docs: Add documentation site with Astro Starlight

.claude/skills/write-docs/SKILL.md

@@ -0,0 +1,95 @@
+---
+name: write-docs
+description: Create or update documentation pages for the Abacus docs site. Use when adding new documentation, updating existing pages, or ensuring docs stay in sync with code changes. Ensures pages follow Starlight patterns and build correctly.
+allowed-tools: Read, Grep, Glob, Edit, Write, Bash
+---
+
+# Write Docs Skill
+
+Create and maintain documentation for the Abacus docs site (Astro Starlight).
+
+## Before Starting
+
+1. Read existing pages in `docs/src/content/docs/` to understand patterns
+2. Check `docs/astro.config.mjs` for sidebar structure
+3. Understand the section you're adding to (getting-started, providers, cli, deployment, development)
+
+## Workflow
+
+### Adding a New Page
+
+1. Create `.mdx` file in the appropriate directory
+2. Add required frontmatter (see below)
+3. Use existing pages as reference for component usage
+4. Run `cd docs && pnpm build` to verify
+
+### Updating an Existing Page
+
+1. Read the current page first
+2. Make changes, preserving existing patterns
+3. Run `cd docs && pnpm build` to verify
+
+## Frontmatter
+
+Every page requires:
+
+```mdx
+---
+title: Page Title
+description: One-line description for SEO
+sidebar:
+  order: 1  # Position within section
+---
+```
+
+## Key Rules
+
+### Links Must Include Base Path
+
+Internal links need `/abacus/` prefix (GitHub Pages requirement):
+
+```mdx
+[Quick Start](/abacus/getting-started/quick-start/)  ✓
+[Quick Start](/getting-started/quick-start/)          ✗
+```
+
+### Import Components Before Use
+
+```mdx
+import { Steps, Aside } from '@astrojs/starlight/components';
+
+<Steps>
+1. First step
+2. Second step
+</Steps>
+
+<Aside type="tip">Helpful note</Aside>
+```
+
+### Code Blocks Need Language Tags
+
+```mdx
+```bash
+pnpm cli sync
+```
+```
+
+## Build Verification
+
+**Always verify before committing:**
+
+```bash
+cd docs && pnpm build
+```
+
+Common errors:
+- Missing imports
+- Invalid frontmatter
+- Broken links (wrong path or missing `/abacus/`)
+
+## Style Guidelines
+
+- Imperative mood ("Run this" not "You should run")
+- Code examples over abstract descriptions
+- Keep paragraphs short - users skim
+- Tables for reference data (env vars, options)

.github/workflows/deploy-docs.yml

@@ -0,0 +1,63 @@
+name: Deploy Documentation
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'docs/**'
+      - '.github/workflows/deploy-docs.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: pages
+  cancel-in-progress: false
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: 'pnpm'
+          cache-dependency-path: docs/pnpm-lock.yaml
+
+      - name: Install dependencies
+        working-directory: docs
+        run: pnpm install --frozen-lockfile
+
+      - name: Build documentation
+        working-directory: docs
+        run: pnpm build
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: docs/dist
+
+  deploy:
+    needs: build
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

AGENTS.md

@@ -80,3 +80,21 @@ Use `ui-design` skill when creating or modifying frontend components. Covers col
 ## Tips & Guides
 
 Use `write-tip` skill when editing tips. Key files: `src/lib/tips.ts`, `.claude/skills/write-tip/SKILL.md`
+
+## Documentation
+
+Documentation lives in `docs/` (Astro Starlight, deployed to GitHub Pages).
+
+**Keep docs in sync with code.** When changing these areas, update the corresponding docs:
+
+| Code Change | Update Docs |
+|-------------|-------------|
+| CLI commands (usage sync) | `docs/src/content/docs/cli/usage-data.mdx` |
+| CLI commands (commits) | `docs/src/content/docs/cli/commit-data.mdx` |
+| CLI commands (mappings) | `docs/src/content/docs/cli/identity-mappings.mdx` |
+| Environment variables | `docs/src/content/docs/getting-started/environment-variables.mdx` |
+| Provider setup/behavior | `docs/src/content/docs/providers/*.mdx` |
+| Cron schedules / Vercel config | `docs/src/content/docs/deployment/vercel.mdx` |
+| Project structure | `docs/src/content/docs/development/architecture.mdx` |
+
+Use `write-docs` skill when creating or updating documentation. See `.claude/skills/write-docs/SKILL.md`

docs/astro.config.mjs

@@ -0,0 +1,60 @@
+import { defineConfig } from 'astro/config';
+import starlight from '@astrojs/starlight';
+
+export default defineConfig({
+  site: 'https://getsentry.github.io',
+  base: '/abacus',
+  image: {
+    service: { entrypoint: 'astro/assets/services/noop' },
+  },
+  integrations: [
+    starlight({
+      title: 'Abacus',
+      description: 'Track and analyze AI coding tool usage across your team',
+      social: {
+        github: 'https://github.com/getsentry/abacus',
+      },
+      customCss: ['./src/styles/custom.css'],
+      head: [
+        {
+          tag: 'script',
+          content: `
+            localStorage.setItem('starlight-theme', 'dark');
+            document.documentElement.dataset.theme = 'dark';
+          `,
+        },
+      ],
+      components: {
+        ThemeSelect: './src/components/ThemeSelect.astro',
+      },
+      sidebar: [
+        { label: 'Welcome', link: '/' },
+        {
+          label: 'Getting Started',
+          autogenerate: { directory: 'getting-started' },
+        },
+        {
+          label: 'Providers',
+          autogenerate: { directory: 'providers' },
+        },
+        {
+          label: 'CLI Reference',
+          autogenerate: { directory: 'cli' },
+        },
+        {
+          label: 'Deployment',
+          autogenerate: { directory: 'deployment' },
+        },
+        {
+          label: 'Development',
+          collapsed: true,
+          autogenerate: { directory: 'development' },
+        },
+      ],
+      editLink: {
+        baseUrl: 'https://github.com/getsentry/abacus/edit/main/docs/',
+      },
+      lastUpdated: true,
+    }),
+  ],
+});

docs/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "abacus-docs",
+  "version": "1.0.0",
+  "private": true,
+  "scripts": {
+    "dev": "astro dev",
+    "build": "astro build",
+    "preview": "astro preview"
+  },
+  "dependencies": {
+    "astro": "^5.0.0",
+    "@astrojs/starlight": "^0.30.0"
+  }
+}