kb-severity-mapping

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name: kb-severity-mapping description: Reference data, not a reviewer. Canonical severity level definitions and cross-domain mapping for web, document, and markdown audits. Score impact ranges, WCAG conformance alignment, and cross-format normalization. license: MIT disable-model-invocation: true user-invocable: false metadata: tier: reference domain: cross-cutting output: none effort: low title: Severity Mapping

Severity Mapping

Canonical severity definitions shared across web, document, and markdown audit domains.

Canonical Severity Levels

Each level, with its definition, WCAG conformance and score impact.

Level	Definition	WCAG Conformance	Score Impact
Critical	Blocks access entirely for one or more user groups. No workaround exists.	Fails Level A	-15 to -22 points
Serious	Severely impairs access; a workaround may exist but is unreasonable.	Fails Level A or AA	-5 to -10 points
Moderate	Causes friction or confusion; most users can still complete the task.	Fails Level AA (advisory)	-2 to -4 points
Minor	Polish issue; no meaningful barrier for most users.	Technique deviation	-1 point

Cross-Domain Equivalents

Each canonical level, with its web (axe-core or playwright), document (office or PDF) and markdown.

Canonical Level	Web (axe-core / Playwright)	Document (Office/PDF)	Markdown
Critical	critical (axe-core)	Missing document title; untagged PDF; missing heading structure	Broken anchor link leading to dead navigation
Serious	serious (axe-core)	Missing alt text on informational image; table has no headers	Ambiguous link text (e.g., "click here"); missing alt text on image
Moderate	moderate (axe-core)	Merged table cells; color-only data encoding	Skipped heading level; missing table caption
Minor	minor (axe-core)	Decorative image with non-empty alt; redundant bookmark	Emoji in heading; em-dash used as list separator

Score Impact Rules

Score impacts listed above are additive per finding. When the same issue recurs across many elements:

• First occurrence — full deduction
• Same issue type, same page/file — no additional deduction (already counted once per issue rule)
• Same issue type, different page/file — full deduction applies again to the new page/file score

Conversion Rules (Normalizing Cross-Domain Reports)

When generating a unified report that combines web, document, and markdown findings:

1. Map each finding to the canonical severity level using the table above.
2. Apply the score impact from the canonical level, not from the domain-specific tool's internal scoring.
3. For aggregated scores (portfolio or project level), compute each page/file score independently, then average.
4. Do not double-count a finding that appears in both an axe-core scan and a Playwright behavioral scan -- deduplicate by rule ID and element location.

Confidence Modifier (Web Domain)

For web audits, confidence level modifies the base deduction:

Confidence	Multiplier	Source Signals
Confirmed	1.2x	axe-core + agent code review + Playwright behavioral test
High (two sources)	1.0x	Any two of the three sources above
High (one source)	1.0x (reduced base)	Single automated tool, high rule reliability
Medium	0.7x	Single source, medium rule reliability
Low	0.3x	Single source, low rule reliability or heuristic

Document and markdown audits do not use confidence multipliers -- they use the base score impact only.