sceptre-mcp-server: Instructions file for Kiro

Coding Style

Immutability

Prefer immutable patterns where practical:

• Return new objects/dicts rather than mutating in place
• Use tuple over list for fixed collections
• Use frozenset for immutable sets
• Use dataclasses(frozen=True) or Pydantic model_config = ConfigDict(frozen=True) for value objects

File Organization

MANY SMALL FILES > FEW LARGE FILES:

• High cohesion, low coupling
• 200-400 lines typical, 500 max
• Extract utilities from large modules
• Organize by feature/domain, not by type

Error Handling

See error-handling.md for comprehensive error handling rules.

Input Validation

ALWAYS validate at system boundaries:

• Validate all user input before processing
• Use Pydantic models or schema-based validation
• Fail fast with clear error messages
• Never trust external data (API responses, user input, file content)

Naming Conventions

• Functions/variables: snake_case (get_user_by_id, calculate_total)
• Classes: PascalCase (UserService, DocumentProcessor)
• Booleans: is_/has_/should_ prefix (is_active, has_permission)
• Constants: UPPER_SNAKE_CASE for true constants
• Files/modules: snake_case matching class or purpose
• Private: prefix with _ (_internal_helper)

Code Quality Checklist

Before marking work complete:

• Code is readable and well-named
• Functions are small (<50 lines)
• Files are focused (<500 lines)
• No deep nesting (>4 levels — use early returns)
• Proper error handling at every level
• No hardcoded values (use constants or config)
• Type hints on all function signatures
• No print() left in production code (use logging)
• Docstrings on public functions and classes