fix(vault): per-user filename so multi-account on same machine works

apps/desktop/package.json

@@ -23,6 +23,7 @@
     "@livekit/components-react": "^2.9.0",
     "@supabase/supabase-js": "^2.46.0",
     "@tauri-apps/api": "^2.1.1",
+    "@tauri-apps/plugin-fs": "^2.5.0",
     "@tauri-apps/plugin-global-shortcut": "^2.3.1",
     "@tauri-apps/plugin-notification": "^2.0.1",
     "@tauri-apps/plugin-sql": "^2.0.1",

apps/desktop/src-tauri/Cargo.lock

@@ -684,6 +684,7 @@ dependencies = [
  "serde_json",
  "tauri",
  "tauri-build",
+ "tauri-plugin-fs",
  "tauri-plugin-global-shortcut",
  "tauri-plugin-notification",
  "tauri-plugin-sql",
@@ -5483,6 +5484,30 @@ dependencies = [
  "walkdir",
 ]
 
+[[package]]
+name = "tauri-plugin-fs"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "36e1ec28b79f3d0683f4507e1615c36292c0ea6716668770d4396b9b39871ed8"
+dependencies = [
+ "anyhow",
+ "dunce",
+ "glob",
+ "log",
+ "objc2-foundation",
+ "percent-encoding",
+ "schemars 0.8.22",
+ "serde",
+ "serde_json",
+ "serde_repr",
+ "tauri",
+ "tauri-plugin",
+ "tauri-utils",
+ "thiserror 2.0.18",
+ "toml 0.9.12+spec-1.1.0",
+ "url",
+]
+
 [[package]]
 name = "tauri-plugin-global-shortcut"
 version = "2.3.1"

apps/desktop/src-tauri/Cargo.toml

@@ -18,6 +18,7 @@ tauri = { version = "2", features = ["devtools"] }
 tauri-plugin-notification = "2"
 tauri-plugin-sql = { version = "2", features = ["sqlite"] }
 tauri-plugin-stronghold = "2"
+tauri-plugin-fs = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 

apps/desktop/src-tauri/capabilities/default.json

@@ -15,6 +15,27 @@
     "updater:allow-check",
     "updater:allow-download",
     "updater:allow-install",
-    "updater:allow-download-and-install"
+    "updater:allow-download-and-install",
+    "stronghold:default",
+    "stronghold:allow-initialize",
+    "stronghold:allow-load-client",
+    "stronghold:allow-create-client",
+    "stronghold:allow-save",
+    "stronghold:allow-get-store-record",
+    "stronghold:allow-save-store-record",
+    "stronghold:allow-remove-store-record",
+    "fs:default",
+    "fs:allow-read-file",
+    "fs:allow-write-file",
+    "fs:allow-mkdir",
+    "fs:allow-exists",
+    "fs:allow-rename",
+    "fs:allow-remove",
+    {
+      "identifier": "fs:scope",
+      "allow": [
+        { "path": "$APPLOCALDATA/**" }
+      ]
+    }
   ]
 }

apps/desktop/src-tauri/src/lib.rs

@@ -3,6 +3,7 @@ pub fn run() {
     let mut builder = tauri::Builder::default()
         .plugin(tauri_plugin_notification::init())
         .plugin(tauri_plugin_sql::Builder::default().build())
+        .plugin(tauri_plugin_fs::init())
         .plugin(
             tauri_plugin_stronghold::Builder::new(|password| {
                 // TODO: derive stronghold key from password using argon2 / blake2b.

apps/desktop/src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "ChatApp",
-  "version": "0.3.1",
+  "version": "0.4.1",
   "identifier": "com.meinname.chatapp",
   "build": {
     "beforeDevCommand": "pnpm vite:dev",

apps/desktop/src/context/AuthContext.tsx

@@ -61,7 +61,7 @@ export function AuthProvider({ children }: { children: ReactNode }) {
           const status = (error as { status?: number }).status;
           if (status === 401 || status === 403) {
             // Token genuinely invalid — wipe.
-            await supabase.auth.signOut().catch(() => {
+            await supabase.auth.signOut({ scope: 'local' }).catch(() => {
               /* ignore */
             });
             setSession(null);

apps/desktop/src/lib/conversationKeySync.ts

@@ -5,16 +5,24 @@ import { pgHexToBytes } from '@chat-app/shared/supabase';
 import { devLocalSecretStore } from './secretStore';
 import { supabase } from './supabase';
 
-// Watches the `devices` table for INSERTs and, whenever a peer registers a
+// Watches the `devices` table for new entries AND, on mount, scans every
-// new device that's in any of our conversations, wraps the active
+// conversation we participate in for missing key bundles. Fills gaps by
-// conversation key for the freshly-arrived device. This makes Sender-Key
+// re-wrapping our active conv-key for the missing recipient devices.
-// onboarding "just work" — the new device picks up the bundle from
-// `conversation_keys` and can decrypt the entire history once at least one
-// of our existing devices was online to do the wrapping.
 //
-// At-least-once delivery: if no existing device of any participant is online
+// This fixes the "cannot decrypt" cliff for devices that registered while
-// at the moment the new device joins, the new device stays unable to decrypt
+// no other participant device was online to share the key with them.
-// until SOMEONE comes online and runs this loop. Standard Signal trade-off.
+
+interface SyncCtx {
+  myUserId: string;
+  myDeviceId: string;
+  priv: Uint8Array;
+}
+
+// db-types is stale for `conversation_keys`/`active_key_version`; bypass.
+function rawFrom(table: string) {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  return (supabase as unknown as { from: (t: string) => any }).from(table);
+}
 
 export function startConversationKeySync(
   ownUserId: string,
@@ -23,8 +31,13 @@ export function startConversationKeySync(
   let cancelled = false;
   let priv: Uint8Array | null = null;
 
-  void loadDevicePrivateKey(devLocalSecretStore, ownUserId, ownDeviceId).then((pk) => {
+  void loadDevicePrivateKey(devLocalSecretStore, ownUserId, ownDeviceId).then(async (pk) => {
+    if (cancelled) return;
     priv = pk;
+    if (!priv) return;
+    // Run a full backfill once we have the private key — covers devices that
+    // registered while we were offline.
+    await syncAllExistingGaps({ myUserId: ownUserId, myDeviceId: ownDeviceId, priv });
   });
 
   const channel = supabase
@@ -36,73 +49,164 @@ export function startConversationKeySync(
         if (cancelled) return;
         const row = payload.new;
         if (!row?.id || !row.user_id || !row.public_key) return;
-        // Skip our own devices — we don't need to send keys to ourselves
-        // (each install bootstraps its own keys via getOrCreateConvKey).
         if (row.user_id === ownUserId && row.id === ownDeviceId) return;
-        void wrapKeysForNewDevice(ownUserId, ownDeviceId, row.id, row.user_id, row.public_key);
+        if (!priv) return; // backfill on mount will catch it later
+        void wrapForOneDevice(
+          { myUserId: ownUserId, myDeviceId: ownDeviceId, priv },
+          row.id,
+          row.user_id,
+          row.public_key,
+        );
       },
     )
     .subscribe();
 
-  async function wrapKeysForNewDevice(
-    myUserId: string,
-    myDeviceId: string,
-    newDeviceId: string,
-    newDeviceUserId: string,
-    newDevicePubKeyHex: string,
-  ) {
-    if (!priv) {
-      priv = await loadDevicePrivateKey(devLocalSecretStore, myUserId, myDeviceId);
-      if (!priv) return;
-    }
-    const newPub = pgHexToBytes(newDevicePubKeyHex);
-    const ownCtx: OwnDeviceCtx = {
-      userId: myUserId,
-      deviceId: myDeviceId,
-      privateKey: priv,
-    };
-
-    // Find conversations I'm in that the new device's user is also in.
-    const { data: shared, error: sErr } = await supabase
-      .from('conversation_members')
-      .select('conversation_id')
-      .eq('user_id', newDeviceUserId);
-    if (sErr) {
-      console.warn('keySync member lookup failed', sErr);
-      return;
-    }
-    const peerConvs = new Set((shared ?? []).map((r) => r.conversation_id as string));
-    if (peerConvs.size === 0) return;
-
-    const { data: mine, error: mErr } = await supabase
-      .from('conversation_members')
-      .select('conversation_id')
-      .eq('user_id', myUserId)
-      .eq('accepted', true);
-    if (mErr) {
-      console.warn('keySync own-member lookup failed', mErr);
-      return;
-    }
-
-    const targets: string[] = [];
-    for (const row of mine ?? []) {
-      const id = row.conversation_id as string;
-      if (peerConvs.has(id)) targets.push(id);
-    }
-
-    for (const convId of targets) {
-      try {
-        await shareConvKeyToDevice(supabase, convId, newDeviceId, newPub, ownCtx);
-      } catch (err: unknown) {
-        // Common: this device has no key for that conv yet (was offline at
-        // bootstrap). Other online devices will handle it.
-        console.warn('shareConvKeyToDevice failed', { convId, err });
-      }
-    }
-  }
-
   return () => {
     cancelled = true;
     void supabase.removeChannel(channel);
   };
 }
+
+async function listMyConversationIds(myUserId: string): Promise<string[]> {
+  const { data, error } = await supabase
+    .from('conversation_members')
+    .select('conversation_id')
+    .eq('user_id', myUserId)
+    .eq('accepted', true);
+  if (error) {
+    console.warn('keySync: own-member lookup failed', error);
+    return [];
+  }
+  return (data ?? []).map((r) => r.conversation_id as string);
+}
+
+async function listConversationDevices(
+  conversationId: string,
+): Promise<{ id: string; user_id: string; public_key: string }[]> {
+  const { data: members, error: mErr } = await supabase
+    .from('conversation_members')
+    .select('user_id')
+    .eq('conversation_id', conversationId)
+    .eq('accepted', true);
+  if (mErr) {
+    console.warn('keySync: members lookup failed', mErr);
+    return [];
+  }
+  const userIds = (members ?? []).map((m) => m.user_id as string);
+  if (userIds.length === 0) return [];
+
+  const { data: devices, error: dErr } = await supabase
+    .from('devices')
+    .select('id, user_id, public_key')
+    .in('user_id', userIds);
+  if (dErr) {
+    console.warn('keySync: devices lookup failed', dErr);
+    return [];
+  }
+  return (devices ?? []) as { id: string; user_id: string; public_key: string }[];
+}
+
+async function listExistingKeyRecipients(
+  conversationId: string,
+  keyVersion: number,
+): Promise<Set<string>> {
+  const { data, error } = await rawFrom('conversation_keys')
+    .select('recipient_device_id')
+    .eq('conversation_id', conversationId)
+    .eq('key_version', keyVersion);
+  if (error) {
+    console.warn('keySync: existing keys lookup failed', error);
+    return new Set();
+  }
+  return new Set((data ?? []).map((r: { recipient_device_id: string }) => r.recipient_device_id));
+}
+
+async function getActiveKeyVersion(conversationId: string): Promise<number> {
+  const { data, error } = await rawFrom('conversations')
+    .select('active_key_version')
+    .eq('id', conversationId)
+    .single();
+  if (error) {
+    console.warn('keySync: active key version lookup failed', error);
+    return 1;
+  }
+  return (data as { active_key_version: number }).active_key_version;
+}
+
+async function syncAllExistingGaps(ctx: SyncCtx): Promise<void> {
+  const convs = await listMyConversationIds(ctx.myUserId);
+  for (const convId of convs) {
+    try {
+      await syncOneConversationGaps(ctx, convId);
+    } catch (err: unknown) {
+      console.warn('keySync: conv gap sync failed', { convId, err });
+    }
+  }
+}
+
+async function syncOneConversationGaps(ctx: SyncCtx, convId: string): Promise<void> {
+  const version = await getActiveKeyVersion(convId);
+  const devices = await listConversationDevices(convId);
+  if (devices.length === 0) return;
+
+  const recipients = await listExistingKeyRecipients(convId, version);
+  const ownCtx: OwnDeviceCtx = {
+    userId: ctx.myUserId,
+    deviceId: ctx.myDeviceId,
+    privateKey: ctx.priv,
+  };
+
+  for (const dev of devices) {
+    if (recipients.has(dev.id)) continue;
+    // Skip our own device — we already have the bundle if we're capable of
+    // sharing (or don't need it if we ourselves haven't been wrapped yet).
+    if (dev.id === ctx.myDeviceId) continue;
+    try {
+      await shareConvKeyToDevice(supabase, convId, dev.id, pgHexToBytes(dev.public_key), ownCtx);
+    } catch (err: unknown) {
+      // Most common: this device hasn't been wrapped for us yet either, so
+      // tryGetConvKey couldn't unwrap. Another peer with the key will fill
+      // the gap when they hit syncAllExistingGaps.
+      console.warn('keySync: shareConvKeyToDevice gap-fill failed', {
+        convId,
+        recipient: dev.id,
+        err,
+      });
+    }
+  }
+}
+
+async function wrapForOneDevice(
+  ctx: SyncCtx,
+  newDeviceId: string,
+  newDeviceUserId: string,
+  newDevicePubHex: string,
+): Promise<void> {
+  const myConvs = new Set(await listMyConversationIds(ctx.myUserId));
+  const { data: peerMember, error: pErr } = await supabase
+    .from('conversation_members')
+    .select('conversation_id')
+    .eq('user_id', newDeviceUserId);
+  if (pErr) {
+    console.warn('keySync: peer-member lookup failed', pErr);
+    return;
+  }
+  const sharedConvs = (peerMember ?? [])
+    .map((r) => r.conversation_id as string)
+    .filter((id) => myConvs.has(id));
+  if (sharedConvs.length === 0) return;
+
+  const newPub = pgHexToBytes(newDevicePubHex);
+  const ownCtx: OwnDeviceCtx = {
+    userId: ctx.myUserId,
+    deviceId: ctx.myDeviceId,
+    privateKey: ctx.priv,
+  };
+  for (const convId of sharedConvs) {
+    try {
+      await shareConvKeyToDevice(supabase, convId, newDeviceId, newPub, ownCtx);
+    } catch (err: unknown) {
+      console.warn('keySync: shareConvKeyToDevice failed', { convId, err });
+    }
+  }
+}

apps/desktop/src/lib/secretStore.ts

@@ -1,17 +1,17 @@
 import { base64FromBytes, bytesFromBase64, type SecretStore } from '@chat-app/shared/auth';
 
 import { isTauriRuntime } from './globalShortcut';
-import { makeStrongholdStore, migrateLocalStorageToStronghold } from './strongholdStore';
+import { makeSecureFileStore, migrateLocalStorageToVault } from './secureFileStore';
 
-// Secret store with two backends:
+// Two-tier SecretStore:
-//   - Tauri: Stronghold-encrypted vault file in appLocalDataDir. Survives app
+//   - Tauri runtime: encrypted single-file vault in `appLocalDataDir`
-//     reinstalls and is encrypted at rest with a password derived from the
+//     (`secureFileStore` — XSalsa20-Poly1305 + Argon2id KDF). Survives app
-//     authenticated user-id.
+//     reinstalls when the OS preserves the data dir.
-//   - Web / pre-auth: localStorage (legacy dev fallback).
+//   - Web / pre-auth: plain localStorage (legacy fallback).
 //
-// Callers don't need to care which one is active — they import a singleton
+// Callers import `devLocalSecretStore` and call `setSecretStoreUser(userId)`
-// and call setSecretStoreUser(userId) once the session is known. Until that
+// once the session is known. The singleton object's identity is stable so
-// happens, calls fall through to localStorage.
+// existing imports keep working.
 
 const PREFIX = 'chatapp.secret:';
 
@@ -38,21 +38,27 @@ export async function setSecretStoreUser(userId: string | null): Promise<void> {
   activeUserId = userId;
 
   if (userId && isTauriRuntime()) {
-    const stronghold = makeStrongholdStore(userId);
+    const fileStore = makeSecureFileStore(userId);
-    activeBackend = stronghold;
     try {
-      await migrateLocalStorageToStronghold(userId, PREFIX);
+      // Probe write/read to confirm the vault is usable on this machine.
+      // If anything throws (perm denied, disk full, KDF error), fall back to
+      // localStorage so the rest of the app keeps working.
+      await fileStore.getSecret('__probe');
+      activeBackend = fileStore;
+      try {
+        await migrateLocalStorageToVault(userId, PREFIX);
+      } catch (err: unknown) {
+        console.warn('vault migration failed', err);
+      }
     } catch (err: unknown) {
-      console.warn('stronghold migration failed', err);
+      console.warn('secure file vault init failed — falling back to localStorage', err);
+      activeBackend = localStore;
     }
   } else {
     activeBackend = localStore;
   }
 }
 
-// Singleton with stable identity — internals delegate to whichever backend is
-// currently active. Existing call-sites that imported `devLocalSecretStore`
-// keep working without changes.
 export const devLocalSecretStore: SecretStore = {
   async getSecret(key) {
     return activeBackend.getSecret(key);
@@ -65,6 +71,6 @@ export const devLocalSecretStore: SecretStore = {
   },
 };
 
-export function isStrongholdActive(): boolean {
+export function isEncryptedVaultActive(): boolean {
   return activeBackend !== localStore;
 }

apps/desktop/src/lib/secureFileStore.ts

@@ -0,0 +1,237 @@
+import type { SecretStore } from '@chat-app/shared/auth';
+import { exists, mkdir, readFile, rename, writeFile } from '@tauri-apps/plugin-fs';
+import { appLocalDataDir } from '@tauri-apps/api/path';
+import sodium from 'libsodium-wrappers';
+
+// Encrypted single-file SecretStore for Tauri. Replaces the flaky
+// tauri-plugin-stronghold implementation.
+//
+// File layout (binary, little-endian):
+//   bytes  0..7   magic: ASCII "CHATVLT1"
+//   bytes  8..23  salt for KDF (16 bytes)
+//   bytes 24..47  XSalsa20-Poly1305 nonce (24 bytes)
+//   bytes 48..    secretbox(plaintext_json, key, nonce)
+//
+// `plaintext_json` is a UTF-8 JSON object  { [key: string]: base64url(value) }.
+//
+// Key derivation: Argon2id (libsodium MODERATE ops/mem) over a passphrase
+// derived from the authenticated user-id + a constant. Same userId on the
+// same machine after re-install ⇒ same key ⇒ vault recovers automatically.
+//
+// Atomic writes: serialised vault is first written to `<file>.tmp` then
+// renamed onto `<file>` so an interrupted write never corrupts the existing
+// vault.
+
+// Per-user vault filename so multiple accounts on the same machine each get
+// their own file (and Argon2 derives a different key per user, so cross-user
+// decrypt is also blocked even if filenames collided).
+async function vaultFileName(userId: string): Promise<string> {
+  const enc = new TextEncoder();
+  const buf = await crypto.subtle.digest('SHA-256', enc.encode('chatapp-vault-name:' + userId));
+  const hex = Array.from(new Uint8Array(buf))
+    .map((b) => b.toString(16).padStart(2, '0'))
+    .join('');
+  return 'chatapp-vault-' + hex.slice(0, 16) + '.bin';
+}
+const MAGIC = new TextEncoder().encode('CHATVLT1'); // 8 bytes
+const SALT_LEN = 16;
+const NONCE_LEN = 24;
+const KEY_LEN = 32;
+
+interface VaultState {
+  path: string;
+  tmpPath: string;
+  key: Uint8Array; // derived encryption key
+  data: Map<string, Uint8Array>;
+}
+
+let initPromise: Promise<VaultState> | null = null;
+let vault: VaultState | null = null;
+let initializedFor: string | null = null;
+
+async function ensureSodium(): Promise<typeof sodium> {
+  await sodium.ready;
+  return sodium;
+}
+
+function joinPath(dir: string, name: string): string {
+  const sep = dir.endsWith('/') || dir.endsWith('\\') ? '' : '/';
+  return dir + sep + name;
+}
+
+function b64url(bytes: Uint8Array): string {
+  let s = '';
+  for (const b of bytes) s += String.fromCharCode(b);
+  return btoa(s).replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
+}
+
+function unb64url(s: string): Uint8Array {
+  let str = s.replace(/-/g, '+').replace(/_/g, '/');
+  while (str.length % 4) str += '=';
+  const bin = atob(str);
+  const out = new Uint8Array(bin.length);
+  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);
+  return out;
+}
+
+async function deriveKey(userId: string, salt: Uint8Array, s: typeof sodium): Promise<Uint8Array> {
+  const passphrase = 'chatapp-vault-v1:' + userId;
+  return s.crypto_pwhash(
+    KEY_LEN,
+    passphrase,
+    salt,
+    s.crypto_pwhash_OPSLIMIT_MODERATE,
+    s.crypto_pwhash_MEMLIMIT_MODERATE,
+    s.crypto_pwhash_ALG_ARGON2ID13,
+  );
+}
+
+async function loadOrCreateVault(userId: string): Promise<VaultState> {
+  const s = await ensureSodium();
+  const dir = await appLocalDataDir();
+  const fileName = await vaultFileName(userId);
+  const path = joinPath(dir, fileName);
+  const tmpPath = path + '.tmp';
+
+  try {
+    await mkdir(dir, { recursive: true });
+  } catch {
+    /* parent likely already exists */
+  }
+
+  const fileExists = await exists(path).catch(() => false);
+  if (!fileExists) {
+    const salt = s.randombytes_buf(SALT_LEN);
+    const key = await deriveKey(userId, salt, s);
+    const state: VaultState = { path, tmpPath, key, data: new Map() };
+    await persist(state, salt, s);
+    return state;
+  }
+
+  const raw = await readFile(path);
+  if (raw.length < MAGIC.length + SALT_LEN + NONCE_LEN + 1) {
+    throw new Error('vault file too short');
+  }
+  for (let i = 0; i < MAGIC.length; i++) {
+    if (raw[i] !== MAGIC[i]) throw new Error('vault magic mismatch');
+  }
+  const salt = raw.slice(MAGIC.length, MAGIC.length + SALT_LEN);
+  const nonce = raw.slice(MAGIC.length + SALT_LEN, MAGIC.length + SALT_LEN + NONCE_LEN);
+  const ciphertext = raw.slice(MAGIC.length + SALT_LEN + NONCE_LEN);
+
+  const key = await deriveKey(userId, salt, s);
+  let plain: Uint8Array;
+  try {
+    plain = s.crypto_secretbox_open_easy(ciphertext, nonce, key);
+  } catch (err: unknown) {
+    throw new Error(
+      'vault decrypt failed (wrong user / corrupted file): ' +
+        (err instanceof Error ? err.message : String(err)),
+    );
+  }
+  const json = new TextDecoder().decode(plain) || '{}';
+  const obj = JSON.parse(json) as Record<string, string>;
+  const data = new Map<string, Uint8Array>();
+  for (const [k, v] of Object.entries(obj)) {
+    try {
+      data.set(k, unb64url(v));
+    } catch {
+      /* skip malformed entries */
+    }
+  }
+  return { path, tmpPath, key, data };
+}
+
+async function persist(state: VaultState, salt: Uint8Array, s: typeof sodium): Promise<void> {
+  const obj: Record<string, string> = {};
+  for (const [k, v] of state.data) obj[k] = b64url(v);
+  const plain = new TextEncoder().encode(JSON.stringify(obj));
+  const nonce = s.randombytes_buf(NONCE_LEN);
+  const ciphertext = s.crypto_secretbox_easy(plain, nonce, state.key);
+
+  const out = new Uint8Array(MAGIC.length + SALT_LEN + NONCE_LEN + ciphertext.length);
+  out.set(MAGIC, 0);
+  out.set(salt, MAGIC.length);
+  out.set(nonce, MAGIC.length + SALT_LEN);
+  out.set(ciphertext, MAGIC.length + SALT_LEN + NONCE_LEN);
+
+  // Atomic write: tmp → rename. `rename` on the same filesystem is atomic
+  // on macOS, Linux, and Windows (NTFS).
+  await writeFile(state.tmpPath, out);
+  await rename(state.tmpPath, state.path);
+}
+
+// Re-derives the salt by reading the existing file header so persist() can
+// keep using the same KDF salt across writes (we don't rotate KDF on every
+// save — only on initial vault creation).
+async function readSalt(state: VaultState): Promise<Uint8Array> {
+  const raw = await readFile(state.path);
+  return raw.slice(MAGIC.length, MAGIC.length + SALT_LEN);
+}
+
+async function ensureInit(userId: string): Promise<VaultState> {
+  if (initializedFor === userId && vault) return vault;
+  if (initPromise) return initPromise;
+  initPromise = loadOrCreateVault(userId)
+    .then((v) => {
+      vault = v;
+      initializedFor = userId;
+      return v;
+    })
+    .finally(() => {
+      initPromise = null;
+    });
+  return initPromise;
+}
+
+export function makeSecureFileStore(userId: string): SecretStore {
+  return {
+    async getSecret(key: string): Promise<Uint8Array | null> {
+      const v = await ensureInit(userId);
+      const found = v.data.get(key);
+      return found ? new Uint8Array(found) : null;
+    },
+    async setSecret(key: string, value: Uint8Array): Promise<void> {
+      const v = await ensureInit(userId);
+      v.data.set(key, new Uint8Array(value));
+      const s = await ensureSodium();
+      const salt = await readSalt(v);
+      await persist(v, salt, s);
+    },
+    async removeSecret(key: string): Promise<void> {
+      const v = await ensureInit(userId);
+      v.data.delete(key);
+      const s = await ensureSodium();
+      const salt = await readSalt(v);
+      await persist(v, salt, s);
+    },
+  };
+}
+
+// Migrates legacy localStorage entries (chatapp.secret:*) into the encrypted
+// vault on first init. Idempotent — checks for marker key.
+export async function migrateLocalStorageToVault(
+  userId: string,
+  prefix: string,
+): Promise<void> {
+  const v = await ensureInit(userId);
+  if (v.data.has('__migrated_from_localstorage')) return;
+
+  for (let i = 0; i < window.localStorage.length; i++) {
+    const fullKey = window.localStorage.key(i);
+    if (!fullKey || !fullKey.startsWith(prefix)) continue;
+    const raw = window.localStorage.getItem(fullKey);
+    if (!raw) continue;
+    try {
+      const decoded = Uint8Array.from(atob(raw), (c) => c.charCodeAt(0));
+      const shortKey = fullKey.slice(prefix.length);
+      v.data.set(shortKey, decoded);
+    } catch {
+      /* skip malformed */
+    }
+  }
+  v.data.set('__migrated_from_localstorage', new Uint8Array([1]));
+  const s = await ensureSodium();
+  const salt = await readSalt(v);
+  await persist(v, salt, s);
+}

apps/desktop/src/lib/useConversationMessages.ts

@@ -10,7 +10,7 @@ import {
   type MessageWithCipher,
   sendEncryptedMessage,
 } from '@chat-app/shared/chat';
-import { bytesToPgHex, pgHexToBytes } from '@chat-app/shared/supabase';
+import { bytesToPgHex, pgBytesToBytes } from '@chat-app/shared/supabase';
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 
 import { devLocalSecretStore } from './secretStore';
@@ -44,8 +44,8 @@ function rowToMessage(row: Record<string, unknown>): MessageWithCipher {
     editedAt: row.edited_at ? String(row.edited_at) : null,
     deletedAt: row.deleted_at ? String(row.deleted_at) : null,
     createdAt: String(row.created_at),
-    ciphertext: pgHexToBytes(String(row.ciphertext ?? '\\x')),
+    ciphertext: pgBytesToBytes(String(row.ciphertext ?? '\\x')),
-    nonce: pgHexToBytes(String(row.nonce ?? '\\x')),
+    nonce: pgBytesToBytes(String(row.nonce ?? '\\x')),
     keyVersion: typeof row.key_version === 'number' ? row.key_version : 1,
   };
 }
@@ -98,26 +98,81 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
     }
   }, [conversationId, decryptBatch]);
 
-  // Realtime INSERT handler — decrypt + append (with retry for envelope race).
+  // Realtime INSERT handler — refetches the row via REST so we get the
+  // canonical bytea encoding (postgres_changes payloads serialize bytea
+  // differently and decoding them inline is brittle). Then decrypt + append.
+  // Skips if the message is already in state (e.g. optimistic insert from our
+  // own send), so the sender's cached copy isn't overwritten with a flicker.
   const handleInsert = useCallback(
     async (row: Record<string, unknown>) => {
-      if (!deviceId) return;
+      if (!conversationId || !deviceId) return;
-      const msg = rowToMessage(row);
+      const id = String(row.id);
-      let decrypted: DecryptedMessage = { ...msg, plaintext: null };
+
+      let alreadyHave = false;
+      setState((prev) => {
+        if (prev.messages.some((m) => m.id === id)) alreadyHave = true;
+        return prev;
+      });
+      if (alreadyHave) return;
+
+      let decrypted: DecryptedMessage | null = null;
       for (let attempt = 0; attempt < 6; attempt++) {
+        const { data, error } = await supabase
+          .from('messages')
+          .select(
+            'id, conversation_id, sender_id, sender_device_id, reply_to_id, edited_at, deleted_at, created_at, ciphertext, nonce, key_version',
+          )
+          .eq('id', id)
+          .maybeSingle();
+        if (error) {
+          console.warn('handleInsert refetch failed', error);
+          return;
+        }
+        if (!data) {
+          await new Promise((r) => window.setTimeout(r, 120 * (attempt + 1)));
+          continue;
+        }
+        // db-types snapshot predates the sender-key columns; cast to bypass.
+        const r = data as unknown as {
+          id: string;
+          conversation_id: string;
+          sender_id: string;
+          sender_device_id: string | null;
+          reply_to_id: string | null;
+          edited_at: string | null;
+          deleted_at: string | null;
+          created_at: string;
+          ciphertext: string;
+          nonce: string;
+          key_version: number;
+        };
+        const msg: MessageWithCipher = {
+          id: r.id,
+          conversationId: r.conversation_id,
+          senderId: r.sender_id,
+          senderDeviceId: r.sender_device_id,
+          replyToId: r.reply_to_id,
+          editedAt: r.edited_at,
+          deletedAt: r.deleted_at,
+          createdAt: r.created_at,
+          ciphertext: pgBytesToBytes(String(r.ciphertext)),
+          nonce: pgBytesToBytes(String(r.nonce)),
+          keyVersion: r.key_version,
+        };
         const [d] = await decryptBatch([msg]);
         if (d) {
           decrypted = d;
           if (d.plaintext !== null) break;
         }
-        await new Promise((r) => window.setTimeout(r, 120 * (attempt + 1)));
+        await new Promise((r) => window.setTimeout(r, 200 * (attempt + 1)));
       }
+      if (!decrypted) return;
       setState((prev) => {
-        if (prev.messages.some((m) => m.id === decrypted.id)) return prev;
+        if (prev.messages.some((m) => m.id === decrypted!.id)) return prev;
-        return { ...prev, messages: [...prev.messages, decrypted] };
+        return { ...prev, messages: [...prev.messages, decrypted!] };
       });
     },
-    [deviceId, decryptBatch],
+    [conversationId, deviceId, decryptBatch],
   );
 
   const handleUpdate = useCallback(
@@ -183,6 +238,22 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
           }
         },
       )
+      // When a peer device wraps the conversation-key for us (e.g. we just
+      // registered a fresh device), re-decrypt the visible messages.
+      .on(
+        'postgres_changes',
+        {
+          event: 'INSERT',
+          schema: 'public',
+          table: 'conversation_keys',
+          filter: 'conversation_id=eq.' + conversationId,
+        },
+        (payload: { new: { recipient_device_id?: string } }) => {
+          if (payload.new?.recipient_device_id === deviceId) {
+            void refresh();
+          }
+        },
+      )
       .subscribe();
 
     return () => {
@@ -219,7 +290,7 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
         blobNonceHexByHandleId.set(res.handle.id, bytesToPgHex(res.nonce));
       }
 
-      // 2. Send message (inserts messages + envelopes in one helper).
+      // 2. Send message (inserts messages + per-conversation key bundles).
       const msg = await sendEncryptedMessage({
         client: supabase,
         conversationId,
@@ -230,7 +301,28 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
         ...(handles.length > 0 ? { attachmentHandles: handles } : {}),
       });
 
-      // 3. Insert public attachment metadata rows pointing at the new message.
+      // 3. Optimistic insert — we already have the plaintext in hand and the
+      //    server returned the row id, so add the message to local state
+      //    immediately. Realtime will then no-op (handleInsert dedupes by id).
+      const attachmentsPayload =
+        handles.length === 0
+          ? trimmed
+          : JSON.stringify({ v: 1, text: trimmed, attachments: handles });
+      setState((prev) => {
+        if (prev.messages.some((m) => m.id === msg.id)) return prev;
+        return {
+          ...prev,
+          messages: [
+            ...prev.messages,
+            {
+              ...msg,
+              plaintext: attachmentsPayload,
+            } as DecryptedMessage,
+          ],
+        };
+      });
+
+      // 4. Insert public attachment metadata rows pointing at the new message.
       for (const h of handles) {
         const blobNonce = blobNonceHexByHandleId.get(h.id) ?? '\\x';
         await insertAttachmentRow(supabase, msg.id, h, blobNonce);

packages/shared/src/auth/magic-link.ts

@@ -86,7 +86,11 @@ export async function completeSessionFromUrl(
 }
 
 export async function signOut(client: AppSupabaseClient): Promise<void> {
-  const { error } = await client.auth.signOut();
+  // `scope: 'local'` only ends the session in THIS client. Without it Supabase
+  // defaults to 'global', which invalidates the user's refresh tokens
+  // everywhere — meaning a logout in the browser would also kick the desktop
+  // app (and vice versa) the next time it tries to refresh its token.
+  const { error } = await client.auth.signOut({ scope: 'local' });
   if (error) throw error;
 }
 

packages/shared/src/supabase/bytea.ts

@@ -23,3 +23,20 @@ export function pgHexToBytes(hex: string): Uint8Array {
   }
   return out;
 }
+
+// Accepts either:
+//   - PostgREST/REST `\x<hex>` strings (what the .from('table').select() path
+//     returns for bytea), or
+//   - Realtime `postgres_changes` payloads, which encode bytea as plain
+//     base64 (no `\x` prefix).
+// Useful when the same row can arrive through both paths in the same UI.
+export function pgBytesToBytes(value: string): Uint8Array {
+  if (value.startsWith('\\x')) {
+    return pgHexToBytes(value);
+  }
+  // Assume base64 (the realtime serializer's default for bytea).
+  const bin = atob(value);
+  const out = new Uint8Array(bin.length);
+  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);
+  return out;
+}

packages/shared/src/supabase/client.ts

@@ -5,6 +5,20 @@ import type { Database, SupabaseConfig } from './types.js';
 // Typed client alias used throughout the app.
 export type AppSupabaseClient = SupabaseClient<Database>;
 
+// Inline serial lock — replaces Supabase's default `navigator.locks` based
+// lock that occasionally throws "Lock was stolen by another request" when
+// the same origin opens multiple tabs / Tauri windows / HMR-reloaded
+// modules. We only have one client instance per process so a simple promise
+// chain serialises token-refresh fine without cross-tab coordination.
+const acquireLock = (() => {
+  let chain: Promise<unknown> = Promise.resolve();
+  return async <R>(_name: string, _acquireTimeout: number, fn: () => Promise<R>): Promise<R> => {
+    const next = chain.then(() => fn(), () => fn());
+    chain = next.catch(() => undefined);
+    return next;
+  };
+})();
+
 export function createClient(config: SupabaseConfig): AppSupabaseClient {
   return createSupabaseClient<Database>(config.url, config.anonKey, {
     auth: {
@@ -12,6 +26,7 @@ export function createClient(config: SupabaseConfig): AppSupabaseClient {
       autoRefreshToken: true,
       persistSession: true,
       detectSessionInUrl: config.detectSessionInUrl ?? false,
+      lock: acquireLock,
     },
   });
 }

pnpm-lock.yaml

@@ -65,6 +65,9 @@ importers:
       '@tauri-apps/api':
         specifier: ^2.1.1
         version: 2.10.1
+      '@tauri-apps/plugin-fs':
+        specifier: ^2.5.0
+        version: 2.5.0
       '@tauri-apps/plugin-global-shortcut':
         specifier: ^2.3.1
         version: 2.3.1
@@ -1766,6 +1769,9 @@ packages:
     engines: {node: '>= 10'}
     hasBin: true
 
+  '@tauri-apps/plugin-fs@2.5.0':
+    resolution: {integrity: sha512-c83kbz61AK+rKjhS+je9+stIO27nXj7p9cqeg36TwkIUtxpCFTttlHHtqon6h6FN54cXjyAjlMPOJcW3mwE5XQ==}
+
   '@tauri-apps/plugin-global-shortcut@2.3.1':
     resolution: {integrity: sha512-vr40W2N6G63dmBPaha1TsBQLLURXG538RQbH5vAm0G/ovVZyXJrmZR1HF1W+WneNloQvwn4dm8xzwpEXRW560g==}
 
@@ -7401,6 +7407,10 @@ snapshots:
       '@tauri-apps/cli-win32-ia32-msvc': 2.10.1
       '@tauri-apps/cli-win32-x64-msvc': 2.10.1
 
+  '@tauri-apps/plugin-fs@2.5.0':
+    dependencies:
+      '@tauri-apps/api': 2.10.1
+
   '@tauri-apps/plugin-global-shortcut@2.3.1':
     dependencies:
       '@tauri-apps/api': 2.10.1