Function try_route 

pub async fn try_route(
    model: &str,
    client: &Client,
    tools_schema: &Arc<Vec<Value>>,
    system_prompt: &Option<String>,
    messages: &[Value],
    tx: &UnboundedSender<StreamEvent>,
    temperature: Option<f32>,
    max_tokens: Option<u32>,
    thinking_budget: u32,
    cancel: &CancellationToken,
) -> Option<Result<Value, Box<dyn Error + Send + Sync>>>

Try to route a request through an OpenAI-compatible provider.

Returns Some(Ok(value)) if the model resolved to an OpenAI provider and the request completed (successfully or with error). Returns None if the model should be handled by the Anthropic path.

This is the single routing entry point — both streaming and non-streaming callers in api.rs use this instead of duplicating the routing logic.