setup

/learn setup

Install the learn-by-mistake hooks for automatic error detection. This command MERGES hooks into your existing configuration — it never overwrites other hooks.

What it does

1. Detect if hooks should go to project level (.claude/hooks.json) or user level (~/.claude/hooks.json)
2. Read existing hooks file (if any)
3. Merge learn-by-mistake hooks into the existing structure
4. Write the merged result
5. Verify installation

Protocol

Step 1: Determine scope

• If the user said /learn setup --global → use ~/.claude/hooks.json
• Otherwise → use .claude/hooks.json in the current project root
• Tell the user which location you're using

Step 2: Read existing hooks

Read the target hooks file. If it exists, parse the JSON. If it doesn't exist, start with:

{"hooks": {}}

Step 3: Merge — NEVER overwrite

For each hook type (PostToolUse, SessionStart, PreCompact):

If the hook type doesn't exist in the target file: add it entirely.

If the hook type already exists: APPEND learn-by-mistake hooks to the existing array. Never remove or modify existing hooks.

To prevent duplicates, check if any existing hook command contains "learn-by-mistake" or "detect-error" before adding.

Step 4: Determine script paths

The hook scripts live in the skill directory. Find them:

# Check common locations
SKILL_DIR=""
for dir in \
  ~/.claude/skills/learn-by-mistake \
  .claude/skills/learn-by-mistake \
  node_modules/learn-by-mistake-skill; do
  if [ -f "$dir/hooks/scripts/detect-error.sh" ]; then
    SKILL_DIR="$dir"
    break
  fi
done

Use ABSOLUTE paths in the hooks.json to avoid working directory issues.

Step 5: Write the merged hooks

The learn-by-mistake hooks to merge:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "bash <SKILL_DIR>/hooks/scripts/detect-error.sh",
            "timeout": 5
          }
        ]
      }
    ],
    "SessionStart": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bash <SKILL_DIR>/hooks/scripts/load-lessons.sh",
            "timeout": 3
          }
        ]
      }
    ],
    "PreCompact": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bash <SKILL_DIR>/hooks/scripts/preserve-lessons.sh",
            "timeout": 3
          }
        ]
      }
    ]
  }
}