PreToolUse/PostToolUse hooks always show 'hook error' on Windows despite exit 0

Summary

On Windows 11 with Claude Code 2.1.96, all PreToolUse and PostToolUse hooks display "hook error" in the transcript even when they exit with code 0 and produce correct output. SessionStart and UserPromptSubmit hooks display "success" correctly.

Reproduction

1. Windows 11 Pro (10.0.26200), shell: Git Bash
2. Claude Code 2.1.96
3. Add a minimal PreToolUse hook to .claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "node -e \"process.exit(0)\""
          }
        ]
      }
    ]
  }
}

1. Run any Bash command in Claude Code
2. Observe: PreToolUse:Bash hook error appears in transcript

What was tested

| Hook variant | Exit code | Stdout | Stderr | Result |
|---|---|---|---|---|
| node -e "process.exit(0)" | 0 | none | none | error |
| bash -c "exit 0" | 0 | none | none | error |
| bash -c "cat; exit 0" (stdin passthrough) | 0 | JSON | none | error |
| Node script outputting {} | 0 | {} | none | error |
| Node script with stderr + exit 0 | 0 | JSON | text | error |

All hooks execute correctly (verified via log files and side effects). The "hook error" label is purely a display issue.

Expected behavior

Hooks exiting with code 0 should display "hook success" (or no message), matching the behavior of SessionStart and UserPromptSubmit hooks.

Impact

Every tool use (Bash, Read, Edit, Write) generates 8-14 "hook error" lines in the transcript, making it very noisy and hard to distinguish real errors from cosmetic ones.

Environment

• OS: Windows 11 Pro 10.0.26200
• Shell: Git Bash (MINGW64)
• Claude Code: 2.1.96
• Node: v24.x
• Hooks tested with both node and bash commands