# AGENTS.md

Instructions for AI coding agents working on this codebase.

## Project overview

An open-source markdown sync site for developers and AI agents. Publish from the terminal with `npm run sync`. Write locally, sync instantly with real-time updates. Powered by Convex and Netlify.

**Key features:**
- Markdown posts with frontmatter
- Four themes (dark, light, tan, cloud)
- Full text search with Command+K
- Real-time analytics at `/stats`
- RSS feeds and sitemap for SEO
- API endpoints for AI/LLM access

## Tech stack

| Layer | Technology |
|-------|------------|
| Frontend | React 18, TypeScript, Vite |
| Backend | Convex (real-time serverless database) |
| Styling | CSS variables, no preprocessor |
| Hosting | Netlify with edge functions |
| Content | Markdown with gray-matter frontmatter |

## Setup commands

```bash
npm install                    # Install dependencies
npx convex dev                 # Initialize Convex (creates .env.local)
npm run dev                    # Start dev server at http://localhost:5173
```

## Content sync commands

```bash
npm run sync                   # Sync markdown to development Convex
npm run sync:prod              # Sync markdown to production Convex
npm run import <url>           # Import external URL as markdown post
```

Content syncs instantly. No rebuild needed for markdown changes.

## Build and deploy

```bash
npm run build                  # Build for production
npx convex deploy              # Deploy Convex functions to production
```

**Netlify build command:**
```bash
npm ci --include=dev && npx convex deploy --cmd 'npm run build'
```

## Code style guidelines

- Use TypeScript strict mode
- Prefer functional components with hooks
- Use Convex validators for all function arguments and returns
- Always return `v.null()` when functions don't return values
- Use CSS variables for theming (no hardcoded colors)
- No emoji in UI or documentation
- No em dashes between words
- Sentence case for headings

## Convex patterns (read this)

### Always use validators

Every Convex function needs argument and return validators:

```typescript
export const myQuery = query({
  args: { slug: v.string() },
  returns: v.union(v.object({...}), v.null()),
  handler: async (ctx, args) => {
    // ...
  },
});
```

### Always use indexes

Never use `.filter()` on queries. Define indexes in schema and use `.withIndex()`:

```typescript
// Good
const post = await ctx.db
  .query("posts")
  .withIndex("by_slug", (q) => q.eq("slug", args.slug))
  .first();

// Bad - causes table scans
const post = await ctx.db
  .query("posts")
  .filter((q) => q.eq(q.field("slug"), args.slug))
  .first();
```

### Make mutations idempotent

Mutations should be safe to call multiple times:

```typescript
export const heartbeat = mutation({
  args: { sessionId: v.string(), currentPath: v.string() },
  returns: v.null(),
  handler: async (ctx, args) => {
    const now = Date.now();
    const existing = await ctx.db
      .query("activeSessions")
      .withIndex("by_sessionId", (q) => q.eq("sessionId", args.sessionId))
      .first();

    if (existing) {
      // Early return if recently updated with same data
      if (existing.currentPath === args.currentPath && 
          now - existing.lastSeen < 10000) {
        return null;
      }
      await ctx.db.patch(existing._id, { currentPath: args.currentPath, lastSeen: now });
      return null;
    }

    await ctx.db.insert("activeSessions", { ...args, lastSeen: now });
    return null;
  },
});
```

### Patch directly without reading

When you only need to update fields, patch directly:

```typescript
// Good - patch directly
await ctx.db.patch(args.id, { content: args.content });

// Bad - unnecessary read creates conflict window
const doc = await ctx.db.get(args.id);
if (!doc) throw new Error("Not found");
await ctx.db.patch(args.id, { content: args.content });
```

### Use event records for counters

Never increment counters on documents. Use separate event records:

```typescript
// Good - insert event record
await ctx.db.insert("pageViews", { path, sessionId, timestamp: Date.now() });

// Bad - counter updates cause write conflicts
await ctx.db.patch(pageId, { views: page.views + 1 });
```

### Frontend debouncing

Debounce rapid mutations from the frontend. Use refs to prevent duplicate calls:

```typescript
const isHeartbeatPending = useRef(false);
const lastHeartbeatTime = useRef(0);

const sendHeartbeat = useCallback(async (path: string) => {
  if (isHeartbeatPending.current) return;
  if (Date.now() - lastHeartbeatTime.current < 5000) return;
  
  isHeartbeatPending.current = true;
  lastHeartbeatTime.current = Date.now();
  
  try {
    await heartbeatMutation({ sessionId, currentPath: path });
  } finally {
    isHeartbeatPending.current = false;
  }
}, [heartbeatMutation]);
```

## Project structure

```
markdown-blog/
├── content/
│   ├── blog/              # Markdown blog posts
│   └── pages/             # Static pages (About, Docs, etc.)
├── convex/
│   ├── schema.ts          # Database schema with indexes
│   ├── posts.ts           # Post queries and mutations
│   ├── pages.ts           # Page queries and mutations
│   ├── stats.ts           # Analytics (conflict-free patterns)
│   ├── search.ts          # Full text search
│   ├── http.ts            # HTTP endpoints (sitemap, API)
│   ├── rss.ts             # RSS feed generation
│   └── crons.ts           # Scheduled cleanup jobs
├── netlify/
│   └── edge-functions/    # Proxies for RSS, sitemap, API
├── public/
│   ├── images/            # Static images and logos
│   ├── robots.txt         # Crawler rules
│   └── llms.txt           # AI agent discovery
├── scripts/
│   └── sync-posts.ts      # Markdown to Convex sync
└── src/
    ├── components/        # React components
    ├── context/           # Theme context
    ├── hooks/             # Custom hooks (usePageTracking)
    ├── pages/             # Route components
    └── styles/            # Global CSS with theme variables
```

## Frontmatter fields

### Blog posts (content/blog/)

| Field | Required | Description |
|-------|----------|-------------|
| title | Yes | Post title |
| description | Yes | SEO description |
| date | Yes | YYYY-MM-DD format |
| slug | Yes | URL path (unique) |
| published | Yes | true to show |
| tags | Yes | Array of strings |
| featured | No | true for featured section |
| featuredOrder | No | Display order (lower first) |
| excerpt | No | Short text for card view |
| image | No | OG image path |

### Static pages (content/pages/)

| Field | Required | Description |
|-------|----------|-------------|
| title | Yes | Page title |
| slug | Yes | URL path |
| published | Yes | true to show |
| order | No | Nav order (lower first) |
| featured | No | true for featured section |
| featuredOrder | No | Display order (lower first) |

## Database schema

Key tables and their indexes:

```typescript
posts: defineTable({
  slug: v.string(),
  title: v.string(),
  description: v.string(),
  content: v.string(),
  date: v.string(),
  published: v.boolean(),
  tags: v.array(v.string()),
  // ... optional fields
})
  .index("by_slug", ["slug"])
  .index("by_published", ["published"])
  .index("by_featured", ["featured"])
  .searchIndex("search_title", { searchField: "title" })
  .searchIndex("search_content", { searchField: "content" })

pages: defineTable({
  slug: v.string(),
  title: v.string(),
  content: v.string(),
  published: v.boolean(),
  // ... optional fields
})
  .index("by_slug", ["slug"])
  .index("by_published", ["published"])
  .index("by_featured", ["featured"])

pageViews: defineTable({
  path: v.string(),
  pageType: v.string(),
  sessionId: v.string(),
  timestamp: v.number(),
})
  .index("by_path", ["path"])
  .index("by_timestamp", ["timestamp"])
  .index("by_session_path", ["sessionId", "path"])

activeSessions: defineTable({
  sessionId: v.string(),
  currentPath: v.string(),
  lastSeen: v.number(),
})
  .index("by_sessionId", ["sessionId"])
  .index("by_lastSeen", ["lastSeen"])
```

## HTTP endpoints

| Route | Description |
|-------|-------------|
| /rss.xml | RSS feed with descriptions |
| /rss-full.xml | Full content RSS for LLMs |
| /sitemap.xml | Dynamic XML sitemap |
| /api/posts | JSON list of all posts |
| /api/post?slug=xxx | Single post JSON or markdown |
| /api/export | Batch export all posts with content |
| /stats | Real-time analytics page |
| /.well-known/ai-plugin.json | AI plugin manifest |
| /openapi.yaml | OpenAPI 3.0 specification |
| /llms.txt | AI agent discovery |

## Content import

Import external URLs as markdown posts using Firecrawl:

```bash
npm run import https://example.com/article
```

Requires `FIRECRAWL_API_KEY` in `.env.local`. Get a key from firecrawl.dev.

## Environment files

| File | Purpose |
|------|---------|
| .env.local | Development Convex URL (auto-created by `npx convex dev`) |
| .env.production.local | Production Convex URL (create manually) |

Both are gitignored.

## Security considerations

- Escape HTML in all HTTP endpoint outputs using `escapeHtml()`
- Escape XML in RSS feeds using `escapeXml()` or CDATA
- Use indexed queries, never scan full tables
- External links must use `rel="noopener noreferrer"`
- No console statements in production code
- Validate frontmatter before syncing content

## Testing

No automated test suite. Manual testing:

1. Run `npm run sync` after content changes
2. Verify content appears at http://localhost:5173
3. Check Convex dashboard for function errors
4. Test search with Command+K
5. Verify stats page updates in real-time

## Write conflict prevention

This codebase implements specific patterns to avoid Convex write conflicts:

**Backend (convex/stats.ts):**
- 10-second dedup window for heartbeats
- Early return when session was recently updated
- Indexed queries for efficient lookups

**Frontend (src/hooks/usePageTracking.ts):**
- 5-second debounce window using refs
- Pending state tracking prevents overlapping calls
- Path tracking skips redundant heartbeats

See `prds/howtoavoidwriteconflicts.md` for full details.

## Configuration

Site config lives in `src/config/siteConfig.ts`:

```typescript
export default {
  name: "Site Name",
  title: "Tagline",
  logo: "/images/logo.svg",  // null to hide
  blogPage: {
    enabled: true,           // Enable /blog route
    showInNav: true,         // Show in navigation
    title: "Blog",           // Nav link and page title
    order: 0,                // Nav order (lower = first)
  },
  displayOnHomepage: true,   // Show posts on homepage
  featuredViewMode: "list",  // 'list' or 'cards'
  showViewToggle: true,
  logoGallery: {
    enabled: true,
    images: [{ src: "/images/logos/logo.svg", href: "https://..." }],
    position: "above-footer",
    speed: 30,
    title: "Trusted by",
  },
};
```

Theme default in `src/context/ThemeContext.tsx`:

```typescript
const DEFAULT_THEME: Theme = "tan";  // dark, light, tan, cloud
```

## Resources

- [Convex Best Practices](https://docs.convex.dev/understanding/best-practices/)
- [Convex Write Conflicts](https://docs.convex.dev/error#1)
- [Convex TypeScript](https://docs.convex.dev/understanding/best-practices/typescript)
- [Project README](./README.md)
- [Changelog](./changelog.md)
- [Files Reference](./files.md)