OptiA11y.Core 0.4.0

OptiA11y.Core

The accessibility rules engine behind OptiA11y, editorial accessibility assistance for Optimizely content authors. Not a compliance certification tool — a clean audit result means OptiA11y found no issues it was able to detect, not proof of WCAG or ADA conformance.

This package has zero Optimizely/CMS dependencies (only HtmlAgilityPack) and is fully unit-testable on its own. It defines the ports-and-adapters core that every host adapter (PaaS, SaaS) and the optional rendered-style slice funnel into:

host content source → adapter → AuditDocument (ContentFragment[]) → RuleEngine → Finding[]

What's in this package

• Model — AuditDocument, Finding, SourceLocation, and the typed ContentFragment shapes (image, link, heading, table, text, media, form field, button, iframe, and more) that every rule operates against. Rules never see raw HTML or a DOM.
• Parsing.HtmlFragmentParser — the single, shared entry point that turns raw HTML into fragments. Every host adapter funnels through this, so rule behaviour is identical regardless of where the content came from.
• Rules — over 30 independently DI-registrable IContentRule implementations covering alt text, headings, links, tables, forms, buttons, ARIA usage, language, colour contrast, reading level, and more. Each declares its own WCAG success criterion and level.
• RuleEngine — runs a set of rules against an AuditDocument and returns findings ordered deterministically by location.

The Confidence model — the honesty mechanism at the centre of this package

Every Finding carries a Confidence:

• Fail — a deterministic, unambiguous violation (a missing alt attribute, a skipped heading level, a contrast ratio below threshold). Reserved for structural facts a rule can be certain about.
• NeedsReview — a heuristic judgement (alt text quality, link text descriptiveness, reading level). The tool cannot know editorial intent, so it flags something worth a human's attention rather than asserting a defect.

Heuristic rules must never report Fail — this is what stops the tool from manufacturing false assurance.

Using this package directly

Most consumers will want OptiA11y.Cms (the Optimizely CMS 13 installable add-on) rather than this package directly. Reach for OptiA11y.Core on its own if you're building a custom adapter for a content source OptiA11y.Cms doesn't cover — implement HtmlFragmentParser-based fragment extraction for your source, register the rules you want via RuleEngine, and evaluate an AuditDocument.

See the main repository README for the full rule catalogue, architecture overview, and versioning notes (this package, OptiA11y.Rendering, and OptiA11y.Cms ship together and must be kept in sync).