Types

types.ts holds DTOs, row shapes, form-step props, and component contracts for a feature. Never duplicated in content.tsx, columns.tsx, or actions.ts.

Categories

Rules

Canonical example — DTO + Row + FormProps

Copyimport type { Teacher } from "@prisma/client"
import { z } from "zod"
 
import { teacherCreateSchema, teacherUpdateSchema } from "./validation"
 
export type TeacherDto = Pick<
  Teacher,
  "id" | "firstName" | "lastName" | "email" | "phone"
>
 
export type TeacherRow = TeacherDto & {
  classCount: number
  subjects: string[]
}
 
export type TeacherCreateInput = z.infer<typeof teacherCreateSchema>
export type TeacherUpdateInput = z.infer<typeof teacherUpdateSchema>
 
export interface TeacherFormProps {
  initialData?: TeacherDto
  onSuccess?: () => void
}

Prisma extension

Copyimport type { Prisma } from "@prisma/client"
 
export type PayrollWithRuns = Prisma.PayrollGetPayload<{
  include: {
    runs: { include: { lines: true } }
    school: { select: { id: true; name: true; currency: true } }
  }
}>

Anti-patterns

• Duplicate ActionResponse (38+ files) — import from @/lib/action-response.
• ExtendedUser redefined (5 files) — canonical is src/components/auth/user.ts.
• PaginationParams redefined (10+ files) — lift to src/lib/types.ts.
• Hand-written Prisma replicas — registration/types.ts had 486 lines retyping a Student. Use Prisma.StudentGetPayload<...>.
• Row types diverging from columns — update types.ts, not columns.tsx.
• any in types.ts (26 occurrences) — replace with inferred Zod or Prisma payload.
• Inline type defs in content.tsx (268), columns.tsx (80), actions.ts (110) — move to types.ts.
• Identical type files in different features — extract to src/lib/types.ts.

Naming

• File: types.ts.
• Suffix-coded: <Name>Dto, <Name>Row, <Name>Input, <Name>Props, <Name>Response, <Name>Filters.
• One concept per name.

See also

• Pattern
• Validation
• Queries
• Actions