git-workflow-and-versioning

name git-workflow-and-versioning description Structures git workflow practices. Use when making any code change. Use when committing, branching, resolving conflicts, splitting uncommitted work in a messy working tree into clean atomic commits, opening or reviewing a pull request (PR), pushing to a remote, or when you need to organize work across multiple parallel streams. Use when cutting a release, choosing a semantic version bump, tagging, or writing a changelog. Git Workflow and Versioning Overview Git is your safety net. Treat commits as save points, branches as sandboxes, and history as documentation. With AI agents generating code at high speed, disciplined version control is the mechanism that keeps changes manageable, reviewable, and reversible. When to Use Always. Every code change flows through git. Core Principles Trunk-Based Development (Recommended) Keep main always deployable. Work in short-lived feature branches that merge back within 1-3 days. Long-lived development branches are hidden costs — they diverge, create merge conflicts, and delay integration. DORA research consistently shows trunk-based development correlates with high-performing engineering teams. main ──●──●──●──●──●──●──●──●──●── (always deployable) ╲ ╱ ╲ ╱ ●──●─╱ ●──╱ ← short-lived feature branches (1-3 days) This is the recommended default. Teams using gitflow or long-lived branches can adapt the principles (atomic commits, small changes, descriptive messages) to their branching model — the commit discipline matters more than the specific branching strategy. Dev branches are costs. Every day a branch lives, it accumulates merge risk. Release branches are acceptable. When you need to stabilize a release while main moves forward. Feature flags > long branches. Prefer deploying incomplete work behind flags rather than keeping it on a branch for weeks. 1. Commit Early, Commit Often Each successful increment gets its own commit. Don't accumulate large uncommitted changes. Work pattern: Implement slice → Test → Verify → Commit → Next slice Not this: Implement everything → Hope it works → Giant commit Commits are save points. If the next change breaks something, you can revert to the last known-good state instantly. 2. Atomic Commits Each commit does one logical thing: # Good: Each commit is self-contained git log --oneline a1b2c3d Add task creation endpoint with validation d4e5f6g Add task creation form component h7i8j9k Connect form to API and add loading state m1n2o3p Add task creation tests (unit + integration) # Bad: Everything mixed together git log --oneline x1y2z3a Add task feature, fix sidebar, update deps, refactor utils 3. Descriptive Messages Commit messages explain the why , not just the what : # Good: Explains intent feat: add email validation to registration endpoint Prevents invalid email formats from reaching the database. Uses Zod schema validation at the route handler level, consistent with existing validation patterns in auth.ts. # Bad: Describes what's obvious from the diff update auth.ts Format: <type>: <short description> <optional body explaining why, not what> Types: feat — New feature fix — Bug fix refactor — Code change that neither fixes a bug nor adds a feature test — Adding or updating tests docs — Documentation only chore — Tooling, dependencies, config 4. Keep Concerns Separate Don't combine formatting changes with behavior changes. Don't combine refactors with features. Each type of change should be a separate commit — and ideally a separate PR: # Good: Separate concerns git commit -m "refactor: extract validation logic to shared utility" git commit -m "feat: add phone number validation to registration" # Bad: Mixed concerns git commit -m "refactor validation and add phone number field" Separate refactoring from feature work. A refactoring change and a feature change are two different changes — submit them separately. This makes each change easier to review, revert, and understand in history. Small cleanups (renaming a variable) can be included in a feature commit at reviewer discretion. 5. Size Your Changes Target ~100 lines per commit/PR. Changes over ~1000 lines should be split. See the splitting strategies in code-review-and-quality for how to break down large changes. ~100 lines → Easy to review, easy to revert ~300 lines → Acceptable for a single logical change ~1000 lines → Split into smaller changes Branching Strategy Feature Branches main (always deployable) │ ├── feature/task-creation ← One feature per branch ├── feature/user-settings ← Parallel work └── fix/duplicate-tasks ← Bug fixes Branch from main (or the team's default branch) Keep branches short-lived (merge within 1-3 days) — long-lived branches are hidden costs Delete branches after merge Prefer feature flags over long-lived branches for incomplete features Branch Naming feature/<short-description> → feature/task-creation fix/<short-description> → fix/duplicate-tasks chore/<short-description> → chore/update-deps refactor/<short-description> → refactor/auth-module Working with Worktrees For parallel AI agent work, use git worktrees to run multiple branches simultaneously: # Create a worktree for a feature branch git worktree add ../project-feature-a feature/task-creation git worktree add ../project-feature-b feature/user-settings # Each worktree is a separate directory with its own branch # Agents can work in parallel without interfering ls ../ project/ ← main branch project-feature-a/ ← task-creation branch project-feature-b/ ← user-settings branch # When done, merge and clean up git worktree remove ../project-feature-a Benefits: Multiple agents can work on different features simultaneously No branch switching needed (each directory has its own branch) If one experiment fails, delete the worktree — nothing is lost Changes are isolated until explicitly merged The Save Point Pattern Agent starts work │ ├── Makes a change │ ├── Test passes? → Commit → Continue │ └── Test fails? → Revert to last commit → Investigate │ ├── Makes another change │ ├── Test passes? → Commit → Continue │ └── Test fails? → Revert to last commit → Investigate │ └── Feature complete → All commits form a clean history This pattern means you never lose more than one increment of work. If an agent goes off the rails, git reset --hard HEAD takes you back to the last successful state. Change Summaries After any modification, provide a structured summary. This makes review easier, documents scope discipline, and surfaces unintended changes: CHANGES MADE: - src/routes/tasks.ts: Added validation middleware to POST endpoint - src/lib/validation.ts: Added TaskCreateSchema using Zod THINGS I DIDN'T TOUCH (intentionally): - src/routes/auth.ts: Has similar validation gap but out of scope - src/middleware/error.ts: Error format could be improved (separate task) POTENTIAL CONCERNS: - The Zod schema is strict — rejects extra fields. Confirm this is desired. - Added zod as a dependency (72KB gzipped) — already in package.json This pattern catches wrong assumptions early and gives reviewers a clear map of the change. The "DIDN'T TOUCH" section is especially important — it shows you exercised scope discipline and didn't go on an unsolicited renovation. Pre-Commit Hygiene Before every commit: # 1. Check what you're about to commit git diff --staged # 2. Ensure no secrets git diff --staged | grep -i "password\|secret\|api_key\|token" # 3. Run tests npm test # 4. Run linting npm run lint # 5. Run type checking npx tsc --noEmit Automate this with git hooks: // package.json (using lint-staged + husky) { "lint-staged" : { "*.{ts,tsx}" : [ "eslint --fix" , "prettier --write" ] , "*.{json,md}" : [ "prettier --write" ] } } Handling Generated Files Commit generated files only if the project expects them (e.g., package-lock.json , Prisma migrations) Don't commit build output ( dist/ , .next/ ), environment files ( .env ), or IDE config ( .vscode/settings.json unless shared) Have a .gitignore that covers: node_modules/ , dist/ , .env , .env.local , *.pem Using Git for Debugging # Find which commit introduced a bug git bisect start git bisect bad HEAD git bisect good <known-good-commit> # Git checkouts midpoints; run your test at each to narrow down # View what changed recently git log --oneline -20 git diff HEAD~5..HEAD -- src/ # Find who last changed a specific line git blame src/services/task.ts # Search commit messages for a keyword git log --grep= "validation" --oneline Release & Versioning Commits are how you track change; a version is how your consumers track it. The moment anything else depends on your code — another team, a published package, a deployed client — "latest on main" stops being a sufficient answer to "what am I running, and is it safe to upgrade?" A version number and a changelog are the contract that answers it. Semantic Versioning For anything with consumers, version MAJOR.MINOR.PATCH and let the number carry meaning: MAJOR breaking change — consumers must change their code to upgrade MINOR new functionality, backward-compatible — safe to upgrade PATCH bug fix, backward-compatible — safe to upgrade The number is a promise, so make the code match it. A "patch" that changes behavior consumers relied on is a major change wearing a disguise (Hyrum's Law — see the api-and-interface-design skill). When unsure whether a change is breaking, assume it is; a surprise major is far cheaper than a broken consumer. Tag the release, and let the tag be the source of truth A release is an immutable point in history, not a moving branch. Tag it so it can always be reproduced: git tag -a v1.4.0 -m "Release 1.4.0" git push origin v1.4.0 Derive the version from the tag rather than hand-editing it in scattered files, so the artifact, the tag, and the changelog can never disagree. Keep a changelog written for humans A changelog is not git log . It's the curated, consumer-facing answer to "what changed and do I care?" — grouped by Added / Changed / Fixed / Deprecated / Removed / Security , newest on top, every entry phrased around user impact, not internal mechanics. ## [1.4.0] - 2025-06-12 ### Added - Bulk task import via CSV ### Fixed - Timezone drift in recurring task due dates ### Deprecated - `GET /v1/tasks/all` — use the paginated `GET /v1/tasks` (removal in 2.0) Write the entry in the same change that makes the change, while the impact is fresh — not reconstructed from commit archaeology at release time. Breaking changes get a migration note and a deprecation window (follow the deprecation-and-migration skill); shipping the actual release is the shipping-and-launch skill's job — this section is the versioning contract that feeds it. Common Rationalizations Rationalization Reality "I'll commit when the feature is done" One giant commit is impossible to review, debug, or revert. Commit each slice. "The message doesn't matter" Messages are documentation. Future you (and future agents) will need to understand what changed and why. "I'll squash it all later" Squashing destroys the development narrative. Prefer clean incremental commits from the start. "Branches add overhead" Short-lived branches are free and prevent conflicting work from colliding. Long-lived branches are the problem — merge within 1-3 days. "I'll split this change later" Large changes are harder to review, riskier to deploy, and harder to revert. Split before submitting, not after. "I don't need a .gitignore" Until .env with production secrets gets committed. Set it up immediately. "It's just a small fix, bump the patch" Check what consumers can observe. A behavior change they relied on is a major, whatever the diff size. "The changelog is just the commit log" Commits are for you; the changelog is for consumers, curated by impact. Generating one from raw commits buries what matters. "We'll write the changelog at release time" By then the impact is reconstructed from memory and half of it is missing. Write the entry with the change. Red Flags Large uncommitted changes accumulating Commit messages like "fix", "update", "misc" Formatting changes mixed with behavior changes No .gitignore in the project Committing node_modules/ , .env , or build artifacts Long-lived branches that diverge significantly from main Force-pushing to shared branches A breaking change shipped under a minor or patch version bump A release with no tag, or a version number hand-edited out of sync with the tag A user-facing release with no changelog entry, or a changelog that's just dumped commit messages Verification For every commit: Commit does one logical thing Message explains the why, follows type conventions Tests pass before committing No secrets in the diff No formatting-only changes mixed with behavior changes .gitignore covers standard exclusions For every release (anything with consumers): The version bump matches the change: breaking → major, additive → minor, fix → patch The release is tagged, and the version is derived from the tag, not hand-edited out of sync The changelog has a curated, human-readable entry grouped by impact for this version