musingfox/hook-guard-update

Hook Guard Update

Update existing hook-guard installation by re-detecting the environment and applying changes.

Workflow

1. Verify Existing Installation

Check that hook-guard is already set up:

• .githooks/pre-commit exists
• .claude/settings.local.json has hook-guard hooks

If not found, suggest running setup instead.

2. Re-detect Environment

Run the same detection as setup. Read these reference files from the setup skill:

• skills/setup/references/detection.md — detection matrix
• skills/setup/references/settings.md — settings schema and defaults

Detect: languages, toolchain, VCS, project structure.

3. Diff Analysis

Compare current detection results with what's currently installed:

Read existing hooks and extract current configuration:

• Parse .githooks/pre-commit for enabled checks and tool commands
• Parse .claude/settings.local.json for CC hook commands
• Read .claude/hook-guard.local.md for user overrides (read skills/setup/references/settings.md for schema)

Identify changes:

• New tools detected (e.g., added eslint to a project that only had prettier)
• Removed tools (e.g., switched from flake8 to ruff)
• New languages detected (e.g., added Python files to a JS project)
• Missing checks that should be enabled

4. Present Changes

Show a diff-style summary:

Hook Guard Update
═══════════════════════════════════════

  Changes detected:

  + ruff detected (new) → update lint/format commands
  - flake8 no longer configured → remove from hooks
  ~ pytest → pytest with coverage flag (pyproject.toml changed)

  Files to update:
    .githooks/pre-commit        (lint/format commands)
    .claude/settings.local.json (PostToolUse command)

  No changes needed:
    .githooks/commit-msg
    Security checks
    File integrity checks

═══════════════════════════════════════

5. Apply Updates

After user confirms, apply changes surgically — do not rewrite unchanged parts.

Read canonical implementations from the setup skill references:

• skills/setup/references/pre-commit-checks.md — check function implementations
• skills/setup/references/cc-hooks.md — Claude Code hooks patterns

For .githooks/pre-commit:

• Read the existing script
• Identify which check functions need updating (tool command changes)
• Replace only those function bodies with canonical implementations from pre-commit-checks.md
• If new checks need adding, insert them in the correct section (security / integrity / structure / skippable)
• Preserve the script structure, configuration variables, and helper functions

For .claude/settings.local.json:

• Read and parse existing JSON
• Update only the hook command strings that changed
• Deep-merge (do not overwrite unrelated settings)

Preserve user customizations from .claude/hook-guard.local.md throughout.

6. Post-Update

• Show summary of changes applied
• Suggest running doctor to verify everything works