flutter_llm_router 1.0.2

A resilient multi-provider LLM router for Flutter AI Toolkit featuring transparent failover, token cost tracking, and attempt logging.

flutter_llm_router

A resilient multi-provider LLM router for Flutter AI Toolkit. RouterLlmProvider implements LlmProvider, so it drops into LlmChatView and adds failover, live cost tracking, and attempt logs.

This package is not published. Use the path dependency and the example app below to test it against real providers before any upload.

Problem

A single upstream outage, HTTP 429, or timeout ends the chat. Token spend is invisible until the provider invoice arrives, and there is no record of which provider answered or failed.

Solution

Point LlmChatView at one RouterLlmProvider. The router tries each ProviderConfig in order:

• HTTP 429, 408, 5xx, timeouts, and dropped sockets raise RetryableLlmException and move to the next provider, as long as no text has been yielded yet.
• HTTP 400, 401, and 403 raise TerminalLlmException and stop the chain.
• If every provider fails, the router throws AllProvidersFailedException with the attempt list.
• A finished stream updates CostTracker and lastAttemptLogs.

Built-in adapter names are openai, anthropic, gemini, and openrouter. openrouter calls https://openrouter.ai/api/v1 with one key. Repeat that name and change model to fail over across OpenRouter slugs.

Quickstart

From an app that sits next to this repo:

dependencies:
  flutter:
    sdk: flutter
  flutter_ai_toolkit: ^0.5.0
  flutter_llm_router:
    path: ../flutter_llm_router

import 'package:flutter_ai_toolkit/flutter_ai_toolkit.dart';
import 'package:flutter_llm_router/flutter_llm_router.dart';

final costTracker = CostTracker();

final router = RouterLlmProvider(
  costTracker: costTracker,
  providers: [
    ProviderConfig(
      name: 'openai',
      apiKey: openAiKey,
      model: 'gpt-4o-mini',
      pricePerInputToken: 0.00000015,
      pricePerOutputToken: 0.0000006,
    ),
    ProviderConfig(
      name: 'gemini',
      apiKey: geminiKey,
      model: 'gemini-2.0-flash',
      pricePerInputToken: 0.0000001,
      pricePerOutputToken: 0.0000004,
    ),
  ],
);

// Pass `router` to LlmChatView. Dispose `router` and `costTracker` yourself
// when the page is disposed, because the tracker was injected.

LlmChatView(
  provider: router,
  welcomeMessage: 'Ask a question. A 429 on OpenAI fails over to Gemini.',
)

The runnable harness is example/. It adds a 429 switch, key entry, the spend label, and the attempt sheet.

Live cost tracking

Prices on ProviderConfig are USD per token. 0.000001 is one micro-dollar. After a successful stream the router uses the provider's reported token counts when the stream includes them, and estimates a missing side as (text.length + 3) ~/ 4, then calls recordUsage.

ValueListenableBuilder<double>(
  valueListenable: router.costTracker.totalCostNotifier,
  builder: (context, totalCost, _) {
    return Text('\$${totalCost.toStringAsFixed(8)}');
  },
)

That figure is the router's estimate, not the provider's invoice. Bind the notifier for a live label, and read totalInputTokens and totalOutputTokens for the counts.

Documentation

• Quickstart
• Configuration
• Cost tracking
• Example app
• Changelog

getDocumentEmbedding and getQueryEmbedding throw UnimplementedError. Chat streaming is the supported path.

License

MIT. See LICENSE.