docs(agents): record offline/dead-relay behaviour + nip05 seeds

AGENTS.md

@@ -499,9 +499,11 @@ session with **no other memory of this project**. So:
   — the app works without one), **proof by signature** (a claim carries a NIP-98
   kind-27235 event in the `x-nip05-auth` header, signed by the pubkey that will
   own the name), and `onlyIfNew` writes so two claims can't clobber each other.
-  Platform names are seeded in code (`skate-spots`, `skatespots` → owner pubkey)
-  and cannot be claimed/released by users; a small `RESERVED` list blocks
-  impersonation words. Client: `src/lib/skateNip05.ts` (shared validation,
+  Platform names are seeded in code (`skate-spots`/`skatespots` → owner pubkey,
+  `skater` → the second admin `caba497f…`) and cannot be claimed/released by
+  users; a small `RESERVED` list blocks impersonation words. Any admin can wear
+  a seeded handle by typing it in Edit Profile → NIP-05 (it verifies against the
+  seed; no claim needed). Client: `src/lib/skateNip05.ts` (shared validation,
   `deriveSkateNip05Handle`, `parseSkateNip05`, `skateApiBase()` for the native
   absolute-URL rule), `src/hooks/useSkateNip05.ts` (check/claim/release), and
   `src/components/SkateNip05Input.tsx` (debounced availability + Claim).
@@ -515,6 +517,27 @@ session with **no other memory of this project**. So:
   functions with a free draft (`netlify deploy --dir=dist`), not a prod deploy.
   Verified end-to-end on a draft (2026-09-28): claim → resolves → a second key
   gets 409 → release → gone.
+- **Offline / dead-relay behaviour (2026-09-28):** the app is a utility, so a
+  relay outage must degrade, not blank. ⚠️ `querySkateContent` used to swallow
+  **every** relay error and return `[]`, so a dead relay looked like "no spots"
+  AND overwrote good cached data with an empty list (which the persister then
+  saved). Now:
+  - `querySkateContent` / `queryCanonical` take an opt-in **`requireAny`** that
+    throws when NO relay answered. Only the map's own feeds pass it
+    (`useSkateSpots`, `useShops`, `useMarketplaceItems`, `useTours`); the other
+    ~75 call sites keep the old behaviour, deliberately.
+  - `useSkateSpots` / `useSkateSpot` catch that error and fall back to the
+    **Dexie spot cache** (`lib/offlineCache`), so the map still works at the
+    park; they only re-throw when nothing is cached (UI shows an offline card).
+  - `shouldDehydrateQuery` **never persists an empty array** — otherwise one
+    blip would wipe the persisted map for the next 24h.
+  - `MapPage` shows "Offline · showing saved spots" + retry, and a "Can't reach
+    the relays" card instead of the false "No spots mapped yet". Reachability
+    reuses the existing **`useRelayStatus(url)`** (`lib/relayProbe`, a real
+    Nostr handshake) plus `useOnlineStatus` — NOT `navigator.onLine` alone,
+    which is true on a captive-portal Wi-Fi.
+  - Not done yet: offline **map tiles** (needs a service worker on web / an
+    IndexedDB tile layer for native) and the app shell offline — the next slice.
 - **Mints directory**: `/mints` page lists Cashu mints from the community
   **MintRadar** project. MintRadar has **no CORS**, so it's fetched same-origin
   at `/api/mints/*` — prod proxies via `public/_redirects` (`/api/mints/* →