Initial commit

skills/analysis/accessibility-audit/reference/severity-rubric.md

@@ -0,0 +1,80 @@
+# Severity Rubric
+
+## Core Principle
+
+**Severity = Impact x Likelihood**, NOT WCAG conformance level.
+
+- Level A vs AA is a *conformance tier*, not a risk rating
+- A Level A failure can be LOW severity (decorative image missing alt)
+- A Level AA failure can be CRITICAL (focus outline removed)
+
+## Severity Levels
+
+### Critical
+- **Description**: Completely blocks access for users with disabilities
+- **Impact**: Prevents task completion
+- **Examples**:
+  - Keyboard trap preventing navigation (2.1.2, Level A)
+  - Missing alt text on primary action image (1.1.1, Level A)
+  - Form submission inaccessible via keyboard (2.1.1, Level A)
+  - Focus outline removed from focusable elements (2.4.7, Level AA)
+
+### High
+- **Description**: Significantly degrades experience or blocks common workflows
+- **Impact**: Makes tasks difficult or requires workarounds
+- **Examples**:
+  - No skip navigation on complex site (2.4.1, Level A)
+  - Poor contrast on primary CTA button (1.4.3, Level AA)
+  - Missing error suggestions on required form (3.3.3, Level AA)
+  - Touch targets too small on mobile (2.5.8, Level AA)
+
+### Medium
+- **Description**: Minor usability impact, affects subset of users
+- **Impact**: Causes confusion or requires extra effort
+- **Examples**:
+  - Decorative icon not hidden but in acceptable context (1.1.1, Level A)
+  - Link text needs slight improvement for clarity (2.4.4, Level A)
+  - Missing autocomplete on optional field (1.3.5, Level AA)
+
+### Low
+- **Description**: Best practice enhancement, minimal user impact
+- **Impact**: Nice-to-have improvement
+- **Examples**:
+  - Could add tooltips for better UX (not required)
+  - Page title could be more descriptive (2.4.2, Level A - but functional)
+
+## Calculation Guide
+
+### Impact Assessment
+| Level | Description | Severity Modifier |
+|-------|-------------|-------------------|
+| Blocker | Prevents access | Critical/High |
+| Degraded | Makes difficult | High/Medium |
+| Friction | Adds effort | Medium/Low |
+| Minor | Barely noticeable | Low |
+
+### Likelihood Assessment
+| Level | Description | Severity Modifier |
+|-------|-------------|-------------------|
+| Core flow | All users hit it | Increase severity |
+| Common | Many users hit it | Base severity |
+| Edge case | Few users hit it | Decrease severity |
+| Rare | Almost never | Low |
+
+## Examples
+
+### Same Criterion, Different Severity
+
+**Missing alt text (1.1.1, Level A)**:
+- Hero image: Impact=Blocker, Likelihood=All users → **CRITICAL**
+- Decorative footer icon: Impact=Minor, Likelihood=Rare → **LOW**
+
+**No skip link (2.4.1, Level A)**:
+- 3-item navigation: Impact=Friction, Likelihood=Common → **MEDIUM**
+- 50-item navigation: Impact=Degraded, Likelihood=All users → **HIGH**
+
+**Poor contrast (1.4.3, Level AA)**:
+- Primary CTA button: **CRITICAL**
+- Body text: **HIGH**
+- Footer link: **MEDIUM**
+- Decorative text: **LOW**