tRPC Scaffolder

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.

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Auto-Triggers

Auto-triggered by keywords:

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

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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
});

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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

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Quick Reference

Query vs Mutation

Common Zod Patterns

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

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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")

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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:

Code examples:

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

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

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