Rules

WCAG rules

Rules mapped to specific WCAG success criteria. Violations may constitute accessibility barriers.

Rule	Code	WCAG	Description
no-color-only	CLR001	1.4.1	Don’t convey information only through color

Policy rules

Best practices for cognitive accessibility. Not WCAG requirements, but improve usability for users with cognitive disabilities.

Rule	Code	Description
line-length	FMT001	Lines should be 120 characters or fewer
no-all-caps	LNG002	Avoid all-caps text (hard to read)
plain-language	LNG001	Avoid technical jargon (EOF, STDIN, etc.)
emoji-moderation	SCR001	Limit emoji use (confuses screen readers)
punctuation	LNG003	Error messages should end with punctuation
error-structure	A11Y003	Errors should explain why and how to fix
no-ambiguous-pronouns	LNG004	Avoid starting with “it”, “this”, etc.

Error message format

All messages follow the What/Why/Fix structure:

[ERROR] CODE: What happened
  Why: Explanation of why this matters
  Fix: Actionable suggestion

[WARN] CODE: What to improve
  Why: Why this matters
  Fix: How to improve (optional)

[OK] CODE: What was checked

Grades vs CI gating

Letter grades (A-F) are informational summaries. For CI pipelines, gate on specific rule failures, error count thresholds, or regressions from a baseline — not on letter grades.