feat: add chat_template field in tabby.json

crates/tabby/src/serve/chat.rs

@@ -21,10 +21,10 @@ pub struct ChatState {
 }
 
 impl ChatState {
-    pub fn new(engine: Arc<Box<dyn TextGeneration>>, prompt_template: String) -> Self {
+    pub fn new(engine: Arc<Box<dyn TextGeneration>>, chat_template: String) -> Self {
         Self {
             engine,
-            prompt_builder: ChatPromptBuilder::new(prompt_template),
+            prompt_builder: ChatPromptBuilder::new(chat_template),
         }
     }
 }

crates/tabby/src/serve/engine.rs

@@ -21,12 +21,18 @@ fn get_param(params: &Value, key: &str) -> String {
 pub fn create_engine(
     model: &str,
     args: &crate::serve::ServeArgs,
-) -> (Box<dyn TextGeneration>, Option<String>) {
+) -> (Box<dyn TextGeneration>, EngineInfo) {
     if args.device != super::Device::ExperimentalHttp {
         let model_dir = get_model_dir(model);
         let metadata = read_metadata(&model_dir);
         let engine = create_local_engine(args, &model_dir, &metadata);
-        (engine, metadata.prompt_template)
+        (
+            engine,
+            EngineInfo {
+                prompt_template: metadata.prompt_template,
+                chat_template: metadata.chat_template,
+            },
+        )
     } else {
         let params: Value = serdeconv::from_json_str(model).expect("Failed to parse model string");
 
@@ -39,7 +45,13 @@ pub fn create_engine(
                 api_endpoint.as_str(),
                 authorization.as_str(),
             ));
-            (engine, Some(VertexAIEngine::prompt_template()))
+            (
+                engine,
+                EngineInfo {
+                    prompt_template: Some(VertexAIEngine::prompt_template()),
+                    chat_template: None,
+                },
+            )
         } else if kind == "fastchat" {
             let model_name = get_param(&params, "model_name");
             let api_endpoint = get_param(&params, "api_endpoint");
@@ -49,13 +61,24 @@ pub fn create_engine(
                 model_name.as_str(),
                 authorization.as_str(),
             ));
-            (engine, Some(FastChatEngine::prompt_template()))
+            (
+                engine,
+                EngineInfo {
+                    prompt_template: Some(FastChatEngine::prompt_template()),
+                    chat_template: None,
+                },
+            )
         } else {
             fatal!("Only vertex_ai and fastchat are supported for http backend");
         }
     }
 }
 
+pub struct EngineInfo {
+    pub prompt_template: Option<String>,
+    pub chat_template: Option<String>,
+}
+
 #[cfg(not(all(target_os = "macos", target_arch = "aarch64")))]
 fn create_local_engine(
     args: &crate::serve::ServeArgs,
@@ -121,6 +144,7 @@ fn get_model_dir(model: &str) -> ModelDir {
 struct Metadata {
     auto_model: String,
     prompt_template: Option<String>,
+    chat_template: Option<String>,
 }
 
 fn read_metadata(model_dir: &ModelDir) -> Metadata {

crates/tabby/src/serve/mod.rs

@@ -25,7 +25,10 @@ use tracing::{info, warn};
 use utoipa::{openapi::ServerBuilder, OpenApi};
 use utoipa_swagger_ui::SwaggerUi;
 
-use self::{engine::create_engine, health::HealthState};
+use self::{
+    engine::{create_engine, EngineInfo},
+    health::HealthState,
+};
 use crate::fatal;
 
 #[derive(OpenApi)]
@@ -188,19 +191,24 @@ pub async fn main(config: &Config, args: &ServeArgs) {
 
 fn api_router(args: &ServeArgs, config: &Config) -> Router {
     let completion_state = {
-        let (engine, prompt_template) = create_engine(&args.model, args);
+        let (
+            engine,
+            EngineInfo {
+                prompt_template, ..
+            },
+        ) = create_engine(&args.model, args);
         let engine = Arc::new(engine);
         let state = completions::CompletionState::new(engine.clone(), prompt_template, config);
         Arc::new(state)
     };
 
     let chat_state = if let Some(chat_model) = &args.chat_model {
-        let (engine, prompt_template) = create_engine(chat_model, args);
-        let Some(prompt_template) = prompt_template else {
+        let (engine, EngineInfo { chat_template, .. }) = create_engine(chat_model, args);
+        let Some(chat_template) = chat_template else {
             panic!("Chat model requires specifying prompt template");
         };
         let engine = Arc::new(engine);
-        let state = chat::ChatState::new(engine, prompt_template);
+        let state = chat::ChatState::new(engine, chat_template);
         Some(Arc::new(state))
     } else {
         None