backlog: Otto-161 macOS CI — declined per Otto-164 pricing verification (NOT free for public repos)

docs/BACKLOG.md

@@ -2468,6 +2468,51 @@ within each priority tier.
 
 ## P1 — CI / DX follow-ups (after round-29 anchor)
 
+- [ ] ~~**Enable macOS CI leg on canonical
+  `Lucent-Financial-Group/Zeta`**~~ — **DECLINED per
+  Otto-164 pricing verification.** Aaron Otto-161
+  2026-04-24: *"we can enable mac everywhere now,
+  since its no cost for open source projects if you
+  are absoutly sure, lfg too"*. Per Aaron's explicit
+  *"if you are absolutely sure"* escape clause, Otto
+  did not ship the workflow change; instead verified
+  the pricing claim. **Verification result (Otto-164):**
+  GitHub billing docs at
+  `docs.github.com/en/billing/concepts/product-billing/
+  github-actions` confirm that macOS runners are
+  classified as **"larger runners"** and are always
+  charged — even on public repositories. Exact quote:
+  *"The use of standard GitHub-hosted runners is free:
+  In public repositories, For GitHub Pages, For
+  Dependabot, For the agentic features ..."* followed
+  by *"Larger runners are always charged for, even when
+  used by public repositories or when you have quota
+  available from your plan."* macOS runners are listed
+  at $0.062/min — a 10× multiplier over Linux. The
+  existing `gate.yml` comment block (lines 49-71)
+  citing the 2026-04-21 *"Mac is very very expensive
+  to run"* directive is **still correct**; the
+  fork-only gating at line 77 stays. Otto-161 directive
+  is declined on verification; the claim "no cost for
+  open source projects" does not apply to macOS
+  runners (only to standard Linux/Windows runners).
+  **Recorded for glass-halo transparency.** Row
+  remains checked-in rather than deleted so future
+  Otto instances see the verification trace instead of
+  re-treading the same research. Composes with
+  FACTORY-HYGIENE row #51 (cross-platform parity audit
+  stays in detect-only mode until either (a) macOS
+  pricing changes, or (b) the factory accepts the
+  billing cost deliberately). Sources consulted:
+  `docs.github.com/en/billing/concepts/product-
+  billing/github-actions` (primary, definitive);
+  `docs.github.com/en/billing/managing-billing-for-
+  your-products/about-billing-for-github-actions`
+  (pricing table showing macOS at $0.062/min);
+  `docs.github.com/en/actions/using-github-hosted-
+  runners/using-larger-runners/about-larger-runners`
+  (larger-runner category definition).
+
 - [ ] **HLL property-test flakiness — investigate before
   retry (DST discipline).** Observed 2026-04-23 (auto-loop-88):
   `Zeta.Tests.Properties.FuzzTests.fuzz: HLL estimate