Multilingual AI Chat System Development

To build a system where multiple user profiles—such as real users, AI personas, or simulated accounts—can chat seamlessly while maintaining distinct identities, languages, and presence statuses, you need a structured set of technical and functional requirements.

Below is a comprehensive **System Requirements Specification** that you can use to build or brief your engineering team.

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## 1. Functional Requirements

### 1.1 Profile & Persona Management

* **FR-1.1 Unique Identity Isolation:** Each profile must have a distinct system identifier (`user_id`), full name, regional profile metadata (age, state, city/town, primary language), and dedicated avatar media.
* **FR-1.2 Language & Cultural Parameters:** Every profile must store localized attributes (e.g., primary language from the 22 scheduled Indian languages, secondary languages, dialect flavor, and greeting templates) to guide chat context.
* **FR-1.3 Profile Classification:** The system must differentiate user types using a boolean or enum flag (e.g., `is_bot: true/false`, `account_type: 'real' | 'virtual' | 'system'`).

### 1.2 Messaging & Chat Engine

* **FR-2.1 One-to-One Messaging:** The system must support real-time text message delivery between any pair of user IDs over WebSockets or HTTP/2.
* **FR-2.2 Automated Chat Routing:** When a message is sent to a target profile with `is_bot = true`, the chat engine must route the payload to an asynchronous AI/Agent worker queue instead of standard socket delivery.
* **FR-2.3 Contextual Persona Response:** The chat worker must load the recipient profile’s metadata (bio, language, location, tone) and prior conversation history to generate in-character responses.
* **FR-2.4 Simulated Typing Delays:** To simulate natural human behavior, automated responses must feature a configurable typing indicator and delivery delay (e.g., 2–5 seconds) before appearing in the recipient's thread.

### 1.3 Presence & Activity Simulation

* **FR-3.1 Status Tracking:** The platform must support dynamic user statuses (`online`, `offline`, `away`).
* **FR-3.2 Randomized Presence Rotation:** For virtual/simulated profiles, a background presence engine must periodically rotate profile statuses (e.g., keeping a dynamic 30%–50% subset online) and update `last_seen` timestamps to reflect natural activity.
* **FR-3.3 Status Visibility:** Real users must be able to view the real-time or last-active status of profiles in chat lists and discovery feeds.

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## 2. Technical & Non-Functional Requirements

### 2.1 Performance & Scalability

* **NFR-1.1 Concurrent Chats:** The chat gateway must handle high concurrency with low latency (