attest 1.2.0

Continuous accessibility-compliance engine for Flutter. Pure-Dart rules that map findings to WCAG and EN 301 549 success criteria, with CI baseline gating.

attest

The pure-Dart core of the attest accessibility-compliance toolkit for Flutter: the data model, the rule engine, the tree-walking rules, report aggregation and baseline diffing.

Honest framing. Automated checks catch roughly 30–40% of accessibility issues. This package provides automated coverage of machine-checkable criteria plus a structured checklist for the rest. It does not certify "EAA compliance."

This package has no Flutter dependency. Every rule is a pure function over a serializable SemanticsSnapshot, which makes rules fast and exhaustively unit-testable. The Flutter-facing helpers (the WidgetTester extension and the raster/text-scale collectors) live in attest_flutter.

Measured correctness

For a compliance tool, trust is the product — so correctness is measured, not claimed. attest ships a validation corpus of 118 hand-labelled cases (positive, clean, adversarial, and composite real-world screens) and computes precision and recall per rule against it on every CI run.

On the current corpus every one of the thirteen rules measures precision 1.0 and recall 1.0, with zero false positives on the clean fixtures. The metrics gate fails the build on any regression, on any false positive on a clean case, or if a heuristic drops below its declared precision bar. The contrast and overflow measurement paths are additionally reference-validated (contrast against independently computed WCAG ratios within 0.1).

This measures that the rules do exactly what they claim on known inputs and stay honest as they change — it is not a claim that automated checks catch every real-world issue. They cover the machine-checkable ~30–40%; the rest is the structured checklist referenced above.

Coverage matrix

attest knows exactly which of its rules maps to which standard clause, and — the honest part — which clauses it does not check. CoverageMatrix.forStandard (and attest coverage on the CLI) emit, per pack, every WCAG Level A/AA success criterion classified as automated, partial or manual, backed by the WcagRegistry single source of truth:

Coverage matrix — en301549_v3_2_1
7 automated, 2 partial, 40 manual (of 49 criteria)

The manual rows are the point: they are what turns findings into a complete audit trail instead of an implied "all clear". A consistency test keeps the registry honest — every bundled rule must map to an automated or partial clause, and every clause it claims to cover must name a real rule.

Standard packs

Audits run against a versioned pack, chosen with RuleConfig.standard:

• Standard.en301549_v3_2_1 (default) — WCAG 2.1 Level AA, the current EU legal baseline.
• Standard.wcag22 — WCAG 2.2 Level AA, the basis for the forthcoming EN 301 549 v4.1.1.

A rule runs only when its cited criterion belongs to the selected pack, so switching packs changes both the checks that run and the criteria cited. For example attest/target-size (WCAG 2.5.8) is new in 2.2, so it is inactive under the default en301549_v3_2_1 pack and active under wcag22.

Migrating to WCAG 2.2: set standard: Standard.wcag22, then re-run attest baseline --update — the newly active rules may add findings you will want to review and accept.

Supported versions

Pure Dart, SDK ≥ 3.6, no Flutter dependency — it runs anywhere Dart runs (the CI gate, scripts, servers). The floor is set by the repository's pub-workspace tooling, not by any language feature the code needs. The policy for the toolkit as a whole: the current and the previous three stable Flutter releases are supported, and each new stable Flutter is tracked within one release cycle.

API stability

Everything exported from package:attest/attest.dart is frozen for 1.0: within a major version it will not break, and rule ids and standard-pack meanings never change silently — both are treated as breaking. Two exceptions, annotated @experimental and free to change in minor releases (always changelogged):

• the validation-corpus library (package:attest/corpus.dart), which is young and will evolve with the corpus;
• TranscriptGenerator — the transcript's exact wording is not frozen until it is cross-validated against real VoiceOver/TalkBack captures.

License

BSD-3-Clause.