audit embedding-abi-m5: milestone close — RATIFY gc_rss trio (evidenced) + DRIFT (one doc-honesty tidy); P2 bench noise causally exonerated, baseline pristine for it

Architect: Invariant 1 PASS (zero data-server in any compiler
crate/runtime; ail-embed its own workspace root); M3 frozen-layout
SSOT unmoved (the lone rc.c change 7bfa11e touched only the global
stats counters); rc.c header-comment honesty accurate. Drift =
[medium] DESIGN.md:2358-2360 stale "additive M4 concern" (PRE-
EXISTING — M4 retired; correctly scoped out of every M5 iter) +
[medium] DESIGN.md §"Embedding ABI" silent-drift (it asserts "no
shared mutable runtime state … data-race-free" but the now-atomic
global RC-stats fallback IS shared mutable state under concurrency;
M5 is AILang's first concurrent consumer) + [low] rc.c:88 "two
unconditional ++" imprecise → one doc-honesty tidy iteration
(embedding-abi-m5.tidy), same honesty axis, not split.

Bencher refuted my pre-audit "gc_rss allocator-orthogonal →
environmental" hypothesis WITH EVIDENCE: the 3x *.gc_rss_kb +32%
are genuine, deterministic, M5-attributable — 7bfa11e's atomic
split a branch in ailang_rc_alloc (reached by GC programs via
str.c int->str at print), spilling %r14/%rbx; a stale interior
list pointer in the new spill slot is conservatively retained by
Boehm, pinning a ~32 MB dead spine (collection #12 freed PRE 32 MB
vs HEAD 32 B); bisects exactly on the commit, IR byte-identical,
ail sha256-identical; RC/bump RSS dead-stable. bump_s + max_us are
pre-existing tracked-P2 noise (bump RC-orthogonal; max_us 1-sample
tail-jitter, PRE often worse, +65->+104% swing between runs) — NOT
M5.

RATIFY the gc_rss trio. Language reason (not effort): Decision 9 —
Boehm is explicitly transitional; AILang's committed model is RC +
uniqueness. The measurable cost of the correct, necessary,
user-approved swarm-safety fix is exclusively a Boehm
conservative-stack-scan false-retention artifact on the
transitional allocator (codegen-layout-fragile; no memory actually
leaked; RC/bump RSS dead-stable). Chasing it with an out-of-scope
codegen change invests in the path being migrated away from; the
committed RC path is unaffected. Selective baseline re-anchor:
bench/baseline.json lines 14/44/64 ONLY -> 137448/137768/137636
(bencher-confirmed steady-state); every other metric byte-pristine
(a wholesale --update-baseline would absorb the P2 noise and break
the established-envelope discipline). Re-run confirms the 3 now ok
at +-0.3%.

bump_s x2 + max_us x2: NO-ratify, causally exonerated, baseline
left pristine — identical disposition to the M2/M3/prelude-decouple
milestone closes.

Friction-harvest recorded (P2 flat-array-decision input):
host-per-tick-FFI ~= ~206 ns/tick at real EURUSD volume.

Ratify discipline: updated baseline JSON + this paired JOURNAL
ratify entry committed together (bench/baseline.json + the audit
journal + INDEX line). M5 closes after the doc-honesty tidy lands
and is Boss-verified.

bench/baseline.json

@@ -11,7 +11,7 @@
       "rc_s":          { "baseline": 0.133,  "tolerance_pct": 10 },
       "gc_over_bump":  { "baseline": 2.98,   "tolerance_pct": 8  },
       "rc_over_bump":  { "baseline": 2.89,   "tolerance_pct": 8  },
-      "gc_rss_kb":     { "baseline": 103980, "tolerance_pct": 5  },
+      "gc_rss_kb":     { "baseline": 137448, "tolerance_pct": 5  },
       "bump_rss_kb":   { "baseline": 97696,  "tolerance_pct": 5  },
       "rc_rss_kb":     { "baseline": 193448, "tolerance_pct": 5  }
     },
@@ -41,7 +41,7 @@
       "rc_s":          { "baseline": 0.136,  "tolerance_pct": 10 },
       "gc_over_bump":  { "baseline": 2.79,   "tolerance_pct": 8  },
       "rc_over_bump":  { "baseline": 2.83,   "tolerance_pct": 8  },
-      "gc_rss_kb":     { "baseline": 103788, "tolerance_pct": 5  },
+      "gc_rss_kb":     { "baseline": 137768, "tolerance_pct": 5  },
       "bump_rss_kb":   { "baseline": 97448,  "tolerance_pct": 5  },
       "rc_rss_kb":     { "baseline": 193640, "tolerance_pct": 5  }
     },
@@ -61,7 +61,7 @@
       "rc_s":          { "baseline": 0.152,  "tolerance_pct": 10 },
       "gc_over_bump":  { "baseline": 2.89,   "tolerance_pct": 8  },
       "rc_over_bump":  { "baseline": 3.14,   "tolerance_pct": 8  },
-      "gc_rss_kb":     { "baseline": 103772, "tolerance_pct": 5  },
+      "gc_rss_kb":     { "baseline": 137636, "tolerance_pct": 5  },
       "bump_rss_kb":   { "baseline": 97636,  "tolerance_pct": 5  },
       "rc_rss_kb":     { "baseline": 142424, "tolerance_pct": 8  }
     }