Setting Up Better Context for GPT Agent via Global Git Hooks

Follow these steps to configure a global Git hooks directory and set up a prepare-commit-msg hook that appends diffs to commit messages.

Step 1: Create a Global Hooks Directory

Create a directory ~/.git/hooks to store your global hooks.
```
mkdir -p ~/.git/hooks
```

Step 2: Configure Git to Use the Global Hooks Directory

Configure Git to use ~/.git/hooks as the global hooks directory.
```
git config --global core.hooksPath ~/.git/hooks
```

Step 3: Create the `commit-msg` Hook

Create the commit-msg hook file and make it executable.

touch ~/.git/hooks/commit-msg
chmod +x ~/.git/hooks/commit-msg

Edit and add the following to the file.

#!/bin/bash

# The commit message file
COMMIT_MSG_FILE="$1"

# Remove lines starting with #
sed -i '/^#/d' "$COMMIT_MSG_FILE"

exit 0

Step 4: Create the `prepare-commit-msg` Hook

Create the prepare-commit-msg hook file and make it executable.

touch ~/.git/hooks/prepare-commit-msg
chmod +x ~/.git/hooks/prepare-commit-msg

Edit the prepare-commit-msg file and add the following script:

#!/bin/sh

# The first argument is the path to the commit message file
commit_msg_file="$1"
commit_source="$2"  # The second argument indicates the source (e.g., commit, merge, cherry-pick)

# Exit if a rebase is in progress
if [ -d "$(git rev-parse --git-dir)/rebase-merge" ] || [ -d "$(git rev-parse --git-dir)/rebase-apply" ]; then
  exit 0
fi

# Exit if this is a cherry-pick
if [ -f "$(git rev-parse --git-dir)/CHERRY_PICK_HEAD" ]; then
  exit 0
fi

# Append the diff to the commit message file as comments without overriding the existing message
git diff --cached | sed 's/^/# /' >> "$commit_msg_file"

Verification

To verify that your global hook is working:

Stage some changes:
```
git add <your-files>
```
Commit the changes:
```
git commit
```

When the commit message editor opens, you should see the default commit message template followed by the diff of the staged changes commented out at the bottom.

klondikemarlen/README, Setting Up Better Context for GPT Agent via Global Git Hooks, 2025-02-19.md