Cometchat Native Core

Purpose

This is the foundational skill for every CometChat React Native UI Kit v5 integration. It teaches Claude HOW CometChat works on RN — initialization order, provider wrapper chain, login, env vars, auth tokens, and the anti-patterns that break real apps.

Read this skill first, before any framework (`cometchat-native-expo-patterns` / `cometchat-native-bare-patterns`) or placement skill.

Ground-truth sources: docs/ui-kit/react-native/overview.mdx, react-native-cli-integration.mdx, expo-integration.mdx, methods.mdx, and @cometchat/chat-uikit-react-native@5.3.3's src/index.ts.

---

1. The init-login-render order

CometChat has exactly one valid lifecycle on React Native:

CometChatUIKit.init(settings)   →   CometChatUIKit.login({ uid })   →   render <CometChat*> components

Breaking this order produces a blank screen, a "CometChat is not initialized" runtime error, or a hung login. No exceptions.

UIKitSettings — the init object

The v5 RN UI Kit's init() takes a flat UIKitSettings object (NOT a UIKitSettingsBuilder like the web kit). Pass fields directly:

import { CometChatUIKit } from "@cometchat/chat-uikit-react-native";

await CometChatUIKit.init({
  appId: APP_ID,                  // Required — from the CometChat dashboard
  region: REGION,                 // Required — "us" | "eu" | "in"
  authKey: AUTH_KEY,              // Required for dev mode. Omit in production.
  subscriptionType: "ALL_USERS",  // Optional — "NONE" | "ALL_USERS" | "ROLES" | "FRIENDS"
});

⚠️ `UIKitSettingsBuilder` does NOT exist in the v5 React Native UI Kit. That's a web-kit pattern. RN expects the flat object. If an agent imports UIKitSettingsBuilder from @cometchat/chat-uikit-react-native, the import resolves to undefined and new UIKitSettingsBuilder() throws at runtime.

Other valid UIKitSettings fields (all optional): autoEstablishSocketConnection, overrideAdminHost, overrideClientHost, disableCalling, extensions, roles, callingExtension. The full type is exported from the package as UIKitSettings; check the installed kit's type defs (node_modules/@cometchat/chat-uikit-react-native) if you need the exact shape.

Init must happen once

Use a module-level flag to prevent double-init. React re-mounts in dev (strict mode, fast refresh, and navigation nesting all trigger effect re-fires):

let initialized = false;

async function initCometChat(): Promise<void> {
  if (initialized) return;
  initialized = true;

  await CometChatUIKit.init({
    appId: APP_ID,
    region: REGION,
    authKey: AUTH_KEY,
    subscriptionType: "ALL_USERS",
  });
}

Init must run before first render

Put the init call in a top-level useEffect (preferred — the provider pattern in section 6 does this) or in App.tsx before the initial navigator mounts. Avoid calling init() in a screen's effect — by the time the screen mounts, the app has already tried to render components that expect init to be done.

---

2. Login

Development mode

let user;
try {
  user = await CometChatUIKit.getLoggedInUser();
} catch (e: any) {
  if (e?.code !== "NOT_FOUND") throw e;   // no-session is the expected "first run" path
}
if (!user) {
  await CometChatUIKit.login({ uid: "cometchat-uid-1" });  // note: OBJECT form
}

⚠️ `getLoggedInUser()` THROWS `code: "NOT_FOUND"` when there's no session — it does NOT return null. An uncaught throw here is the #1 cause of "app stuck on splash screen" — the provider's setReady(true) never fires. Always wrap in try/catch and treat NOT_FOUND as the normal first-run path. (Validated on @cometchat/chat-uikit-react-native@5.3.5, kit source CometChatUIKit.getLoggedInUser.)

⚠️ `login()` takes an object `{ uid: "..." }` on React Native, not a bare string like on the web. Passing "cometchat-uid-1" directly silently fails.

Every new CometChat app ships 5 pre-seeded test users — cometchat-uid-1 through cometchat-uid-5. Use one for development.

⚠️ login() is safe sequentially, NOT concurrently

A second login() call fired while the first is in-flight throws "Please wait until the previous login request ends." Classic trap in React Native because:

• React strict mode double-mounts effects
• react-navigation remounts screens on tab switches
• Fast Refresh triggers effect re-runs in dev

Guard with a module-level in-flight promise, same pattern as the web skill:

let loginInFlight: Promise<unknown> | null = null;

async function ensureLoggedIn(uid: string, authToken?: string): Promise<void> {
  let existing;
  try {
    existing = await CometChatUIKit.getLoggedInUser();
  } catch (e: any) {
    if (e?.code !== "NOT_FOUND") throw e;   // first-run path
  }
  if (existing) return;
  if (loginInFlight) {
    await loginInFlight;   // reuse the pending promise
    return;
  }
  loginInFlight = authToken
    ? CometChatUIKit.login({ authToken })
    : CometChatUIKit.login({ uid });
  try {
    await loginInFlight;
  } finally {
    loginInFlight = null;
  }
}

Call ensureLoggedIn() from the provider / effect. Both mounts resolve against the same promise; only one login request hits the server.

Production mode

Use CometChatUIKit.login({ authToken }) with a token from your backend. The backend generates the token with the CometChat REST API using the server-only REST API Key (not the client-side Auth Key). See cometchat-native-production for the server-side token endpoint patterns.

Logout

await CometChatUIKit.logout();

Clears the local CometChat session. Call from your app's sign-out handler.

---

3. Provider wrapper chain (mandatory order)

Every CometChat RN app has this wrapper chain at the root. Missing wrappers cause silent layout breakage, broken gestures, or hard crashes — each wrapper is required by a specific RN ecosystem piece the UI Kit depends on.

// App.tsx (bare) or the root of your Expo app
import "react-native-gesture-handler";   // MUST be the first import
import { GestureHandlerRootView } from "react-native-gesture-handler";
import { SafeAreaProvider } from "react-native-safe-area-context";
import { CometChatThemeProvider } from "@cometchat/chat-uikit-react-native";

export default function App() {
  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <SafeAreaProvider>
        <CometChatThemeProvider>
          <CometChatProvider>    {/* your own init/login provider — see section 6 */}
            <AppNavigator />
          </CometChatProvider>
        </CometChatThemeProvider>
      </SafeAreaProvider>
    </GestureHandlerRootView>
  );
}

Why each wrapper is mandatory:

The cometchat-native-expo-patterns and cometchat-native-bare-patterns skills show framework-specific nuances (Expo adds expo-splash-screen, bare adds pod setup), but the four-wrapper chain is fixed.

Recommended: include `<CometChatI18nProvider>` as a fifth wrapper. The kit's own SampleApp + SampleAppExpo always wrap <CometChatI18nProvider> between SafeAreaProvider and CometChatThemeProvider — even when the app is English-only. It's a no-op for default-locale apps and the wiring is identical to the other wrappers, so add it by default. The four-wrapper minimum is the strict floor; the five-wrapper shape is what every shipped sample uses. See cometchat-native-theming § 9 for the full chain (gesture → safe-area → i18n → theme → provider) and localization config.

---

4. Environment variables

Values to set

Where they live

• Bare RN: .env at project root + a runtime reader like react-native-config or babel-plugin-dotenv-import. Access: Config.APP_ID.
• Expo managed: app.json extra section + read via Constants.expoConfig?.extra?.APP_ID from expo-constants. Or use .env with expo-dotenv / expo-router's built-in support depending on SDK version. The cometchat-native-expo-patterns skill covers this in detail.

Do NOT bundle the REST_API_KEY into the client — RN bundles everything visible. Server endpoints live outside the RN app (Express / Hono / Cloud Functions); see cometchat-native-production.

.env / extra example

# client-side (safe to ship in the RN bundle for dev mode)
APP_ID=your_app_id
REGION=us
AUTH_KEY=your_auth_key

# server-only (NEVER ship — used by your token endpoint)
# REST_API_KEY=your_rest_api_key

---

5. Android + iOS platform notes

The UI Kit is cross-platform, but a few concerns only apply to one target:

The framework skills (cometchat-native-expo-patterns, cometchat-native-bare-patterns) apply these platform settings with the right syntax for each workflow.

---

6. Provider pattern

Instead of inlining init + login in every component, create a reusable CometChatProvider that gates rendering on isReady. Drop it below <CometChatThemeProvider> in the wrapper chain.

// CometChatProvider.tsx
import React, { createContext, useContext, useEffect, useState, type ReactNode } from "react";
import { CometChatUIKit } from "@cometchat/chat-uikit-react-native";

interface CometChatContextValue {
  isReady: boolean;
  error: string | null;
}

const CometChatContext = createContext<CometChatContextValue>({
  isReady: false,
  error: null,
});

export const useCometChat = () => useContext(CometChatContext);

// Module-level state — shared across all mounts
let initialized = false;
let loginInFlight: Promise<unknown> | null = null;

async function ensureLoggedIn(uid: string, authToken?: string): Promise<void> {
  let existing;
  try {
    existing = await CometChatUIKit.getLoggedInUser();
  } catch (e: any) {
    if (e?.code !== "NOT_FOUND") throw e;   // first-run path
  }
  if (existing) return;
  if (loginInFlight) {
    await loginInFlight;
    return;
  }
  loginInFlight = authToken
    ? CometChatUIKit.login({ authToken })
    : CometChatUIKit.login({ uid });
  try {
    await loginInFlight;
  } finally {
    loginInFlight = null;
  }
}

interface CometChatProviderProps {
  appId: string;
  region: string;
  authKey?: string;
  authToken?: string;
  uid?: string;
  children: ReactNode;
}

export function CometChatProvider({
  appId,
  region,
  authKey,
  authToken,
  uid = "cometchat-uid-1",
  children,
}: CometChatProviderProps) {
  const [isReady, setIsReady] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    async function setup() {
      try {
        if (!initialized) {
          initialized = true;
          await CometChatUIKit.init({
            appId,
            region,
            authKey,
            subscriptionType: "ALL_USERS",
          });
        }
        await ensureLoggedIn(uid, authToken);
        setIsReady(true);
      } catch (e) {
        setError(String(e));
      }
    }
    setup();
  }, [appId, region, authKey, authToken, uid]);

  if (error) {
    return null;  // or your app's error boundary — don't render CometChat components
  }
  if (!isReady) {
    return null;  // or a splash / loading screen
  }

  return (
    <CometChatContext.Provider value={{ isReady, error }}>
      {children}
    </CometChatContext.Provider>
  );
}

Children of <CometChatProvider> can use useCometChat() to check isReady — useful if some UI wants to render before chat is ready.

---

7. Anti-patterns

1. Do NOT call `CometChatUIKit.init()` during render. Init is async with side effects; calling during render triggers infinite re-renders. Always inside useEffect or before createRoot equivalent.

2. Do NOT call `login("uid")` with a string. RN's login() expects an object: login({ uid: "..." }). Passing a string silently no-ops.

3. Do NOT skip the four-wrapper chain (GestureHandlerRootView → SafeAreaProvider → CometChatThemeProvider → your provider). Each wrapper is required.

4. Guard concurrent `login()` with a module-level in-flight promise. login() is only safe sequentially. Two calls racing (React strict mode, tab remount, Fast Refresh) throw "Please wait until the previous login request ends."

5. Do NOT hardcode `AUTH_KEY` in source files. Use env vars for dev. Use login({ authToken }) in production.

6. Do NOT render CometChat components before `isReady`. The provider's isReady: false branch should return null (or a splash), not try to render children.

7. Do NOT re-initialize on navigation. Init and login belong at app root, not per-screen. Re-init causes WebSocket churn and lost messages mid-switch.

8. Do NOT invent component names. Only use components exported from @cometchat/chat-uikit-react-native. See cometchat-native-components for the catalog.

9. Do NOT forget `import "react-native-gesture-handler"` at the top of the entry file (App.tsx or index.js). Without it, swipe gestures in the composer and bottom sheets silently disable.

10. Do NOT bundle the REST API key. It's server-only. Token generation happens on your backend; the RN client never sees it.

---

8. Docs MCP (recommended, not required)

The CometChat docs MCP gives runtime access to the most current RN UI Kit docs. Install:

claude mcp add --transport http cometchat-docs https://www.cometchat.com/docs/mcp

Use the MCP to verify prop signatures, callback names, theme token names, or error message meanings before writing any non-obvious code. Everything the skills describe here is grounded in the docs — the MCP is how you double-check during generation.

Not required to install. The skills ship with the current truth baked in. The MCP is the fallback for edge cases and for upstream changes between skill releases.

---

9. Package dependencies

Minimum peer deps to install before the UI Kit works:

npm install \
  @cometchat/chat-sdk-react-native \
  @cometchat/chat-uikit-react-native \
  react-native-gesture-handler \
  react-native-safe-area-context \
  punycode

Why `punycode`? The kit's CometChatAIAssistantMessageBubble pulls in markdown-it, which does require('punycode'). Node 22+ removed punycode from core, so Metro can't resolve it without the userland package. Missing it = bundle 500 with Unable to resolve module punycode. (Validated 2026-05-26 on @cometchat/chat-uikit-react-native@5.3.5 + Expo SDK 56 + RN 0.85.3.)

Note: react-native-reanimated is NOT a peer dependency of the kit (verified against @cometchat/chat-uikit-react-native@5.x peerDependencies). Add it only if your own app uses it for other animations.

Expo adds expo-av / expo-image-picker depending on which features you enable. Calls require the separate package PLUS four polyfill peers the calls-sdk imports but doesn't declare:

npm install @cometchat/calls-sdk-react-native \
  react-native-background-timer \
  react-native-url-polyfill \
  react-native-performance \
  valibot

The calls-sdk dist/polyfills/browser.js imports react-native-background-timer, react-native-url-polyfill/auto, and react-native-performance at module top; valibot is consumed deeper in the calls state machine. None are in the calls-sdk peerDependencies array — they fail at bundle resolution if missing. (Validated 2026-05-26 on @cometchat/calls-sdk-react-native@5.0.0.) Then run npx expo prebuild (Expo) or cd ios && pod install (bare) so the three native modules get autolinked into the next debug build.

See cometchat-native-features for when to add the calls SDK.

---

Skill routing reference

Visual Builder integration

When the dispatcher's Step 3.1 sets customize=visual and the framework maps to builder platform react-native, skills runs `cometchat builder export --platform react-native` — a single CLI command that downloads the canonical static template ZIP from preview.cometchat.com/downloads/cometchat-builder-react-native.zip, fetches the per-builder settings JSON via GET /vcb/builders/{id}, applies F3 + F10 missing-field defaults, and writes the result to --output (default: src/config/).

The canonical app uses a Zustand-backed config store (src/config/store.ts) that exposes useConfig(selector) — components read theme tokens and feature flags reactively. The exported config.json carries the envelope shape { builderId, name, settings: {...} } — the store reads config.settings.* from it (F9 envelope finding, verified 2026-05-22 against the canonical Zustand store).

This is intentionally lighter than the React web copy (full src/CometChat/ directory). The RN builder repo is a QR-driven sample with custom navigation that doesn't fit cleanly into the customer's existing navigator. So builder export extracts the configuration plumbing only (per the repo's own README §"Integration in Your Existing React Native App"), then skills writes a minimal wrapper that consumes the config in the customer's existing four-wrapper chain.

1. Run cometchat builder export

cometchat builder export --platform react-native --json

Defaults to --output src/config/. The command writes:

Resync = re-run the same command with --force (full re-download + replace). See cometchat-core §11.6 for the resync contract.

Files patched

Entry-file init pattern (bare RN / Expo)

// App.tsx
import './gesture-handler'; // bare RN: line 1, before any other import
import React, { useEffect, useState } from 'react';
import { Platform } from 'react-native';
import { SafeAreaProvider, SafeAreaView } from 'react-native-safe-area-context';
import { GestureHandlerRootView } from 'react-native-gesture-handler';
import {
  CometChatUIKit,
  UIKitSettings,
  CometChatThemeProvider,
  CometChatI18nProvider,
  CometChatTheme,
} from '@cometchat/chat-uikit-react-native';
import { CometChat } from '@cometchat/chat-sdk-react-native';
import type { DeepPartial } from '@cometchat/chat-uikit-react-native/src/shared/helper/types';

import { useConfig } from './src/config/store';
import RootStackNavigator from './src/navigation/RootStackNavigator'; // your existing navigator

// Map builder font name → platform-specific PostScript / asset name.
// Verbatim from the canonical `App.tsx` inside the React Native Visual Builder
// ZIP (download from https://preview.cometchat.com/downloads/cometchat-builder-react-native.zip).
const FONT_MAP: Record<string, { regular: string; medium: string; bold: string }> = {
  'times new roman': {
    regular: Platform.OS === 'ios' ? 'TimesNewRomanPSMT' : 'times_new_roman_regular',
    medium: Platform.OS === 'ios' ? 'TimesNewRomanPSMT' : 'times_new_roman_medium',
    bold: Platform.OS === 'ios' ? 'TimesNewRomanPS-BoldMT' : 'times_new_roman_bold',
  },
  inter: {
    regular: Platform.OS === 'ios' ? 'Inter-Regular' : 'inter_regular',
    medium: Platform.OS === 'ios' ? 'Inter-Medium' : 'inter_medium',
    bold: Platform.OS === 'ios' ? 'Inter-Bold' : 'inter_bold',
  },
  roboto: {
    regular: Platform.OS === 'ios' ? 'Roboto-Regular' : 'roboto_regular',
    medium: Platform.OS === 'ios' ? 'Roboto-Medium' : 'roboto_medium',
    bold: Platform.OS === 'ios' ? 'Roboto-Bold' : 'roboto_bold',
  },
};

export default function App() {
  const styleConfig = useConfig(state => state.settings.style);
  const [isReady, setIsReady] = useState(false);

  useEffect(() => {
    const settings = new UIKitSettings.UIKitSettingsBuilder()
      .setAppId(process.env.EXPO_PUBLIC_COMETCHAT_APP_ID!)
      .setRegion(process.env.EXPO_PUBLIC_COMETCHAT_REGION!)
      .setAuthKey(process.env.EXPO_PUBLIC_COMETCHAT_AUTH_KEY!)
      .subscribePresenceForAllUsers()
      .build();
    CometChatUIKit.init(settings).then(() => setIsReady(true)).catch(console.error);
  }, []);

  const fontKey = styleConfig.typography.font.toLowerCase().trim();
  const fontVariants = FONT_MAP[fontKey] ?? FONT_MAP.inter;

  const theme: { light: DeepPartial<CometChatTheme>; dark: DeepPartial<CometChatTheme> } = {
    light: {
      color: {
        primary: styleConfig.color.brandColor,
        textPrimary: styleConfig.color.primaryTextLight,
        textSecondary: styleConfig.color.secondaryTextLight,
      },
      typography: { fontFamily: fontVariants.regular },
    },
    dark: {
      color: {
        primary: styleConfig.color.brandColor,
        textPrimary: styleConfig.color.primaryTextDark,
        textSecondary: styleConfig.color.secondaryTextDark,
      },
      typography: { fontFamily: fontVariants.regular },
    },
  };

  if (!isReady) return null;

  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <SafeAreaProvider>
        <SafeAreaView edges={['top', 'bottom']} style={{ flex: 1 }}>
          <CometChatThemeProvider theme={theme}>
            <CometChatI18nProvider>
              <RootStackNavigator />
            </CometChatI18nProvider>
          </CometChatThemeProvider>
        </SafeAreaView>
      </SafeAreaProvider>
    </GestureHandlerRootView>
  );
}

Critical:

• useConfig(state => state.settings.style) is the canonical hook — not a static import of the JSON. The store hydrates from AsyncStorage on first read; importing the JSON directly would freeze the initial values and skip QR-update / resync flows that may follow.
• CometChatThemeProvider's theme prop takes a { light, dark } object (NOT a string like "dark"). The string-form theme="dark" was a v4-era shape and was removed in chat-uikit-react-native@5+.
• The four-wrapper rule still applies: GestureHandlerRootView → SafeAreaProvider → CometChatThemeProvider → CometChatI18nProvider. Skipping any of the four breaks gestures, safe areas, theming, or i18n — and fails silently in dev.
• CometChatUIKit.init(settings) returns a Promise — isReady gate before render prevents RootStackNavigator from mounting chat components before init resolves.
• The canonical RN builder app also registers a CometChat.addCallListener at the App level (handles incoming calls / busy / cancelled / ended). When callFeatures.voiceAndVideoCalling.* is true, copy that listener block verbatim from the canonical App.tsx inside the React Native Visual Builder ZIP (download from https://preview.cometchat.com/downloads/cometchat-builder-react-native.zip) (look for 'app' listener id).

Feature flag access

Components throughout the customer's app can read flags reactively:

const reactionsEnabled = useConfig(s => s.settings.chatFeatures.deeperEngagement.reactions);
const audioCallsEnabled = useConfig(
  s => s.settings.callFeatures.voiceAndVideoCalling.oneOnOneVoiceCalling,
);

Hide buttons / disable composer actions / skip mounting components based on these. The full AppConfig typings are in the copied src/config/store.ts.

Resync flow

The "Re-sync visual builder" iteration menu option (see cometchat/SKILL.md § Step 7) is a one-command re-run:

cometchat builder export --platform react-native --force --json

--force is required (it explicitly authorizes replacing the existing src/config/). The command re-downloads the canonical static template, re-fetches the per-builder settings, and replaces the directory entirely.

Per the SKILLS-AUTO-GENERATED contract (see cometchat-core §11.6): customer hand-edits inside src/config/ are lost on resync. Override via App.tsx (outside src/config/) or via the useConfig selector pattern documented in §"Theme derivation".

The customer reloads the dev build (r in Metro) — useConfig rehydrates from AsyncStorage on next mount.

Calls + builder

If callFeatures.voiceAndVideoCalling.* is true: 1. Add @cometchat/calls-sdk-react-native@5.0.0 + the Cloudsmith @cometchat/calls-lib-webrtc tarball (per cometchat-native-calls). 2. Wire CometChat.addCallListener + CometChatUIEventHandler.addCallListener in App.tsx — copy the listener block verbatim from the canonical app's App.tsx. 3. Mount <CometChatIncomingCall> between <CometChatI18nProvider> and <RootStackNavigator> when an incomingCall ref is set. The full pattern is in the canonical App.tsx. 4. Configure iOS PushKit + Android FCM data-message wiring — defer to cometchat-native-push and invoke it after the Visual Builder section completes.

What is NOT honored in v1

noCode.docked (floating-widget shape) and layout.withSideBar don't have RN-native equivalents — RN uses tabs / stacks, not sidebars. The canonical RootStackNavigator from the builder repo IS NOT copied — the customer's existing navigator stays. Layout-tab features like layout.tabs: ['chats','calls','users','groups'] need the customer's existing bottom-tabs navigator to add those tabs manually (skills can do this in a follow-up cometchat-native-placement flow). Theme + typography + chat features + call features ARE honored via useConfig.