bug fix - allow image content to pass through (#539)

fixes https://github.com/katanemo/archgw/issues/535

crates/brightstaff/src/handlers/chat_completions.rs

@@ -32,6 +32,8 @@ pub async fn chat_completions(
 
     let chat_request_bytes = request.collect().await?.to_bytes();
 
+    debug!("Received request body (raw utf8): {}", String::from_utf8_lossy(&chat_request_bytes));
+
     let chat_request_parsed = serde_json::from_slice::<serde_json::Value>(&chat_request_bytes)
         .inspect_err(|err| {
             warn!(

crates/hermesllm/src/providers/openai/types.rs

@@ -35,9 +35,16 @@ pub enum MultiPartContentType {
     ImageUrl,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub struct ImageUrl {
+    pub url: String,
+}
+
+#[skip_serializing_none]
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub struct MultiPartContent {
     pub text: Option<String>,
+    pub image_url: Option<ImageUrl>,
     #[serde(rename = "type")]
     pub content_type: MultiPartContentType,
 }
@@ -307,10 +314,12 @@ mod tests {
             MultiPartContent {
                 text: Some("This is a text part.".to_string()),
                 content_type: MultiPartContentType::Text,
+                image_url: None,
             },
             MultiPartContent {
                 text: Some("https://example.com/image.png".to_string()),
                 content_type: MultiPartContentType::ImageUrl,
+                image_url: None,
             },
         ]);
         assert_eq!(multi_part_content.to_string(), "This is a text part.");
@@ -364,6 +373,61 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_chat_completions_request_image_content() {
+        const CHAT_COMPLETIONS_REQUEST: &str = r#"
+            {
+              "stream": true,
+              "model": "openai/gpt-4o",
+              "messages": [
+                {
+                  "role": "user",
+                  "content": [
+                    {
+                      "type": "text",
+                      "text": "describe this photo pls"
+                    },
+                    {
+                      "type": "image_url",
+                      "image_url": {
+                        "url": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/...=="
+                      }
+                    }
+                  ]
+                }
+              ]
+            }"#;
+
+        let chat_completions_request: ChatCompletionsRequest =
+            serde_json::from_str(CHAT_COMPLETIONS_REQUEST).unwrap();
+        assert_eq!(chat_completions_request.model, "openai/gpt-4o");
+        if let Some(ContentType::MultiPart(multi_part_content)) =
+            chat_completions_request.messages[0].content.as_ref()
+        {
+            assert_eq!(multi_part_content.len(), 2);
+            assert_eq!(
+                multi_part_content[0].content_type,
+                MultiPartContentType::Text
+            );
+            assert_eq!(
+                multi_part_content[0].text,
+                Some("describe this photo pls".to_string())
+            );
+            assert_eq!(
+                multi_part_content[1].content_type,
+                MultiPartContentType::ImageUrl
+            );
+            assert_eq!(
+                multi_part_content[1].image_url,
+                Some(ImageUrl {
+                    url: "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/...==".to_string(),
+                })
+            );
+        } else {
+            panic!("Expected MultiPartContent");
+        }
+    }
+
     #[test]
     fn test_sse_streaming() {
         let json_data = r#"data: {"id":"chatcmpl-123","object":"chat.completion.chunk","created":1700000000,"model":"gpt-3.5-turbo","choices":[{"index":0,"delta":{"role":"assistant"},"finish_reason":null}]}

demos/use_cases/llm_routing/arch_config.yaml

@@ -12,6 +12,9 @@ llm_providers:
   - access_key: $OPENAI_API_KEY
     model: openai/gpt-4o-mini
 
+  - access_key: $OPENAI_API_KEY
+    model: openai/gpt-4.1
+
   - access_key: $OPENAI_API_KEY
     model: openai/gpt-4o
     default: true