coding-standards

name	coding-standards
description	Auto-enforce coding standards after every code change in Code mode. Checks file size, nesting, naming, error handling, and anti-patterns.
risk	safe
source	self
tags	["coding-standards","quality","enforcement"]

Coding Standards Enforcement

When to Use

Trigger after EVERY code change in Code mode — automatically verify standards compliance.

Quick Checks (run mentally after each edit)

1. Size Limits

• Functions: ≤50 lines. If larger → split into focused helpers.
• Files: 200-400 lines typical, 800 max. If larger → extract modules.
• Nesting: ≤4 levels deep. Use early returns and extract helpers.

2. Naming Conventions

• camelCase for variables/functions
• PascalCase for types/interfaces/components
• UPPER_SNAKE_CASE for constants
• is/has/should prefix for booleans
• File names: match primary export name

3. Error Handling

• ✅ PASS: catch (error: unknown) { if (error instanceof Error) { ... } }
• ❌ FAIL: catch (e) { console.log(e) } — empty/generic catch
• ❌ FAIL: catch (error: any) — never use any
• Always handle Promise rejections — no floating promises

4. Anti-patterns to Flag

• console.log in production code → use proper logger
• debugger statements left behind
• any type usage → use unknown + narrowing
• var keyword → use const (prefer) or let
• Commented-out code blocks → remove or add TODO with issue number
• Mutation of function parameters → use spread/copy

5. Import & Dependency Hygiene

• No circular imports
• No unused imports
• Group: external deps → internal modules → relative paths
• Prefer named exports over default exports

6. Simplicity First (from incremental-implementation)

Before writing any code, ask: "What is the simplest thing that could work?"

After writing code, review against these checks:

• Can this be done in fewer lines?
• Are these abstractions earning their complexity?
• Would a staff engineer say "why didn't you just..."?
• Am I building for hypothetical future requirements, or the current task?

SIMPLICITY CHECK:
✗ Generic EventBus with middleware pipeline for one notification
✓ Simple function call

✗ Abstract factory pattern for two similar components
✓ Two straightforward components with shared utilities

✗ Config-driven form builder for three forms
✓ Three form components

Three similar lines of code is better than a premature abstraction. Implement the naive, obviously-correct version first. Optimize only after correctness is proven with tests.

Reference

For full TypeScript rules, pre-coding checklist, and self-review process, see .roo/rules-code/coding-standards.md.