feat(nostr): encrypted DMs with inbox and thread view (M11.2)

NIP-04 encrypted DMs with IDB persistence. DM inbox tab in Nostr
section with contact list, message threads, and new conversation
initiation. Added decodeNpub utility. Sub-tab switcher (Feed/Messages).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/src/composables/useNostrDMs.ts

@@ -0,0 +1,214 @@
+import { ref, computed } from 'vue'
+import { useNostrIdentity } from './useNostrIdentity'
+
+export interface DirectMessage {
+  id: string
+  fromPubkey: string
+  toPubkey: string
+  content: string
+  created_at: number
+  decrypted: boolean
+}
+
+export interface DMThread {
+  contactPubkey: string
+  contactName: string
+  messages: DirectMessage[]
+  lastMessage: DirectMessage | null
+  unread: number
+}
+
+const DB_NAME = 'aiui-nostr-dms'
+const DB_VERSION = 1
+const STORE_NAME = 'messages'
+
+const threads = ref<DMThread[]>([])
+const activeContact = ref<string | null>(null)
+const isLoading = ref(false)
+
+let dbPromise: Promise<IDBDatabase> | null = null
+
+function openDMDB(): Promise<IDBDatabase> {
+  if (dbPromise) return dbPromise
+  dbPromise = new Promise<IDBDatabase>((resolve, reject) => {
+    const req = indexedDB.open(DB_NAME, DB_VERSION)
+    req.onupgradeneeded = () => {
+      const db = req.result
+      if (!db.objectStoreNames.contains(STORE_NAME)) {
+        const store = db.createObjectStore(STORE_NAME, { keyPath: 'id' })
+        store.createIndex('contact', 'contactPubkey', { unique: false })
+        store.createIndex('created_at', 'created_at', { unique: false })
+      }
+    }
+    req.onsuccess = () => resolve(req.result)
+    req.onerror = () => {
+      dbPromise = null
+      reject(req.error)
+    }
+  })
+  return dbPromise
+}
+
+interface StoredDM extends DirectMessage {
+  contactPubkey: string
+}
+
+function truncatePubkey(pk: string): string {
+  if (pk.length <= 12) return pk
+  return pk.slice(0, 8) + '...' + pk.slice(-4)
+}
+
+async function saveDM(msg: DirectMessage, myPubkey: string): Promise<void> {
+  const db = await openDMDB()
+  const contactPubkey = msg.fromPubkey === myPubkey ? msg.toPubkey : msg.fromPubkey
+  const record: StoredDM = { ...msg, contactPubkey }
+
+  return new Promise((resolve, reject) => {
+    const tx = db.transaction(STORE_NAME, 'readwrite')
+    tx.objectStore(STORE_NAME).put(record)
+    tx.oncomplete = () => resolve()
+    tx.onerror = () => reject(tx.error)
+  })
+}
+
+async function loadAllDMs(): Promise<StoredDM[]> {
+  const db = await openDMDB()
+  return new Promise((resolve, reject) => {
+    const tx = db.transaction(STORE_NAME, 'readonly')
+    const req = tx.objectStore(STORE_NAME).getAll()
+    req.onsuccess = () => resolve(req.result)
+    req.onerror = () => reject(req.error)
+  })
+}
+
+function buildThreads(messages: StoredDM[]): DMThread[] {
+  const threadMap = new Map<string, DirectMessage[]>()
+
+  for (const msg of messages) {
+    const existing = threadMap.get(msg.contactPubkey) ?? []
+    existing.push(msg)
+    threadMap.set(msg.contactPubkey, existing)
+  }
+
+  const result: DMThread[] = []
+  for (const [contactPubkey, msgs] of threadMap) {
+    msgs.sort((a, b) => a.created_at - b.created_at)
+    result.push({
+      contactPubkey,
+      contactName: truncatePubkey(contactPubkey),
+      messages: msgs,
+      lastMessage: msgs[msgs.length - 1] ?? null,
+      unread: 0,
+    })
+  }
+
+  // Sort by latest message
+  result.sort((a, b) => (b.lastMessage?.created_at ?? 0) - (a.lastMessage?.created_at ?? 0))
+  return result
+}
+
+export function useNostrDMs() {
+  const { pubkey, isLoggedIn } = useNostrIdentity()
+
+  const activeThread = computed(() => {
+    if (!activeContact.value) return null
+    return threads.value.find(t => t.contactPubkey === activeContact.value) ?? null
+  })
+
+  async function loadDMs() {
+    if (!isLoggedIn.value) return
+    isLoading.value = true
+    try {
+      const all = await loadAllDMs()
+      threads.value = buildThreads(all)
+    } catch {
+      // IDB error
+    } finally {
+      isLoading.value = false
+    }
+  }
+
+  async function sendDM(toPubkey: string, plaintext: string): Promise<boolean> {
+    if (!window.nostr?.nip04 || !pubkey.value) return false
+
+    try {
+      const encrypted = await window.nostr.nip04.encrypt(toPubkey, plaintext)
+
+      const unsigned = {
+        kind: 4,
+        created_at: Math.floor(Date.now() / 1000),
+        tags: [['p', toPubkey]],
+        content: encrypted,
+      }
+
+      const signed = await window.nostr.signEvent(unsigned)
+      if (!signed) return false
+
+      // Store locally
+      const dm: DirectMessage = {
+        id: signed.id,
+        fromPubkey: pubkey.value,
+        toPubkey,
+        content: plaintext,
+        created_at: signed.created_at,
+        decrypted: true,
+      }
+      await saveDM(dm, pubkey.value)
+
+      // Broadcast to relays (reuse useNostr relay infra)
+      const { publishEvent } = await import('./useNostr').then(m => m.useNostr())
+      await publishEvent(signed)
+
+      // Refresh threads
+      const all = await loadAllDMs()
+      threads.value = buildThreads(all)
+
+      return true
+    } catch {
+      return false
+    }
+  }
+
+  async function receiveDM(eventId: string, fromPubkey: string, encryptedContent: string, createdAt: number): Promise<void> {
+    if (!window.nostr?.nip04 || !pubkey.value) return
+
+    try {
+      const plaintext = await window.nostr.nip04.decrypt(fromPubkey, encryptedContent)
+
+      const dm: DirectMessage = {
+        id: eventId,
+        fromPubkey,
+        toPubkey: pubkey.value,
+        content: plaintext,
+        created_at: createdAt,
+        decrypted: true,
+      }
+      await saveDM(dm, pubkey.value)
+
+      const all = await loadAllDMs()
+      threads.value = buildThreads(all)
+    } catch {
+      // Decryption failed
+    }
+  }
+
+  function selectContact(contactPubkey: string) {
+    activeContact.value = contactPubkey
+  }
+
+  function clearActiveContact() {
+    activeContact.value = null
+  }
+
+  return {
+    threads,
+    activeThread,
+    activeContact,
+    isLoading,
+    loadDMs,
+    sendDM,
+    receiveDM,
+    selectContact,
+    clearActiveContact,
+  }
+}