roadmap: close Embedding ABI — M5 ([~]->[x]) — M1–M5 arc complete, audited+ratified+doc-honest; WhatsNew + P2 reframed

M5 done 2026-05-19: real backtest over real Pepperstone tick data
through the real external data-server into the shipped M3-frozen
kernel, across a per-thread-ctx thread swarm; symbol-fan (headline
existence proof) + time-shard (first actual proof of chunk-boundary
invisibility); globally leak-free, deterministic. Zero
language/compiler change; one runtime change (7bfa11e atomic
global RC-stats fallback — user-adjudicated bounce-back, RED-first,
+ a build-dep staleness root-caused & fixed). Audit: Invariant 1
PASS, M3 frozen-layout unmoved, gc_rss trio evidenced-RATIFY
(Boehm conservative-scan artefact, Decision-9 transitional), P2
noise causally exonerated baseline-pristine, doc-honesty tidy
clean. Friction-harvest: host-per-tick-FFI ~= ~206 ns/tick at real
EURUSD volume.

- roadmap M5 [~]->[x] with the done-state summary (stays one cycle
  for context, then prune).
- roadmap P2 "Flat array/slice primitive" reframed: the
  M4-retirement forward note's deferred reconciliation is now
  done — the obsolete "1024-cell cons-chain per chunk / M4 ships
  it" framing replaced with the real residual (host-per-tick-FFI
  vs. batch crossing) anchored on M5's measured ~206 ns/tick; the
  M5-dependency is now satisfied (the justification input exists).
- WhatsNew.md done-state entry (verbatim == the notify text):
  user-facing, no internals — the embedding arc is complete.

Done-state notification fired (user away per /boss). The next
roadmap item is a new milestone (the P2 flat-array decision or
another P0) — a deliberate user call, not autonomous.

docs/roadmap.md

@@ -304,29 +304,45 @@ work progresses.
     `docs/journals/2026-05-18-audit-embedding-abi-m3.md`;
     `docs/journals/2026-05-18-iter-embedding-abi-m3.tidy.md`.
 
-- [~] **\[milestone\]** Embedding ABI — M5: `ail-embed` adapter +
-  `data-server` wiring + thread-swarm backtest. **In-flight**: spec
-  written + user-approved + grounding-check PASS 2026-05-19. The
-  host-side adapter — a lean reusable embedding module (`extern "C"`
-  to the M3-frozen ABI + frozen-layout box helpers, zero finance
-  knowledge) **plus** the real E2E on top; in-repo but
-  `[workspace]`-excluded; sole `data-server`↔AILang meeting point
-  (Invariant 1) — wires the **real external** `data-server`'s
-  `while let next_chunk` loop to the shipped M3 kernel by
-  **unrolling each chunk host-side** into per-tick
-  `(State, Tick) -> State` calls (the adapter, not the kernel, owns
-  chunk iteration; M4's cons-list crossing was retired). **Zero
-  language/compiler/runtime change.** A real backtest runs over real
-  Pepperstone tick data on a thread swarm: symbol-fan (headline) +
-  time-shard (first actual proof of the chunk-boundary invisibility
-  the M4 retirement rests on). Terminal embedding milestone:
-  existence proof of the whole goal + friction harvest feeding the
-  host-per-tick-FFI vs. batch-crossing perf decision (the P2
-  flat-array item). Coherent stop: the goal itself.
+- [x] **\[milestone\]** Embedding ABI — M5: `ail-embed` adapter +
+  `data-server` wiring + thread-swarm backtest — **DONE 2026-05-19**,
+  audited + ratified + doc-honest. Terminal milestone of the M1–M5
+  Embedding ABI arc: a real backtest runs over **real Pepperstone
+  tick data** through the real external `data-server` crate into the
+  shipped M3-frozen AILang kernel, across a thread swarm of
+  independent per-thread embedding contexts. `ail-embed` is a lean
+  reusable embedding module (`extern "C"` to the M3-frozen ABI +
+  frozen-layout box helpers, zero finance knowledge) **plus** the
+  real E2E on top — in-repo but its own cargo workspace root
+  (`[workspace]`-excluded), the sole `data-server`↔AILang meeting
+  point (Invariant 1, architect-confirmed PASS at close). The
+  adapter (not the kernel) owns chunk iteration, unrolling each
+  chunk host-side into per-tick `(State, Tick) -> State` calls (M4's
+  cons-list crossing was retired as speculative infra). Symbol-fan
+  swarm = the headline existence proof (per-thread bit-exact vs an
+  independent host reference); time-shard swarm = the **first actual
+  proof** of the chunk/window-boundary invisibility the M4
+  retirement rests on (per-shard bit-exact). Globally leak-free,
+  deterministic. Zero language/compiler change; one runtime change
+  (`7bfa11e`: the global RC-stats fallback counters made
+  atomic-relaxed — the swarm exposed that AILang's first concurrent
+  consumer needed it; user-adjudicated bounce-back → RED-first fix,
+  then a build-dependency staleness root-caused + fixed). Audit:
+  Invariant 1 PASS, M3 frozen-layout SSOT unmoved, bench `gc_rss`
+  trio evidenced-RATIFY (a Boehm conservative-scan artefact of the
+  necessary atomic fix; Decision-9 Boehm-transitional), P2 noise
+  causally exonerated baseline-pristine; doc-honesty tidy clean.
+  **Friction-harvest deliverable: host-per-tick-FFI ≈ ~206 ns/tick
+  at real EURUSD volume** — the P2 flat-array decision input.
+  Stays one cycle for context, then prune.
   - depends on: Embedding ABI — M3 (shipped); Tick-coverage on M3
     (shipped `170464f`).
-  - context: `docs/specs/2026-05-19-embedding-abi-m5.md`;
-    M4 retirement
+  - context: `docs/specs/2026-05-19-embedding-abi-m5.md`; iter
+    journals `2026-05-19-iter-embedding-abi-m5.{1,2,3,tidy}.md` +
+    `…-m5.2-resume-attempt.md` + bugfix
+    `…-rc-global-stats-race.md` / `…-swarm-rc-alloc-undercount.md`;
+    audit `docs/journals/2026-05-19-audit-embedding-abi-m5.md`; M4
+    retirement
     `docs/journals/2026-05-18-brainstorm-embedding-abi-m4-retired.md`.
 
 - [x] **\[milestone\]** Heap-`Str` ABI — runtime infrastructure for
@@ -465,19 +481,27 @@ work progresses.
 - [ ] **\[milestone\]** Flat array/slice primitive — performance
   follow-up to the Embedding ABI arc, *not* a capability gap.
   AILang's only sequence is the recursive `List` ADT (one RC cell
-  per element); marshalling a 1024-record chunk across the
-  embedding boundary builds a 1024-cell cons-chain per chunk on a
-  multi-GB hot path (Embedding ABI M4 ships the capability this
-  way). A contiguous array/slice primitive would remove that, but
-  it is a *language* change (interacts with uniqueness inference,
-  RC, and the structurally-decreasing-recursion totality story)
-  and is explicitly out of the ABI arc's scope. Sequenced after
-  M5 so the decision is driven by M5's fieldtest measurements,
-  not speculation.
-  - depends on: Embedding ABI — M5 (for the measured
-    justification).
-  - context: 2026-05-18 chat (user deferred this explicitly to
-    keep the ABI arc clean).
+  per element). The ABI arc resolved chunk-crossing by having the
+  M5 adapter unroll each `data-server` chunk host-side into per-tick
+  `(State, Tick) -> State` calls (M4's cons-list crossing was
+  retired as speculative infra) — so the residual perf question is
+  no longer "1024-cell cons-chain per chunk" but **host-per-tick-FFI
+  vs. an eventual batch/flat-array crossing**. M5's friction-harvest
+  measured the per-tick FFI at **≈ ~206 ns/tick at real EURUSD
+  volume** (≈ 658 ms / 3.19 M ticks). Open decision: whether a
+  contiguous array/slice primitive (to amortise that per-tick cost
+  via a batch crossing) is worth a *language* change — it interacts
+  with uniqueness inference, RC, and the
+  structurally-decreasing-recursion totality story, and is out of
+  the (now-closed) ABI arc's scope. Now decidable on the measured
+  number, not speculation.
+  - depends on: Embedding ABI — M5 (shipped; measured ~206 ns/tick
+    — the justification input now exists).
+  - context: 2026-05-18 chat (user deferred this to keep the ABI
+    arc clean); M5 audit
+    `docs/journals/2026-05-19-audit-embedding-abi-m5.md` (the
+    friction-harvest number); M4 retirement
+    `docs/journals/2026-05-18-brainstorm-embedding-abi-m4-retired.md`.
 
 - [ ] **\[milestone\]** Iteration-totality story — structural +
   Int-bounded total recursion with *enforced* non-negativity.