tRPC Scaffolder

Automate creation of type-safe tRPC endpoints with Zod validation.

TL;DR: Run scripts to create routers/schemas, register in _app.ts, validate with scripts.

Auto-Triggers

Auto-triggered by keywords:

•"new endpoint", "create endpoint", "tRPC procedure"
•"new router", "API", "Zod schema"

Quick Standards

File Locations

code

lib/trpc/routers/
  _app.ts          # Register all routers here ⚠️
  {name}.ts        # Router files

lib/trpc/schemas/
  {entity}.schema.ts  # Zod schemas

Router Pattern

typescript

export const nameRouter = router({
  doThing: publicProcedure
    .input(inputSchema)
    .output(outputSchema)
    .mutation(async ({ input }) => { /* logic */ }),
});

Schema Pattern

typescript

export const inputSchema = z.object({
  field: z.string().min(1),
});

export type Input = z.infer<typeof inputSchema>;  // ⚠️ Required!

Registration (Required!)

typescript

// In _app.ts
export const appRouter = router({
  ai: aiRouter,
  name: nameRouter,  // ⬅️ Add new routers here
});

Run Scripts

Create Router

bash

./.claude/skills/trpc-scaffolder/scripts/create-router.sh user
# Creates: lib/trpc/routers/user.ts
# ⚠️ Remember to register in _app.ts!

Add Procedure

bash

./.claude/skills/trpc-scaffolder/scripts/add-procedure.sh ai getHints query
# Outputs code snippet to add to router

Create Schema

bash

./.claude/skills/trpc-scaffolder/scripts/create-schema.sh hint
# Creates: lib/trpc/schemas/hint.schema.ts

Validate Setup

bash

./.claude/skills/trpc-scaffolder/scripts/validate-trpc.sh
# Checks: router registration, type exports

Quick Reference

Query vs Mutation

Type	Use For	Method
Query	Fetch data (GET)	`.query(async ({ input }) => ...)`
Mutation	Modify data (POST/PUT/DELETE)	`.mutation(async ({ input }) => ...)`

Common Zod Patterns

Type	Pattern	Example
String	`z.string().min(1).max(100)`	Name validation
Number	`z.number().int().min(0).max(10)`	Difficulty 0-10
Email	`z.string().email()`	Email validation
Optional	`z.string().optional()`	Optional field
Array	`z.array(z.string()).min(1)`	At least 1 item
Enum	`z.enum(["a", "b", "c"])`	Fixed choices
Object	`z.object({ field: z.string() })`	Nested object

Naming Conventions

•Routers: {domain}Router (e.g., aiRouter, userRouter)
•Procedures: camelCase (e.g., generateQuestions, getHints)
•Schemas: {action}{Entity}{Input\|Output}Schema
•Files: {entity}.schema.ts, {domain}.ts

Error Codes

Code	When	Example
`NOT_FOUND`	Resource doesn't exist	User not found
`BAD_REQUEST`	Invalid input	Validation failed
`UNAUTHORIZED`	Not authenticated	Login required
`FORBIDDEN`	Not authorized	Access denied
`INTERNAL_SERVER_ERROR`	Server error	API failure

Common Fixes

Router Not Registered

typescript

// ❌ Forgot this step
// ✅ Add to _app.ts:
import { userRouter } from "./user";
export const appRouter = router({ ai: aiRouter, user: userRouter });

Missing Type Exports

typescript

// ❌ Schema without types
export const userSchema = z.object({ name: z.string() });

// ✅ Always export inferred types
export type User = z.infer<typeof userSchema>;

Wrong Procedure Type

typescript

// ❌ Using mutation for fetching data
getData: publicProcedure.mutation(...)

// ✅ Use query for GET operations
getData: publicProcedure.query(...)

Schema Validation Error

typescript

// ❌ No validation
field: z.string()

// ✅ Add constraints
field: z.string().min(1, "Field is required")

When to Load Additional Docs

SKILL.md is self-sufficient for:

•Creating routers and schemas
•Running scripts
•Fixing common errors

Load additional docs when needed:

Need	Load
Step-by-step tutorial	`docs/quick-start-guide.md`
Advanced Zod patterns	`docs/trpc-patterns.md` (lines 1-80)
Error handling strategies	`docs/trpc-patterns.md` (lines 150-220)
Testing procedures	`docs/trpc-patterns.md` (lines 220-270)
Context & middleware	`docs/trpc-patterns.md` (lines 80-150)

Code examples:

•✅ Perfect: examples/good-router.ts, examples/good-schema.ts

Full project docs: Docs/api-design.md, Docs/api-transition/trpc-migration.md

Version: 1.0.0 | Updated: October 2025 Pattern: Follows quality-reviewer structure (optimized)