CRITICAL data-loss bug: creating pages in Docmost (which start UNTITLED) and then
typing a title could soft-delete OTHER pages. Untitled pages all serialize to the
`_` fallback filename; the layout disambiguates them (`_.md`, `_ ~slug.md`).
Retitling one frees the bare `_` and another untitled page's file relocates into
it. git's rename detection (`-M`) can't see the move (the tiny meta-only files are
too dissimilar), so `git diff` reports it as DELETE(old) + ADD/MODIFY(new). The
push took the DELETE literally and trashed a live page.
Root cause is that the push trusted git's path-level rename heuristic for page
IDENTITY. Identity is the pageId. Fix: before emitting any delete, coalesce by
pageId — a pageId that is BOTH deleted (pre-image) AND present on the surviving
side (current meta of an ADD or a MODIFY, since a relocation into an occupied path
shows as M) is one page that MOVED, classified as a rename/move and NEVER a delete.
Reproduced + verified on a live stand: 4 untitled pages + retitle one trashed a
different page before; after the fix, retitling one (and stress-retitling all)
trashes nothing. Engine suite 598 green; 3 new computePushActions cases (ghost
D+A move -> rename; real delete still deletes; unrelated D+A stay delete+update).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The implementation spec docs/git-sync-plan.md was removed as completed, but ~44
code comments still cited it as "plan §N". Strip those citations (comments only),
keeping each comment grammatical. The vendored engine's own "SPEC §N" references
point at a different, still-present spec and are left untouched.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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>
