Language Rules

Language rules apply only to files matching that language's extension.

go

Scope: **/*.go

Key rules:

• Return errors, never panic in library code
• Wrap errors with fmt.Errorf("context: %w", err)
• Interfaces belong in the package that uses them, not the one that implements them
• Keep goroutines owned — every goroutine has a clear owner responsible for its lifetime
• Protect shared state with mutexes or channels — never access shared data from multiple goroutines without synchronization
• NEVER use ioutil functions (ioutil.ReadFile, ioutil.WriteFile, etc.) — use os and io equivalents (deprecated since Go 1.16)
• Standard project layout: cmd/, internal/, pkg/

typescript

Scope: **/*.ts, **/*.tsx

Key rules:

• strict: true — no exceptions
• Never use any — use unknown and narrow it
• Prefer async/await over .then() chains
• Validate external data with Zod at system boundaries
• Use discriminated unions for state modeling

python

Scope: **/*.py

Key rules:

• Type hints on all function signatures
• PEP 8 — enforced by Ruff
• Prefer dataclasses or Pydantic models over raw dicts
• Use pytest — no unittest
• Explicit over implicit — avoid magic

php

Scope: **/*.php

Key rules:

• declare(strict_types=1) in every file
• PHP 8+ features — named args, enums, match expressions, fibers
• PSR-12 coding standard
• Constructor property promotion for simple DTOs
• Composer autoloading — no manual requires