Beagle SCM

ULOG-004: cheap conflicts accessor — con paths since the last get/post barrier

Per DIS-080: conflict liveness is row-scoped, not content-scoped (resolved==posted). Provide one cheap accessor that fishes out the current conflict list — an array of paths — by scanning the wtlog backward from the tip to the most recent get/post barrier, collecting con <path> rows. Every consumer (classify/status, diff view, post's gate) reads this instead of marker-scanning bytes.

Input

Context

• wtlog.conPaths() (shared/wtlog.js:333-341) already collects con rows but with the wrong floor for the new rule; classify then re-verifies markers on disk (classify.js:56-63, 423-427) — that liveness check dies with markers.
• wtlog is append-only; con rows are never deleted; a post/get row is the natural expiry barrier.

Goals

1. wtlog.conflicts() (name TBD): backward scan, stop at the first get/post row, dedup, return paths. O(rows since last barrier).
2. Consumers switch: classify's con bucket, quad's ! wt char, status summary tally, POST-035 gate, DIFF-016 yellow spans — all row-driven, zero byte scans.
3. Old conPaths() + marker liveness path retired with the switch.

Constraints

• Which rows are barriers exactly (bare get vs scoped get, post commit vs post advance) — decide and document in the fn header; a scoped get should not amnesty unrelated paths.
• No log ts read-back games — row order in the log is the truth ([no-log-readback-run-ts] applies to ts, not order).

WIP

Design decisions

• Name: wtlog.conflicts() → array of paths, oldest-first, deduped (kept conPaths() untouched for its live callers).
• BARRIER = a get/post row bearing a full sha whose path is NOT wt-relative (absent, or under a scheme/authority — a seed/sub re-attach address). Both bare and scoped-branch gets and both post shapes (commit ?br#sha, FF advance) qualify: each moves the tip.
• NOT barriers: patch (multi-patch stacking must accumulate con rows), put/delete (DIS-080 §4: put is not an ack), a ref-less store anchor (pins nothing), and a wt-relative path row — a scoped get <path> amnesties nothing (today restorePath writes no wtlog row at all, so the rule is a guard for the future).
• Ordering is row order only, no ts games; a merge-get's own con rows are written AFTER its tip row, so they survive their own barrier.

TODOs

• accessor in shared/wtlog.js + unit test (con, con+post, con+get, multi-patch dups)
• switch classify/quad/status to it
• retire marker-liveness (wtHasMarker) once DIFF-016/POST-035 land

Outcome

• shared/wtlog.js conflicts() + test/wtlog_con.js (9 legs), registered as be-js-unit-wtlog_con; full suite 317/317 green.
• Consumers NOT switched yet (TODO 2) — conPaths() and marker liveness untouched, so this lands as a pure addition.
• Landed as ///be/#543269d6 (2026-07-29 20:06).
• Consumer-switch + wtHasMarker retirement TODOs carried by STATUS-017 and POST-035.