feat(cli): add doctor_handler to check git hooks directory

[Seif-Mamdouh]

Problem Description

Users were encountering a FileNotFoundError when running pip3 install git-ai-commit followed by gac.

The error occurred during the git hook setup process:
FileNotFoundError: [Errno 2] No such file or directory: '/Users/user'sname/projs/cookd/.git/worktrees/candidate-search/hooks/prepare-commit-msg'

The issue was specifically happening in git worktrees, where the hooks directory doesn't exist by default and the code was using an incorrect path resolution method.

Root Cause Analysis

The problem was in two key areas:

Incorrect Path Resolution: The GitService.get_git_prepare_commit_msg_hook_path() method was using simple string concatenation (git_directory + "/hooks/prepare-commit-msg") instead of Git's proper path resolution.

Missing Directory Creation: The handle_setup_hook() function didn't create the hooks directory if it didn't exist, which is common in git worktrees.

Test Plan

recreated the bug by removing the the hook directory doesn't exist

Run this script to verify that the fix works correctly:

python3 test_hook_setup.py

Expected Outcome

[Copilot]

Pull Request Overview

This PR fixes a bug in git hook setup for worktrees by correcting the path resolution and ensuring that the hooks directory is created when missing. It also adds a new doctor_handler to check the git hooks directory and updates relevant tests to verify the changes.

• Fix wrong hook path resolution in git_service by using git's built-in command.
• Ensure handle_setup_hook creates missing directories.
• Add doctor_handler to provide status information about the git hooks directory.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test_hook_setup.py	Adds tests for verifying that missing hooks directories are created and checking local git hooks.
ai_commit_msg/services/llm_service.py	Minor formatting update; no functional changes.
ai_commit_msg/services/git_service.py	Updates hook path determination to use git's rev-parse command.
ai_commit_msg/cli/hook_handler.py	Ensures hooks directory is created before writing the hook file.
ai_commit_msg/cli/doctor_handler.py	Introduces a new utility for checking the git hooks directory.

Comments suppressed due to low confidence (1)

test_hook_setup.py:34

• [nitpick] Consider using assert statements to validate test outcomes instead of relying solely on print outputs, which would enable automated test failure detection.

print("✅ Test completed successfully!")

[Copilot]

Consider using os.path.join(hooks_dir, 'prepare-commit-msg') to build the path, which improves cross-platform compatibility.