chat-openrouter 0.1.2

# chat-openrouter

[OpenRouter](https://openrouter.ai/) provider for [chat-rs](https://github.com/EggerMarc/chat-rs). OpenRouter exposes two OpenAI-compatible wires; the builder picks one and hands off to the matching wire crate:

- **Responses API (Beta)** (default) → [`chat-responses`](https://crates.io/crates/chat-responses), `build()` returns a `ResponsesClient`.
- **Chat Completions** (opt in via `.with_completions()`) → [`chat-completions`](https://crates.io/crates/chat-completions), `build()` returns a `ChatCompletionsClient`.

OpenRouter is a unified gateway in front of hundreds of models from many vendors. The model slug selects which one, and is vendor-prefixed (e.g. `anthropic/claude-sonnet-4`, `openai/gpt-4o`, `google/gemini-2.5-pro`).

## Install

```toml
[dependencies]
chat-core = "0.4.0"
chat-openrouter = "0.1.0"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
```

Or via the umbrella crate: `chat-rs = { version = "0.5.0", features = ["openrouter"] }`.

## Usage

```rust
use chat_openrouter::OpenRouterBuilder;
use chat_core::{builder::ChatBuilder, types::messages};

// Default: Responses API.
let client = OpenRouterBuilder::new()
    .with_model("anthropic/claude-sonnet-4")
    .build();

// Opt in to Chat Completions instead.
let client = OpenRouterBuilder::new()
    .with_completions()
    .with_model("openai/gpt-4o")
    .build();

let mut chat = ChatBuilder::new().with_model(client).build();

let mut msgs = messages::from_user(vec!["Hello!"]);
let response = chat.complete(&mut msgs).await?;
```

Set `OPENROUTER_API_KEY` in your environment or call `.with_api_key()` on the builder.

## Capabilities

- **Completions** — text generation with tool calling and structured output, on either wire
- **Streaming** — token-by-token output over SSE (requires the `stream` feature); both wire clients implement it
- **Reasoning** — `.with_reasoning_effort("high")` for reasoning-capable models (Responses wire only)

## Notes

- **Two wires.** OpenRouter speaks both the OpenAI Responses API (Beta) and Chat Completions. The builder picks one upstream — `.with_completions()` switches from the default Responses wire — and returns the underlying wire client directly (`ResponsesClient` or `ChatCompletionsClient`); there is no wrapper type. Both already implement the chat-rs provider traits.
- **Stateless.** The OpenRouter Responses API persists no server-side state and has no `previous_response_id` round-trip. The builder always disables response-id reuse and sends the full conversation each turn.
- **No WebSocket.** OpenRouter has no WebSocket/realtime endpoint; streaming is SSE over HTTP. The builder is still generic over `Transport`, so a custom transport can be supplied via `.with_transport(...)`.

## Custom Endpoint / Transport

Override the base URL with `.with_base_url(...)` or supply a custom transport with `.with_transport(...)`.

## Feature Flags

Streaming is gated on the `stream` feature:

```toml
chat-openrouter = { version = "0.1.0", features = ["stream"] }
```