[isekovanic]

Ticket: https://linear.app/stream/issue/RN-485

Stacked on #3920.

🎯 Goal

Groundwork for the agent conversation views: strings that follow the chat's language, and an AI sample that talks to a real agent backend, so the next PRs have reasoning and tool-call steps to show.

🛠 Implementation details

Translations

• useAITranslation() reads the chat SDK's TranslationContext. Inside <Chat> it returns the chat's t. Without one, it falls back to English with {{ name }} placeholders filled.
• It's a thin adapter rather than useTranslationContext() because ours throws outside a provider, which would crash AI-only apps.
• defaultTranslatorFunction moved from Streami18n.ts to utils/i18n/utils.ts, so TranslationContext.tsx no longer imports Streami18n (i18next and every locale). Streami18n still re-exports it, and the public API is unchanged.
• TranslationContext.tsx, isTestEnvironment.ts and utils/i18n/utils.ts are on the AI entry's allowlist. The AI entry gains plain dayjs and nothing else.
• TranslationProvider is re-exported from /ai-components for apps without <Chat>.

ExpoChatGPTSample

• It talks to a Vision-Agents router through @stream-io/calypso and no longer uses the old Heroku demo backend.
• Each conversation is a router session and its agent channel. Questions go through session.responses.create, with photos sent as data URIs. Stop goes through session.interrupt().
• The drawer lists the user's agent channels. A conversation that was never asked anything is deleted when you leave it.
• The reply's ai_* steps are hidden through the UnsupportedAttachment slot until their views land.
• Config is read from .env.local, and .env.example documents it. The README covers running the router.
• Hermes has no crypto.randomUUID, so the sample polyfills it with stream-chat-js's generateUUIDv4.
• <Channel> and <MessageList> are stand-ins until AIConversation exists. After that the sample reads the low-level client directly, the same way React's Juno sample does.

🎨 UI Changes

No SDK UI. The sample now shows real agent replies.

🧪 Testing

• Unit tests for the translation adapter. They cover English without <Chat>, a real Streami18n instance (a French string with a placeholder) and the override provider.
• On an Android emulator against a local router:
  • asking a question, the thinking indicator, the stop button showing and the streamed answer;
  • router-titled conversations, and resuming one;
  • an unused session being deleted;
  • no "Unsupported Attachment" cards for the steps.
• Not tested: iOS, pressing stop mid-reply, photos, voice mode.
• yarn lint, yarn typecheck, yarn build and yarn test:unit pass.

☑️ Checklist

• I have signed the Stream CLA (required)
• PR targets the develop branch (stacked on feat(ai-components): parse agent reply steps from message attachments #3920)
• Documentation is updated (sample README)
• New code is tested in main example apps, including all possible scenarios
  • SampleApp iOS and Android
  • Expo iOS and Android

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
js_bundle_size	2037 KB	2038 KB	+213 B	🟢
ai_components_size	163 KB	169 KB	+5968 B	🔴