Typescript Types

Goal

Generate complete TypeScript type code and file updates, not concept-only guidance.

Required Folder Convention

Always follow this structure:

src/
	types/
		auth/
			types.ts
		users/
			types.ts
		posts/
			types.ts
		common/
			types.ts
		index.ts

Rules:

• One feature per folder under src/types/<feature>.
• One types.ts file per feature folder.
• Do not mix multiple features in one types file.
• Shared definitions go only in src/types/common/types.ts.
• Re-export all feature/common types from src/types/index.ts.

Generation Workflow

When asked to add or create types for a feature:

1. Create or update src/types/<feature>/types.ts.
2. Organize definitions in section order:
   • Enums
   • Core interfaces
   • DTO interfaces
   • Response interfaces
   • Utility types
3. Update src/types/index.ts exports.
4. If request touches shared contracts, update src/types/common/types.ts.
5. If request extends req.user, update src/types/express.d.ts (not feature file).

Interface vs Type Rules

Use interface for object shapes by default:

• Entities
• DTO objects
• API response object shapes
• Class contracts
• Objects likely to be extended

Use type for:

• Unions
• Intersections
• Primitive aliases
• Tuples
• Conditional and mapped utility types
• Closed definitions that should not be declaration-merged

Do not replace object interfaces with type aliases when interface is sufficient.

Enum Rules

Use string enum or const enum only:

• Feature-specific enums in feature types.ts.
• Shared enums in src/types/common/types.ts.

Prefer union type over enum only for tiny, local-only literal sets.

Never generate numeric enums.

Naming Rules

• Interface names: PascalCase
• Type aliases: PascalCase
• Enum names: PascalCase
• Enum members: SCREAMING_SNAKE_CASE
• Folders: lowercase singular
• File names: lowercase, use types.ts

Integration Rules

• Controllers consume DTO interfaces for request typing.
• Services return typed entities/response interfaces.
• Middlewares use enums for role/status checks.
• Prisma model contracts should map 1:1 with entity interfaces.
• Derive public response types from entities using Omit/Pick (for example strip passwordHash).
• Express request extension belongs in src/types/express.d.ts only.

Use standardized API success/error shapes in common types for cross-feature consistency.

Required Outputs Per Task

If user asks for feature types, generate:

• src/types/<feature>/types.ts with complete definitions.
• src/types/index.ts export update.

If user asks for shared types, generate:

• src/types/common/types.ts updates.
• src/types/index.ts export update.

If user asks interface/type/enum design question:

• Provide decision with examples.
• If project files are present, also generate concrete type code in correct files.

References To Load

Read these references when generating:

• references/decision-guide.md
• references/feature-templates.md
• references/utility-types.md

Output Style For This Skill

When triggered:

• Prefer file creation/edits with complete imports/exports.
• Produce ready-to-use interfaces/types/enums with no placeholders.
• Keep exports clean and centralized via src/types/index.ts.

Source: CharvitZalavadiya/GitChat — distributed by TomeVault.