perf(popular-threads): show board-count loading state for popular threads

src/hooks/__tests__/use-state-string.test.tsx

@@ -139,4 +139,12 @@ describe('use-state-string', () => {
 
     expect(latestValue).toBe('Resolving 2 addresses from ens.example.com, downloading 2 boards, 1 threads, 1 page from gateway.example.com, ipfs.io');
   });
+
+  it('shows an immediate board-specific loading string before detailed multi-board states arrive', () => {
+    act(() => {
+      root.render(createElement(FeedStateStringHarness, { addresses: ['music-posting.eth', 'tech-posting.eth'] }));
+    });
+
+    expect(latestValue).toBe('Downloading 2 boards');
+  });
 });

src/hooks/use-state-string.ts

@@ -157,12 +157,16 @@ export const useFeedStateString = (subplebbitAddresses?: string[]): string | und
       }
     }
 
+    if (!stateString && subplebbitAddresses?.length) {
+      stateString = `downloading ${subplebbitAddresses.length} boards`;
+    }
+
     // capitalize first letter
     stateString = stateString.charAt(0).toUpperCase() + stateString.slice(1);
 
     // if string is empty, return undefined instead
     return stateString === '' ? undefined : stateString;
-  }, [states, subplebbitAddress]);
+  }, [states, subplebbitAddress, subplebbitAddresses]);
 
   if (singleSubplebbitFeedStateString) {
     return singleSubplebbitFeedStateString;