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Custom Provider

Build a custom provider to integrate any LLM backend with Corvus.

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Overview

Providers implement the Provider trait from src/providers/traits.rs. The simplest implementation requires only chat_with_system().

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Step 1: Create the Provider

Create src/providers/my_provider.rs: 
use crate::providers::traits::Provider;
use anyhow::Result;
use async_trait::async_trait;
use reqwest::Client;

pub struct MyProvider {
    api_key: String,
    base_url: String,
    client: Client,
}

impl MyProvider {
    pub fn new(api_key: &str, base_url: Option<&str>) -> Self {
        Self {
            api_key: api_key.to_string(),
            base_url: base_url.unwrap_or("https://api.example.com").to_string(),
            client: Client::new(),
        }
    }
}

#[async_trait]
impl Provider for MyProvider {
    async fn chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
    ) -> Result<String> {
        let url = format!("{}/v1/chat/completions", self.base_url);
        
        let mut messages = Vec::new();
        
        if let Some(sys) = system_prompt {
            messages.push(serde_json::json!({
                "role": "system",
                "content": sys
            }));
        }
        
        messages.push(serde_json::json!({
            "role": "user",
            "content": message
        }));
        
        let body = serde_json::json!({
            "model": model,
            "messages": messages,
            "temperature": temperature,
        });
        
        let resp = self.client
            .post(&url)
            .header("Authorization", format!("Bearer {}", self.api_key))
            .json(&body)
            .send()
            .await?
            .json::<serde_json::Value>()
            .await?;
        
        resp["choices"][0]["message"]["content"]
            .as_str()
            .map(|s| s.to_string())
            .ok_or_else(|| anyhow::anyhow!("No content in response"))
    }
}

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Step 2: Register the Provider

Add to src/providers/mod.rs: 
pub mod my_provider;

pub fn create_provider(name: &str, config: &Config) -> Result<Box<dyn Provider>> {
    match name {
        "my_provider" => Ok(Box::new(my_provider::MyProvider::new(
            &config.api_key,
            None,
        ))),
        // ... existing providers
        _ => Err(anyhow::anyhow!("Unknown provider: {}", name)),
    }
}

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Step 3: Configure

Update ~/.corvus/config.toml: 
api_key = "your-api-key"
default_provider = "my_provider"
default_model = "my-model-v1"

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Step 4: Test

Add tests in src/providers/my_provider.rs: 
#[cfg(test)]
mod tests {
    use super::*
;

    #[tokio::test]
    async fn test_my_provider() {
        let provider = MyProvider::new("test-key", None);
        
        // Mock API call or use test endpoint
        let result = provider.chat_with_system(
            Some("You are helpful"),
            "Hello",
            "test-model",
            0.7,
        ).await;
        
        assert!(result.is_ok());
    }
}
Run tests: 
cargo test providers::my_provider

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Advanced Features

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Native Tool Calling

If your provider supports native tool calling: 
impl Provider for MyProvider {
    fn capabilities(&self) -> ProviderCapabilities {
        ProviderCapabilities {
            native_tool_calling: true,
        }
    }
    
    async fn chat_with_tools(
        &self,
        messages: &[ChatMessage],
        tools: &[serde_json::Value],
        model: &str,
        temperature: f64,
    ) -> Result<ChatResponse> {
        // Format tools for your API
        // Parse tool_use from response
        // Return ChatResponse with tool_calls
    }
}

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Streaming

For streaming support: 
use futures_util::stream::BoxStream;

impl Provider for MyProvider {
    fn supports_streaming(&self) -> bool {
        true
    }
    
    fn stream_chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
        options: StreamOptions,
    ) -> BoxStream<'static, StreamResult<StreamChunk>> {
        // Return async stream of chunks
    }
}

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Full Example

See examples/custom_provider.rs:19-59 for a complete Ollama integration.