fix: return actual source nodes with compact and refine response synt…

…hesizer

Before we were only returning the packed text chunks in
EngineResponse.sourceNodes for this response synthesizer. This is
different than how every other synthesizer works.

.changeset/new-cups-dress.md

@@ -0,0 +1,5 @@
+---
+"@llamaindex/core": patch
+---
+
+The compact and refine response synthesizer (retrieved by using `getResponseSynthesizer('compact')`) has been fixed to return the original source nodes that were provided to it in its response. Previous to this it was returning the compacted text chunk documents.

packages/core/src/response-synthesizers/factory.ts

@@ -77,6 +77,16 @@ class Refine extends BaseSynthesizer {
     }
   }
 
+  async getResponse(
+    query: MessageContent,
+    nodes: NodeWithScore[],
+    stream: true,
+  ): Promise<AsyncIterable<EngineResponse>>;
+  async getResponse(
+    query: MessageContent,
+    nodes: NodeWithScore[],
+    stream: false,
+  ): Promise<EngineResponse>;
   async getResponse(
     query: MessageContent,
     nodes: NodeWithScore[],
@@ -197,6 +207,16 @@ class Refine extends BaseSynthesizer {
  * CompactAndRefine is a slight variation of Refine that first compacts the text chunks into the smallest possible number of chunks.
  */
 class CompactAndRefine extends Refine {
+  async getResponse(
+    query: MessageContent,
+    nodes: NodeWithScore[],
+    stream: true,
+  ): Promise<AsyncIterable<EngineResponse>>;
+  async getResponse(
+    query: MessageContent,
+    nodes: NodeWithScore[],
+    stream: false,
+  ): Promise<EngineResponse>;
   async getResponse(
     query: MessageContent,
     nodes: NodeWithScore[],
@@ -216,17 +236,24 @@ class CompactAndRefine extends Refine {
     const newTexts = this.promptHelper.repack(maxPrompt, textChunks);
     const newNodes = newTexts.map((text) => new TextNode({ text }));
     if (stream) {
-      return super.getResponse(
+      const streamResponse = await super.getResponse(
         query,
         newNodes.map((node) => ({ node })),
         true,
       );
+      return streamConverter(streamResponse, (chunk) => {
+        chunk.sourceNodes = nodes;
+        return chunk;
+      });
     }
-    return super.getResponse(
+
+    const originalResponse = await super.getResponse(
       query,
       newNodes.map((node) => ({ node })),
       false,
     );
+    originalResponse.sourceNodes = nodes;
+    return originalResponse;
   }
 }