[Windows] Blank terminal window opens on Claude Code startup due to -l flag in run-hook.cmd

[PAMulligan]

Describe the bug
When starting Claude Code on Windows with the Superpowers plugin enabled, a blank Windows terminal window opens and remains visible. The terminal has no content and cannot accept input. This happens every time Claude Code starts or resumes a session.

To Reproduce
Steps to reproduce the behavior:

1. Install Superpowers plugin via /plugin install superpowers@superpowers-marketplace
2. Ensure the plugin is enabled in ~/.claude/settings.json
3. Start Claude Code (or resume an existing session)
4. Observe a blank terminal window appears alongside the Claude Code interface

Expected behavior
The SessionStart hook should execute silently in the background without creating any visible terminal windows. The hook should inject context into Claude without user-visible side effects.

Logs
The hook executes successfully (no errors), showing:
SessionStart:startup hook success: Success

However, the terminal window remains open throughout the Claude Code session.

Additional context
Root Cause:

The issue is in hooks/run-hook.cmd line 11:
"C:\Program Files\Git\bin\bash.exe" -l "%~dp0%~1" %2 %3 %4 %5 %6 %7 %8 %9

The -l (login shell) flag causes Git Bash to open a visible terminal window on Windows. This flag appears to be unnecessary for hook execution.

Suggested Fix:

Remove the -l flag from the bash invocation:
"C:\Program Files\Git\bin\bash.exe" "%~dp0%~1" %2 %3 %4 %5 %6 %7 %8 %9

Environment:

• OS: Windows 11 (also confirmed on Windows 10)
• Claude Code version: 2.1.9+
• Superpowers version: 4.0.3
• Git Bash location: C:\Program Files\Git\bin\bash.exe

Impact:

• Hook functionality works correctly
• Terminal window is distracting but can be minimized
• No data loss or functional issues, purely UX problem

[obra]

Related to #317 (Claude Code Windows SessionStart hook failures). This specific issue about the -l flag causing a visible terminal window is a distinct UX problem but shares the same root cause: the polyglot run-hook.cmd approach has multiple Windows compatibility issues.

[obra]

This issue is resolved by PR #331.

Background: The blank terminal window was caused by the -l (login shell) flag in run-hook.cmd when invoking Git Bash.

Fix: PR #331 changes the hook execution model so that run-hook.cmd is no longer used. Instead, hooks.json now calls session-start.sh directly:

"command": "${CLAUDE_PLUGIN_ROOT}/hooks/session-start.sh"

Claude Code 2.1.x automatically handles bash invocation on Windows without the -l flag that was causing the visible terminal window.

The deprecated run-hook.cmd is kept for reference but is no longer invoked by the hooks system.

[obra]

Closed by PR #331