JS-102: ulog handle is a raw pointer in a JS number — double free / UAF / forgeable

Proposed by the 2026-07-07 jab multi-agent review; confirmed by both skeptic verifiers. The ULOG binding is the only one that hands a raw heap pointer across the JS boundary, so script-level misuse becomes native memory corruption.

Input

Context

JABCulogOpen returns (double)(size_t)h (jab ulog.hpp:258); JABCulogHandle casts any positive JS number straight back to jabc_ulog* with no validation (ulog.hpp:261-266).
JABCulogClose does ULOGClose(...); free(h); (ulog.hpp:337-338) but nothing is nulled JS-side: ulog._close(h) twice is a double free; _append/_count after close is a UAF.
Any script can crash the runtime with abc._ulog_count(12345) — a forged number is dereferenced.

Goals

Repro first: double-close and forged-handle tests expecting a clean JS throw.
A validated handle table (small index -> jabc_ulog*, tombstoned on close) in the binding; no raw pointers cross the boundary.

Constraints

Keep the JS API shape (numeric handle) so be/ lib callers don't change.

WIP

TODOs

repro: double-close, use-after-close, forged handle (expect throw)
handle table in ulog.hpp; audit no other binding leaks pointers