fix: pass Haiku prompt via stdin to avoid cmd.exe quoting (v1.2.1)

[JonyanDunh]

The bug

v1.2.0 was broken on native Windows Claude Code. `/watchdog:start` would run forever, always returning `AMBIGUOUS` verdicts. Diagnosed from the real Windows log (after enabling the new `CLAUDE_CODE_WATCHDOG_LOG_ENABLED=1`):

```
askHaiku verdict: AMBIGUOUS (raw head: Hey! I'm ready to help. What would you like to work on today? I've got context about your...)
```

The headless Haiku classifier was getting no prompt at all and falling into Claude Code's interactive greeting mode.

Root cause: cmd.exe quoting destroyed the prompt

`lib/judge.js` spawned Haiku like this:

```js
spawnSync('claude', ['-p', '--model', 'haiku', '--no-session-persistence', promptText], {
shell: isWindows,
})
```

On Windows, `shell: true` is required because `claude` resolves to a `.cmd` shim via PATHEXT, which means Node forwards the whole command line through cmd.exe. cmd.exe's quoting rules cannot round-trip a string containing CJK characters, newlines, embedded double quotes, AND JSON braces — which is exactly what the classifier prompt is. The `promptText` got shredded before reaching the child claude process, so claude saw no positional prompt and read nothing from stdin (we had it closed with `input: ''`), so it fell back to interactive greeting mode.

On Linux/macOS (`shell: false`), Node passes the argv array straight to `execve` with zero shell interpretation, so the same code path was fine there. This is why it shipped green in CI but broke on the first real Windows test.

The fix (one line)

Pass the prompt via stdin instead of argv:

```diff

• spawnSync('claude', ['-p', '--model', 'haiku', '--no-session-persistence', promptText], {
• input: '',

• spawnSync('claude', ['-p', '--model', 'haiku', '--no-session-persistence'], {
• input: promptText,
  shell: isWindows,
  })
  ```

cmd.exe now has no idea what the prompt contains — stdin is piped through Node directly into the child process, bypassing the shell entirely. Same code path across Linux/macOS/Windows.

Also in this release

Windows `findClaudePid` fast path

`lib/claude-pid.js` now does ONE PowerShell call that walks the ancestry in-process (WMI loop + in-memory traversal) instead of one PowerShell cold-start per level. The naive per-level walk was blowing past Claude Code's internal hook timeout on Windows with ~20 PowerShell spawns × ~2 s each = 40 s per hook.

Haiku 30 s timeout

`lib/judge.js` adds `timeout: 30000` to the `spawnSync` call so a hung `claude -p` aborts cleanly instead of dragging the hook past Claude Code's internal hook timeout.

Dropped pre-flight CLI probe

Removed the `claudeCliAvailable()` check — it was an extra ~2-3 s PowerShell cold-start on Windows for zero value. If the CLI is missing, the real subprocess call below fails with `ENOENT`, which we now catch and classify as `CLI_MISSING` directly.

Optional file logging

Set `CLAUDE_CODE_WATCHDOG_LOG_ENABLED=1` to mirror every log call to a file:

• Default path: `os.tmpdir() + '/claude-code-watchdog.log'` (cross-platform)
• Override: `CLAUDE_CODE_WATCHDOG_LOG_FILE=`

A new `debug()` level is file-only (never touches stderr) and is used liberally through hot paths for trace-style diagnostics — `findClaudePid` timing, Haiku subprocess timing, verdict head, state file path, total hook latency per fire. This is exactly how the Windows diagnosis was made — I told the user to set the env var, re-ran the failing `/watchdog:start`, and the log told us claude was replying with "Hey! I'm ready to help" across every iteration.

Tests

• New `test/log.test.js` (5 tests): default disabled, all 5 log levels mirror to file when enabled, `debug()` is file-only, multi-process append safety, log-write failures don't crash the caller.
• Total: 80 tests, 78 active + 2 skipped-inside-Claude-Code, 0 fail (up from 75 in v1.2.0).

Test plan

• 80-test suite passes locally
• Haiku path verified with mock CLI via `test/stop-hook-haiku.test.js` (all verdict branches)
• File logging path verified with 5 new tests
• Manifests bumped to 1.2.1 (plugin.json + marketplace.json)
• CI will confirm across 9 matrix jobs (ubuntu/macos/windows × Node 18/20/22)

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com