Kai Engine

A modular, extensible AI chat engine built with a pipeline-based architecture.

Packages

This repository is a monorepo containing the following packages:

Package	Pub	Description
kai_engine		Core AI chat engine with pipeline-based architecture
kai_engine_firebase_ai		Firebase AI (Gemini) adapter for Kai Engine
kai_engine_chat_ui		Flutter chat UI widgets for Kai Engine
prompt_block		Structured prompt blocks for AI applications

Overview

The Kai Engine is a flexible framework for building AI-powered chat applications with a clean, modular architecture. It follows a pipeline-first pattern, allowing developers to easily customize and extend the processing pipeline with domain-specific logic.

Architecture

flowchart TD
    subgraph UI["UI / Application Layer"]
        A[UI Component] --> B[ChatControllerBase]
    end

    subgraph Orchestration["Orchestration Layer"]
        B --> C[ConversationManager]
        B --> D[QueryEngine]
        B --> E[ContextEngine]
        B --> F[GenerationServiceBase]
        B --> G[PostResponseEngine]
    end

    subgraph Context["Context Building"]
        E --> I[System Prompt]
        E --> J[History Context]
        E --> K[Custom Context]
        E --> L[User Input]
    end

    subgraph Generation["AI Generation"]
        F --> M[Token Streaming]
        M --> N[Tool Calling]
    end

    subgraph Data["Data Layer"]
        C --> Q[MessageRepository]
    end

    subgraph External["External Services"]
        F --> R[LLM Provider]
    end

    style B fill:#e1f5fe
    style C fill:#e8f5e9
    style D fill:#fff3e0
    style E fill:#fff3e0
    style F fill:#fff3e0
    style G fill:#fff3e0
    style Q fill:#e8f5e9
    style R fill:#fce4ec

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Features

• Modular Pipeline Architecture: Each processing step is a separate component that can be customized or replaced
• Extensible Design: Unlimited extensibility through component composition
• Generic Type Support: Full generic support for using your own message types
• Stream-Based Responses: Real-time streaming responses for better user experience
• Optimistic UI Updates: Immediate UI feedback with rollback on errors
• Flexible Context Building: Advanced prompt engineering with parallel and sequential context building
• Tool Calling Support: Native support for AI function/tool calling with type-safe schemas
• Structured Prompt Blocks: Create and manage structured prompt blocks
• Post-Response Processing: Process AI responses after generation with custom pipelines
• Type Safety: Strong typing throughout the system
• Comprehensive Testability: Designed for easy unit and integration testing

Quick Start

Installation

dependencies:
  kai_engine: ^0.1.1
  kai_engine_firebase_ai: ^0.1.1  # For Firebase AI integration
  kai_engine_chat_ui: ^0.1.1      # For Flutter UI widgets
  prompt_block: ^0.1.1            # For structured prompts

Basic Usage

import 'package:kai_engine/kai_engine.dart';
import 'package:kai_engine_firebase_ai/kai_engine_firebase_ai.dart';

// 1. Create the generation service
final generationService = FirebaseAiGenerationService(
  firebaseAi: FirebaseAI.googleAI(),
  config: GenerativeConfig(model: 'gemini-2.0-flash'),
);

// 2. Create a chat controller
final class MyChatController extends ChatControllerBase<MyMessage> {
  MyChatController({
    required super.conversationManager,
    required super.generationService,
  });

  @override
  ContextEngine build() => ContextEngine.builder([
    PromptTemplate.system("You are a helpful AI assistant."),
    PromptTemplate.buildSequential(HistoryContext()),
    PromptTemplate.input(),
  ]);

  @override
  GenerationExecuteConfig generativeConfigs(IList<CoreMessage> prompts) {
    return GenerationExecuteConfig.none();
  }
}

// 3. Use the controller
final controller = MyChatController(
  conversationManager: myConversationManager,
  generationService: generationService,
);

await controller.submit('Hello, world!');

With Flutter UI

import 'package:kai_engine_chat_ui/kai_engine_chat_ui.dart';

KaiChatView(
  messages: messages,
  generationState: generationState,
  onSend: (text) => controller.submit(text),
  onCancel: controller.cancel,
)

Documentation

See the individual package READMEs for detailed documentation:

• kai_engine README - Core engine documentation
• kai_engine_firebase_ai README - Firebase AI integration
• kai_engine_chat_ui README - Flutter UI widgets
• prompt_block README - Structured prompt blocks

Contributing

Contributions are welcome! Please read our Contributing Guide for details on how to submit pull requests, report issues, or request features.

License

This project is licensed under the MIT License - see the LICENSE file for details.