Configure Hooks

Configure hook-based event handling for AI Developer Workflow observability.

Arguments

• $ARGUMENTS: <hook-type> [configuration]
  • hook-type: Type of hook (PreToolUse, PostToolUse, Notification, Stop)
  • configuration: Optional JSON configuration or description

Hook Types

Documentation Verification: Hook event types are Claude Code internal types that may change between releases. For authoritative current event types, verify via hook-management skill → docs-management.

Hook	Trigger	Use Case
PreToolUse	Before tool execution	Capture intent, validate
PostToolUse	After tool execution	Capture result, summarize
Notification	Workflow events	Alert, log, broadcast
Stop	Error conditions	Halt execution

Instructions

Step 1: Identify Hook Requirements

Determine what events need capturing:

Common Scenarios:

• Observability: Capture all tool calls for monitoring
• Cost Tracking: Track token usage per workflow
• Debugging: Log decision points for review
• Broadcasting: Stream events to external systems

Step 2: Design Hook Configuration

Create hook configuration in settings.json format:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Write|Edit|Bash",
        "hooks": [
          {
            "type": "command",
            "command": "python /path/to/pre_tool_hook.py"
          }
        ]
      }
    ],
    "PostToolUse": [
      {
        "matcher": "*",
        "hooks": [
          {
            "type": "command",
            "command": "python /path/to/post_tool_hook.py"
          }
        ]
      }
    ]
  }
}

Step 3: Create Hook Script Template

Generate hook script based on type:

PreToolUse Script:

#!/usr/bin/env python3
"""PreToolUse hook for ADW observability."""
import json
import sys
import os

def main():
    # Read hook input from stdin
    input_data = json.load(sys.stdin)

    tool_name = input_data.get("tool_name", "unknown")
    tool_input = input_data.get("tool_input", {})
    adw_id = os.environ.get("ADW_ID", "no-adw")

    # Log event
    event = {
        "type": "PreToolUse",
        "adw_id": adw_id,
        "tool": tool_name,
        "input_preview": str(tool_input)[:100]
    }

    # Write to log or broadcast
    with open(f"agents/{adw_id}/events.jsonl", "a") as f:
        f.write(json.dumps(event) + "\n")

    # Return decision (continue or block)
    print(json.dumps({"decision": "continue"}))

if __name__ == "__main__":
    main()

PostToolUse Script:

#!/usr/bin/env python3
"""PostToolUse hook for ADW observability."""
import json
import sys
import os

def main():
    # Read hook input from stdin
    input_data = json.load(sys.stdin)

    tool_name = input_data.get("tool_name", "unknown")
    tool_result = input_data.get("tool_result", "")
    adw_id = os.environ.get("ADW_ID", "no-adw")

    # Log event
    event = {
        "type": "PostToolUse",
        "adw_id": adw_id,
        "tool": tool_name,
        "result_preview": str(tool_result)[:200]
    }

    # Write to log or broadcast
    with open(f"agents/{adw_id}/events.jsonl", "a") as f:
        f.write(json.dumps(event) + "\n")

if __name__ == "__main__":
    main()

Step 4: Environment Variable Setup

Define ADW context variables:

export ADW_ID="a1b2c3d4"
export ADW_STEP="build"
export ADW_WORKFLOW="plan_build_review"
export ADW_OUTPUT_DIR="agents/${ADW_ID}"

Step 5: Create Output Directory

Ensure event output location exists:

mkdir -p agents/${ADW_ID}

Output

## Hook Configuration Report

**Hook Type:** {hook_type}
**Configuration:** {config}

### Generated Files

| File | Purpose |
| --- | --- |
| `hooks/pre_tool_hook.py` | PreToolUse event capture |
| `hooks/post_tool_hook.py` | PostToolUse event capture |

### Settings Configuration

```json
{settings snippet}

Environment Variables

Variable	Value	Purpose
ADW_ID	{id}	Workflow correlation
ADW_STEP	{step}	Current step context
ADW_OUTPUT_DIR	{path}	Event output location

Verification

Run test command to verify hook fires:

# In Claude Code session with hooks configured
echo "Test hook" > /dev/null
# Check agents/{adw_id}/events.jsonl for captured events

Next Steps

1. Add hook scripts to version control
2. Configure settings.json with hook entries
3. Test with sample ADW execution
4. Add WebSocket broadcasting (see /broadcast-event)

Event Payloads

PreToolUse Payload

{
  "tool_name": "Write",
  "tool_input": {
    "file_path": "/path/to/file.py",
    "content": "..."
  }
}

PostToolUse Payload

{
  "tool_name": "Write",
  "tool_input": {...},
  "tool_result": "File written successfully"
}

Cross-References

• @hook-event-patterns.md - Event types and payloads
• @websocket-architecture.md - Broadcasting events
• hook-event-architecture skill - Event system design
• event-broadcaster agent - Broadcasting design