Retry each metadata failure exactly once per gateway flip

The gateway-flip retry effect had two churn paths (Bugbot, PR Chia-Network#3029):
retrying an errored entry re-inserts its key with a fresh in-flight
promise synchronously, and Map.forEach revisits keys re-added during
the pass - so the effect attached a rejection retry to the very fetch
it had just started, double-fetching a failure. And rapid toggles could
stack rejection handlers on one promise; when it rejected, each handler
invalidated in turn, the later ones discarding the refetch the first
had started - even a successful one.

The effect now iterates a snapshot of the map, and a rejection handler
retries only the failure it saw: the fetch's own catch stores its
rejection as the entry's error, so an entry that has moved on - already
retried by a stacked handler, or settled successfully - is left alone.
Each failure is retried exactly once per flip and successful results
are never dropped.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017NXWAjaHb9SFafLeguTHd8

Author: jlobue10

packages/gui/src/components/nfts/provider/hooks/useMetadataData.ts

@@ -178,7 +178,12 @@ export default function useMetadataData(props: UseMetadataDataProps) {
     // started under the old preference and may fail because of it — after
     // this effect has run, nothing else would retry that failure — so it is
     // retried on rejection; a result that arrives successfully is kept.
-    metadatasOnDemand.forEach((metadataOnDemand, nftId) => {
+    //
+    // Iterate a snapshot: retrying an errored entry re-inserts its key with a
+    // fresh in-flight promise synchronously, and Map.forEach revisits keys
+    // re-added during the pass — the live map would attach a rejection retry
+    // to the very fetch this effect just started, double-fetching a failure.
+    Array.from(metadatasOnDemand.entries()).forEach(([nftId, metadataOnDemand]) => {
       const retry = () =>
         invalidate(nftId).catch((e) => {
           log(`Error retrying metadata for nftId: ${nftId}`, e);
@@ -187,7 +192,16 @@ export default function useMetadataData(props: UseMetadataDataProps) {
       if (metadataOnDemand.error) {
         retry();
       } else if (metadataOnDemand.promise) {
-        metadataOnDemand.promise.catch(retry);
+        metadataOnDemand.promise.catch((e) => {
+          // Retry only the failure this handler saw. The fetch's own catch
+          // stores its rejection as the entry's error, so anything else here
+          // means the entry has moved on — a stacked handler from another
+          // toggle already retried it, or a newer fetch succeeded — and a
+          // retry would discard that state and fetch again for nothing.
+          if (metadatasOnDemand.get(nftId)?.error === e) {
+            retry();
+          }
+        });
       }
     });
   }, [ipfsGateway, invalidate /* immutable */, metadatasOnDemand /* immutable */]);