Avoid duplicate chat turn save if chat cancelled during final response

Save to conversation in normal flow should only be done if
interrupt wasn't triggered.

Saving conversations on interrupt is handled completely by the
disconnect monitor since the improvements to interrupt.

This abort is handled correctly for steps before final response. But
not if interrupt occurs while final response is being sent. This
changes checks for cancellation after final response send attempt and
avoids duplicate chat turn save.

src/khoj/routers/api_chat.py

@@ -1425,6 +1425,13 @@ async def event_generator(
                 logger.warning(f"Error during streaming. Stopping send: {e}")
             break
 
+    # Check if the user has disconnected
+    if cancellation_event.is_set():
+        logger.debug(f"Stopping LLM response to user {user} on {common.client} client.")
+        # Cancel the disconnect monitor task if it is still running
+        await cancel_disconnect_monitor()
+        return
+
     # Save conversation once finish streaming
     asyncio.create_task(
         save_to_conversation_log(
@@ -1450,16 +1457,16 @@ async def event_generator(
     )
 
     # Signal end of LLM response after the loop finishes
-    if not cancellation_event.is_set():
-        async for result in send_event(ChatEvent.END_LLM_RESPONSE, ""):
-            yield result
-        # Send Usage Metadata once llm interactions are complete
-        if tracer.get("usage"):
-            async for event in send_event(ChatEvent.USAGE, tracer.get("usage")):
-                yield event
-        async for result in send_event(ChatEvent.END_RESPONSE, ""):
-            yield result
-        logger.debug("Finished streaming response")
+    async for result in send_event(ChatEvent.END_LLM_RESPONSE, ""):
+        yield result
+
+    # Send Usage Metadata once llm interactions are complete
+    if tracer.get("usage"):
+        async for event in send_event(ChatEvent.USAGE, tracer.get("usage")):
+            yield event
+    async for result in send_event(ChatEvent.END_RESPONSE, ""):
+        yield result
+    logger.debug("Finished streaming response")
 
     # Cancel the disconnect monitor task if it is still running
     await cancel_disconnect_monitor()