chore(mobile): phase 1 quality-review fixups

Three small follow-ups from the post-Phase-1 quality review:

  * authContext.tsx — drop the dead `userId` extraction + the `void
    userId` suppressor that masked an unused-locals warning. The session
    is already implicitly threaded through the supabase client, so no
    consumer of ensureDevice needed the value.
  * authContext.tsx — switch the device-name string concat to a
    template literal for consistency with the rest of the codebase.
  * ErrorBoundary.tsx — replace the four inline hex literals with their
    `theme/colors.ts` constants. The boundary was authored in Phase 0
    before the theme module existed; this brings it in line with every
    Phase 1 screen.
  * apps/mobile/README.md — drop the stale Phase-0 paragraph about the
    `lib/sharedSmoke.ts` canary (deleted in Phase 1) and add a short
    pointer to the env-var setup.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/mobile/README.md

@@ -55,16 +55,23 @@ pnpm mobile:typecheck    # tsc --noEmit
 ## Architecture notes
 
 - Expo Router (file-based) — screens live under `app/`.
-- `expo-secure-store` — Keychain / Keystore-backed secret store (used by
-  the mobile `SecretStore` adapter in Phase 1).
-- `expo-sqlite` — local encrypted history (Phase 1).
-- `react-native-libsodium` — crypto primitives (Phase 1's
-  `CryptoBackend` adapter wraps this).
-- `@chat-app/shared` — business logic shared with the desktop, including
-  the `CryptoBackend` and `SecretStore` interfaces the mobile adapters
-  plug into.
-- `lib/sharedSmoke.ts` exists only to prove Metro can resolve the
-  workspace package; it's deleted in Phase 1.
+- `expo-secure-store` — Keychain / Keystore-backed secret store, wrapped
+  by `lib/secretStore.ts` to implement `@chat-app/shared`'s `SecretStore`.
+- `@react-native-async-storage/async-storage` — Supabase session-token
+  storage, surfaced via `lib/sessionStorage.ts`.
+- `expo-sqlite` — local encrypted history (slated for a later phase).
+- `react-native-libsodium` — crypto primitives, wrapped by
+  `lib/cryptoBackend.ts` to implement `@chat-app/shared`'s `CryptoBackend`.
+  Registered once at boot in `app/_layout.tsx`.
+- `@chat-app/shared` — business logic shared with the desktop; the mobile
+  adapters plug into its `CryptoBackend` + `SecretStore` interfaces, and
+  every chat / auth call goes through the namespace exports.
+
+## Env vars
+
+Copy `.env.example` to `.env.local` and fill in the same Supabase host +
+anon key the desktop uses. Expo bundles only `EXPO_PUBLIC_*`-prefixed
+vars into the JS, which is what the three required values use.
 
 ## Roadmap
 

apps/mobile/components/ErrorBoundary.tsx

@@ -1,6 +1,8 @@
 import React from 'react';
 import { Pressable, StyleSheet, Text, View } from 'react-native';
 
+import { colors } from '../theme/colors';
+
 // Catch render errors anywhere below this boundary and show a readable
 // fallback. Without it, a thrown error during render produces a white
 // screen on TestFlight / production builds with no way for the user to
@@ -53,16 +55,16 @@ const styles = StyleSheet.create({
     flex: 1,
     alignItems: 'center',
     justifyContent: 'center',
-    backgroundColor: '#0b0b0f',
+    backgroundColor: colors.bg,
     padding: 24,
   },
-  title: { color: '#fff', fontSize: 22, fontWeight: '600', marginBottom: 8 },
-  message: { color: '#9ca3af', textAlign: 'center', marginBottom: 24 },
+  title: { color: colors.text, fontSize: 22, fontWeight: '600', marginBottom: 8 },
+  message: { color: colors.textMuted, textAlign: 'center', marginBottom: 24 },
   button: {
-    backgroundColor: '#5865f2',
+    backgroundColor: colors.accent,
     paddingHorizontal: 20,
     paddingVertical: 12,
     borderRadius: 10,
   },
-  buttonText: { color: '#fff', fontWeight: '600' },
+  buttonText: { color: colors.text, fontWeight: '600' },
 });

apps/mobile/lib/authContext.tsx

@@ -37,8 +37,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
 
   // Resolve or create the device record for this install given an active
   // session. Stores the private key in expo-secure-store on first run.
-  const ensureDevice = useCallback(async (currentSession: Session): Promise<void> => {
-    const userId = currentSession.user.id;
+  const ensureDevice = useCallback(async (_currentSession: Session): Promise<void> => {
     const savedDeviceId = await secretStore.getSecret(KEY_DEVICE_ID);
     const savedPrivKey = await secretStore.getSecret(KEY_DEVICE_PRIVKEY);
 
@@ -59,7 +58,7 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     const kp = backend.generateKeyPair();
     const platform = Platform.OS === 'ios' ? 'ios' : Platform.OS === 'android' ? 'android' : 'linux';
     const record = await auth.registerDevice(supabase, {
-      name: 'Netralax Mobile (' + Platform.OS + ')',
+      name: `Netralax Mobile (${Platform.OS})`,
       platform,
       publicKey: kp.publicKey,
     });
@@ -67,7 +66,6 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     await secretStore.setSecret(KEY_DEVICE_PRIVKEY, kp.privateKey);
     setDevice(record);
     setOwnPrivateKey(kp.privateKey);
-    void userId;
   }, []);
 
   useEffect(() => {