saorsa-ai: Unified multi-provider LLM API.

Provides a common interface for streaming completions, tool calling, and authentication across multiple LLM providers.

Architecture Overview

┌─────────────────────────────────────────────────────────────┐
│                 Application / Agent Layer                   │
│  (Sends CompletionRequest, receives StreamEvent stream)     │
└─────────────────────────────────────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────┐
│              ProviderRegistry (Factory)                     │
│  ProviderKind → ProviderConfig → Box<dyn Provider>          │
└─────────────────────────────────────────────────────────────┘
                             │
               ┌─────────────┼─────────────┬─────────────┐
               ▼             ▼             ▼             ▼
      ┌──────────────┬──────────────┬──────────────┬──────────────┐
      │  Anthropic   │   OpenAI     │   Gemini     │   Ollama     │
      │   Provider   │   Provider   │   Provider   │   Provider   │
      └──────────────┴──────────────┴──────────────┴──────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────┐
│         Streaming HTTP (reqwest, Server-Sent Events)        │
│  POST /v1/messages → stream of JSON events → StreamEvent    │
└─────────────────────────────────────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────┐
│          Message Protocol (vendor-agnostic types)           │
│  Message, ContentBlock, ToolDefinition, ContentDelta        │
└─────────────────────────────────────────────────────────────┘

Provider Abstraction

All providers implement the Provider trait:

• stream_completion: Returns Pin<Box<dyn Stream<Item = Result<StreamEvent>>>>
• Unified event types: StreamEvent::{ContentDelta, ToolUse, Done, Error}
• Model metadata: Context windows, tool support, vision capabilities

Supported Providers

• Anthropic: Claude models with streaming, tool use, vision
• OpenAI: GPT models with streaming, function calling, vision
• Gemini: Google Gemini with streaming and tool use
• Ollama: Local model hosting with OpenAI-compatible API
• OpenAI-Compatible: Generic adapter for compatible APIs (Groq, etc.)

Key Types

• Provider: Core trait for LLM completion providers
• CompletionRequest: Vendor-agnostic request (messages, tools, params)
• StreamEvent: Streaming events (content deltas, tool calls, completion)
• Message: Conversation message with role and content blocks
• ToolDefinition: JSON Schema-based tool specification