# Journal — 2026-05-05

## 2026-05-05 — `mark_publish` `on_conflict: "merge"` landed

Implemented the conflict-merge plan (`/plans/conflict-merge.md`). New package `client/internal/merge/` ships a line-based diff3 (LCS + hunk-walking) and a `MergeAndPublish` orchestrator. The MCP handler now accepts `on_conflict: "fail" | "merge"` on `mark_publish`; merge mode fetches base via `/path/vN`, fetches current, runs diff3, republishes if clean, escalates with git-style markers if overlapping. Retries up to 3 on contention. Wire protocol unchanged. `mark_append` deliberately untouched (append-as-stream is the right primitive there).

Hit one notable pitfall during dev: stable-points from independent `LCS(base, ours)` and `LCS(base, theirs)` undercounts true stable lines when LCS ties pick different subsets — produced false conflicts on disjoint same-line edits like `("a\nb\nc", "a\nB\nc", "a\nb\nC")`. Fixed by switching to hunk-based walking (compute edit hunks per side, walk base advancing through hunks with `<` strict overlap test). Property test in place to catch regressions.