---
name: Convex Backend
slug: convex-backend
category: DevOps
description: Convex Backend provides development guidelines for building Convex backends with TypeScript, covering function syntax, validators, schemas, queries, mutations, actions, scheduling, and file storage. Use it when writing Convex functions, database operations, real-time subscriptions, or serverless functions.
github: "https://github.com/CloudAI-X/claude-workflow-v2/tree/main/skills/convex-backend"
language: Python
stars: 1405
forks: 187
install: "npx degit https://github.com/CloudAI-X/claude-workflow-v2/tree/main/skills/convex-backend ~/.claude/skills/convex-backend"
installs_to: ~/.claude/skills/convex-backend
source_path: skills/convex-backend/SKILL.md
collection_size: 14
category_size: 798
collection_url: "https://dirskills.com/collections/CloudAI-X/claude-workflow-v2"
added: 2026-08-19T07:27:33.139Z
last_synced: 2026-08-19T07:27:33.139Z
canonical_url: "https://dirskills.com/skills/convex-backend"
---

# Convex Backend

Convex Backend provides development guidelines for building Convex backends with TypeScript, covering function syntax, validators, schemas, queries, mutations, actions, scheduling, and file storage. Use it when writing Convex functions, database operations, real-time subscriptions, or serverless functions.

**Install:**

```bash
npx degit https://github.com/CloudAI-X/claude-workflow-v2/tree/main/skills/convex-backend ~/.claude/skills/convex-backend
```

## README

# Convex Backend Guidelines

### When to Load

- **Trigger**: Convex-specific development, writing Convex functions, schemas, queries, mutations, actions, or real-time subscriptions
- **Skip**: Project does not use Convex as its backend

Comprehensive guide for building Convex backends with TypeScript. Covers function syntax, validators, schemas, queries, mutations, actions, scheduling, and file storage.

## When to Apply

Reference these guidelines when:

- Writing new Convex functions (queries, mutations, actions)
- Defining database schemas and validators
- Implementing real-time data fetching
- Setting up cron jobs or scheduled functions
- Working with file storage
- Designing API structure

## Rule Categories

| Category          | Impact   | Description                                   |
| ----------------- | -------- | --------------------------------------------- |
| Function Syntax   | CRITICAL | New function syntax with args/returns/handler |
| Validators        | CRITICAL | Type-safe argument and return validation      |
| Schema Design     | HIGH     | Table definitions, indexes, system fields     |
| Query Patterns    | HIGH     | Efficient data fetching with indexes          |
| Mutation Patterns | MEDIUM   | Database writes, patch vs replace             |
| Action Patterns   | MEDIUM   | External API calls, Node.js runtime           |
| Scheduling        | MEDIUM   | Crons and delayed function execution          |
| File Storage      | LOW      | Blob storage and metadata                     |

## Quick Reference

### Function Registration

```typescript
// Public functions (exposed to clients)
import { query, mutation, action } from "./_generated/server";

// Internal functions (only callable from other Convex functions)
import {
  internalQuery,
  internalMutation,
  internalAction,
} from "./_generated/server";
```

### Function Syntax (Always Use This)

```typescript
export const myFunction = query({
  args: { name: v.string() },
  returns: v.string(),
  handler: async (ctx, args) => {
    return "Hello " + args.name;
  },
});
```

### Common Validators

| Type     | Validator                         | Example       |
| -------- | --------------------------------- | ------------- |
| String   | `v.string()`                      | `"hello"`     |
| Number   | `v.number()`                      | `3.14`        |
| Boolean  | `v.boolean()`                     | `true`        |
| ID       | `v.id("tableName")`               | `doc._id`     |
| Array    | `v.array(v.string())`             | `["a", "b"]`  |
| Object   | `v.object({...})`                 | `{name: "x"}` |
| Optional | `v.optional(v.string())`          | `undefined`   |
| Union    | `v.union(v.string(), v.number())` | `"x"` or `1`  |
| Literal  | `v.literal("status")`             | `"status"`    |
| Null     | `v.null()`                        | `null`        |

### Function References

```typescript
// Public functions
import { api } from "./_generated/api";
api.example.myQuery; // convex/example.ts → myQuery

// Internal functions
import { internal } from "./_generated/api";
internal.example.myInternalMutation;
```

### Query with Index

```typescript
// Schema
messages: defineTable({...}).index("by_channel", ["channelId"])

// Query
await ctx.db
  .query("messages")
  .withIndex("by_channel", (q) => q.eq("channelId", channelId))
  .order("desc")
  .take(10);
```

### Key Rules

1. **Always include `args` and `returns` validators** on all functions
2. **Use `v.null()` for void returns** - never omit return validator
3. **Use `withIndex()` not `filter()`** - define indexes in schema
4. **Use `internalQuery/Mutation/Action`** for private functions
5. **Actions cannot access `ctx.db`** - use runQuery/runMutation instead
6. **Include type annotations** when calling functions in same file

## Full Compiled Document

For the complete guide with all rules and detailed code examples, see [AGENTS.md](AGENTS.md).