Slash command $ARGUMENTS breaks with multi-line input — affects 16+ commands across official plugins

Bug Description

When invoking slash commands that use $ARGUMENTS, multi-line input gets broken. This is a systemic issue affecting every command/skill that uses $ARGUMENTS — not just one plugin. The root cause is in how Claude Code passes $ARGUMENTS to shell scripts and command templates.

Scope of Impact

We audited all installed plugins and found 16+ commands affected in a single user installation:

Official Claude Plugins (claude-plugins-official)

| Command | Plugin | Usage |
|---------|--------|-------|
| /ralph-loop | ralph-loop | setup-ralph-loop.sh $ARGUMENTS (shell script) |
| /review-pr | pr-review-toolkit | "$ARGUMENTS" (inline template) |
| /feature-dev | feature-dev | $ARGUMENTS (inline template) |
| /hookify | hookify | $ARGUMENTS (inline template) |
| /create-plugin | plugin-dev | $ARGUMENTS (inline template) |
| /new-sdk-app | agent-sdk-dev | $ARGUMENTS (inline template) |

Everything Claude Code Plugin

| Command | Usage |
|---------|-------|
| /orchestrate | $ARGUMENTS (inline template) |
| /checkpoint | $ARGUMENTS (inline template) |
| /eval | $ARGUMENTS (inline template) |
| /verify | $ARGUMENTS (inline template) |

User Custom Commands

| Command | Usage |
|---------|-------|
| /explore-webapp | $ARGUMENTS (inline template) |
| /test-frontend-cli | $ARGUMENTS (inline template) |
| /test-frontend | $ARGUMENTS (inline template) |

Yuno Plugin (3rd party)

| Command | Usage |
|---------|-------|
| /prd | $ARGUMENTS (inline template) |
| /service-info | "$ARGUMENTS" (inline template) |
| /login | ${ARGUMENTS:-all} (shell script) |

Root Cause Analysis

There are two different failure modes depending on how $ARGUMENTS is used:

1. Shell script commands (e.g., ralph-loop)

In ralph-loop.md:

"${CLAUDE_PLUGIN_ROOT}/scripts/setup-ralph-loop.sh" $ARGUMENTS

The $ARGUMENTS is passed unquoted to a bash script. When input contains newlines:

/ralph-loop Build an API that:
- handles auth  
- has CRUD endpoints
--max-iterations 10

The shell splits on newlines, breaking argument parsing completely. The script receives garbled positional arguments.

2. Inline template commands (e.g., feature-dev, prd)

In feature-dev.md:

Initial request: $ARGUMENTS

When $ARGUMENTS contains newlines, the template substitution itself may work, but the input parsing at Claude Code level truncates or corrupts the multi-line input before it reaches the template.

Steps to Reproduce

Test 1: ralph-loop (shell script mode)

/ralph-loop Build a REST API with:
- GET /users
- POST /users
- Authentication middleware
--max-iterations 5

Expected: Script receives full multi-line prompt
Actual: Breaks on newline, only first line or garbled input received

Test 2: Any inline template command

/prd A payment gateway integration that supports:
- Credit card processing
- Refund handling
- Webhook notifications

Expected: Full multi-line text substituted into $ARGUMENTS
Actual: Truncated or only first line captured

Current Workarounds (all painful)

1. Collapse to single line: Loses readability for complex prompts
2. Write to file first: echo "prompt" > /tmp/prompt.txt then /ralph-loop $(cat /tmp/prompt.txt) — adds friction
3. Use INLINE format: Write everything without line breaks — unreadable for structured tasks

Suggested Solutions (in order of preference)

1. Preserve newlines in $ARGUMENTS: When Claude Code captures user input after a slash command, preserve the full input including newlines. Pass to templates as-is, and to shell scripts as a properly quoted single argument.

1. Multi-line input mode: When a command has argument-hint defined, show a multi-line text input area instead of single-line parsing.

1. Here-doc support for shell commands: Instead of script.sh $ARGUMENTS, support script.sh <<< "$ARGUMENTS" or pipe the arguments via stdin.

1. File-based argument passing: Automatically write $ARGUMENTS to a temp file and pass the file path, so scripts can cat it.

Environment

• macOS Darwin 24.6.0
• Claude Code CLI (Claude Opus 4.6)
• Plugins: ralph-loop, pr-review-toolkit, everything-claude-code, feature-dev, hookify, plugin-dev, agent-sdk-dev, yuno

🤖 Generated with Claude Code