# convex-schema-validator

Designs Convex tables, validators, indexes, and document relationships in convex/schema.ts. Use it when a schema changes or validation fails during development.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 3000 installs · ★ 405
- Author: waynesutton
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/waynesutton/builder-skills/tree/HEAD/skills/convex-schema-validator/SKILL.md
- Updated: 2026-09-28
- HTML: https://affpapa.org/en/nevibecode/skills/convex-schema-validator

## What it does

This skill works on `convex/schema.ts` to define Convex tables, field validators, indexes, and relationships. It can guide a new table or field change, model documents with different shapes through `v.union`, and address a validation error from `npx convex dev`.

Each `withIndex` call needs a matching `.index()` whose name and field order follow the query. Equality conditions use an index prefix, followed by at most one range condition on the next field. A `.filter()` in a query is a reason to check whether the query should use an index and `withIndex` instead.

It distinguishes missing fields with `v.optional` from fields that must exist but may contain `null`. Relationships use `v.id("table")`; Convex does not verify that the referenced document exists, so write logic needs to account for that.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add waynesutton/builder-skills --skill convex-schema-validator -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/convex-schema-validator/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/convex-schema-validator/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add waynesutton/builder-skills --skill convex-schema-validator -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/convex-schema-validator/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add waynesutton/builder-skills --skill convex-schema-validator -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/convex-schema-validator/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install waynesutton/builder-skills convex-schema-validator
```

2. **Manually: put the files in place**
- File: `.github/skills/convex-schema-validator/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add waynesutton/builder-skills --skill convex-schema-validator -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/waynesutton/builder-skills --path skills/convex-schema-validator
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/convex-schema-validator/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add waynesutton/builder-skills --skill convex-schema-validator -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/waynesutton/builder-skills/tree/HEAD/skills/convex-schema-validator/SKILL.md

## When to use it
- define a table in `convex/schema.ts`
- add a field to a table with existing documents
- match `withIndex` calls to `.index()` declarations
- replace a `.filter()` query with `withIndex`
- model a relationship with `v.id("table")`

## Example prompts
- Review `convex/schema.ts` and add indexes for every `withIndex` call.
- Add a field to an existing Convex table without breaking validation for older data.
- Replace this `.filter()` query with `withIndex` and declare the required index.

## Source text · SKILL.md · Apache-2.0

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BEGIN THIRD-PARTY FILE 5048e31f088663bf
````text
---
name: convex-schema-validator
description: Designs convex/schema.ts tables, validators, indexes, and relationships, and keeps the schema honest as data evolves. Use when creating tables, adding fields, choosing index fields, modeling relationships, or when a validator error appears at deploy time.
---

# Convex schema validator

Produces a `convex/schema.ts` that types every document, indexes every query path, and passes validation against the data already in the database. The one rule: every `withIndex` in a function needs a matching `.index()` here, named after its fields, queried in field order.

## When to reach for this

- Creating a new table or adding a field to an existing one
- A query uses `.filter()` and needs an index instead
- Deciding whether to embed an object or link with `v.id`
- Modeling a document that comes in several shapes
- `npx convex dev` fails with a schema validation error

## Schema skeleton

```typescript
// convex/schema.ts
import { defineSchema, defineTable } from "convex/server";
import { v } from "convex/values";

export default defineSchema({
  users: defineTable({
    name: v.string(),
    email: v.string(),
    avatarUrl: v.optional(v.string()),
  }).index("by_email", ["email"]),

  tasks: defineTable({
    userId: v.id("users"),
    title: v.string(),
    completed: v.boolean(),
    priority: v.union(v.literal("low"), v.literal("medium"), v.literal("high")),
  })
    .index("by_userId", ["userId"])
    .index("by_userId_and_completed", ["userId", "completed"]),
});
```

`defineTable` takes either an object of field validators or a single `v.union` of `v.object` validators (see discriminated unions). Every table gets `_id` and `_creationTime` for free. Do not declare them.

## Validators

| Validator | TypeScript type | Note |
| --- | --- | --- |
| `v.string()` | `string` | UTF-8, under 1 MB |
| `v.number()` | `number` | Float64. Use for timestamps and counts |
| `v.boolean()` | `boolean` | |
| `v.null()` | `null` | `undefined` is not a Convex value. Return `null` instead |
| `v.int64()` | `bigint` | Not `v.bigint()`, which is deprecated |
| `v.bytes()` | `ArrayBuffer` | Under 1 MB |
| `v.id("table")` | `Id<"table">` | Typed reference. Convex does not enforce that the target exists |
| `v.array(t)` | `T[]` | At most 8192 items |
| `v.object({...})` | `{...}` | At most 1024 entries. Keys cannot start with `$` or `_` |
| `v.record(k, t)` | `Record<K, T>` | Dynamic ASCII keys. No `v.map` or `v.set` |
| `v.union(a, b)` | `A \| B` | Use `v.literal` members for enums |
| `v.literal("x")` | `"x"` | |
| `v.optional(t)` | `T \| undefined` | Field may be absent |
| `v.any()` | `any` | Last resort. Loses type safety and validation |
````
END THIRD-PARTY FILE 5048e31f088663bf

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