perf(core)!: measure in one layout pass, drop the shape alias

[JaceThings]

highlight() was measuring every range twice: once through computeAnchor to find the column, then again for the line rects. The anchor was only ever a fallback for columnBounds, which the caller already passes whenever there's an anchor host, so the second layout pass bought nothing in the common path.

Measurement is now a single pass per range, rangesToLineRects takes the anchor as optional, and computeAnchor stays exported for callers measuring a column themselves. Alongside it: style writes go through a per-element cache so a re-render resolving to the same declaration skips the DOM write, smoothEdge walks edge vertices directly instead of materialising two intermediate arrays per frame, and buildMarkGeometry shifts edges into mark space in place rather than mapping copies. The typeof x !== "undefined" guards scattered across targeting and the tiers collapse into one hasGlobal().

Breaking: shape and ShapeType are gone

ShapeType was export type ShapeType = MarkType, and shape? was an undocumented alias for markType? that mergeOptions already collapsed into markType and then deleted. It only ever gave one concept a second name. Callers pass markType and import MarkType. Nothing else in the public surface moved, and neither name appears anywhere in the README or docs. The changeset is a major, so the linked group takes all four packages to 2.0.0.

The rest: parse at the boundary, don't assert at the use

Same idea applied inward, across core, the wrappers, the site and the tests.

Core stopped indexing el.style through a CSSStyleDeclaration & Record<string, string> cast and calls setProperty with real CSS property names. That turned out to fix a latent lie rather than just a type: a camelCase el.style.maskPosition = v write only creates an expando in jsdom and never a real declaration, so four test assertions moved to getPropertyValue and check something real now. mergeRectsByLine returns real DOMRect instances instead of object literals wearing the type. Every walker.nextNode() as Text goes through one nextTextNode helper.

The website gained a single browser-env module that reads the environment once into a named capability record, so components branch on a domain value instead of probing globals inline. The playground's option paths are a real union derived from PlaygroundOptions with a value type per path, which removed the unknown that ran from set() all the way down through the option demos. The consumer smoke scripts share one export-contract parser instead of scattering typeof x === "function" across four files, and the react hook's test injects a runtime through the provider seam instead of mocking the core module.

Two behaviour changes worth naming. findSelectionAnchor now skips a positioned ancestor that isn't an HTMLElement instead of returning it as one; that's only reachable through a positioned SVG ancestor, where the old result couldn't host an overlay anyway. And the two mergeOptions tests that covered the shape alias were replaced with ones covering what the merge actually does now: the override wins, and an explicit undefined keeps the base.

Where to start

packages/core/src/render/highlight.ts and targeting/line-rects.ts carry the measure change and everything else follows from it. render/renderer.ts has the style cache and the setProperty switch, geometry/clip-path.ts the edge walk, and apps/website/src/playground/options-context.tsx the typed option paths. The comment strip in 643fb25 is mechanical and skimmable; the code inside it is not.

Verified

pnpm typecheck, pnpm test (241 pass), pnpm build, pnpm knip, pnpm size and pnpm consumer-smoke all green locally. Core sits at 14.8 kB brotlied against its 15 kB budget.

The type work was driven by a linter run locally and removed afterwards, so nothing new is vendored or added to the toolchain. It went from 278 findings to 3, all three being Vue's String as PropType<…> / Object as SlotsType<…> prop declarations, which are the documented way to declare Vue runtime props and can't be written without the assertion.

scripts/bench.mjs (pnpm bench) is new so the geometry hot paths can be timed instead of guessed at. It needs pnpm build first.

[JaceThings]

Pushed 0bfd730. Two things changed since the last review pass: shape/ShapeType are removed, which makes this a major and retitles the PR, and the type-assertion cleanup described above landed across core, the wrappers, the site and the tests. The changeset went from patch to major.