[BUG] Superpowers plugin SessionStart hook error on macOS

Bug Description

The superpowers plugin (v5.0.2) shows SessionStart:startup hook error and UserPromptSubmit hook error on every conversation start on macOS. The errors are cosmetic — the hook context injection still works — but the error messages are noisy.

Environment

• OS: macOS (Darwin 25.3.0, Apple Silicon)
• Claude Code: latest
• Plugin: superpowers@claude-plugins-official v5.0.2
• Shell: zsh

Steps to Reproduce

1. Install superpowers plugin: claude plugins add superpowers@claude-plugins-official
2. Start a new Claude Code conversation
3. Observe SessionStart:startup hook error in output

Expected Behavior

No error displayed — the hook runs successfully (context injection works fine).

Actual Behavior

Error messages appear:

SessionStart:startup hook error
UserPromptSubmit hook error

Additional Context

• Running the hook script manually succeeds and produces valid JSON output
• Existing open issues (#21468, #22449, #22934) are Windows-specific; this occurs on macOS
• The hook at hooks/session-start exits cleanly with valid JSON when invoked directly

🤖 Generated with Claude Code