R-1254 (ceremony half, HUNT-3 H2): after a failed escrow upload, ask the hub which package it holds before wording the result

The hub holds the new package -> success; another package -> 502 'previous code still works' (now true);
cannot be asked -> 504, no promise. Tests TestR1254_* red before the fix. Commit only; the agent release needs the vouch.

CHANGELOG.md

@@ -1,3 +1,19 @@
+## Unreleased (2026-10-28 night) — R-1254 (the ceremony half, review round 2 HUNT-3 H2): the agent asks the hub which package it holds before it words a failed upload — commit only; the next agent release (needs the operator's vouch)
+
+- **The defect:** the claim's (R-978) and the confirm's (R-1151) package upload can lose its answer, or answer late
+  (30 s), AFTER the hub stored the new package. The agent then answered 502 „the previous code still works" — false: the
+  hub's current package opens only with the NEW code.
+- **Now (`internal/localapi/escrow_ceremony.go`):** after a failed upload the agent asks the hub (`HubHolds`, 15 s,
+  outside the lock, the slot still marked claiming): the hub holds THIS package → a success (the code is handed out /
+  the confirm completes; a WARN line names the lost answer); the hub holds another package → 502 and the old sentence,
+  now true; the hub cannot be asked → **504** with a sentence that promises nothing about either code, and the wait goes
+  on (a retry decides). `cmd/felhom-agent`: `HubHolds` compares the pending package's identity blob with the one the hub
+  serves back (`GET /api/v1/hosts/<id>/escrow`, the read-back the agent already uses; ciphertext only, nothing logged);
+  a package without an identity blob cannot be compared → unknown. Tests `TestR1254_*` (localapi, red before the fix:
+  502 while the hub held the new package) and `TestR1254_HubHoldsComparesTheIdentityBlob` (red-proved by mutation).
+- Needs controller ≥ the R-1254 controller commit (2026-10-28 night) to word 504 for the household; an older controller
+  shows its generic „A kód lekérése nem sikerült." (claim) / its 502 sentence (confirm) for it.
+
 ## v0.167.0 (2026-10-27) — the BYO SSH clean-up in the SAME update (R-1285); a reinstalled box's whole-guest tier is due at once (R-1232); Go 1.27.3 (R-972) — RELEASED (release-agent.sh from a clean clone; agent sha256 28bdd282…d826f0, bundle 9d034416…ed1268; signed updates committed on demo-felhom, Tester 1, demo-hp; VOUCHED by the operator 2026-10-27, Day-0 pin set)
 
 - **R-972: Go 1.27.3** (`go.mod`; released 2026-10-19 with a security fix to `crypto/x509`). `govulncheck` v1.8.0 before: