claude code agent 227 f86b8b69a0 fix(mcp): structural-diff write-back so agent edits don't jump the cursor (#152) ...

mutatePageContent wrote agent edits back by DELETING the whole Yjs fragment and
re-applying a fresh Y.Doc. Yjs is a CRDT — the editor anchors its selection to
node ids — so wiping every id made an open editor's cursor lose its anchor and
snap to the end of the document on every agent write. It was most visible on
comment anchoring (issue #152): a comment changes no text, yet the cursor jumped.
(Before commit 4201f0a3 the anchoring silently no-op'd, so the destructive write
never ran for comments — hence the regression.)

Fix: write via `updateYFragment` (y-prosemirror) — the same routine the editor
uses to sync its own edits into Yjs. It structurally diffs the new doc against
the live fragment and touches only changed nodes, preserving the ids of unchanged
ones, so the cursor stays put. This improves ALL agent write tools (text edits,
node ops, comments, replace) — minimal diff instead of full replace: less collab
noise, stable block-ids, other users' cursors no longer disrupted.

- collaboration.ts: new `applyDocToFragment` (sanitize -> PMNode.fromJSON against
  a memoized docmost schema -> updateYFragment in one transact), keeping the
  `findUnstorableAttr` encode diagnostic; swap the destructive write-back for it.
- package.json: `y-prosemirror` promoted to a direct dependency (was transitive).
- test: comment-cursor-stability.test.mjs — a Yjs RelativePosition (the cursor
  anchor) survives both a sibling edit and a comment-mark anchoring (the old
  full-replace tombstoned it -> null). 292 package tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2026-06-24 05:56:32 +03:00

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