hook.register Skill

Validates and registers hook manifest files, adding them to the Hook Registry for automatic enforcement.

Purpose

While hook.define creates hooks on-the-fly and updates the live configuration (.claude/hooks.yaml), the hook.register skill formalizes this by validating a hook manifest and adding it to a versioned registry (/registry/hooks.json). This enables:

• Version Control: Track hooks as code with full history
• Review Process: Hook manifests can go through code review before activation
• Centralized Management: Single source of truth for all hooks in the organization
• Formal Schema: Ensures hooks conform to required structure

This skill is part of Betty's Layer 5 (Hooks/Policy) infrastructure, enabling automated governance and validation.

Difference from hook.define

Usage

python skills/hook.register/hook_register.py <path_to_hook_manifest.yaml>

Arguments

Hook Manifest Schema

Required Fields

• name: Unique hook identifier (kebab-case recommended, e.g., validate-openapi-specs)
• version: Semantic version (e.g., 0.1.0)
• description: Human-readable description of what the hook does
• event: Hook trigger event (see Valid Events table below)
• command: Command to execute when hook triggers

Optional Fields

• when: Conditional execution
  • pattern: File pattern to match (e.g., "*.openapi.yaml", "specs/**/*.yaml")
• blocking: Whether hook should block operation if it fails (default: false)
• timeout: Timeout in milliseconds (default: 30000)
• on_failure: What to do on failure: show_errors, silent, log_only (default: show_errors)
• status: Hook status (draft or active, defaults to draft)
• tags: Array of tags for categorization (e.g., ["api", "validation", "compliance"])

Valid Events

Validation Rules

The skill performs comprehensive validation:

1. Required Fields – Ensures name, version, description, event, and command are present
2. Name Format – Validates hook name is non-empty and follows naming conventions
3. Version Format – Ensures version follows semantic versioning (e.g., 0.1.0)
4. Event Type – Verifies event is one of the supported triggers
5. Command Validation – Ensures command is non-empty
6. Type Checking – Validates blocking is boolean, timeout is positive number
7. Pattern Validation – If when.pattern is provided, ensures it's a valid string
8. Name Uniqueness – Checks that hook name doesn't conflict with existing hooks in registry

Outputs

Success Response

{
  "ok": true,
  "status": "registered",
  "errors": [],
  "path": "hooks/validate-openapi.yaml",
  "details": {
    "valid": true,
    "status": "registered",
    "registry_updated": true,
    "manifest": {
      "name": "validate-openapi-specs",
      "version": "0.1.0",
      "description": "Validate OpenAPI specs against Zalando guidelines",
      "event": "on_file_edit",
      "command": "python skills/api.validate/api_validate.py {file_path} zalando",
      "when": {
        "pattern": "*.openapi.yaml"
      },
      "blocking": true,
      "timeout": 10000,
      "status": "active",
      "tags": ["api", "validation", "openapi"]
    }
  }
}

Failure Response

{
  "ok": false,
  "status": "failed",
  "errors": [
    "Invalid event: 'on_file_change'. Must be one of: on_file_edit, on_file_save, on_commit, on_push, on_tool_use, on_agent_start, on_workflow_end"
  ],
  "path": "hooks/invalid-hook.yaml",
  "details": {
    "valid": false,
    "errors": [
      "Invalid event: 'on_file_change'. Must be one of: on_file_edit, on_file_save, on_commit, on_push, on_tool_use, on_agent_start, on_workflow_end"
    ],
    "path": "hooks/invalid-hook.yaml"
  }
}

Examples

Example 1: Register OpenAPI Validation Hook

Hook Manifest (hooks/validate-openapi.yaml):

name: validate-openapi-specs
version: 0.1.0
description: "Validate OpenAPI specs against Zalando guidelines on every edit"

event: on_file_edit
command: "python skills/api.validate/api_validate.py {file_path} zalando"

when:
  pattern: "*.openapi.yaml"

blocking: true
timeout: 10000

status: active
tags: [api, validation, openapi, zalando]

Registration Command:

$ python skills/hook.register/hook_register.py hooks/validate-openapi.yaml
{
  "ok": true,
  "status": "registered",
  "errors": [],
  "path": "hooks/validate-openapi.yaml",
  "details": {
    "valid": true,
    "status": "registered",
    "registry_updated": true
  }
}

Example 2: Register Breaking Change Detection Hook

Hook Manifest (hooks/prevent-breaking-changes.yaml):

name: prevent-breaking-changes
version: 0.1.0
description: "Block commits that introduce breaking API changes"

event: on_commit
command: "python skills/api.compatibility/check_compatibility.py {file_path} --fail_on_breaking"

when:
  pattern: "specs/**/*.yaml"

blocking: true
timeout: 30000

on_failure: show_errors

status: active
tags: [api, compatibility, breaking-changes, commit-hook]

Example 3: Register Audit Log Hook

Hook Manifest (hooks/audit-tool-usage.yaml):

name: audit-tool-usage
version: 0.1.0
description: "Log all tool usage for compliance audit trail"

event: on_tool_use
command: "python skills/audit.log/log_tool_usage.py {tool_name} {timestamp}"

blocking: false
timeout: 5000

on_failure: log_only

status: active
tags: [audit, compliance, logging]

Integration

With Workflows

Hooks can be registered as part of a workflow:

# workflows/setup_governance.yaml
steps:
  - skill: hook.register
    args:
      - "hooks/validate-openapi.yaml"
    required: true

  - skill: hook.register
    args:
      - "hooks/prevent-breaking-changes.yaml"
    required: true

With CI/CD

Validate hooks in continuous integration:

# .github/workflows/validate-hooks.yml
name: Validate Hooks
on: [push, pull_request]
jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Validate all hooks
        run: |
          for hook in hooks/*.yaml; do
            python skills/hook.register/hook_register.py "$hook" || exit 1
          done

Loading Hooks at Runtime

Once registered, hooks can be loaded from the registry:

import json

with open('/registry/hooks.json') as f:
    registry = json.load(f)

active_hooks = [h for h in registry['hooks'] if h['status'] == 'active']

Common Errors

Files Modified

• Registry: /registry/hooks.json – Updated with new or modified hook entry
• Logs: Hook validation and registration logged to Betty's logging system

Hook Registry Structure

The /registry/hooks.json file has this structure:

{
  "registry_version": "1.0.0",
  "generated_at": "2025-10-23T12:00:00Z",
  "hooks": [
    {
      "name": "validate-openapi-specs",
      "version": "0.1.0",
      "description": "Validate OpenAPI specs against Zalando guidelines",
      "event": "on_file_edit",
      "command": "python skills/api.validate/api_validate.py {file_path} zalando",
      "when": {
        "pattern": "*.openapi.yaml"
      },
      "blocking": true,
      "timeout": 10000,
      "on_failure": "show_errors",
      "status": "active",
      "tags": ["api", "validation", "openapi"]
    }
  ]
}

See Also

• hook.define – Use this for immediate hook creation in the dev environment (documented in hook.define SKILL.md)
• Hook Manifest Schema – See Command & Hook Infrastructure for field definitions
• Betty Architecture – Five-Layer Model for understanding how hooks fit into the governance layer
• Hooks in Claude Code – Claude Code Hooks Documentation

Exit Codes

• 0: Success (manifest valid and registered)
• 1: Failure (validation errors or registry update failed)

Best Practices

1. Version Control: Keep hook manifests in your repository (hooks/ directory)
2. Review Process: Require code review for hook changes (they can block operations)
3. Start with Draft: Register new hooks with status: draft, test them, then promote to active
4. Descriptive Names: Use clear, kebab-case names that describe the hook's purpose
5. Appropriate Blocking: Only set blocking: true for critical validations (it will stop operations)
6. Reasonable Timeouts: Set realistic timeouts based on hook complexity (avoid too short or too long)
7. Tag Appropriately: Use tags for easy filtering and organization
8. Test Patterns: Test file patterns thoroughly to avoid unintended matches

Status

Active – This skill is production-ready and actively used in Betty's hook infrastructure.

Version History

• 0.1.0 (Oct 2025) – Initial implementation with full validation and registry management