feat(routing): add hooks and utilities for directory-based board routing

src/hooks/use-resolved-subplebbit-address.ts

@@ -0,0 +1,48 @@
+import { useMemo } from 'react';
+import { useParams } from 'react-router-dom';
+import { useDefaultSubplebbits } from './use-default-subplebbits';
+import { getSubplebbitAddress, getBoardPath } from '../lib/utils/route-utils';
+
+/**
+ * Hook to resolve boardIdentifier from URL params to subplebbitAddress
+ * Handles both directory codes (e.g., "biz") and full addresses (e.g., "someboard.eth")
+ *
+ * Performance: Uses useMemo to avoid recalculating when params/defaultSubplebbits haven't changed.
+ * The defaultSubplebbits reference is stable (from cache) after initial load, so memoization works effectively.
+ */
+export const useResolvedSubplebbitAddress = (): string | undefined => {
+  const params = useParams();
+  const defaultSubplebbits = useDefaultSubplebbits();
+
+  // Try boardIdentifier first (new format), then subplebbitAddress (old format for backward compatibility)
+  const boardIdentifier = params.boardIdentifier || params.subplebbitAddress;
+
+  return useMemo(() => {
+    if (!boardIdentifier) {
+      return undefined;
+    }
+
+    // Resolve directory code to address if needed
+    // getSubplebbitAddress uses internal caching, so this is efficient
+    return getSubplebbitAddress(boardIdentifier, defaultSubplebbits);
+  }, [boardIdentifier, defaultSubplebbits]);
+};
+
+/**
+ * Hook to get the board path (directory code or address) for use in links
+ *
+ * Performance: Uses useMemo to avoid recalculating when subplebbitAddress/defaultSubplebbits haven't changed.
+ * The defaultSubplebbits reference is stable (from cache) after initial load, so memoization works effectively.
+ */
+export const useBoardPath = (subplebbitAddress: string | undefined): string | undefined => {
+  const defaultSubplebbits = useDefaultSubplebbits();
+
+  return useMemo(() => {
+    if (!subplebbitAddress) {
+      return undefined;
+    }
+
+    // getBoardPath uses internal caching, so this is efficient
+    return getBoardPath(subplebbitAddress, defaultSubplebbits);
+  }, [subplebbitAddress, defaultSubplebbits]);
+};