feat: add chat_template_kwargs param to v1/chat/completion (#3016)

Signed-off-by: Chi McIsaac <chixie.mcisaac@gmail.com>

lib/llm/src/entrypoint/input/batch.rs

@@ -228,6 +228,7 @@ async fn evaluate(
         inner,
         common: Default::default(),
         nvext: None,
+        chat_template_args: None,
     };
     let mut stream = engine.generate(Context::new(req)).await?;
     let mut output = String::new();

lib/llm/src/entrypoint/input/text.rs

@@ -111,6 +111,7 @@ async fn main_loop(
             inner,
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
 
         // Call the model

lib/llm/src/http/service/openai.rs

@@ -1350,6 +1350,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_required_fields(&request);
         assert!(result.is_err());
@@ -1377,6 +1378,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_required_fields(&request);
         assert!(result.is_ok());
@@ -1549,6 +1551,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
 
         let result = validate_chat_completion_fields_generic(&request);
@@ -1576,6 +1579,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_fields_generic(&request);
         assert!(result.is_err());
@@ -1602,6 +1606,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_fields_generic(&request);
         assert!(result.is_err());
@@ -1628,6 +1633,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_fields_generic(&request);
         assert!(result.is_err());
@@ -1656,6 +1662,7 @@ mod tests {
                 .build()
                 .unwrap(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_fields_generic(&request);
         assert!(result.is_err());
@@ -1682,6 +1689,7 @@ mod tests {
             },
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         };
         let result = validate_chat_completion_fields_generic(&request);
         assert!(result.is_err());

lib/llm/src/preprocessor/prompt.rs

@@ -20,6 +20,7 @@
 
 use anyhow::Result;
 use minijinja::value::Value;
+use std::collections::HashMap;
 use std::sync::Arc;
 
 mod template;
@@ -57,6 +58,11 @@ pub trait OAIChatLikeRequest {
 
     fn should_add_generation_prompt(&self) -> bool;
 
+    /// Optional additional args to merge into the chat template context
+    fn chat_template_args(&self) -> Option<&HashMap<String, serde_json::Value>> {
+        None
+    }
+
     /// Returns the type of input for the prompt. Default is Text.
     fn prompt_input_type(&self) -> PromptInput {
         PromptInput::Text(TextInput::Single(String::new()))

lib/llm/src/preprocessor/prompt/template/oai.rs

@@ -114,6 +114,10 @@ impl OAIChatLikeRequest for NvCreateChatCompletionRequest {
     fn extract_text(&self) -> Option<TextInput> {
         Some(TextInput::Single(String::new()))
     }
+
+    fn chat_template_args(&self) -> Option<&std::collections::HashMap<String, serde_json::Value>> {
+        self.chat_template_args.as_ref()
+    }
 }
 
 impl OAIChatLikeRequest for NvCreateCompletionRequest {
@@ -207,9 +211,13 @@ impl OAIPromptFormatter for HfTokenizerConfigJsonFormatter {
             ..mixins
         };
 
-        let ctx = context! { ..ctx, ..context! {
-
-        }};
+        // Merge any additional args into the context last so they take precedence
+        let ctx = if let Some(args) = req.chat_template_args() {
+            let extra = Value::from_serialize(args);
+            context! { ..ctx, ..extra }
+        } else {
+            ctx
+        };
 
         let tmpl: minijinja::Template<'_, '_> = if has_tools {
             self.env.get_template("tool_use")?

lib/llm/src/protocols/openai/chat_completions.rs

@@ -41,6 +41,10 @@ pub struct NvCreateChatCompletionRequest {
 
     #[serde(skip_serializing_if = "Option::is_none")]
     pub nvext: Option<NvExt>,
+
+    /// Extra args to pass to the chat template rendering context
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub chat_template_args: Option<std::collections::HashMap<String, serde_json::Value>>,
 }
 
 /// A response structure for unary chat completion responses, embedding OpenAI's

lib/llm/src/protocols/openai/responses.rs

@@ -175,6 +175,7 @@ impl TryFrom<NvCreateResponse> for NvCreateChatCompletionRequest {
             },
             common: Default::default(),
             nvext: resp.nvext,
+            chat_template_args: None,
         })
     }
 }

lib/llm/tests/http-service.rs

@@ -768,6 +768,7 @@ async fn test_nv_custom_client() {
         inner: inner_request,
         common: Default::default(),
         nvext: None,
+        chat_template_args: None,
     };
 
     let result = nv_custom_client.chat_stream(request).await;
@@ -807,6 +808,7 @@ async fn test_nv_custom_client() {
         inner: inner_request,
         common: Default::default(),
         nvext: None,
+        chat_template_args: None,
     };
 
     let result = nv_custom_client.chat_stream(request).await;
@@ -847,6 +849,7 @@ async fn test_nv_custom_client() {
         inner: inner_request,
         common: Default::default(),
         nvext: None,
+        chat_template_args: None,
     };
 
     let result = nv_custom_client

lib/llm/tests/preprocessor.rs

@@ -270,6 +270,7 @@ impl Request {
             inner,
             common: Default::default(),
             nvext: None,
+            chat_template_args: None,
         }
     }
 }

lib/llm/tests/test_common_ext.rs

@@ -67,6 +67,7 @@ fn test_sampling_parameters_include_stop_str_in_output_extraction() {
             .build()
             .unwrap(),
         nvext: None,
+        chat_template_args: None,
     };
 
     let sampling = request.extract_sampling_options().unwrap();
@@ -327,6 +328,7 @@ fn test_serialization_preserves_structure() {
             ignore_eos: Some(false),
             ..Default::default()
         }),
+        chat_template_args: None,
     };
 
     let json = serde_json::to_value(&request).unwrap();
@@ -376,6 +378,7 @@ fn test_sampling_parameters_extraction() {
             .build()
             .unwrap(),
         nvext: None,
+        chat_template_args: None,
     };
 
     let sampling_options = request.extract_sampling_options().unwrap();

lib/llm/tests/test_streaming_usage.rs

@@ -146,6 +146,7 @@ fn create_chat_request(include_usage: Option<bool>) -> NvCreateChatCompletionReq
         inner,
         common: Default::default(),
         nvext: None,
+        chat_template_args: None,
     }
 }