Justanesta Claude Code Resources Git Advanced Operations

Git Advanced Operations

Power-user Git workflows for rewriting history, recovery, automation, and large repo management.

Core Principles

1. Understand the object model - Commits are immutable snapshots; branches are movable pointers; HEAD tracks your current position
2. Reflog is your safety net - Every HEAD movement is recorded for 90 days; almost nothing in Git is truly lost
3. Non-destructive by default - Prefer operations that create new commits over those that destroy history
4. Never rewrite shared history - Only rebase or amend commits that have not been pushed to a shared branch
5. Automate repetitive checks - Use hooks to enforce standards before code leaves your machine

Interactive Rebase

Rewrite, reorder, squash, and clean up commit history before sharing

# Rebase last 5 commits interactively
git rebase -i HEAD~5

# In the editor, change pick to the desired action:
# pick   abc1234 Add user model
# squash abc1235 Fix typo in user model
# reword abc1236 Add auth middleware
# edit   abc1237 Add login endpoint
# drop   abc1238 WIP debugging

# Autosquash: auto-arrange fixup/squash commits
git commit --fixup=abc1234
git rebase -i --autosquash HEAD~5

# Rebase onto a different base branch
git rebase --onto main feature-base feature-branch

See interactive-rebase.md for:

• Squash vs fixup vs reword workflows
• Edit mode for splitting commits
• Autosquash with --fixup and --squash commits
• Rebase onto for transplanting branches
• Handling rebase conflicts

Reflog and Recovery

Recover lost commits and undo destructive operations

# View recent HEAD movements
git reflog --date=relative

# Recover a commit after accidental reset
git reflog
# abc1234 HEAD@{2}: commit: important work
git checkout -b recovery-branch abc1234

# Undo a rebase by resetting to pre-rebase state
git reflog
# abc1234 HEAD@{5}: rebase (start): checkout main
git reset --hard HEAD@{5}

# Recover a deleted branch
git reflog | grep "checkout: moving from deleted-branch"
git checkout -b restored-branch abc1234

See reflog-recovery.md for:

• Reflog navigation and time-based references
• Recovering commits after reset, rebase, or amend
• Restoring deleted branches and stashes
• Using git fsck for dangling objects

Git Hooks

Automate checks and enforce standards at key Git events

# Pre-commit hook: lint and format before committing
cat > .git/hooks/pre-commit << 'HOOK'
#!/bin/sh
# Run linter on staged files only
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep '\.py$')
if [ -n "$STAGED_FILES" ]; then
    ruff check $STAGED_FILES || exit 1
    ruff format --check $STAGED_FILES || exit 1
fi
HOOK
chmod +x .git/hooks/pre-commit

# Commit-msg hook: enforce conventional commit format
cat > .git/hooks/commit-msg << 'HOOK'
#!/bin/sh
PATTERN='^(feat|fix|docs|style|refactor|test|chore)(\(.+\))?: .{1,72}$'
if ! head -1 "$1" | grep -qE "$PATTERN"; then
    echo "ERROR: Commit message must follow Conventional Commits format"
    echo "Example: feat(auth): add OAuth2 login flow"
    exit 1
fi
HOOK
chmod +x .git/hooks/commit-msg

See git-hooks.md for:

• Pre-push hooks for test enforcement
• Husky and lint-staged setup for team projects
• Sharing hooks via a committed .githooks/ directory
• All available hook types and their arguments

Worktrees

Work on multiple branches simultaneously without stashing or cloning

# Create a worktree for reviewing a PR
git worktree add ../review-pr-42 pr-42-feature

# Create a worktree with a new branch
git worktree add -b hotfix/login-bug ../hotfix main

# List active worktrees
git worktree list

# Remove a worktree when done
git worktree remove ../review-pr-42

# Prune stale worktree references
git worktree prune

See worktree-patterns.md for:

• PR review workflow with worktrees
• Parallel development across features
• Worktree cleanup and maintenance
• Bare repo with worktree-only workflow

Stash Management

Save and restore work-in-progress without committing

# Stash with a descriptive message
git stash push -m "WIP: refactoring auth middleware"

# Stash only specific files
git stash push -m "partial save" -- src/auth.py src/config.py

# Stash including untracked files
git stash push --include-untracked -m "with new files"

# List stashes and inspect contents
git stash list
git stash show -p stash@{0}

# Apply without removing from stash stack
git stash apply stash@{1}

# Create a branch from a stash
git stash branch new-feature stash@{0}

See stash-lfs-patterns.md for:

• Partial stash with --patch
• Recovering dropped stashes from reflog
• Stash-based workflow patterns

Git LFS

Track large binary files without bloating the repository

# Install and initialize LFS
git lfs install

# Track file patterns
git lfs track "*.psd" "*.zip" "datasets/*.parquet"

# Verify tracked patterns
cat .gitattributes

# Check LFS status
git lfs status
git lfs ls-files

# Migrate existing large files to LFS
git lfs migrate import --include="*.bin" --everything

See stash-lfs-patterns.md for:

• LFS setup and migration workflow
• Handling LFS in CI/CD
• Storage and bandwidth considerations

Anti-Patterns

Performance

Optimizations for large repositories

# Partial clone: skip downloading all blobs upfront
git clone --filter=blob:none https://github.com/org/large-repo.git

# Sparse checkout: only materialize needed directories
git sparse-checkout init --cone
git sparse-checkout set src/my-module tests/my-module

# Shallow clone: limit history depth
git clone --depth=1 --single-branch https://github.com/org/repo.git

# Speed up status in large repos
git config core.fsmonitor true
git config core.untrackedCache true

# Maintenance: schedule background optimization
git maintenance start

# Commit graph: speed up log and merge-base operations
git commit-graph write --reachable

source: Git documentation, Pro Git book, Git LFS documentation

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