ai_broker 0.2.1

Provider-agnostic Dart abstraction over Claude, OpenAI, and Gemini. One interface for listing models, completions, multi-turn chat, and streaming responses.

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ai_broker

Provider-agnostic Dart abstraction over Claude, OpenAI, and Gemini. One interface for listing models, single-shot completions, multi-turn chat, and token streaming.

Why

Several apps in this workspace (powerdb, chitbot, heylang, compledo) each grew their own AI provider wrappers. ai_broker consolidates them so a feature implemented against AiBroker can run against any provider — and so adding the next provider is one file in lib/src/brokers/, not three.

Shape

abstract class AiBroker {
  String get id;                                        // 'openai' | 'anthropic' | 'gemini'
  String get label;
  Future<List<String>> listModels(String apiKey);
  Future<String> complete({ ... });                     // single-shot
  Future<String> chat({ ... ChatRequest request });     // multi-turn
  Stream<String> stream({ ... ChatRequest request });   // token-by-token
}

Concrete brokers: OpenAiBroker, AnthropicBroker, GeminiBroker. Wire once via AiBrokerRegistry, look up by id thereafter.

Quick start

import 'package:ai_broker/ai_broker.dart';

void main() async {
  AiBrokerRegistry.instance
    ..register(OpenAiBroker())
    ..register(AnthropicBroker())
    ..register(GeminiBroker());

  final broker = AiBrokerRegistry.instance.lookup('anthropic')!;
  final keys = EnvKeyResolver();                 // reads ANTHROPIC_API_KEY
  final apiKey = await keys.require(broker.id);

  final answer = await broker.complete(
    apiKey: apiKey,
    model: 'claude-opus-4-7',
    system: 'You answer concisely.',
    user: 'Capital of France?',
  );
  print(answer);

  // Streaming:
  final stream = broker.stream(
    apiKey: apiKey,
    model: 'claude-opus-4-7',
    request: const ChatRequest(
      system: 'You write short prose.',
      messages: [AiMessage.user('Describe an ocean sunset.')],
    ),
  );
  await for (final chunk in stream) {
    stdout.write(chunk);
  }
}

Key resolution

API keys arrive per call. Pick a KeyResolver:

Resolver	Use when
EnvKeyResolver	CLI / backend code. Reads OPENAI_API_KEY, ANTHROPIC_API_KEY, GEMINI_API_KEY (overridable).
MapKeyResolver	Tests, or apps that already hold keys in a map.
(your own)	Flutter apps using secure storage — implement KeyResolver against your store.

For Flutter apps that already manage settings + secure storage (like powerdb), you can skip KeyResolver and pass apiKey: directly.

What it doesn't do

• No safety gate. powerdb has a SQL read-only enforcer; that belongs at the call site, not in this package.
• No persistence. Settings, key storage, model selection — caller's problem.
• No tools / function calling. Add when a consumer actually needs it; today nothing in the workspace does.
• No Flutter widgets. Pure Dart. Build pickers / settings dialogs on top in the consuming app.

Files

lib/
  ai_broker.dart                    # public entry — re-exports src
  _common.dart                      # internal umbrella (dart:* + http + meta)
  src/
    broker.dart                     # AiBroker, AiBrokerRegistry, AiBrokerException
    message.dart                    # AiMessage, AiRole, ChatRequest
    key_resolver.dart               # KeyResolver, EnvKeyResolver, MapKeyResolver
    retry.dart                      # exponential backoff for 429/503/529
    sse.dart                        # shared SSE decoder for streaming
    brokers/
      openai_broker.dart
      anthropic_broker.dart
      gemini_broker.dart

Run the example

dart pub get
ANTHROPIC_API_KEY=sk-... dart run example/example.dart anthropic
OPENAI_API_KEY=sk-...    dart run example/example.dart openai gpt-4o-mini
GEMINI_API_KEY=...       dart run example/example.dart gemini gemini-2.5-flash

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🔍 For more information, refer to the API reference.

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💬 Contributing and Discussions

This is an open-source project, and we warmly welcome contributions from everyone, regardless of experience level. Whether you're a seasoned developer or just starting out, contributing to this project is a fantastic way to learn, share your knowledge, and make a meaningful impact on the community.

☝️ Ways you can contribute

• Find us on Discord: Feel free to ask questions and engage with the community here: https://discord.gg/gEQ8y2nfyX.
• Share your ideas: Every perspective matters, and your ideas can spark innovation.
• Help others: Engage with other users by offering advice, solutions, or troubleshooting assistance.
• Report bugs: Help us identify and fix issues to make the project more robust.
• Suggest improvements or new features: Your ideas can help shape the future of the project.
• Help clarify documentation: Good documentation is key to accessibility. You can make it easier for others to get started by improving or expanding our documentation.
• Write articles: Share your knowledge by writing tutorials, guides, or blog posts about your experiences with the project. It's a great way to contribute and help others learn.

No matter how you choose to contribute, your involvement is greatly appreciated and valued!

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LICENSE

This project is released under the MIT License. See LICENSE for more information.