tRPC Scaffolder

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

TL;DR: Run scripts to create routers/schemas, register in

_app.ts

Auto-Triggers

Auto-triggered by keywords:

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

Quick Standards

File Locations

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

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

Router Pattern

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

Schema Pattern

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

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

Registration (Required!)

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

Run Scripts

Create Router

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

Add Procedure

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

Create Schema

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

Validate Setup

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

Quick Reference

Query vs Mutation

.query(async ({ input }) => ...)

.mutation(async ({ input }) => ...)

Common Zod Patterns

z.string().min(1).max(100)

z.number().int().min(0).max(10)

z.string().email()

z.string().optional()

z.array(z.string()).min(1)

z.enum(["a", "b", "c"])

z.object({ field: z.string() })

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

NOT_FOUND

BAD_REQUEST

UNAUTHORIZED

FORBIDDEN

INTERNAL_SERVER_ERROR

Common Fixes

Router Not Registered

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

Missing Type Exports

// ❌ 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

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

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

Schema Validation Error

// ❌ 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:

docs/quick-start-guide.md

docs/trpc-patterns.md

docs/trpc-patterns.md

docs/trpc-patterns.md

docs/trpc-patterns.md

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)