---
trigger: always_on
---

# TypeScript Rules

## Core Standards

- **Strict Mode** — all strict checks enforced.
- **ZERO `any` types** — use proper types or `unknown` + narrowing.
- **ZERO `console.log`** — use NestJS `Logger` (backend) or remove before commit (frontend).
- **English for Code** — use English for all code identifiers, variables, and logic.
- **Thai for Comments** — use Thai for comments, documentation, and JSDoc.
- **Explicit Typing** — explicitly define types for all variables, parameters, and return values.
- **JSDoc** — use JSDoc for all public classes and methods (in **Thai**).

## File & Function Structure

- **File Headers** — every file MUST start with `// File: path/filename` on the first line.
  - Use **absolute path** from project root (e.g., `// File: backend/src/modules/correspondence/correspondence.service.ts`)
  - Do NOT use relative path (e.g., `// File: src/example.service.ts`)
- **Change Log** — include `// Change Log` at the top of the file.
- **Single Export** — export **only one main symbol** per file.
- **Function Style** — avoid unnecessary blank lines inside functions.

## i18n Guidelines

- **No Hardcoded Text:** Use i18n keys for all user-facing text
- **Reference:** `specs/05-Engineering-Guidelines/05-08-i18n-guidelines.md`
- **Pattern:** Use `t('key.path')` from i18n hook instead of hardcoded strings

## Patterns

```typescript
// ✅ CORRECT
// File: src/example.service.ts
// Change Log:
// - 2026-05-13: Initial creation

/**
 * บริการตัวอย่างสำหรับ LCBP3
 */
export class ExampleService {
  public doSomething(data: string): boolean {
    return data.length > 0;
  }
}
```