Make model field optional in request types, resolve from default provider (#768)

crates/brightstaff/src/handlers/agent_chat_completions.rs

@@ -2,15 +2,17 @@ use std::sync::Arc;
 use std::time::Instant;
 
 use bytes::Bytes;
+use common::llm_providers::LlmProviders;
 use hermesllm::apis::OpenAIMessage;
 use hermesllm::clients::SupportedAPIsFromClient;
 use hermesllm::providers::request::ProviderRequest;
 use hermesllm::ProviderRequestType;
 use http_body_util::combinators::BoxBody;
 use http_body_util::BodyExt;
-use hyper::{Request, Response};
+use hyper::{Request, Response, StatusCode};
 use opentelemetry::trace::get_active_span;
 use serde::ser::Error as SerError;
+use tokio::sync::RwLock;
 use tracing::{debug, info, info_span, warn, Instrument};
 
 use super::agent_selector::{AgentSelectionError, AgentSelector};
@@ -40,6 +42,7 @@ pub async fn agent_chat(
     _: String,
     agents_list: Arc<tokio::sync::RwLock<Option<Vec<common::configuration::Agent>>>>,
     listeners: Arc<tokio::sync::RwLock<Vec<common::configuration::Listener>>>,
+    llm_providers: Arc<RwLock<LlmProviders>>,
 ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, hyper::Error> {
     // Extract request_id from headers or generate a new one
     let request_id: String = match request
@@ -71,6 +74,7 @@ pub async fn agent_chat(
             orchestrator_service,
             agents_list,
             listeners,
+            llm_providers,
             request_id,
         )
         .await
@@ -155,6 +159,7 @@ async fn handle_agent_chat_inner(
     orchestrator_service: Arc<OrchestratorService>,
     agents_list: Arc<tokio::sync::RwLock<Option<Vec<common::configuration::Agent>>>>,
     listeners: Arc<tokio::sync::RwLock<Vec<common::configuration::Listener>>>,
+    llm_providers: Arc<RwLock<LlmProviders>>,
     request_id: String,
 ) -> Result<Response<BoxBody<Bytes, hyper::Error>>, AgentFilterChainError> {
     // Initialize services
@@ -221,16 +226,36 @@ async fn handle_agent_chat_inner(
             AgentFilterChainError::RequestParsing(serde_json::Error::custom(err_msg))
         })?;
 
-    let client_request = match ProviderRequestType::try_from((&chat_request_bytes[..], &api_type)) {
-        Ok(request) => request,
-        Err(err) => {
-            warn!("failed to parse request as ProviderRequestType: {}", err);
-            let err_msg = format!("Failed to parse request: {}", err);
-            return Err(AgentFilterChainError::RequestParsing(
-                serde_json::Error::custom(err_msg),
-            ));
+    let mut client_request =
+        match ProviderRequestType::try_from((&chat_request_bytes[..], &api_type)) {
+            Ok(request) => request,
+            Err(err) => {
+                warn!("failed to parse request as ProviderRequestType: {}", err);
+                let err_msg = format!("Failed to parse request: {}", err);
+                return Err(AgentFilterChainError::RequestParsing(
+                    serde_json::Error::custom(err_msg),
+                ));
+            }
+        };
+
+    // If model is not specified in the request, resolve from default provider
+    if client_request.model().is_empty() {
+        match llm_providers.read().await.default() {
+            Some(default_provider) => {
+                let default_model = default_provider.name.clone();
+                info!(default_model = %default_model, "no model specified in request, using default provider");
+                client_request.set_model(default_model);
+            }
+            None => {
+                let err_msg = "No model specified in request and no default provider configured";
+                warn!("{}", err_msg);
+                let mut bad_request =
+                    Response::new(ResponseHandler::create_full_body(err_msg.to_string()));
+                *bad_request.status_mut() = StatusCode::BAD_REQUEST;
+                return Ok(bad_request);
+            }
         }
-    };
+    }
 
     let message: Vec<OpenAIMessage> = client_request.get_messages();
 

crates/brightstaff/src/handlers/llm.rs

@@ -150,9 +150,30 @@ async fn llm_chat_inner(
         Some(SupportedAPIsFromClient::OpenAIResponsesAPI(_))
     );
 
+    // If model is not specified in the request, resolve from default provider
+    let model_from_request = client_request.model().to_string();
+    let model_from_request = if model_from_request.is_empty() {
+        match llm_providers.read().await.default() {
+            Some(default_provider) => {
+                let default_model = default_provider.name.clone();
+                info!(default_model = %default_model, "no model specified in request, using default provider");
+                client_request.set_model(default_model.clone());
+                default_model
+            }
+            None => {
+                let err_msg = "No model specified in request and no default provider configured";
+                warn!("{}", err_msg);
+                let mut bad_request = Response::new(full(err_msg.to_string()));
+                *bad_request.status_mut() = StatusCode::BAD_REQUEST;
+                return Ok(bad_request);
+            }
+        }
+    } else {
+        model_from_request
+    };
+
     // Model alias resolution: update model field in client_request immediately
     // This ensures all downstream objects use the resolved model
-    let model_from_request = client_request.model().to_string();
     let temperature = client_request.get_temperature();
     let is_streaming_request = client_request.is_streaming();
     let alias_resolved_model = resolve_model_alias(&model_from_request, &model_aliases);

crates/brightstaff/src/main.rs

@@ -202,6 +202,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
                             fully_qualified_url,
                             agents_list,
                             listeners,
+                            llm_providers,
                         )
                         .with_context(parent_cx)
                         .await;

crates/hermesllm/src/apis/anthropic.rs

@@ -102,6 +102,7 @@ pub struct McpServer {
 #[skip_serializing_none]
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct MessagesRequest {
+    #[serde(default)]
     pub model: String,
     pub messages: Vec<MessagesMessage>,
     pub max_tokens: u32,

crates/hermesllm/src/apis/openai.rs

@@ -74,6 +74,7 @@ impl ApiDefinition for OpenAIApi {
 #[derive(Serialize, Deserialize, Debug, Clone, Default)]
 pub struct ChatCompletionsRequest {
     pub messages: Vec<Message>,
+    #[serde(default)]
     pub model: String,
     // pub audio: Option<Audio> // GOOD FIRST ISSUE: future support for audio input
     pub frequency_penalty: Option<f32>,

crates/hermesllm/src/apis/openai_responses.rs

@@ -29,6 +29,7 @@ impl TryFrom<&[u8]> for ResponsesAPIResponse {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ResponsesAPIRequest {
     /// The model to use for generating the response
+    #[serde(default)]
     pub model: String,
 
     /// Text, image, or file inputs to the model