Rendered page facts

RecursiveAI.OneRender.Accessibility lays a document out with the engine and returns OneHtml's RenderedFacts (format version 1) for it: the same facts, with the same meaning, that a DOMSnapshot.captureSnapshot capture from a browser yields, so a consumer can switch sources without changing its rules.

Route

The package reads the laid-out page and hands each box straight to OneHtml.Accessibility's RenderedFactsBuilder (OneHtml 1.2): no snapshot JSON is written or parsed, and there is no cap on the size of the page as bytes. RenderedFactsLimits (FactsOptions.Limits) bound boxes, text boxes and strings and throw RenderedFactsLimitException before storing past a bound; FactsOptions.BackgroundScanLimit (default 16384 display items) bounds the backward scan for colors behind one text box. All walks are iterative; cost is linear in nodes, text boxes and display items. Nodes are numbered as a snapshot would number them (document order, pseudo-elements included, the doctype counted but not a node of the facts), so BackendNodeId is that number plus one and SnapshotNodeIndex the number. Generated content (::marker, ::before, ::after) is added as generated boxes of its host: the pseudo-element's own box, then the box of its generated text.

The facts are the same as the earlier snapshot route gave on the text-block, templates and tailwind pages (every box, text box, style value, paint order and color), except that StackingContextNodeIndex is set for every node, as the builder derives it, including the doctype that the adapter left at -1.

API

• Low level: AccessibilityFacts.FromLayout(page, queries, displayList, paintTrace, options, styleContext, ct) for a page the host already laid out and painted, with a PaintTrace (an IPaintObserver) attached to the host's Painter.
• Mid level: FromPage(HtmlPage, …) paints and queries itself; FromInteractive(InteractivePage, …) reads the page's own layout and style context, so hover and focus state show in the facts.
• Happy path: AccessibilityFacts.Render(html or Document, HtmlPageOptions, FactsOptions?, ct) returns a RenderedPage (document, page, facts).
• FactsOptions.ComputedStyles lists the properties to serialize; StandardStyleList is the 96-property list used by the browser captures.

Fact semantics

• Boxes. One layout item per element that has a principal-box fragment: the union of its fragments' border boxes in document coordinates, CSS px, ignoring transforms. display: none and display: contents have no box; visibility: hidden and opacity: 0 keep theirs. Generated ::before, ::after and ::marker boxes are child nodes with a box item.
• Text. A text item exists only where a text fragment exists. Text boxes are in layout order (not sorted), as UTF-16 start and length into the layout text; a preserved line feed gets an extra zero-width box. The layout text is the source text with text-transform applied when that keeps its length.
• Rects. Offset, client and scroll rectangles come from the CSSOM View queries; br and wbr report zeros.
• Paint order. A "layer" is any positioned box, stacking context, or box that clips (overflow other than visible). Layers are numbered in the order the painter enters them (the root element is 1, the document 0); boxes painted into the same layer share a value. Stacking-context flags come from the painter (CSS 2.2 Appendix E, plus the CSS Transforms, Compositing and Filter Effects triggers).
• Color behind text. Given only for an element with no element children and non-blank painted direct text. The display list is scanned backward from the text for fills (solid; a gradient counts as its first stop) covering the text box origin, composited over white with alpha quantized to 8 bits and each channel rounded when two colors mix. Opacity groups that enclose the text are not part of the background and count in the text opacity; groups that closed earlier flatten their fills with their opacity. The color is absent when an image, inline SVG or backdrop filter covers the point, or when a fill sits inside a closed filter, mask or non-normal blend scope (those change pixels in ways one color can't express); fills inside mask layers are skipped.
• Text opacity. The product of the opacities of the groups enclosing the text, as a 32-bit float.
• Computed styles. Resolved values in the browser's serialization: used width/height, used padding and margin when specified as percent or auto, currentcolor replaced by the color, unitless line-height as px, min-*: auto as 0px outside flex and grid, word-spacing: normal as 0px, outline-width: none as 3px, numbers with six significant digits.
• Form state. inputValue for every input (empty by default; on for checkbox and radio), checked, textarea text, option selectedness by the HTML selectedness algorithm. No click-ability facts.

Known differences from the browser captures

Markers have no text and their boxes are shapes, not text-width boxes; authored oklch() and similar colors serialize as rgb(); transforms are not applied to bounds; scroll offsets are ignored at the blending point; option elements get boxes inside select and progress gets none; initial text-align, font-family and top/left resolved values differ in places; sub-pixel layout rounding differs in offset rects (agreement within 1 px is 100% on the text-block set).

Agreement with the browser

tools/geomdiff commands facts-capture and facts-compare (scripts/run-facts.sh) capture the browser's facts on the same page with the same font files and compare fact by fact. Per-set summaries for the committed sets are in results/facts/<set>/.