Milestone-close fieldtest of the typed-MIR work, run by a downstream
LLM author exercising only the public interface. Four curated scenarios
plus a reduction-bisect set, derived top-down from the milestone promise
(heap-Str-across-recur, new-over-user-ADT, cross-module print__<UserType>,
combined render loop).
Three [working] findings ratified: new-over-user-ADT + Show + print
(#51/#53 class), cross-module synthesised print, and heap-Str-across-recur
value correctness all produced correct output first try.
One [bug] found and orchestrator-verified: returning an owned heap-Str
from a callee fn across the call boundary leaks exactly one RC slab
(live=1) — producer-independent (str_concat, int_to_str), loop-independent,
silent (output correct). It sits in the coverage gap the curated
*_no_leak_pin fixtures leave open (they keep the heap-Str expression inside
main). Distinct from #49 (loop-carried within one frame); this is the
function-return leg. Routed to debug RED-first; blocks the deliberate
milestone-close until GREEN.
Brummel
7a99c5dbfa