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

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