fix(ui): restore cross-block annotations over list markers and alert titles from drafts - #1542

Closes the two restore shapes that still failed closed after #1535/#1541: a selection spanning two list items, and a drag from a GitHub alert's icon through its title into its body restored from a draft. Both came back from a reload with the comment in the panel and no highlight anywhere in the document.

The two causes

List markers were painted but never selected. ListMarker is select-none, so no browser puts the bullet or numeral in a selection string — it is absent from the quote an annotation stores. It was not absent from what the highlighter painted, so a restore spanning two items resolved onto a•b while its quote read a\n\nb; compactText only removes whitespace, the bullet survived it, the content verification rejected a perfectly correct restore, and the text-search rescue could not bridge the blocks either.

Stored positions can resolve into excluded chrome. web-highlighter's textOffset counts every text node under the parent it records — the alert's visually hidden "Tip: " included — and its resolver puts a boundary landing exactly at one text node's end back onto that node. The start therefore resumed inside the hidden span, which painting never enters, so every run before the last one was dropped. Creation was already fine (#1541 snaps the live range); only the draft path was.

And the rescue could not bridge a block boundary at all. The document's text nodes are joined with nothing between them while the browser's selection string carries a blank line, so no cross-block quote could ever match the whitespace-collapsing fallback.

What changed

1. ListMarker carries annotation-exclude, so the painted text and the stored quote agree by construction. The verification reads painted text through the same exclusion instead of raw textContent (chrome inside a wrapper can never reintroduce the asymmetry), and the manual text-search wrapper skips excluded runs the way the search that produced its range does. Block starts are normalized as whitespace on the haystack side of the search — the same place the needle already has it.
2. A tap on web-highlighter's Serialize.Restore hook moves either restored boundary onto the nearest annotatable text node, refusing the snap if it would invert the range. Normalizing the metas at creation time is not available — they are only meaningful in the resolver's own coordinates, which count the excluded text — and it would do nothing for drafts already on disk.
3. The Unanchored chip now covers markdown surfaces. useAnnotationHighlighter reports each restore pass (onRestoreReport: what it attempted, which of those ended unanchored), the Viewer forwards it, and the editor keeps a markdown set beside the HTML one; an id the pass re-anchors clears its own chip, and a document or message change clears the set.

Edit Mode diagnosis (item 3)

Not a separate bug. applyEditedDocument re-anchors by looking for a block whose content contains the quote, which no single block does for a quote spanning two — so every cross-block annotation loses its stored positions on every edit-mode commit, whether or not the edit came near it. Text search was then the only path left, and it could not bridge a boundary, so one word changed in an unannotated list item unpainted every cross-block comment at once ("5 annotations no longer match the text"). Fixed by the search change in commit 1; packages/editor/App.editModeCrossBlockHighlights.test.tsx pins the whole loop through the real App.

Browser verification

Re-ran the QA harness against this build (plan review + annotate, ports 19850-19855), same seven shapes, same fixtures:

Zero restore warnings on the console on either surface (previously four, for C and E). Export quotes unchanged and correct on both: "First list item about caching behaviour\nSecond list item about retry" with no bullet, "Browser quirks\nSafari clamps the selection" with no hidden "Tip: ", and the reviewer's own "Tip: real prose" intact. Edit Mode: 7 highlights before an edit to an unannotated list item, 7 after (previously 5 → 2). Drift is still fail-closed — positions drifted with the quote still present are rescued onto the right text, positions drifted with the quote gone paint nothing and now carry the Unanchored chip.

Checks

bun run typecheck, DOM_TESTS=1 bun test packages/ui packages/editor (1732 pass; the 4 DocBadges failures are pre-existing on origin/main in the same whole-suite run and pass in isolation), bun test scripts/dom-test-allowlist.test.ts, bun run --cwd packages/ui smoke:package, bun run --cwd apps/guides-show check:manifest.

Three DOM-gated test files added and registered in .github/workflows/test.yml; Viewer.crossBlockRestore.test.tsx's "two list items" fixture was corrected to the real browser shape (it previously put the bullet into originalText, which no browser does, and passed for the wrong reason).