Try fixing initialization

backend/models.py

@@ -93,6 +93,19 @@ class SignalPreKey(Base):
     __table_args__ = (UniqueConstraint('user_id', 'prekey_id', name='_user_prekey_uc'),)
 
 
+class SignalSession(Base):
+    __tablename__ = "signal_session"
+
+    id = Column(Integer, primary_key=True, index=True)
+    user_id = Column(Integer, ForeignKey("user.id"), nullable=False, index=True)
+    recipient_id = Column(Integer, nullable=False, index=True)  # The other user in the session
+    device_id = Column(Integer, default=1, nullable=False)  # Device ID (always 1 for now)
+    encrypted_session_data = Column(Text, nullable=False)  # Encrypted session record (JSON with salt, iv, ciphertext)
+    updated_at = Column(DateTime, default=datetime.now, onupdate=datetime.now)
+    
+    __table_args__ = (UniqueConstraint('user_id', 'recipient_id', 'device_id', name='_user_recipient_device_uc'),)
+
+
 class DMEnvelope(Base):
     __tablename__ = "dm_envelope"
 

backend/routes/account.py

@@ -10,7 +10,7 @@ from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
 
 from constants import OWNER_USERNAME
 from dependencies import get_current_user, get_db
-from models import LoginRequest, RegisterRequest, ChangePasswordRequest, User, CryptoPublicKey, CryptoBackup, DeviceSession
+from models import LoginRequest, RegisterRequest, ChangePasswordRequest, User, CryptoPublicKey, CryptoBackup, DeviceSession, SignalSession
 from utils import create_token, get_password_hash, verify_password, get_client_ip
 from validation import is_valid_password, is_valid_username, is_valid_display_name
 import os
@@ -707,6 +707,89 @@ def get_prekey_bundle_of(
         raise HTTPException(status_code=500, detail="Invalid bundle data")
 
 
+@router.post("/crypto/signal/sessions")
+@rate_limit_per_ip("100/minute")
+def upload_signal_sessions(
+    request: Request,
+    payload: dict,
+    current_user: User = Depends(get_current_user),
+    db: Session = Depends(get_db)
+):
+    """Upload encrypted Signal Protocol sessions for the current user"""
+    import json
+    from datetime import datetime
+    
+    sessions = payload.get("sessions")
+    if not isinstance(sessions, list):
+        raise HTTPException(status_code=400, detail="sessions must be a list")
+    
+    uploaded_count = 0
+    for session_data in sessions:
+        if not isinstance(session_data, dict):
+            continue
+        
+        recipient_id = session_data.get("recipientId")
+        device_id = session_data.get("deviceId", 1)
+        encrypted_data = session_data.get("encryptedData")
+        
+        if not recipient_id or not encrypted_data:
+            continue
+        
+        try:
+            # Validate encrypted_data is valid JSON
+            json.loads(encrypted_data)
+        except (json.JSONDecodeError, TypeError):
+            continue
+        
+        # Store or update session
+        existing = db.query(SignalSession).filter(
+            SignalSession.user_id == current_user.id,
+            SignalSession.recipient_id == recipient_id,
+            SignalSession.device_id == device_id
+        ).first()
+        
+        if existing:
+            existing.encrypted_session_data = encrypted_data
+            existing.updated_at = datetime.now()
+        else:
+            new_session = SignalSession(
+                user_id=current_user.id,
+                recipient_id=recipient_id,
+                device_id=device_id,
+                encrypted_session_data=encrypted_data
+            )
+            db.add(new_session)
+        uploaded_count += 1
+    
+    db.commit()
+    return {"status": "ok", "uploaded_count": uploaded_count}
+
+
+@router.get("/crypto/signal/sessions")
+@rate_limit_per_ip("60/minute")
+def get_signal_sessions(
+    request: Request,
+    current_user: User = Depends(get_current_user),
+    db: Session = Depends(get_db)
+):
+    """Get all encrypted Signal Protocol sessions for the current user"""
+    sessions = db.query(SignalSession).filter(
+        SignalSession.user_id == current_user.id
+    ).all()
+    
+    return {
+        "sessions": [
+            {
+                "recipientId": s.recipient_id,
+                "deviceId": s.device_id,
+                "encryptedData": s.encrypted_session_data,
+                "updatedAt": s.updated_at.isoformat()
+            }
+            for s in sessions
+        ]
+    }
+
+
 @router.get("/users/search")
 @rate_limit_per_ip("60/minute")  # Per-IP limit to prevent abuse
 def search_users(request: Request, q: str, current_user: User = Depends(get_current_user), db: Session = Depends(get_db)):

frontend/src/core/api/chats/dm.ts

@@ -132,8 +132,17 @@ export async function decrypt(envelope: DmEnvelope, senderId: number): Promise<s
         throw new Error(`Invalid base64 in ciphertext body: ${error instanceof Error ? error.message : String(error)}`);
     }
     
-    const plaintext = await signalService.decryptMessage(senderId, signalCiphertext);
+    try {
-    return plaintext;
+        const plaintext = await signalService.decryptMessage(senderId, signalCiphertext);
+        return plaintext;
+    } catch (error) {
+        // If decryption fails, check if it's a session issue
+        const errorMessage = error instanceof Error ? error.message : String(error);
+        if (errorMessage.includes("No session exists") || errorMessage.includes("No record for device")) {
+            console.warn(`Session missing for sender ${senderId} (envelope ID: ${envelope.id}). This may happen after page reload if the session was not properly restored.`);
+        }
+        throw error;
+    }
 }
 
 export async function fetchMessages(userId: number, token: string, limit: number = 50, beforeId?: number): Promise<{ messages: DmEnvelope[]; has_more: boolean }> {
@@ -158,7 +167,13 @@ export async function send(recipientId: number, plaintext: string, authToken: st
     const signalService = new SignalProtocolService(user.id.toString());
     
     // Check if we have a session, if not, fetch prekey bundle and establish one
-    const hasSession = await signalService.hasSession(recipientId);
+    let hasSession = false;
+    try {
+        hasSession = await signalService.hasSession(recipientId);
+    } catch (error) {
+        console.warn("Failed to check session, will attempt to establish new one:", error);
+    }
+    
     if (!hasSession) {
         try {
             const bundle = await api.crypto.prekeys.fetchPreKeyBundle(recipientId, authToken);
@@ -168,13 +183,27 @@ export async function send(recipientId: number, plaintext: string, authToken: st
             if (error instanceof api.crypto.prekeys.PrekeyExhaustedError) {
                 throw error;
             }
+            // Log other errors for debugging
+            console.error("Failed to establish session:", {
+                recipientId,
+                error: error instanceof Error ? error.message : String(error)
+            });
             // Re-throw other errors
             throw error;
         }
     }
     
     // Encrypt with Signal Protocol
-    const ciphertext = await signalService.encryptMessage(recipientId, plaintext);
+    let ciphertext: { type: number; body: string };
+    try {
+        ciphertext = await signalService.encryptMessage(recipientId, plaintext);
+    } catch (error) {
+        console.error("Failed to encrypt message:", {
+            recipientId,
+            error: error instanceof Error ? error.message : String(error)
+        });
+        throw error;
+    }
     
     // Verify the body is valid base64 before stringifying
     if (ciphertext.body && typeof ciphertext.body === "string") {
@@ -214,7 +243,7 @@ export async function send(recipientId: number, plaintext: string, authToken: st
     
     // Add padding to obfuscate message size (anti-censorship)
     const paddedCiphertext = addPadding(ciphertextJson);
-    
+
     const payload: SendDMRequest = {
         recipientId: recipientId,
         iv: "", // Not used for Signal Protocol

frontend/src/core/api/crypto/sessions.ts

@@ -0,0 +1,53 @@
+/**
+ * API functions for managing Signal Protocol sessions on the server
+ */
+
+import { API_BASE_URL } from "@/core/config";
+import { getAuthHeaders } from "../user/auth";
+
+export interface SessionData {
+    recipientId: number;
+    deviceId: number;
+    encryptedData: string; // JSON string of encrypted session
+}
+
+/**
+ * Upload encrypted Signal Protocol sessions to the server
+ */
+export async function uploadSessions(sessions: SessionData[], token: string): Promise<void> {
+    const headers = getAuthHeaders(token, true);
+    
+    const payload = {
+        sessions
+    };
+
+    const res = await fetch(`${API_BASE_URL}/crypto/signal/sessions`, {
+        method: "POST",
+        headers,
+        body: JSON.stringify(payload)
+    });
+    
+    if (!res.ok) {
+        throw new Error(`Failed to upload sessions: ${res.statusText}`);
+    }
+}
+
+/**
+ * Fetch all encrypted Signal Protocol sessions from the server
+ */
+export async function fetchSessions(token: string): Promise<SessionData[]> {
+    const headers = getAuthHeaders(token, true);
+    
+    const res = await fetch(`${API_BASE_URL}/crypto/signal/sessions`, {
+        method: "GET",
+        headers
+    });
+    
+    if (!res.ok) {
+        throw new Error(`Failed to fetch sessions: ${res.statusText}`);
+    }
+    
+    const data = await res.json();
+    return data.sessions || [];
+}
+

frontend/src/core/api/index.ts

@@ -7,6 +7,7 @@ import * as userSearch from "./user/search";
 import * as cryptoPrekeys from "./crypto/prekeys";
 import * as cryptoIdentity from "./crypto/identity";
 import * as cryptoBackup from "./crypto/backup";
+import * as cryptoSessions from "./crypto/sessions";
 import * as moderationBlocklist from "./moderation/blocklist";
 import * as moderationUsers from "./moderation/users";
 import * as callsModule from "./calls";
@@ -27,7 +28,8 @@ const api = {
     crypto: {
         prekeys: cryptoPrekeys,
         identity: cryptoIdentity,
-        backup: cryptoBackup
+        backup: cryptoBackup,
+        sessions: cryptoSessions
     },
     moderation: {
         blocklist: moderationBlocklist,

frontend/src/pages/auth/LoginForm.tsx

@@ -98,10 +98,22 @@ export function LoginForm({ onSwitchMode }: LoginFormProps) {
                         // Run Signal Protocol initialization in background to avoid blocking navigation
                         (async () => {
                             try {
+                                console.log("Starting Signal Protocol initialization...");
                                 const { SignalProtocolService } = await import("@/utils/crypto/signalProtocol");
                                 const { uploadPreKeyBundle, uploadAllPreKeys } = await import("@/core/api/crypto/prekeys");
+                                const { restoreSessionsFromServer, uploadAllSessionsToServer, initializeSessionSync } = await import("@/utils/crypto/sessionSync");
+                                
                                 const signalService = new SignalProtocolService(data.user!.id.toString());
                                 await signalService.initialize();
+                                console.log("Signal Protocol initialized");
+                                
+                                // Initialize session sync (enables automatic upload of new sessions)
+                                console.log("Initializing session sync...");
+                                initializeSessionSync(data.user!.id.toString(), password, data.token);
+                                console.log("Session sync initialized");
+                                
+                                // Restore sessions from server (encrypted with password)
+                                await restoreSessionsFromServer(data.user!.id.toString(), password, data.token);
                                 
                                 // Upload base bundle with one prekey (for backward compatibility)
                                 const bundle = await signalService.getPreKeyBundle();
@@ -112,6 +124,9 @@ export function LoginForm({ onSwitchMode }: LoginFormProps) {
                                 const prekeys = await signalService.getAllPreKeys();
                                 await uploadAllPreKeys(baseBundle, prekeys, data.token);
                                 
+                                // Upload all current sessions to server (backup)
+                                await uploadAllSessionsToServer(data.user!.id.toString(), password, data.token);
+                                
                                 console.log(`Uploaded ${prekeys.length} prekeys to server`);
                             } catch (e) {
                                 console.error("Key setup failed:", e);

frontend/src/pages/auth/RegisterForm.tsx

@@ -120,6 +120,40 @@ export function RegisterForm({ onSwitchMode }: RegisterFormProps) {
 
                 try {
                     await api.user.auth.ensureKeysOnLogin(password, data.token);
+                    
+                    // Initialize Signal Protocol after keys are set up (non-blocking)
+                    if (data.user?.id) {
+                        // Run Signal Protocol initialization in background to avoid blocking navigation
+                        (async () => {
+                            try {
+                                const { SignalProtocolService } = await import("@/utils/crypto/signalProtocol");
+                                const { uploadPreKeyBundle, uploadAllPreKeys } = await import("@/core/api/crypto/prekeys");
+                                const { uploadAllSessionsToServer, initializeSessionSync } = await import("@/utils/crypto/sessionSync");
+                                
+                                const signalService = new SignalProtocolService(data.user!.id.toString());
+                                await signalService.initialize();
+                                
+                                // Initialize session sync (enables automatic upload of new sessions)
+                                initializeSessionSync(data.user!.id.toString(), password, data.token);
+                                
+                                // Upload base bundle with one prekey (for backward compatibility)
+                                const bundle = await signalService.getPreKeyBundle();
+                                await uploadPreKeyBundle(bundle, data.token);
+                                
+                                // Upload all prekeys for server-side rotation
+                                const baseBundle = await signalService.getBaseBundle();
+                                const prekeys = await signalService.getAllPreKeys();
+                                await uploadAllPreKeys(baseBundle, prekeys, data.token);
+                                
+                                // Upload all current sessions to server (backup - will be empty on registration)
+                                await uploadAllSessionsToServer(data.user!.id.toString(), password, data.token);
+                                
+                                console.log(`Uploaded ${prekeys.length} prekeys to server`);
+                            } catch (e) {
+                                console.error("Key setup failed:", e);
+                            }
+                        })();
+                    }
                 } catch (e) {
                     console.error("Key setup failed:", e);
                 }

frontend/src/pages/chat/hooks/useDM.ts

@@ -166,8 +166,21 @@ export function useDM() {
 
             for (const env of messages) {
                 try {
-                    const text = await decryptDm(env, env.senderId);
+                    // Check if this is a message sent by the current user
-                    const isAuthor = env.senderId !== userId;
+                    const isAuthor = env.senderId === user.currentUser?.id;
+                    let text: string;
+                    
+                    if (isAuthor) {
+                        // For sent messages, we can't decrypt them in Signal Protocol
+                        // The plaintext should be stored when sending, but for now we'll skip them
+                        // or try to get it from the envelope if available
+                        // Skip this message for now - we'll need to store plaintext when sending
+                        continue; // Skip sent messages - they'll be handled by the send flow
+                    } else {
+                        // Decrypt incoming messages
+                        text = await decryptDm(env, env.senderId);
+                    }
+                    
                     const username = isAuthor ? (user.currentUser?.username || "Unknown") : "Other User";
 
                     decryptedMessages.push({

frontend/src/pages/chat/ui/right/panels/DMPanel.ts

@@ -58,7 +58,20 @@ export class DMPanel extends MessagePanel {
     }
 
     private async parseTextPayload(env: DmEnvelope, decryptedMessages: Message[]) {
-        const plaintext = await decryptDm(env, env.senderId);
+        // Check if this is a message sent by the current user
+        const isSentByUs = env.senderId === this.currentUser.currentUser?.id;
+        
+        let plaintext: string;
+        if (isSentByUs) {
+            // Can't decrypt our own sent messages in Signal Protocol
+            // The plaintext should be stored when sending, but for now we'll skip it
+            // This message should have been displayed immediately when sent
+            throw new Error("Cannot decrypt own sent message - should be displayed from send flow");
+        } else {
+            // Decrypt incoming messages
+            plaintext = await decryptDm(env, env.senderId);
+        }
+        
         const username = formatDMUsername(
             env.senderId,
             env.recipientId,

frontend/src/state/user.ts

@@ -7,6 +7,7 @@ import { isElectron } from "@/core/electron/electron";
 import { onlineStatusManager } from "@/core/onlineStatusManager";
 import { typingManager } from "@/core/typingManager";
 import type { UserState } from "./types";
+import { clearSessionSync } from "@/utils/crypto/sessionSync";
 
 interface UserStore {
     user: UserState;
@@ -58,6 +59,9 @@ export const useUserStore = create<UserStore>((set) => ({
         typingManager.setAuthToken(null);
         onlineStatusManager.cleanup();
         typingManager.cleanup();
+        
+        // Clear session sync
+        clearSessionSync();
 
         set({
             user: {
@@ -104,6 +108,22 @@ export const useUserStore = create<UserStore>((set) => ({
                     onlineStatusManager.setAuthToken(token);
                     typingManager.setAuthToken(token);
 
+                    // Initialize Signal Protocol after restoring user (non-blocking)
+                    // Note: We can't restore sessions without the password, but we can initialize
+                    // Signal Protocol so new sessions can be created when needed
+                    if (user.id) {
+                        (async () => {
+                            try {
+                                const { SignalProtocolService } = await import("@/utils/crypto/signalProtocol");
+                                const signalService = new SignalProtocolService(user.id.toString());
+                                await signalService.initialize();
+                                console.log("Signal Protocol initialized after restore (sessions will be re-established when needed)");
+                            } catch (e) {
+                                console.error("Signal Protocol initialization failed (restored):", e);
+                            }
+                        })();
+                    }
+
                     // Ping will be sent automatically on WebSocket reconnect
                     // No need to send here to avoid duplicate pings
 

frontend/src/utils/crypto/sessionEncryption.ts

@@ -0,0 +1,60 @@
+/**
+ * Functions for encrypting/decrypting Signal Protocol session data
+ * Uses password-derived key (same as backup encryption)
+ */
+
+import { aesGcmDecrypt, aesGcmEncrypt } from "./symmetric";
+import { importPassword, deriveKEK, randomBytes } from "./kdf";
+import { b64, ub64 } from "../utils";
+
+export interface EncryptedSessionData {
+    salt: Uint8Array; // for PBKDF2 derivation of KEK
+    iv: Uint8Array; // AES-GCM IV
+    ciphertext: Uint8Array; // encrypted session record (string)
+}
+
+/**
+ * Encrypt session record using password-derived key
+ */
+export async function encryptSessionWithPassword(password: string, sessionRecord: string): Promise<EncryptedSessionData> {
+    const salt = randomBytes(16);
+    const pw = await importPassword(password);
+    const kek = await deriveKEK(pw, salt);
+    const sessionBytes = new TextEncoder().encode(sessionRecord);
+    const { iv, ciphertext } = await aesGcmEncrypt(kek, sessionBytes);
+    return { salt, iv, ciphertext };
+}
+
+/**
+ * Decrypt session record using password-derived key
+ */
+export async function decryptSessionWithPassword(password: string, blob: EncryptedSessionData): Promise<string> {
+    const pw = await importPassword(password);
+    const kek = await deriveKEK(pw, blob.salt);
+    const plaintext = await aesGcmDecrypt(kek, blob.iv, blob.ciphertext);
+    return new TextDecoder().decode(plaintext);
+}
+
+/**
+ * Encode encrypted session data to JSON string for storage
+ */
+export function encodeSessionBlob(blob: EncryptedSessionData): string {
+    return JSON.stringify({
+        salt: b64(blob.salt),
+        iv: b64(blob.iv),
+        ciphertext: b64(blob.ciphertext)
+    });
+}
+
+/**
+ * Decode encrypted session data from JSON string
+ */
+export function decodeSessionBlob(json: string): EncryptedSessionData {
+    const obj = JSON.parse(json);
+    return {
+        salt: ub64(obj.salt),
+        iv: ub64(obj.iv),
+        ciphertext: ub64(obj.ciphertext)
+    };
+}
+

frontend/src/utils/crypto/sessionSync.ts

@@ -0,0 +1,268 @@
+/**
+ * Service for syncing Signal Protocol sessions with the server
+ * Sessions are encrypted with password-derived key and stored on server
+ */
+
+import { SignalProtocolStorage, setSessionSyncCallback, setRestoring } from "./signalStorage";
+import { encryptSessionWithPassword, decryptSessionWithPassword, encodeSessionBlob, decodeSessionBlob } from "./sessionEncryption";
+import { uploadSessions, fetchSessions, type SessionData } from "@/core/api/crypto/sessions";
+
+// Global state for session sync
+let syncPassword: string | null = null;
+let syncToken: string | null = null;
+let syncUserId: string | null = null;
+
+/**
+ * Initialize session sync - sets up automatic upload of sessions when they're created
+ * Called after login when password is available
+ */
+export function initializeSessionSync(userId: string, password: string, token: string): void {
+    console.log("Initializing session sync for user", userId);
+    syncUserId = userId;
+    syncPassword = password;
+    syncToken = token;
+    
+    // Set up callback to upload sessions when they're stored
+    setSessionSyncCallback(async (address: string, record: string) => {
+        console.log(`Session sync callback invoked for address: ${address}`);
+        if (!syncPassword || !syncToken || !syncUserId) {
+            console.warn("Session sync not initialized (missing password/token/userId)");
+            return; // Not initialized yet
+        }
+        
+        try {
+            const parts = address.split(".");
+            const recipientId = parseInt(parts[0], 10);
+            const deviceId = parts.length > 1 ? parseInt(parts[1], 10) : 1;
+            
+            if (isNaN(recipientId)) {
+                console.warn(`Invalid address format: ${address}`);
+                return;
+            }
+            
+            console.log(`Encrypting session for recipient ${recipientId}...`);
+            const encryptedBlob = await encryptSessionWithPassword(syncPassword, record);
+            const encryptedData = encodeSessionBlob(encryptedBlob);
+            
+            console.log(`Uploading session for recipient ${recipientId} to server...`);
+            await uploadSessions([
+                {
+                    recipientId,
+                    deviceId,
+                    encryptedData
+                }
+            ], syncToken);
+            console.log(`Successfully uploaded session for recipient ${recipientId} to server`);
+        } catch (error) {
+            console.error("Failed to sync session to server:", error);
+            // Don't throw - session is already stored in IndexedDB, sync failure shouldn't break anything
+        }
+    });
+    console.log("Session sync callback set successfully");
+}
+
+/**
+ * Clear session sync - called on logout
+ */
+export function clearSessionSync(): void {
+    syncUserId = null;
+    syncPassword = null;
+    syncToken = null;
+    setSessionSyncCallback(null);
+}
+
+/**
+ * Restore all sessions from server and populate IndexedDB
+ * Called after login when password is available
+ */
+export async function restoreSessionsFromServer(
+    userId: string,
+    password: string,
+    token: string
+): Promise<void> {
+    try {
+        console.log("Restoring sessions from server...");
+        
+        // Fetch encrypted sessions from server
+        const encryptedSessions = await fetchSessions(token);
+        
+        if (encryptedSessions.length === 0) {
+            console.log("No sessions to restore from server");
+            return; // No sessions to restore
+        }
+        
+        console.log(`Found ${encryptedSessions.length} sessions on server, restoring...`);
+        
+        const storage = new SignalProtocolStorage(userId);
+        
+        // Set restoring flag to prevent sync callback from re-uploading restored sessions
+        setRestoring(true);
+        
+        let restoredCount = 0;
+        let failedCount = 0;
+        
+        try {
+            // Decrypt and restore each session
+            for (const sessionData of encryptedSessions) {
+                try {
+                    const address = `${sessionData.recipientId}.${sessionData.deviceId}`;
+                    
+                    // Check if we already have a local session - if so, skip restoration
+                    // This prevents overwriting a newer session with an older one
+                    const existingSession = await storage.loadSession(address);
+                    if (existingSession) {
+                        console.log(`Skipping restoration for recipient ${sessionData.recipientId} - local session already exists`);
+                        continue;
+                    }
+                    
+                    const encryptedBlob = decodeSessionBlob(sessionData.encryptedData);
+                    const sessionRecord = await decryptSessionWithPassword(password, encryptedBlob);
+                    
+                    // Store in IndexedDB (sync callback won't fire because isRestoring is true)
+                    await storage.storeSession(address, sessionRecord);
+                    restoredCount++;
+                    console.log(`Restored session for recipient ${sessionData.recipientId}`);
+                } catch (error) {
+                    failedCount++;
+                    console.warn(`Failed to restore session for recipient ${sessionData.recipientId}:`, error);
+                    // Continue with other sessions
+                }
+            }
+        } finally {
+            // Always clear the restoring flag
+            setRestoring(false);
+        }
+        
+        console.log(`Restored ${restoredCount}/${encryptedSessions.length} sessions from server${failedCount > 0 ? ` (${failedCount} failed)` : ""}`);
+    } catch (error) {
+        console.error("Failed to restore sessions from server:", error);
+        // Don't throw - allow login to continue even if session restore fails
+    }
+}
+
+/**
+ * Upload all sessions to server
+ * Called after login/registration to backup all current sessions
+ */
+export async function uploadAllSessionsToServer(
+    userId: string,
+    password: string,
+    token: string
+): Promise<void> {
+    try {
+        console.log("Uploading sessions to server...");
+        
+        const storage = new SignalProtocolStorage(userId);
+        
+        // Get all sessions from IndexedDB
+        const sessions = await storage.getAllSessions();
+        
+        if (sessions.length === 0) {
+            console.log("No sessions in IndexedDB to upload");
+            return; // No sessions to upload
+        }
+        
+        console.log(`Found ${sessions.length} sessions in IndexedDB, uploading...`);
+        
+        // Encrypt and prepare sessions for upload
+        const sessionData: SessionData[] = [];
+        let failedCount = 0;
+        
+        for (const { address, record } of sessions) {
+            try {
+                // Parse address to get recipientId and deviceId
+                const parts = address.split(".");
+                const recipientId = parseInt(parts[0], 10);
+                const deviceId = parts.length > 1 ? parseInt(parts[1], 10) : 1;
+                
+                if (isNaN(recipientId)) {
+                    console.warn(`Invalid address format: ${address}`);
+                    failedCount++;
+                    continue;
+                }
+                
+                // Encrypt session record
+                const encryptedBlob = await encryptSessionWithPassword(password, record);
+                const encryptedData = encodeSessionBlob(encryptedBlob);
+                
+                sessionData.push({
+                    recipientId,
+                    deviceId,
+                    encryptedData
+                });
+            } catch (error) {
+                failedCount++;
+                console.warn(`Failed to encrypt session ${address}:`, error);
+                // Continue with other sessions
+            }
+        }
+        
+        if (sessionData.length > 0) {
+            await uploadSessions(sessionData, token);
+            console.log(`Uploaded ${sessionData.length} sessions to server${failedCount > 0 ? ` (${failedCount} failed)` : ""}`);
+        } else if (failedCount > 0) {
+            console.warn(`Failed to upload all ${sessions.length} sessions to server`);
+        }
+    } catch (error) {
+        console.error("Failed to upload sessions to server:", error);
+        // Don't throw - allow login to continue even if upload fails
+    }
+}
+
+/**
+ * Store a session in IndexedDB and upload to server
+ * This should be called instead of direct storage.storeSession when password is available
+ */
+export async function storeSessionWithSync(
+    userId: string,
+    address: string,
+    record: string,
+    password: string,
+    token: string
+): Promise<void> {
+    const storage = new SignalProtocolStorage(userId);
+    
+    // Store in IndexedDB first (for immediate use)
+    await storage.storeSession(address, record);
+    
+    // Parse address to get recipientId and deviceId
+    const parts = address.split(".");
+    const recipientId = parseInt(parts[0], 10);
+    const deviceId = parts.length > 1 ? parseInt(parts[1], 10) : 1;
+    
+    if (isNaN(recipientId)) {
+        console.warn(`Invalid address format: ${address}`);
+        return;
+    }
+    
+    // Encrypt and upload to server
+    try {
+        const encryptedBlob = await encryptSessionWithPassword(password, record);
+        const encryptedData = encodeSessionBlob(encryptedBlob);
+        
+        await uploadSessions([
+            {
+                recipientId,
+                deviceId,
+                encryptedData
+            }
+        ], token);
+    } catch (error) {
+        console.error("Failed to upload session to server:", error);
+        // Don't throw - session is still stored in IndexedDB
+    }
+}
+
+/**
+ * Remove a session from IndexedDB
+ * Note: We don't remove from server immediately because we need password for encryption.
+ * Stale sessions on server will be overwritten on next login when we upload all current sessions.
+ */
+export async function removeSessionLocal(
+    userId: string,
+    address: string
+): Promise<void> {
+    const storage = new SignalProtocolStorage(userId);
+    await storage.removeSession(address);
+}
+

frontend/src/utils/crypto/signalProtocol.ts

@@ -295,16 +295,17 @@ export class SignalProtocolService {
      * Encrypt a message for a recipient
      */
     async encryptMessage(recipientId: number, plaintext: string): Promise<{ type: number; body: string }> {
-        const address = new SignalProtocolAddress(recipientId.toString(), 1);
+        try {
+            const address = new SignalProtocolAddress(recipientId.toString(), 1);
 
-        const sessionCipher = new SessionCipher(this.storage, address);
+            const sessionCipher = new SessionCipher(this.storage, address);
-        const plaintextBuffer = toArrayBuffer(new TextEncoder().encode(plaintext).buffer);
+            const plaintextBuffer = toArrayBuffer(new TextEncoder().encode(plaintext).buffer);
-        const encryptResult = await sessionCipher.encrypt(plaintextBuffer);
+            const encryptResult = await sessionCipher.encrypt(plaintextBuffer);
-        const { type, body } = encryptResult;
+            const { type, body } = encryptResult;
 
-        if (!body) {
+            if (!body) {
-            throw new Error("Encryption failed: no body in ciphertext");
+                throw new Error("Encryption failed: no body in ciphertext");
-        }
+            }
 
         // The library returns body as ArrayBuffer or Uint8Array, we need to convert it to base64 string
         // Always convert to Uint8Array first, then to base64, regardless of input type
@@ -351,6 +352,16 @@ export class SignalProtocolService {
         }
 
         return { type, body: bodyBase64 };
+        } catch (error) {
+            // Log detailed error information for debugging
+            const errorMessage = error instanceof Error ? error.message : String(error);
+            console.error("Signal Protocol encryption failed:", {
+                recipientId,
+                plaintextLength: plaintext.length,
+                error: errorMessage
+            });
+            throw new Error(`Failed to encrypt message: ${errorMessage}`);
+        }
     }
 
     /**
@@ -412,8 +423,14 @@ export class SignalProtocolService {
                 } catch (resetError) {
                     console.error("Failed to remove session:", resetError);
                 }
-            } else if (errorMessage.includes("Tried to decrypt on a sending chain") || errorMessage.includes("No record for device")) {
+            } else if (
-                // These errors indicate the session state is corrupted or missing
+                errorMessage.includes("Tried to decrypt on a sending chain") || 
+                errorMessage.includes("No record for device") ||
+                errorMessage.includes("Message key not found") ||
+                errorMessage.includes("counter was repeated") ||
+                errorMessage.includes("key was not filled")
+            ) {
+                // These errors indicate the session state is corrupted, missing, or out of sync
                 // Remove the session so it can be re-established
                 console.warn(`Session state error for sender ${senderId}: ${errorMessage}. Removing session.`);
                 try {

frontend/src/utils/crypto/signalStorage.ts

@@ -46,7 +46,9 @@ function openDB(): Promise<IDBDatabase> {
                 db.createObjectStore("signedPreKeys", { keyPath: "userId" });
             }
 
-            // Sessions store: key = userId + deviceId, value = { userId, deviceId, record }
+            // Sessions store: key = userId + recipientId, value = { userId, recipientId, deviceId, record }
+            // Note: recipientId is stored in the deviceId field for backward compatibility
+            // The actual deviceId is always 1 for now
             if (!db.objectStoreNames.contains("sessions")) {
                 const sessionsStore = db.createObjectStore("sessions", { keyPath: ["userId", "deviceId"] });
                 sessionsStore.createIndex("userId", "userId", { unique: false });
@@ -115,6 +117,19 @@ function toUint8Array(ab: ArrayBuffer | Uint8Array): Uint8Array {
     return new Uint8Array(ab);
 }
 
+// Global session sync callback - set by sessionSync service
+let sessionSyncCallback: ((address: string, record: string) => Promise<void>) | null = null;
+// Flag to prevent sync callback during restoration (to avoid re-uploading restored sessions)
+let isRestoring = false;
+
+export function setSessionSyncCallback(callback: ((address: string, record: string) => Promise<void>) | null): void {
+    sessionSyncCallback = callback;
+}
+
+export function setRestoring(restoring: boolean): void {
+    isRestoring = restoring;
+}
+
 export class SignalProtocolStorage implements StorageType {
     private userId: string;
 
@@ -322,51 +337,142 @@ export class SignalProtocolStorage implements StorageType {
 
     // Session Management
     async loadSession(encodedAddress: string): Promise<string | undefined> {
-        // encodedAddress format: "userId.deviceId"
+        // encodedAddress format: "recipientId.deviceId" (from Signal Protocol)
+        // recipientId is the other user's ID, deviceId is always 1 for now
         const parts = encodedAddress.split(".");
-        const deviceId = parts.length > 1 ? parts[1] : encodedAddress;
+        const recipientId = parts[0]; // First part is the recipient's user ID
         
+        // Load using recipientId as the key (stored in deviceId field for backward compatibility)
+        // Ensure we search with string to match how we stored it
         const store = await getStore("sessions");
         const result = await new Promise<string | undefined>((resolve, reject) => {
-            const request = store.get([this.userId, deviceId]);
+            const request = store.get([this.userId, String(recipientId)]);
             request.onsuccess = () => {
                 const data = request.result;
-                resolve(data ? data.record : undefined);
+                if (data && data.record && typeof data.record === "string" && data.record.length > 0) {
+                    resolve(data.record);
+                } else {
+                    // Try with number if string didn't work (backward compatibility)
+                    if (!data && !isNaN(Number(recipientId))) {
+                        const numRequest = store.get([this.userId, Number(recipientId)]);
+                        numRequest.onsuccess = () => {
+                            const numData = numRequest.result;
+                            if (numData && numData.record && typeof numData.record === "string" && numData.record.length > 0) {
+                                resolve(numData.record);
+                            } else {
+                                console.warn(`Session record missing or invalid for recipient ${recipientId} (address: ${encodedAddress})`);
+                                resolve(undefined);
+                            }
+                        };
+                        numRequest.onerror = () => {
+                            console.warn(`Session record missing for recipient ${recipientId} (address: ${encodedAddress})`);
+                            resolve(undefined);
+                        };
+                    } else {
+                        console.warn(`Session record missing or invalid for recipient ${recipientId} (address: ${encodedAddress})`);
+                        resolve(undefined);
+                    }
+                }
+            };
+            request.onerror = () => {
+                console.error(`Failed to load session for recipient ${recipientId}:`, request.error);
+                reject(request.error);
             };
-            request.onerror = () => reject(request.error);
         });
 
         return result;
     }
 
     async storeSession(encodedAddress: string, record: string): Promise<void> {
-        // encodedAddress format: "userId.deviceId"
+        // encodedAddress format: "recipientId.deviceId" (from Signal Protocol)
+        // recipientId is the other user's ID, deviceId is always 1 for now
         const parts = encodedAddress.split(".");
-        const deviceId = parts.length > 1 ? parts[1] : encodedAddress;
+        const recipientId = parts[0]; // First part is the recipient's user ID
         
+        // Validate record
+        if (!record || typeof record !== "string" || record.length === 0) {
+            console.warn(`Invalid session record for address ${encodedAddress}`);
+            return;
+        }
+        
+        // Store with recipientId as the key (using deviceId field for backward compatibility)
+        // Ensure recipientId is stored as string to match how we load it
         const store = await getStore("sessions", "readwrite");
         await new Promise<void>((resolve, reject) => {
             const request = store.put({
                 userId: this.userId,
-                deviceId: deviceId,
+                deviceId: String(recipientId), // Store recipientId as string in deviceId field
                 record: record
             });
-            request.onsuccess = () => resolve();
+            request.onsuccess = () => {
+                resolve();
+                // If session sync callback is set and we're not restoring, upload to server in background (non-blocking)
+                // Do this AFTER resolve() to ensure storage completes even if sync fails
+                if (sessionSyncCallback && !isRestoring) {
+                    // Use setTimeout to make it truly async and non-blocking
+                    setTimeout(() => {
+                        sessionSyncCallback!(encodedAddress, record).then(() => {
+                            console.log(`Session synced to server for ${encodedAddress}`);
+                        }).catch(err => {
+                            console.error(`Failed to sync session to server for ${encodedAddress}:`, err);
+                        });
+                    }, 0);
+                }
+            };
             request.onerror = () => reject(request.error);
         });
     }
 
     async removeSession(encodedAddress: string): Promise<void> {
-        // encodedAddress format: "userId.deviceId"
+        // encodedAddress format: "recipientId.deviceId" (from Signal Protocol)
+        // recipientId is the other user's ID, deviceId is always 1 for now
         const parts = encodedAddress.split(".");
-        const deviceId = parts.length > 1 ? parts[1] : encodedAddress;
+        const recipientId = parts[0]; // First part is the recipient's user ID
         
+        // Remove using recipientId as the key (stored in deviceId field for backward compatibility)
         const store = await getStore("sessions", "readwrite");
         await new Promise<void>((resolve, reject) => {
-            const request = store.delete([this.userId, deviceId]);
+            const request = store.delete([this.userId, recipientId]);
             request.onsuccess = () => resolve();
             request.onerror = () => reject(request.error);
         });
     }
+
+    /**
+     * Get all sessions for this user
+     * Returns array of { address, record } where address is "recipientId.deviceId"
+     * Note: In IndexedDB, deviceId field actually stores the recipientId from the Signal Protocol address
+     */
+    async getAllSessions(): Promise<Array<{ address: string; record: string }>> {
+        const store = await getStore("sessions");
+        const sessions: Array<{ address: string; record: string }> = [];
+        
+        return new Promise((resolve, reject) => {
+            const request = store.index("userId").openCursor(IDBKeyRange.only(this.userId));
+            request.onsuccess = () => {
+                const cursor = request.result;
+                if (cursor) {
+                    const data = cursor.value;
+                    // In Signal Protocol, address format is "recipientId.deviceId"
+                    // We stored it with recipientId in the deviceId field (for backward compatibility)
+                    // The actual deviceId is always 1 for now
+                    const recipientId = data.deviceId; // This is actually the recipientId from the address
+                    const deviceId = 1; // Always 1 for now
+                    const address = `${recipientId}.${deviceId}`;
+                    
+                    // Validate that record exists and is a string
+                    if (data.record && typeof data.record === "string" && data.record.length > 0) {
+                        sessions.push({ address, record: data.record });
+                    } else {
+                        console.warn(`Invalid session record for recipient ${recipientId}:`, data);
+                    }
+                    cursor.continue();
+                } else {
+                    resolve(sessions);
+                }
+            };
+            request.onerror = () => reject(request.error);
+        });
+    }
 }