feat: add localStorage caching for profile resolution

- Add localStorage caching functions to profileService.ts following articleService.ts pattern
  - getCachedProfile: get single cached profile with TTL validation (30 days)
  - cacheProfile: save profile to localStorage with error handling
  - loadCachedProfiles: batch load multiple profiles from cache
- Modify fetchProfiles() to check localStorage cache first, only fetch missing/expired profiles, and cache fetched profiles
- Update useProfileLabels hook to check localStorage before EventStore, add cached profiles to EventStore for consistency
- Update logging to show cache hits from localStorage
- Benefits: instant profile resolution on page reload, reduced relay queries, offline support for previously-seen profiles

src/hooks/useProfileLabels.ts

@@ -3,7 +3,7 @@ import { Hooks } from 'applesauce-react'
 import { Helpers, IEventStore } from 'applesauce-core'
 import { getContentPointers } from 'applesauce-factory/helpers'
 import { RelayPool } from 'applesauce-relay'
-import { fetchProfiles } from '../services/profileService'
+import { fetchProfiles, loadCachedProfiles } from '../services/profileService'
 
 const { getPubkeyFromDecodeResult, encodeDecodeResult } = Helpers
 
@@ -52,32 +52,58 @@ export function useProfileLabels(content: string, relayPool?: RelayPool | null):
   const [profileLabels, setProfileLabels] = useState<Map<string, string>>(new Map())
   const lastLoggedSize = useRef<number>(0)
 
-  // Build initial labels from eventStore, then fetch missing profiles
+  // Build initial labels: localStorage cache -> eventStore -> fetch from relays
   useEffect(() => {
     const startTime = Date.now()
     console.log(`[${ts()}] [npub-resolve] Building labels, profileData:`, profileData.length, 'hasEventStore:', !!eventStore)
     
-    // First, get profiles from eventStore synchronously
+    // Extract all pubkeys
+    const allPubkeys = profileData.map(({ pubkey }) => pubkey)
+    
+    // First, check localStorage cache (synchronous, instant)
+    const cachedProfiles = loadCachedProfiles(allPubkeys)
+    console.log(`[${ts()}] [npub-resolve] Found in localStorage cache:`, cachedProfiles.size, 'out of', allPubkeys.length)
+    
+    // Add cached profiles to EventStore for consistency
+    if (eventStore) {
+      for (const profile of cachedProfiles.values()) {
+        eventStore.add(profile)
+      }
+    }
+    
+    // Build initial labels from localStorage cache and eventStore
     const labels = new Map<string, string>()
     const pubkeysToFetch: string[] = []
     
     profileData.forEach(({ encoded, pubkey }) => {
-      if (eventStore) {
-        const profileEvent = eventStore.getEvent(pubkey + ':0')
-        if (profileEvent) {
-          try {
-            const profileData = JSON.parse(profileEvent.content || '{}') as { name?: string; display_name?: string; nip05?: string }
-            const displayName = profileData.display_name || profileData.name || profileData.nip05
-            if (displayName) {
-              labels.set(encoded, `@${displayName}`)
-              console.log(`[${ts()}] [npub-resolve] Found in eventStore:`, encoded, '->', displayName)
-            } else {
-              pubkeysToFetch.push(pubkey)
-            }
-          } catch {
+      let profileEvent: { content: string } | null = null
+      let foundSource = ''
+      
+      // Check localStorage cache first
+      const cachedProfile = cachedProfiles.get(pubkey)
+      if (cachedProfile) {
+        profileEvent = cachedProfile
+        foundSource = 'localStorage cache'
+      } else if (eventStore) {
+        // Then check EventStore (in-memory from current session)
+        const eventStoreProfile = eventStore.getEvent(pubkey + ':0')
+        if (eventStoreProfile) {
+          profileEvent = eventStoreProfile
+          foundSource = 'eventStore'
+        }
+      }
+      
+      if (profileEvent) {
+        try {
+          const profileData = JSON.parse(profileEvent.content || '{}') as { name?: string; display_name?: string; nip05?: string }
+          const displayName = profileData.display_name || profileData.name || profileData.nip05
+          if (displayName) {
+            labels.set(encoded, `@${displayName}`)
+            console.log(`[${ts()}] [npub-resolve] Found in ${foundSource}:`, encoded.slice(0, 30) + '...', '->', displayName)
+          } else {
             pubkeysToFetch.push(pubkey)
           }
-        } else {
+        } catch {
           pubkeysToFetch.push(pubkey)
         }
       } else {
@@ -85,7 +111,7 @@ export function useProfileLabels(content: string, relayPool?: RelayPool | null):
       }
     })
     
-    // Update labels with what we found in eventStore
+    // Update labels with what we found in localStorage cache and eventStore
     setProfileLabels(new Map(labels))
     
     // Fetch missing profiles asynchronously

src/services/profileService.ts

@@ -6,9 +6,86 @@ import { prioritizeLocalRelays, partitionRelays } from '../utils/helpers'
 import { rebroadcastEvents } from './rebroadcastService'
 import { UserSettings } from './settingsService'
 
+interface CachedProfile {
+  event: NostrEvent
+  timestamp: number
+}
+
+const PROFILE_CACHE_TTL = 30 * 24 * 60 * 60 * 1000 // 30 days in milliseconds (profiles change less frequently than articles)
+const PROFILE_CACHE_PREFIX = 'profile_cache_'
+
+function getProfileCacheKey(pubkey: string): string {
+  return `${PROFILE_CACHE_PREFIX}${pubkey}`
+}
+
+/**
+ * Get a cached profile from localStorage
+ * Returns null if not found, expired, or on error
+ */
+export function getCachedProfile(pubkey: string): NostrEvent | null {
+  try {
+    const cacheKey = getProfileCacheKey(pubkey)
+    const cached = localStorage.getItem(cacheKey)
+    if (!cached) {
+      return null
+    }
+
+    const { event, timestamp }: CachedProfile = JSON.parse(cached)
+    const age = Date.now() - timestamp
+
+    if (age > PROFILE_CACHE_TTL) {
+      localStorage.removeItem(cacheKey)
+      return null
+    }
+
+    return event
+  } catch (err) {
+    // Silently handle cache read errors
+    return null
+  }
+}
+
+/**
+ * Cache a profile to localStorage
+ * Handles errors gracefully (quota exceeded, invalid data, etc.)
+ */
+export function cacheProfile(profile: NostrEvent): void {
+  try {
+    if (profile.kind !== 0) return // Only cache kind:0 (profile) events
+
+    const cacheKey = getProfileCacheKey(profile.pubkey)
+    const cached: CachedProfile = {
+      event: profile,
+      timestamp: Date.now()
+    }
+    localStorage.setItem(cacheKey, JSON.stringify(cached))
+  } catch (err) {
+    // Silently fail - don't block the UI if caching fails
+    // Handles quota exceeded, invalid data, and other errors gracefully
+  }
+}
+
+/**
+ * Batch load multiple profiles from localStorage cache
+ * Returns a Map of pubkey -> NostrEvent for all found profiles
+ */
+export function loadCachedProfiles(pubkeys: string[]): Map<string, NostrEvent> {
+  const cached = new Map<string, NostrEvent>()
+  
+  for (const pubkey of pubkeys) {
+    const profile = getCachedProfile(pubkey)
+    if (profile) {
+      cached.set(pubkey, profile)
+    }
+  }
+  
+  return cached
+}
+
 /**
  * Fetches profile metadata (kind:0) for a list of pubkeys
- * Stores profiles in the event store and optionally to local relays
+ * Checks localStorage cache first, then fetches from relays for missing/expired profiles
+ * Stores profiles in the event store and caches to localStorage
  */
 export const fetchProfiles = async (
   relayPool: RelayPool,
@@ -22,26 +99,45 @@ export const fetchProfiles = async (
     }
 
     const uniquePubkeys = Array.from(new Set(pubkeys))
+    
+    // First, check localStorage cache for all requested profiles
+    const cachedProfiles = loadCachedProfiles(uniquePubkeys)
+    const profilesByPubkey = new Map<string, NostrEvent>()
+    
+    // Add cached profiles to the map and EventStore
+    for (const [pubkey, profile] of cachedProfiles.entries()) {
+      profilesByPubkey.set(pubkey, profile)
+      // Ensure cached profiles are also in EventStore for consistency
+      eventStore.add(profile)
+    }
+    
+    // Determine which pubkeys need to be fetched from relays
+    const pubkeysToFetch = uniquePubkeys.filter(pubkey => !cachedProfiles.has(pubkey))
+    
+    // If all profiles are cached, return early
+    if (pubkeysToFetch.length === 0) {
+      return Array.from(profilesByPubkey.values())
+    }
 
+    // Fetch missing profiles from relays
     const relayUrls = Array.from(relayPool.relays.values()).map(relay => relay.url)
     const prioritized = prioritizeLocalRelays(relayUrls)
     const { local: localRelays, remote: remoteRelays } = partitionRelays(prioritized)
 
-    // Keep only the most recent profile for each pubkey
-    const profilesByPubkey = new Map<string, NostrEvent>()
-
     const processEvent = (event: NostrEvent) => {
       const existing = profilesByPubkey.get(event.pubkey)
       if (!existing || event.created_at > existing.created_at) {
         profilesByPubkey.set(event.pubkey, event)
         // Store in event store immediately
         eventStore.add(event)
+        // Cache to localStorage for future use
+        cacheProfile(event)
       }
     }
 
     const local$ = localRelays.length > 0
       ? relayPool
-          .req(localRelays, { kinds: [0], authors: uniquePubkeys })
+          .req(localRelays, { kinds: [0], authors: pubkeysToFetch })
           .pipe(
             onlyEvents(),
             tap((event: NostrEvent) => processEvent(event)),
@@ -52,7 +148,7 @@ export const fetchProfiles = async (
 
     const remote$ = remoteRelays.length > 0
       ? relayPool
-          .req(remoteRelays, { kinds: [0], authors: uniquePubkeys })
+          .req(remoteRelays, { kinds: [0], authors: pubkeysToFetch })
           .pipe(
             onlyEvents(),
             tap((event: NostrEvent) => processEvent(event)),
@@ -70,8 +166,10 @@ export const fetchProfiles = async (
     // Only the logged-in user's profile image is preloaded (in SidebarHeader).
 
     // Rebroadcast profiles to local/all relays based on settings
-    if (profiles.length > 0) {
-      await rebroadcastEvents(profiles, relayPool, settings)
+    // Only rebroadcast newly fetched profiles, not cached ones
+    const newlyFetchedProfiles = profiles.filter(p => pubkeysToFetch.includes(p.pubkey))
+    if (newlyFetchedProfiles.length > 0) {
+      await rebroadcastEvents(newlyFetchedProfiles, relayPool, settings)
     }
 
     return profiles