From b60540679170713ca91b3d04c6f6bb1a524b81dd Mon Sep 17 00:00:00 2001
From: Noah Cristino <noah.cristino@mail.utoronto.ca>
Date: Sat, 30 Nov 2024 10:48:09 -0500
Subject: [PATCH] Move concatSupported to RunnableConfig and handle when it is
 false

---
 langchain-core/src/runnables/base.ts  | 4 +++-
 langchain-core/src/runnables/types.ts | 5 +++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/langchain-core/src/runnables/base.ts b/langchain-core/src/runnables/base.ts
index 1cab402513ec..f6c6a387585d 100644
--- a/langchain-core/src/runnables/base.ts
+++ b/langchain-core/src/runnables/base.ts
@@ -1989,7 +1989,7 @@ export class RunnableSequence<
       otherOptions?.runName
     );
     const steps = [this.first, ...this.middle, this.last];
-    let concatSupported = true;
+    let concatSupported = options?.concatSupported ?? true;
     let finalOutput;
     async function* inputGenerator() {
       yield input;
@@ -2029,6 +2029,8 @@ export class RunnableSequence<
               concatSupported = false;
             }
           }
+        } else {
+          finalOutput = chunk;
         }
       }
     } catch (e) {
diff --git a/langchain-core/src/runnables/types.ts b/langchain-core/src/runnables/types.ts
index f40d80ee3831..499c5d046f28 100644
--- a/langchain-core/src/runnables/types.ts
+++ b/langchain-core/src/runnables/types.ts
@@ -107,4 +107,9 @@ export interface RunnableConfig<
    * @see https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal
    */
   signal?: AbortSignal;
+
+  /**
+   * Whether to concatenate the stream of outputs into a single output or not.
+   */
+  concatSupported?: boolean;
 }