Brummel
7a99c5dbfa
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.