refactor: get rid of unnecessary serialization and deserialization

lib/captain/base_editor_service.rb

@@ -78,18 +78,17 @@ class Captain::BaseEditorService
     "#{endpoint}/v1"
   end
 
-  def make_api_call(body)
-    parsed_body = JSON.parse(body)
-    instrumentation_params = build_instrumentation_params(parsed_body)
+  def make_api_call(payload)
+    instrumentation_params = build_instrumentation_params(payload)
 
     instrument_llm_call(instrumentation_params) do
-      execute_ruby_llm_request(parsed_body)
+      execute_ruby_llm_request(payload)
     end
   end
 
-  def execute_ruby_llm_request(parsed_body)
-    messages = parsed_body['messages']
-    model = parsed_body['model']
+  def execute_ruby_llm_request(payload)
+    messages = payload['messages']
+    model = payload['model']
 
     Llm::Config.with_api_key(api_key, api_base: api_base) do |context|
       chat = context.chat(model: model)

lib/captain/label_suggestion_service.rb

@@ -33,7 +33,7 @@ class Captain::LabelSuggestionService < Captain::BaseEditorService
         },
         { role: 'user', content: content }
       ]
-    }.to_json
+    }
   end
 
   def labels_with_messages

lib/captain/reply_suggestion_service.rb

@@ -11,7 +11,7 @@ class Captain::ReplySuggestionService < Captain::BaseEditorService
       messages: [
         { role: 'system', content: prompt_from_file('reply') }
       ].concat(conversation_messages(in_array_format: true))
-    }.to_json
+    }
   end
 
   def conversation_messages(in_array_format: false)

lib/captain/rewrite_service.rb

@@ -37,14 +37,14 @@ class Captain::RewriteService < Captain::BaseEditorService
   private
 
   def call_llm_with_prompt(system_content, user_content = event['data']['content'])
-    body = {
+    payload = {
       model: GPT_MODEL,
       messages: [
         { role: 'system', content: system_content },
         { role: 'user', content: user_content }
       ]
-    }.to_json
-    make_api_call(body)
+    }
+    make_api_call(payload)
   end
 
   def render_liquid_template(template_content, variables = {})

lib/captain/summary_service.rb

@@ -12,7 +12,7 @@ class Captain::SummaryService < Captain::BaseEditorService
         { role: 'system', content: prompt_from_file('summary') },
         { role: 'user', content: conversation_messages }
       ]
-    }.to_json
+    }
   end
 
   def conversation_messages(in_array_format: false)