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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// ❌ No validation
field: z.string()

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