docs: F9/F20-BUG2/F20-BUG3 FIXED (agent v0.31.0, live-validated); queue golden controller-tag follow-up

documentation/backlog/README.md

@@ -9,6 +9,10 @@ Verified-LIVE findings with implementable fix plans that are **not yet implement
 - **FIX-M19-NOTES.md** — `deriveStackName` misattribution edge (low-incidence correctness). **FIXED** in
   controller v0.62.0 @ `6bab68b` (2026-06-14). (was on the deleted branch `fix/m19-stackname-crossref`.)
 
+- **FOLLOWUP-golden-default-controller-tag.md** — the golden bakes a stale controller `:0.43.0`
+  (`build-golden.sh:43`); a fresh provision would stand up an ancient controller. Bump it + validate the
+  full destroy→provision→first-boot path (warrants a supervised re-provision). Queued 2026-06-14.
+
 Related: the live-drive fixspec (`../audits/live-drive-fixspec-2026-06-14.md`) carries the **deferred
 supervised items** F9 (HDD provisioning/guest-attach), F20-BUG2 (durable_id scheme), F20-BUG3 (async
 mkfs) — to be implemented in the agent/golden supervised session.