Upgrades the 2-way body merge to a real diff3 three-way merge (review #5), so a
block ONLY the human changed is KEPT when git changed a DIFFERENT block — the
2-way merge would revert it to git's stale version.
Engine: the push update loop reads the last-synced pre-image
(`git.showFileAtRef(refs/docmost/last-pushed, path)`) and passes it as the
optional `baseMarkdown` to `client.importPageMarkdown` (the common ancestor).
Server: gitmost-datasource converts base+incoming, and writeBody runs a block-
level diff3 (new three-way-merge.ts `diff3Plan`): live-only change -> keep live,
git-only change -> take git, both-changed -> git wins (conflict policy), inserts/
deletes from either side preserved. Without a base (createPage) it falls back to
the 2-way merge. Crash-safety unchanged (docs built before the connection opens).
Tests: three-way-merge.spec.ts (14 — every diff3 case incl. the cross-block
preservation and conflict policy), yjs-body-merge 3-way (real Y.Docs: human's
block instance preserved while git's block is applied), plus an engine test that
the base is forwarded from showFileAtRef. Existing push assertions updated for the
new base arg. git-sync 589 pass; server merge/datasource/gate 62 pass; typecheck
clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Supersedes the active-session "defer" guard with a real merge (review #5 —
"запись делать через мерж", not skip-while-editing).
writeBody no longer does delete-all + re-insert (which discarded a concurrent
editor's in-flight changes on every sync). It now diffs the live body against the
incoming git body at TOP-LEVEL BLOCK granularity (LCS over a canonical structural
serialization) and applies only the minimal inserts/deletes:
- a block a human is editing is left UNTOUCHED when git changed a DIFFERENT block;
- an unchanged resync is a complete 0-op write;
- Yjs CRDT-merges the minimal ops with concurrent edits.
New yjs-body-merge.ts (mergeXmlFragments + cloneXmlNode + diffBlocks) is pure-Yjs
and unit-tested with real Y.Docs (8 tests): identical->0 ops, edit-one-block keeps
the other block instances, append/delete keep neighbours, marks survive the
cross-doc clone. Crash-safety kept: the incoming doc is built before the
connection opens, so a transform failure can't empty the body.
Removed: the ActiveEditSessionError defer path and the now-unused
CollaborationGateway.getActiveEditorCount.
Honest limitation: this is a 2-way merge — for a block BOTH sides changed since the
last sync, git wins (no common ancestor to decide). A full 3-way merge would need
the last-synced base plumbed from the engine; the dominant cases (unchanged
resync, edits to different blocks) are now lossless.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
