Bug Description

The setup-ralph-loop.sh script fails with an unbound variable error when set -u (strict mode) is enabled and no prompt arguments are provided before options.

Error

PROMPT_PARTS[*]: unbound variable

Root Cause

Line 113 in scripts/setup-ralph-loop.sh:

PROMPT="${PROMPT_PARTS[*]}"

When PROMPT_PARTS array is empty (e.g., when only options like --help are passed, or in certain edge cases), bash's strict mode (set -u on line 6) causes this to fail.

Fix

Change line 113 from:

PROMPT="${PROMPT_PARTS[*]}"

To:

PROMPT="${PROMPT_PARTS[*]:-}"

The :-} provides a default empty string when the array is empty, preventing the unbound variable error while maintaining strict mode for catching other bugs.

Environment

• macOS (Darwin 25.1.0)
• Bash (zsh-compatible)
• Claude Code CLI

Steps to Reproduce

1. Install the ralph-loop plugin
2. Run /ralph-loop --help or any command that might result in an empty PROMPT_PARTS array
3. Observe the unbound variable error

The fix is a one-line change that maintains backward compatibility.