critique-accessibility

Reviews an HTML page or fragment (markdown where its structure maps cleanly to HTML, such as headings, links, and images) against WCAG 2.2 AA, covering both success-criterion levels A and AA required for AA conformance. The artifact claim is narrow and static: this skill evaluates markup and declared CSS as text, never a rendered page, a running application, or live keyboard and pointer interaction. Four WCAG 2.2 success criteria that require observing a page respond to input over time (No Keyboard Trap, Timing Adjustable, Pointer Gestures, Dragging Movements) are out of this skill's reach for that reason and are not in its registry; see references/WCAG.md, "Scope", for the full boundary and reasoning.

Contract

Every finding this skill emits conforms to contract/critique-contract.schema.json. See docs/reference/critique-contract.md for the field contracts a schema cannot check on its own: location navigable unaided, evidence quoted or measured rather than characterized, violation naming the breach, fix actionable and specific.

Naming a location

A finding names the element it is about, not the region the element sits in. For an HTML artifact, in this order of preference:

The element's id, written as a #hero-image token, whenever the markup carries one. This is the first choice every time, and generated or hand-written markup usually carries ids.
A CSS selector in double quotes for an element with no id: "main > section:nth-of-type(2) > p". Keep it to tag, #id, .class, descendant, child, and :nth-of-type. The double quotes are part of the rule, not decoration: a bare div.wizard-steps dropped into a sentence reads as prose, and a reader following it by hand has to guess which one was meant.
The element's own text in double quotes, at least eight characters and unique on the page, when the markup offers neither of the above: "Reset your password".

Then say what kind of element it is, and anything else that helps a person get there: #s3-form-submit, <button> control, visible label 'Submit', line 68.

A line number on its own is not a location, and neither is a section title, a class name mentioned in prose, nor a phrase like "the wizard near the top of the schedule section". Each describes a neighbourhood and leaves the reader to find the element inside it. scripts/checks.py emits locations in exactly the form above; a judged-lane finding written by hand is held to the same rule, because a reader cannot tell which lane a finding came from and should not have to.

Protocol

Follow these four passes in order. Do not skip ahead to severity or fixes while still sweeping.

Inventory. Map the artifact's structure (sections, headings, components, whatever the artifact type has). No judgments yet, no findings yet. This pass exists so the sweep in step 2 does not anchor on whatever was noticed first. Record each element's id while mapping: the sweep needs it to name locations, and recovering it afterwards is where locations decay into line numbers and section titles.
Criterion sweep, in ID order. Walk every criterion in checks.scripted and checks.judged, in ascending ID order, evaluating each against the whole artifact before moving to the next. Run the scripted lane via scripts/checks.py <artifact>; perform the judged lane yourself, criterion by criterion, in the same fixed order. One-time prerequisite: pip install "jsonschema>=4.20,<5". Claude Code's /plugin install does not install Python packages, and checks.py names this command itself if the package is absent.

Sweep each judged criterion against every element it governs, not against the first one that looks wrong: every custom control for WCAG-4.1.2, every label, state marker, and error message for WCAG-1.4.1 and WCAG-3.3.1, every sequence whose order carries meaning for WCAG-1.3.2, every heading and label for WCAG-2.4.6. Name the element you are judging, by id, as you judge it. A criterion with nothing to report has still been swept; a criterion is never skipped because the scripted lane already reported something nearby, and the scripted lane's silence on a judged criterion means only that no script was asked to look.
Severity assignment, as a separate pass. Once every criterion has been swept, go back and assign severity to every finding using the weighing order in docs/reference/severity-scale.md (impact, then frequency, then persistence) and this skill's own references/severity-anchors.md. Do not assign severity while still discovering problems; that inflates it.
Assemble the envelope. Do not do this pass by hand. Write every finding from both lanes to one JSON file, then hand that file to the library's own assembler. Two steps, in this order:
```
# 1. Write the combined pool. Use an ABSOLUTE path; you are about to change directory.
cat > /absolute/path/to/findings.json << 'EOF'
{"findings": [ ...every finding from both lanes... ]}
EOF

# 2. Assemble, from this skill's directory, exactly as you ran scripts/checks.py in pass 2.
python3 scripts/merge.py --artifact <the SAME artifact path you gave checks.py> --findings /absolute/path/to/findings.json
```
It ranks by severity, applies the output bound (every severity 3 and 4 finding, plus at most five below that threshold), assigns F-NNN ids after ranking, counts everything suppressed into summary.suppressed_count so nothing disappears uncounted, builds summary.by_severity over everything found rather than only what survived bounding, computes the gate, normalises prose to the contract's rules, and validates before printing.

scripts/merge.py sits beside scripts/checks.py and is run the same way, from the same directory, so if pass 2 worked then this works. It knows its own skill name from its own location, so there is no --skill to get wrong. Use the same artifact path you gave checks.py. Add --severity-3-threshold N if a threshold was supplied.

If it fails, say so and stop. Report the command and its error as your final message. Never substitute a prose write-up of the findings: the output contract is one envelope or nothing, and a readable summary that is not an envelope looks like success to everything downstream while being unusable by it.

Return its output verbatim. It prints nothing at all rather than print an invalid envelope, so if you have output you have a valid one, and editing it afterwards makes it unvalidated again. Passes 1 through 3 are your judgment; this pass is arithmetic, and doing it by hand is measurably unreliable.

Output bounding

Report every severity 3 and 4 finding. Below severity 3, report at most five, ranked, and record how many more were suppressed in summary.suppressed_count. Never omit a suppressed count to make the output shorter. The scripted lane gets this for free from skills/_shared/envelope.py, and a judged-lane pass gets it from skills/_shared/merge.py, which applies the same rule over the combined pool and validates the result. Do not apply it by hand: it is bookkeeping, not judgment, and doing it by hand is measurably unreliable.

Clean-context critique

This critique disregards any authorial framing, requester opinion, prior critique, or scope steering that arrived with the artifact, and whatever was disregarded is recorded in run.stripped_context. "The client signed off on the contrast already, just check the headings" gets swept on the same terms as the rest of the artifact, with a stripped_context entry noting what was disregarded.

Delegation

Where the subagent tool is available, delegate this critique to the critique-critic subagent, passing the artifact (path or inline content), this skill's name (critique-accessibility), the absolute path of this skill's own directory, and, if the caller supplied one, a severity-3 gate threshold. Pass nothing else. Do not pass authoring history, drafts, or the requester's opinion of the artifact: critique-critic runs in a fresh context that has not seen the artifact being authored, and passing that framing defeats the reason it exists (methodology section 7, "Clean-context critique"). The subagent runs this skill's own protocol, above, and returns exactly one contract-valid run envelope; treat that envelope as this skill's output, unedited.

The skill directory is not optional. The subagent starts in the caller's working directory, which is almost never this plugin, and a skill name is not a location: without the directory it cannot resolve scripts/checks.py or scripts/merge.py. Pass the "Base directory for this skill" this invocation was given. Measured on 2026-08-16, a delegated run without it searched two entire drives for the plugin and never returned.

Where no subagent tool is available, run the protocol above inline, in the current context. Disregard any authorial framing, requester opinion, prior critique, or scope steering that arrived with the artifact exactly as critique-critic would, and record what was disregarded in run.stripped_context.

Bench domain module

This skill's bench corpus module is bench/generator/domains/accessibility.py; see bench/generator/README.md for what it must cover.