Add support for json based content types in Message (#480)

demos/use_cases/preference_based_routing/arch_config.yaml

@@ -14,26 +14,26 @@ llm_providers:
 
   - name: archgw-v1-router-model
     provider_interface: openai
-    model: cotran2/llama-1b-4-26
-    base_url: http://35.192.87.187:8000/v1
-
-  - name: gpt-4o-mini
-    provider_interface: openai
-    access_key: $OPENAI_API_KEY
-    model: gpt-4o-mini
-    default: true
+    model: cotran2/llama-4-epoch
+    base_url: http://34.46.85.85:8000/v1
 
   - name: gpt-4o
     provider_interface: openai
     access_key: $OPENAI_API_KEY
     model: gpt-4o
-    usage: Generating original content such as scripts, articles, or creative materials.
+    default: true
 
-  - name: o4-mini
+  - name: code_generation
     provider_interface: openai
     access_key: $OPENAI_API_KEY
-    model: o4-mini
-    usage: Requesting topic ideas specifically related to personal finance and budgeting.
+    model: gpt-4o
+    usage: Generating new code snippets, functions, or boilerplate based on user prompts or requirements
+
+  - name: code_understanding
+    provider_interface: openai
+    access_key: $OPENAI_API_KEY
+    model: gpt-4.1
+    usage: understand and explain existing code snippets, functions, or libraries
 
 tracing:
   random_sampling: 100

demos/use_cases/preference_based_routing/hurl_tests/simple.hurl

@@ -12,7 +12,7 @@ Content-Type: application/json
 HTTP 200
 [Asserts]
 header "content-type" == "application/json"
-jsonpath "$.model" matches /^o4-mini/
+jsonpath "$.model" matches /^gpt-4o/
 jsonpath "$.usage" != null
 jsonpath "$.choices[0].message.content" != null
 jsonpath "$.choices[0].message.role" == "assistant"

demos/use_cases/preference_based_routing/hurl_tests/simple_stream.hurl

@@ -13,4 +13,4 @@ Content-Type: application/json
 HTTP 200
 [Asserts]
 header "content-type" matches /text\/event-stream/
-body matches /^data: .*?o4-mini.*?\n/
+body matches /^data: .*?gpt-4o.*?\n/