The server's 3-way content merge was incorrectly triggering on sequential
edits by the same user. When a user checked then unchecked a checklist
item, the merge saw local === base (both unchecked) and kept the server's
checked state, silently discarding the uncheck.
Now the merge only runs when there's an actual concurrent edit
(baseVersion < existing.version), meaning another user saved between the
client's load and this save. For single-user sequential edits, the
client's content is used directly.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
