The primitive behind "Apply comment suggestion": walk the XmlFragment, collect
the delta segments carrying the `comment` mark for a commentId, and replace them
with new text ONLY if the run is intact (single Y.XmlText, contiguous, and the
joined text still equals the expected anchor). Otherwise return a verdict
{ applied:false, currentText } — null when the anchor is gone, else the current
text — so the caller can report "someone changed it". On apply it deletes the
run and re-inserts the new text re-attaching the same comment mark (thread stays
anchored). Mutates in place for the caller's connection.transact(); opens no
transaction of its own.
Non-string inserts (embeds) advance the offset by their 1-unit index length so a
marked segment after an embed gets the right position and an embed inside a run
is correctly rejected as a changed anchor.
Tests (yjs.util.spec.ts): happy path (mark preserved, surrounding text and no
mark-bleed), resolved-mark match, changed text, deleted anchor, paragraph split,
interleaved unmarked text, and embed before/inside the run. 17 passed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude code agent 227
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