PreToolUse:Bash hook - OPC script directory guard

[udhaya10]

Problem

When running /research-external, Claude can deviate from documented commands (cd $CLAUDE_OPC_DIR && uv run python scripts/mcp/...) and run from ~/.claude/ instead. This causes uv run to miss opc/pyproject.toml and its dependencies, resulting in ModuleNotFoundError.

Solution

Create a PreToolUse:Bash hook that:

1. Detects scripts/(mcp|core)/ references in Bash commands
2. Blocks execution unless prefixed with cd $CLAUDE_OPC_DIR &&
3. Returns a deny message with the corrected command

Files

• ~/.claude/hooks/src/mcp-directory-guard.ts — hook implementation
• ~/.claude/settings.json — register PreToolUse:Bash matcher