JS-105: abc.index re-sorts the memtable via native qsort on every read

Proposed by the 2026-07-07 jab multi-agent review; confirmed by both skeptic verifiers. Every get/range/prefix/seek pays a full O(m log m) introsort on a warm memtable where one O(log m) binary search is expected.

Input

Context

JABC_CONT_JS querySources() runs idx.mem.sort() unconditionally whenever mem.size > 0 (jab cont.cpp:711); called by idx.get, idx.range/prefix, idx.seek.
mem.sort is the native _sort_<lane> leaf (hit.hpp:91-103) -> sSort introsort (dog/abc/QSORTx.h:130) with no already-sorted early exit; no dirty/sorted flag exists anywhere in the path.
Default memtable is 4096 slots (cont.cpp:586) and puts never auto-flush, so q point reads cost O(q*m log m) — the keeper/spot registry lookups this index serves (cf. JS-056).

Goals

A memDirty flag: set in idx.put, sort only when dirty, clear on sort/flush; q reads on a warm memtable sort once.

Constraints

Flag lives in the JS bundle; no native API change needed.

WIP

TODOs

memDirty in idx.put/querySources/flush
index.js test: interleaved put/get stays correct; optional timing check