# Coding — Golden Rules

## Size

- One responsibility per file.
- One responsibility per function.
- No function longer than **50** lines.
- No file longer than **400** lines (hard preference; split earlier if possible).
- No circular dependency.

## Go

- Business packages by domain: `auth`, `profile`, `report`, `order`, `payment` — not `utils`.
- Interface defined at **caller** (usually handler), implemented by service.
- First parameter of I/O methods: `context.Context`.
- Errors: `return fmt.Errorf("create user: %w", err)`.
- Never `panic` in request path.
- Never use package-level mutable globals for request state.
- Export comments required on public funcs (what / in / out / side effects).

## TypeScript / Vue

- `strict: true`. No casual `any`.
- Components: `PascalCase.vue` (`UserCard.vue`).
- Pages under `src/pages/`, composables under `src/hooks/`.
- No direct `fetch` in pages — use SDK.
- Shared domain types go to `packages/types`.

## Naming

- Consistent domain words: profile, report, scale, membership, order.
- Prefer boring clear names over clever short names.

## Comments

- Public APIs: always document.
- Do not narrate obvious code. Document intent, invariants, side effects.