cometchat-android-v5-extensions— agent skill

Ground truth: com.cometchat:chat-uikit-android:5.x (legacy/maintenance-only; +calls-sdk-android:5.x) — resolved AAR (javap) + ui-kit/android. Official docs: https://www.cometchat.com/docs/fundamentals/extensions-overview · Docs MCP: claude mcp add --transport http cometchat-docs https://www.cometchat.com/docs/mcp (or fetch the URL directly without MCP). Verify symbols against the installed package/source before relying on them.

Companion skills: cometchat-android-v5-customization covers DataSource decorators; cometchat-android-v5-features covers the feature catalog.

Purpose

This skill covers the CometChat extension architecture — how extensions plug into the UI Kit, the built-in extensions, and how to create custom ones.

Use this skill when

• "How do extensions work?"
• "How do I add a custom extension?"
• "How do I disable an extension?"
• Working with ExtensionsDataSource or ExtensionDecorator

Do not use this skill when

• Enabling a backend extension or AI feature → use cometchat-android-v5-features (which routes to cometchat apply-feature <id> --app-id <X>)
• Writing custom message templates → use cometchat-android-v5-customization

1. Extension architecture

Extensions are split into two class types:

• Registrar classes (e.g. PollsExtension, StickerExtension) — extend ExtensionsDataSource. These are what you pass to setExtensions(...) to enable a built-in extension.
• Decorator classes (e.g. PollsExtensionDecorator, StickerExtensionDecorator) — extend DataSourceDecorator. These are the runtime decorators that wrap the active DataSource chain. The kit creates them internally; you don't construct them directly.

ChatConfigurator.getDataSource()
    └── SmartRepliesExtensionDecorator   (created by SmartRepliesExtension)
        └── PollsExtensionDecorator      (created by PollsExtension)
            └── StickerExtensionDecorator (created by StickerExtension)
                └── MessagesDataSource (base)

2. Built-in extensions

3. Enabling/disabling extensions

Extensions are enabled by default. To customize which extensions are active, pass a custom list to UIKitSettingsBuilder:

List<ExtensionsDataSource> extensions = new ArrayList<>();
extensions.add(new PollsExtension());            // registrar, NOT PollsExtensionDecorator
extensions.add(new StickerExtension());         // registrar, NOT StickerExtensionDecorator
extensions.add(new SmartRepliesExtension());
// Omit extensions you don't want

UIKitSettings settings = new UIKitSettings.UIKitSettingsBuilder()
    .setAppId(APP_ID)
    .setRegion(REGION)
    .setAuthKey(AUTH_KEY)
    .setExtensions(extensions)
    .build();

Why not `PollsExtensionDecorator`? *ExtensionDecorator extends DataSourceDecorator, not ExtensionsDataSource — so it won't compile when added to a List<ExtensionsDataSource>. The kit's runtime decorator chain is built by the registrar's enable() method internally; you don't add decorators directly.

4. Creating a custom extension

A custom extension has TWO classes:

1. A registrar that extends ExtensionsDataSource (gets added to setExtensions(...))
2. A decorator that extends DataSourceDecorator (created by the registrar via ChatConfigurator.enable(...))

// 1. Decorator — extends DataSourceDecorator, overrides per-message behavior
public class MyExtensionDecorator extends DataSourceDecorator {
    public MyExtensionDecorator(DataSource dataSource) {
        super(dataSource);
    }
    // Override methods to add custom behavior
}

// 2. Registrar — extends ExtensionsDataSource, implements getExtensionId() + addExtension()
public class MyExtension extends ExtensionsDataSource {
    @Override
    public String getExtensionId() {
        return "my-custom-extension";
    }

    @Override
    public void addExtension() {
        // addExtension() is the ABSTRACT method you must implement. The inherited
        // concrete enable() calls it after confirming the extension is on (dashboard).
        ChatConfigurator.enable(dataSource -> new MyExtensionDecorator(dataSource));
    }
}

// Then add the registrar to UIKitSettings:
extensions.add(new MyExtension());

Hard rules

• Two classes per extension. A registrar (ExtensionsDataSource, implements abstract getExtensionId() + addExtension(); enable() is inherited) and a decorator (DataSourceDecorator, holds the per-message override). setExtensions(...) wants registrars; the chain builds decorators automatically.
• Register after init. ChatConfigurator.enable() must be called after CometChatUIKit.init() succeeds.
• Backend extension toggle still applies. Even if an extension is registered client-side, it needs to be enabled on the app's backend. Use cometchat apply-feature <id> --app-id <X> (the CLI hits the dashboard API). For dashboard-only extensions (Giphy / Stipop / Tenor / Chatwoot / Intercom — those needing third-party API keys), the user has to enter the third-party config in the dashboard manually.