fix: eliminate duplicate API requests by deduplicating user fetch calls

- Add request deduplication to getOrFetchUser using RequestDeduplicator
- Consolidates multiple simultaneous calls for same user into single API request
- Prevents duplicate 401 errors and wasted network traffic
- Matches pattern already used by fetchUsers and fetchUserStats
- Remove backwards compatibility aliases (getOrFetchUserByName, getOrFetchUserByUsername)
- Update all call sites to use canonical getOrFetchUser method

Fixes issue where PagedMemoList, useMemoViewState, MainLayout, and UserProfile
were making duplicate user fetch requests when loading user data.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

web/src/components/Inbox/MemoCommentMessage.tsx

@@ -50,7 +50,7 @@ const MemoCommentMessage = observer(({ notification }: Props) => {
         });
         setCommentMemo(comment);
 
-        const sender = await userStore.getOrFetchUserByName(notification.sender);
+        const sender = await userStore.getOrFetchUser(notification.sender);
         setSender(sender);
         setInitialized(true);
       }

web/src/components/MemoReactionListView/hooks.ts

@@ -15,7 +15,7 @@ export const useReactionGroups = (reactions: Reaction[]): ReactionGroup => {
     const fetchReactionGroups = async () => {
       const newReactionGroup = new Map<string, User[]>();
       for (const reaction of reactions) {
-        const user = await userStore.getOrFetchUserByName(reaction.creator);
+        const user = await userStore.getOrFetchUser(reaction.creator);
         const users = newReactionGroup.get(reaction.reactionType) || [];
         users.push(user);
         newReactionGroup.set(reaction.reactionType, uniq(users));

web/src/components/MemoView/hooks/useMemoViewState.ts

@@ -116,7 +116,7 @@ export const useMemoCreator = (creatorName: string) => {
     if (fetchedRef.current) return;
     fetchedRef.current = true;
     (async () => {
-      const user = await userStore.getOrFetchUserByName(creatorName);
+      const user = await userStore.getOrFetchUser(creatorName);
       setCreator(user);
     })();
   }, [creatorName]);

web/src/components/PagedMemoList/PagedMemoList.tsx

@@ -67,7 +67,7 @@ const PagedMemoList = observer((props: Props) => {
         // This significantly improves perceived performance by pre-populating the cache
         if (response?.memos && props.showCreator) {
           const uniqueCreators = Array.from(new Set(response.memos.map((memo) => memo.creator)));
-          await Promise.allSettled(uniqueCreators.map((creator) => userStore.getOrFetchUserByName(creator)));
+          await Promise.allSettled(uniqueCreators.map((creator) => userStore.getOrFetchUser(creator)));
         }
       } finally {
         setIsRequesting(false);

web/src/layouts/MainLayout.tsx

@@ -35,7 +35,7 @@ const MainLayout = observer(() => {
         // Fetch or get user to obtain user name (e.g., "users/123")
         // Note: User stats will be fetched by useFilteredMemoStats
         userStore
-          .getOrFetchUserByUsername(username)
+          .getOrFetchUser(`users/${username}`)
           .then((user) => {
             setProfileUserName(user.name);
           })

web/src/pages/UserProfile.tsx

@@ -30,7 +30,7 @@ const UserProfile = observer(() => {
     }
 
     userStore
-      .getOrFetchUserByUsername(username)
+      .getOrFetchUser(`users/${username}`)
       .then((user) => {
         setUser(user);
         loadingState.setFinish();

web/src/store/user.ts

@@ -72,44 +72,28 @@ const userStore = (() => {
   const state = new LocalState();
   const deduplicator = new RequestDeduplicator();
 
-  const getOrFetchUserByName = async (name: string) => {
+  const getOrFetchUser = async (name: string) => {
     const userMap = state.userMapByName;
     if (userMap[name]) {
       return userMap[name] as User;
     }
-    const user = await userServiceClient.getUser({
-      name: name,
-    });
-    state.setPartial({
-      userMapByName: {
-        ...userMap,
-        [name]: user,
-      },
-    });
-    return user;
-  };
-
-  const getOrFetchUserByUsername = async (username: string) => {
-    const userMap = state.userMapByName;
-    for (const name in userMap) {
-      if (userMap[name].username === username) {
-        return userMap[name];
+    const requestKey = createRequestKey("getOrFetchUser", { name });
+    return deduplicator.execute(requestKey, async () => {
+      // Double-check cache in case another request finished first
+      if (state.userMapByName[name]) {
+        return state.userMapByName[name] as User;
       }
-    }
-    // Use GetUser with username - supports both "users/{id}" and "users/{username}"
-    const user = await userServiceClient.getUser({
-      name: `users/${username}`,
-    });
-    if (!user) {
-      throw new Error(`User with username ${username} not found`);
-    }
-    state.setPartial({
-      userMapByName: {
-        ...userMap,
-        [user.name]: user,
-      },
+      const user = await userServiceClient.getUser({
+        name: name,
+      });
+      state.setPartial({
+        userMapByName: {
+          ...state.userMapByName,
+          [name]: user,
+        },
+      });
+      return user;
     });
-    return user;
   };
 
   const getUserByName = (name: string) => {
@@ -292,8 +276,7 @@ const userStore = (() => {
 
   return {
     state,
-    getOrFetchUserByName,
-    getOrFetchUserByUsername,
+    getOrFetchUser,
     getUserByName,
     fetchUsers,
     updateUser,