@anthropic-ai\claude-code\bin\claude.exe'

Suggested fix

On Windows, resolve and spawn the agent's underlying .exe directly (or ensure the child's stdout is inherited/piped through the cmd.exe layer) instead of launching the .cmd shim — likely applies to the other npm-shim agents (codex, opencode) too.