audit close: Floats milestone — clean (architect/bench/rustdoc all green; carry-on)

docs/JOURNAL.md

@@ -13679,3 +13679,55 @@ Next dispatch (orchestrator): `audit` skill — milestone-close
 drift review + bench-regression diagnostics + rustdoc audit.
 After audit closes clean: `fieldtest` skill — 2-4 `.ailx`
 real-world examples exercising the new Float surface.
+
+## 2026-05-10 — Audit close: Floats milestone
+
+Audit ran in three stages:
+
+**Drift review (architect):** clean. No orphan
+`unimplemented!("Floats milestone iter ...")` markers. The deferred
+`float_to_str` correctly returns `CodegenError::Internal` (not a
+panic) per the iter-4.4 fixup. Cross-crate lockstep intact:
+`is_static_callee` recognises every name `lower_app` inlines;
+`builtin_binop_typed`'s 3-tuple shape consistent at all consumer
+sites; `CheckError::FloatPatternNotAllowed`'s `code()` arm present
+(`"float-pattern-not-allowed"`). DESIGN.md sweep for stale
+`(Int, Int) -> Int` builtin signatures returned only `%` itself
+(correctly Int-only). 405 tests pass; 18 rustdoc warnings (= 16
+pre-existing in `ailang-check` registry/uniqueness/synth + 2
+summary lines), none referencing Float code.
+
+**Bench regression (bencher gate, no investigation):** all three
+scripts exit 0.
+- `bench/check.py`: 63 metrics, 0 regressed, 4 improved beyond
+  tolerance (`latency.explicit_at_rc.{p99, p99_9, max,
+  p99_over_median}`, all -33% to -39%), 59 stable.
+- `bench/compile_check.py`: 24 metrics, 0 regressed, 0 improved
+  beyond tolerance, 24 stable.
+- `bench/cross_lang.py`: 25 metrics, 0 regressed, 0 improved
+  beyond tolerance, 25 stable.
+
+The 4 explicit_at_rc tail-latency improvements are informational
+(the audit gate is "0 regressed"). They are isolated to one
+metric family and 3 of 4 are tail-latency p99/p99.9/max which are
+notoriously high-variance — most likely environmental
+(CPU thermal state, scheduler noise, page-cache warmth) rather
+than a real code-path improvement from the Floats milestone. The
+milestone did not intentionally touch the RC explicit-position
+codegen path; if these improvements are real and reproduce on
+next milestone's audit run, ratify with `--update-baseline` then.
+For now: carry-on without baseline update. The improvements would
+re-trigger the same "improved beyond tolerance" status next run
+if real.
+
+**Rustdoc audit:** N/A — 0 new warnings introduced by the
+milestone. The 16 pre-existing warnings (all in `ailang-check`
+private-link / typeclass-registry / and `ailang-core` desugar
+private-link) are the queued P2 sweep from
+`docs/roadmap.md` and unchanged.
+
+**Verdict:** carry-on. Milestone closes clean.
+
+Next dispatch: `fieldtest` skill — 2-4 real-world `.ailx` examples
+exercising the Float surface to surface friction / spec gaps from
+an LLM-author-only-DESIGN.md perspective.