ferix: Skill for Claude Code

Convex Best Practices

Build production-ready Convex applications by following established patterns for function organization, query optimization, validation, TypeScript usage, and error handling.

Documentation Sources

Before implementing, do not assume; fetch the latest documentation:

• Primary: https://docs.convex.dev/understanding/best-practices/
• Error Handling: https://docs.convex.dev/functions/error-handling
• Write Conflicts: https://docs.convex.dev/error#1
• For broader context: https://docs.convex.dev/llms.txt

Instructions

The Zen of Convex

1. Convex manages the hard parts - Let Convex handle caching, real-time sync, and consistency
2. Functions are the API - Design your functions as your application's interface
3. Schema is truth - Define your data model explicitly in schema.ts
4. TypeScript everywhere - Leverage end-to-end type safety
5. Queries are reactive - Think in terms of subscriptions, not requests

Function Organization

Organize your Convex functions by domain:

// convex/users.ts - User-related functions
import { query, mutation } from "./_generated/server";
import { v } from "convex/values";

export const get = query({
  args: { userId: v.id("users") },
  returns: v.union(v.object({
    _id: v.id("users"),
    _creationTime: v.number(),
    name: v.string(),
    email: v.string(),
  }), v.null()),
  handler: async (ctx, args) => {
    return await ctx.db.get(args.userId);
  },
});

Argument and Return Validation

Always define validators for arguments AND return types:

export const createTask = mutation({
  args: {
    title: v.string(),
    description: v.optional(v.string()),
    priority: v.union(v.literal("low"), v.literal("medium"), v.literal("high")),
  },
  returns: v.id("tasks"),
  handler: async (ctx, args) => {
    return await ctx.db.insert("tasks", {
      title: args.title,
      description: args.description,
      priority: args.priority,
      completed: false,
      createdAt: Date.now(),
    });
  },
});