JS-029: `bin/lib/be.js` + `wtlog.js` — repo discovery + wtlog reader

Now: DONE

The SDK foundation: locate a .be store/worktree and read the wtlog ULOG. Part of JS-027. Method: Issues.

Input

Context

Every script must find the repo and read its per-wt state. .be discovery is a walk up from cwd (like require's resolve); the wtlog is a ULOG (anchor row 0, get/post/patch/put/del rows, ts stamp-set). JABC has a ULOG codec already.

Goals

be.js: .be discovery walk → {root, wt, storePath, project}; respect HOME.
wtlog.js: open the wtlog ULOG → cur tip (?branch#sha), baseline tip, pd/patch boundaries, has(ts) stamp-set test, iterate put/del rows since a floor.

Constraints

libdog+abc ONLY (ULOG + io). Sequential ULOG drain; if has(ts) random access is too slow, note a libdog ULOG-index leaf for JS-034 — never link a dog.

WIP

Design decisions

has(ts) v1 = build a ron60→idx abc.index from the drained rows (pure JS).

TODOs

Smoke bin/refs.js: print cur branch + baseline sha for the live repo.
Parity probe (test/bin/): assert cur/baseline match be status's header on a toy repo. Test with a stable jabc (no rebuild needed for this ticket).

Blockers

None (independent of JS-028).

Outcome

(pending)