Add GitHub Actions CI workflow and update Git workflow documentation

Setup automated CI pipeline that runs on all pushes and PRs:
- Type checking with TypeScript
- Linting with ESLint
- Build verification with Next.js

Updated CLAUDE.md to reflect new PR-based workflow:
- All changes go through GitHub Pull Requests
- Never merge to main locally
- Never push main branch directly
- CI validates all changes before merge

This ensures code quality and establishes a proper CI/CD foundation
for the project, even as a solo developer.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: lucbrinkman

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: ['**']
+  pull_request:
+    branches: ['**']
+
+jobs:
+  quality-checks:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Type check
+        run: npm run type-check
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Build
+        run: npm run build

CLAUDE.md

@@ -7,6 +7,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 Next.js application called "Map of AI Futures" - an interactive probability flowchart visualizing potential AI future scenarios. Users adjust probability sliders to explore how different decisions affect outcome likelihoods.
 
 **Key Features:**
+
 - Interactive probability sliders with real-time DAG-based calculations
 - Zoom and pan canvas navigation
 - Supabase authentication (passwordless magic link)
@@ -16,17 +17,20 @@ Next.js application called "Map of AI Futures" - an interactive probability flow
 ## Development
 
 **Commands:**
+
 - `npm run dev` - Start dev server (http://localhost:3000)
 - `npm run build` - Build for production
 - `npm run lint` - Run ESLint
 
 **Process Management:**
+
 - **To stop a dev server cleanly:** `fuser -k <port>/tcp` (e.g., `fuser -k 3000/tcp`)
   - This kills all processes using that port, including orphaned child processes
   - More reliable than KillShell which can leave next-server processes running
   - Prevents accumulation of zombie processes that consume CPU/memory
 
 **Environment Variables:**
+
 - `NEXT_PUBLIC_SUPABASE_URL`
 - `NEXT_PUBLIC_SUPABASE_ANON_KEY`
 - `SUPABASE_SERVICE_ROLE_KEY` (server-side only)
@@ -38,63 +42,78 @@ Next.js application called "Map of AI Futures" - an interactive probability flow
 **Important:** This repository uses **multiple worktrees** - the user may be working in different directories on different branches simultaneously.
 
 **Worktree Safety Rule:**
+
 - **NEVER** make edits to files in any worktree other than the one Claude Code was started in
 - Only read from, write to, and execute commands within the current working directory
 - If the user needs changes in a different worktree, they will navigate there and start a new session
 
 **Development Model:**
-- Solo developer project - no GitHub PRs or code review process
-- Merge feature branches to main locally, then push to GitHub
-- Direct push workflow: test locally → merge to main → push
 
-**Branch Merging Protocol:**
-**IMPORTANT:** Only merge to main when the user explicitly says it's time to merge. Do not automatically merge or test for merging during development - features may need multiple iterations before being ready.
+- Solo developer project using GitHub Pull Request workflow
+- All changes go through PRs with automated CI checks
+- Work on feature branches → push to GitHub → create PR → merge via GitHub UI
+- **NEVER merge to main locally**
+- **NEVER push main branch directly**
 
-When the user says to merge a feature branch to main, ALWAYS follow this sequence:
+**Pull Request Workflow:**
+
+1. **Create and push feature branch:**
 
-1. **First, update the feature branch with main:**
    ```bash
-   git checkout feature-branch
-   git merge main
-   # Resolve any conflicts HERE on the feature branch, never on main
+   git checkout -b feature-branch
+   # Make your changes and commit
+   git push origin feature-branch
    ```
 
-2. **Test after merging:**
-   - Clear the Next.js cache: `rm -rf .next`
-   - Start dev server: `npm run dev`
-   - Verify it runs without errors before proceeding
+2. **Create Pull Request:**
+   - Use GitHub UI or `gh pr create` command
+   - CI automatically runs type-check, lint, and build
+   - PR cannot be merged until all CI checks pass
 
-3. **Only then, merge to main using fast-forward only:**
-   ```bash
-   git checkout main
-   git merge --ff-only feature-branch
-   # If this fails, return to step 1 - there are unresolved issues
-   git push origin main
-   ```
+3. **Merge via GitHub:**
+   - Once CI passes and changes are ready, merge via GitHub PR interface
+   - Delete feature branch after merging (can be done automatically)
+   - Pull latest main locally: `git checkout main && git pull origin main`
+
+**CI/CD Pipeline:**
+
+- GitHub Actions workflow runs on all pushes and PRs (`.github/workflows/ci.yml`)
+- Checks: TypeScript type-check, ESLint, Next.js build
+- PRs blocked from merging if CI fails
+- Local pre-commit hooks run same checks (via Husky) to catch issues early
+
+**Branch Protection (configure in GitHub settings):**
+
+- Require PR reviews before merging (optional for solo dev)
+- Require status checks to pass (CI workflow)
+- Require branches to be up to date before merging
 
 **Key Rules:**
-- NEVER merge to main unless the user explicitly says to merge
-- NEVER resolve merge conflicts while on `main` branch
-- ALWAYS use `--ff-only` when merging into main (ensures clean, conflict-free merge)
-- ALWAYS test the dev server after merging but before pushing
-- If user says "merge to main", first update feature branch with main, then merge to main
+
+- NEVER merge to main locally - always use GitHub PRs
+- NEVER push main branch directly - only push feature branches
+- Let CI validate all changes before merging
+- If CI fails, fix issues and push updates to the PR branch
 
 ## Architecture
 
 ### Core System
 
 **Probability Engine:**
+
 - **DAG Structure** (`lib/graphData.ts`, `graphData.json`): Nodes (question/start/outcome types) and edges with conditional probabilities
 - **Calculation** (`lib/probability.ts`): Recursive probability propagation with memoization. Question nodes (21 total) use slider values to control YES/NO branch probabilities
 - **URL State** (`lib/urlState.ts`): Slider values encoded as `?p=50i70i25i...` (integers separated by 'i')
 
 **Unified Document Storage:**
+
 - Single `documents` table replaces old `saved_scenarios` and `user_graphs` tables
 - Each document contains: graph nodes, slider values, metadata (all in one JSONB field)
 - Auto-save with 2-second debounce for authenticated users
 - localStorage fallback for anonymous users with auto-migration on signup
 
 **Authentication:**
+
 - Supabase passwordless magic link (`lib/supabase/`)
 - Server actions in `lib/actions/documents.ts`
 - Custom `useAuth` hook (`hooks/useAuth.ts`) with localStorage migration logic
@@ -113,23 +132,27 @@ When the user says to merge a feature branch to main, ALWAYS follow this sequenc
 ### Important Implementation Details
 
 **Node Interaction:**
+
 - Clicking a node sets it as probability root (recalculates all probabilities from that point)
 - Clicking same node again resets to start node
 - Slider hover highlights corresponding flowchart node
 
 **Edge Rendering:**
+
 - Uses refs to track actual DOM node bounds for accurate arrow positioning
 - Adjusts for zoom scale when calculating edge paths
 - Adaptive opacity/width based on probability values
 
 **State Management:**
+
 - Auto-save hook (`lib/autoSave.ts`) with 2-second debounce for cloud saves
 - localStorage (`lib/documentState.ts`) for anonymous user drafts
 - Document state unified: graph structure, slider values, node positions all in one
 - `useMemo` for probability calculations to prevent unnecessary recomputation
 - Undo stack tracks slider history
 
 **Storage Flow:**
+
 - **Anonymous users**: Changes save instantly to localStorage
 - **Authenticated users**: Changes auto-save to cloud (debounced)
 - **On signup**: localStorage draft automatically migrates to cloud as "My First Map"