git-workflow

Git Workflow

Conventional Commit Format

<type>(<scope>): <description>

[optional body]

[optional footer(s)]

Commit Types

Type	Purpose	Example
feat	New feature for the user	feat(auth): add OAuth2 login flow
fix	Bug fix for the user	fix(cart): correct quantity calculation
refactor	Code change that neither fixes nor adds	refactor(api): simplify request middleware
docs	Documentation only changes	docs(readme): add setup instructions
test	Adding or correcting tests	test(auth): add login failure scenarios
chore	Maintenance tasks, dependencies	chore(deps): upgrade lodash to 4.17.21
perf	Performance improvement	perf(query): add index for user lookup
style	Formatting, whitespace, semicolons	style(lint): fix indentation in models
ci	CI configuration and scripts	ci(actions): add Node 20 to test matrix
revert	Reverts a previous commit	revert: revert feat(auth) commit abc123

Commit Message Rules

• Subject line: max 72 characters, imperative mood, no trailing period
• Body: wrap at 80 characters, explain what and why (not how)
• Footer: reference issues with Closes #123 or Refs #456
• Breaking changes: add BREAKING CHANGE: in the footer or ! after type

feat(api)!: change authentication endpoint response shape

The /auth/login endpoint now returns a nested token object instead
of a flat structure. This aligns with our OAuth2 token standard.

BREAKING CHANGE: response.token is now response.auth.access_token
Closes #892

Commit Atomicity

Each commit must represent exactly one logical change.

• Address a single concern (one bug fix, one feature slice, one refactor)
• Leave the codebase in a working state (tests pass, code compiles)
• Be revertable without side effects on unrelated code
• Include related test changes alongside the code change
• Never mix formatting with logic changes
• Never bundle unrelated bug fixes together

# Stage specific hunks, specific files, then verify
git add -p
git add src/auth/login.ts src/auth/login.test.ts
git diff --cached

Interactive Rebase

git rebase -i HEAD~5      # Rebase last N commits
git rebase -i main        # Rebase onto a branch

Rebase Commands

Command	Short	Effect
pick	p	Keep the commit as-is
reword	r	Keep the commit but edit the message
edit	e	Pause to amend the commit (add files, split)
squash	s	Merge into the previous commit, keep message
fixup	f	Merge into previous commit, discard message
drop	d	Remove the commit entirely

Squash WIP commits:

pick   a1b2c3d feat(auth): add login endpoint
fixup  e4f5g6h wip
fixup  i7j8k9l fix tests

Fixup a commit further back:

git commit --fixup=<target-sha>
git rebase -i --autosquash main

Split a commit (mark as "edit"):

git reset HEAD~1
git add src/models/user.ts
git commit -m "refactor(models): extract user validation"
git add src/routes/auth.ts
git commit -m "feat(auth): add login route"
git rebase --continue

Merge vs Rebase

Use Rebase	Use Merge
Updating feature branch from main	Integrating feature branch into main (--no-ff)
Cleaning up local commits before pushing	Shared branches others have based work on
Maintaining linear history on personal branch	Preserving context of parallel development

• Never rebase commits pushed to a shared branch
• Always rebase local work before pushing
• Use git pull --rebase to avoid unnecessary merge commits

git checkout feature/login && git rebase main          # Update feature
git checkout main && git merge --no-ff feature/login   # Merge feature

Conflict Resolution

1. Identify: git status -- look for "both modified" entries
2. Understand both sides:

   git show :1:path/to/file    # base version
   git show :2:path/to/file    # ours (current branch)
   git show :3:path/to/file    # theirs (incoming branch)
   

3. Resolve each conflict block, then mark resolved:

   git add path/to/file
   git rebase --continue    # or git merge --continue
   

Strategy	When to Use
Accept ours	Their change is outdated or wrong
Accept theirs	Our change was superseded
Manual merge	Both changes are needed, combine them
Re-implement	Both sides diverged too far, rewrite the block

Abort with: git merge --abort or git rebase --abort

.gitignore Patterns

# Node.js                    # Python                     # Java / Kotlin
node_modules/                 __pycache__/                  *.class
dist/                         *.py[cod]                     target/
*.log                         .venv/                        build/
coverage/                     *.egg-info/                   .gradle/

# IDE and OS                  # Secrets (always ignore)
.idea/                        *.pem
.vscode/                      *.key
.DS_Store                     .env*
Thumbs.db                     !.env.example

Pattern	Matches
*.log	All .log files in any directory
/build	build directory in repo root only
build/	build directory anywhere
**/logs	logs directory at any depth
!important	Negate a previous ignore rule
doc/**/*.txt	txt files anywhere under doc/

Git Hooks

Hook	Trigger	Common Use
pre-commit	Before commit is created	Lint, format, run fast tests
commit-msg	After message is written	Validate conventional commit format
pre-push	Before push to remote	Run full test suite
prepare-commit-msg	Before editor opens	Add branch name or ticket number

#!/usr/bin/env bash
# .git/hooks/commit-msg
commit_msg=$(cat "$1")
pattern='^(feat|fix|refactor|docs|test|chore|perf|style|ci|revert)(\(.+\))?(!)?: .{1,72}'
if ! echo "$commit_msg" | grep -qE "$pattern"; then
  echo "ERROR: Commit message does not follow conventional format."
  exit 1
fi

Stashing

git stash push -m "wip: login form validation"   # Save with message
git stash list                                     # List all stashes
git stash apply                                    # Apply most recent (keep in list)
git stash pop                                      # Apply and remove most recent
git stash apply stash@{2}                          # Apply specific stash
git stash drop stash@{0}                           # Drop specific stash
git stash clear                                    # Clear all stashes
git stash push -u -m "include new files"           # Include untracked files
git stash branch feature/from-stash stash@{0}      # Create branch from stash

Cherry-Picking

git cherry-pick -x abc123              # Always use -x to record source
git cherry-pick abc123..def456         # Cherry-pick a range
git cherry-pick --no-commit abc123     # Stage only, do not commit
git cherry-pick --abort                # Abort a conflicted cherry-pick

The -x flag appends (cherry picked from commit ...) for traceability.

Git Bisect

git bisect start
git bisect bad                         # Mark current state as bad
git bisect good v2.1.0                 # Mark a known good commit
# Test each checkout, then: git bisect good / git bisect bad
git bisect start HEAD v2.1.0           # Automate with a test script
git bisect run npm test
git bisect reset                       # When done, return to original state

Amending Commits Safely

git commit --amend -m "fix(auth): correct token expiry check"
git add forgotten-file.ts && git commit --amend --no-edit
git commit --amend --author="Name <email@example.com>"

Safety Checklist

• The commit has NOT been pushed to a shared branch
• No one else has based work on this commit
• Never amend commits on main, master, develop, or release branches
• Use --force-with-lease instead of --force when pushing amended commits

Daily Workflow

git checkout main && git pull --rebase
git checkout -b feature/ticket-123-description
git add -p && git commit -m "feat(module): add feature description"
git fetch origin && git rebase origin/main
git rebase -i origin/main              # Clean up before review
git push -u origin feature/ticket-123-description