diff --git a/app/app/v1alpha/app_public_service.proto b/app/app/v1alpha/app_public_service.proto
index 94513c24..bbc6b7e1 100644
--- a/app/app/v1alpha/app_public_service.proto
+++ b/app/app/v1alpha/app_public_service.proto
@@ -146,4 +146,16 @@ service AppPublicService {
     option (google.api.http) = {post: "/v1alpha/namespaces/{namespace_id}/apps/{app_id}/ai_assistant_playground/restart"};
     option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_operation) = {tags: "Playground"};
   }
+  // Chat
+  //
+  // Chat sends a message asynchronously and streams back the response.
+  // This method is intended for real-time conversation with a chatbot
+  // and the response needs to be processed incrementally.
+  rpc Chat(ChatRequest) returns (stream ChatResponse) {
+    option (google.api.http) = {
+      post: "/v1alpha/namespaces/{namespace_id}/apps/{app_id}/chat-stream"
+      body: "*"
+    };
+    option (grpc.gateway.protoc_gen_openapiv2.options.openapiv2_operation) = {tags: "App"};
+  }
 }
diff --git a/app/app/v1alpha/conversation.proto b/app/app/v1alpha/conversation.proto
index 4bf890ca..80086c56 100644
--- a/app/app/v1alpha/conversation.proto
+++ b/app/app/v1alpha/conversation.proto
@@ -2,8 +2,12 @@ syntax = "proto3";
 
 package app.app.v1alpha;
 
+// Artifact definitions
+import "artifact/artifact/v1alpha/chunk.proto";
+// Google API
 import "google/api/field_behavior.proto";
 // Protocol Buffers Well-Known Types
+import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";
 
 // Conversation represents a chat conversation
@@ -230,3 +234,26 @@ message DeleteMessageRequest {
 
 // DeleteMessageResponse is empty as no content needs to be returned
 message DeleteMessageResponse {}
+
+// ChatRequest represents a request to send a message
+// to a chatbot synchronously and streams back the results.
+message ChatRequest {
+  // Namespace ID
+  string namespace_id = 1 [(google.api.field_behavior) = REQUIRED];
+  // App ID
+  string app_id = 2 [(google.api.field_behavior) = REQUIRED];
+  // Catalog ID
+  string catalog_id = 3 [(google.api.field_behavior) = REQUIRED];
+  // Conversation UID
+  string conversation_uid = 4 [(google.api.field_behavior) = REQUIRED];
+  // User message
+  string message = 5 [(google.api.field_behavior) = REQUIRED];
+}
+
+// ChatResponse contains the chatbot response.
+message ChatResponse {
+  // Conversation responses.
+  repeated google.protobuf.Struct outputs = 1 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Reference chunks
+  repeated artifact.artifact.v1alpha.SimilarityChunk chunks = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+}