development-conventions

Development Conventions

This document outlines coding standards, conventions, and best practices for the Kaneo project.

Code Style

Biome Configuration

Kaneo uses Biome for linting and formatting. Configuration is in biome.json.

Formatting Rules

• Indentation: Tabs (not spaces) for TypeScript/TSX
• JavaScript: Spaces for indentation (legacy support)
• Quote Style: Double quotes (")
• Semicolons: Required

// Good: Tabs, double quotes, semicolons
function example() {
	const value = "hello";
	return value;
}

// Bad: Spaces, single quotes, no semicolons
function example() {
  const value = 'hello'
  return value
}

Linting Rules

Key Biome rules enabled:

• noParameterAssign: Don't reassign function parameters
• useAsConstAssertion: Use as const for literal types
• useDefaultParameterLast: Default parameters must be last
• useSelfClosingElements: Use self-closing JSX elements
• useSingleVarDeclarator: One variable per declaration
• noInferrableTypes: Don't add explicit types that can be inferred

// Good: Follows Biome rules
const items = ["a", "b"] as const;
function greet(name: string, greeting = "Hello") {
	return `${greeting}, ${name}`;
}
const x = 1;
const y = 2;

// Bad: Violates Biome rules
const items: string[] = ["a", "b"];
function greet(greeting = "Hello", name: string) {
	return `${greeting}, ${name}`;
}
const x = 1, y = 2;

Running Linter

# Check and auto-fix
pnpm lint

# Check only (no fixes)
pnpm biome check .

TypeScript Conventions

Type Definitions

• Types: Prefer types for all type definitions (object shapes, unions, intersections, computed types)
• Interfaces: Only use interfaces when extending/merging is needed (rare)
• Inference: Prefer type inference when types are obvious

// Good: Type for object shape
type Task = {
	id: string;
	title: string;
	status: string;
};

// Good: Type for union
type Status = "to-do" | "in-progress" | "done";

// Good: Type inference
const tasks: Task[] = []; // Explicit for arrays
const count = tasks.length; // Inferred