a11y-core

Shared rules for every skill in the Accessibility Agents package. Skills point here instead of repeating this text. Read the section you need.

Tiers

Every skill sits in one of four tiers. The tier decides who can start it and what it is allowed to cost.

Tier	What it is	Who invokes it
router	The six entry points: accessibility-lead, web-accessibility-wizard, document-accessibility-wizard, markdown-a11y-assistant, developer-hub, github-hub	The model or the user
specialist	One accessibility domain, one checklist, one findings payload	A router, by pointer
helper	Mechanical work: inventory, scanning one file, CSV export, scan config	A router, by pointer
reference	Rule tables, URL registries, scoring formulas. `kb-` prefix	Cited by a skill that needs the data

Only routers are model-invocable. Specialists and helpers stay out of every client's skill catalog so they cost nothing until a router names one.

Dispatch contract

A router dispatches a specialist with the client's own subagent primitive. Keep the prompt at this shape and this size. Never read a specialist's instructions into the router's own context, and never paste a specialist body into a prompt.

Activate the skill "aria-specialist". If skill activation is unavailable,
read skills/aria-specialist/SKILL.md and follow it.
Task: <one paragraph, what to check and why>
Scope: <file list or glob>
Rules: semantic HTML before ARIA; report, do not edit.
Return ONLY JSON matching skills/a11y-core/schemas/findings.schema.json.

Per client: Claude Code uses the Agent tool, Codex spawns a worker subagent, Copilot uses a subagent or handoff, Gemini and Antigravity use the generalist agent. The prompt is the same in all four.

The specialist reads its own instructions inside its own context. The router receives JSON. Nothing else crosses the boundary.

Output contract

Skills declare metadata.output, and it decides what they return.

findings - only JSON matching schemas/findings.schema.json. No prose, no preamble, no restated instructions.
report - collect findings JSON from each dispatched skill, write them to .a11y-history/<timestamp>/, then render with node skills/a11y-core/scripts/render-report.mjs. Never type a report by hand.
artifact - produce the file or script asked for; report the paths written and what each changes.
guidance - answer the question, cite the criterion or API by name, stop.

Severity is one of critical, serious, moderate, minor. Confidence is high, medium or low. A finding without a location and a fix is not a finding.

Non-negotiable standards

These hold for every web skill in the package and do not need restating in a dispatch prompt.

Semantic HTML before ARIA. A button element beats div role="button".
One H1 per page. Never skip heading levels.
Every interactive element reachable and operable by keyboard.
Text contrast 4.5:1. UI component and graphical object contrast 3:1.
No information carried by color alone.
Focus managed on route change, dynamic content and deletion.
Dialogs trap focus and return it on close.
Dynamic content updates are announced.

Report requirements

Any audit report this package produces carries all of these, or it is a triage result and must say so in its opening line.

Metadata: date, tool versions, scope, scan configuration used
Executive summary: score out of 100, A-F grade, counts by severity, verdict
Findings: rule ID, WCAG criterion, severity, location, description, fix
Severity breakdown by critical, serious, moderate, minor
Remediation priorities, ordered by impact against effort
Next steps and a re-scan timeline
Delta against the previous report when one exists: fixed, new, persistent, regressed

The renderer emits all seven from findings JSON and embeds the merged JSON in a fenced block at the end of the report, which is what makes the next delta cheap.

Files here

schemas/findings.schema.json - the one findings shape
references/sources.md - every specification the skills cite, grouped by skill
scripts/measure-context.mjs - context cost accounting and budget check

Scan configuration

If the workspace root holds .a11y-office-config.json, .a11y-pdf-config.json, .a11y-epub-config.json or .a11y-web-config.json, read it and honour it. Do not fall back to defaults when a config file exists. Profiles for strict, moderate and minimal live in templates/.