From aa704e9f389b09d2d6a5f66ccc23532150fffd11 Mon Sep 17 00:00:00 2001
From: Dario Gieselaar <dario.gieselaar@elastic.co>
Date: Wed, 21 Jun 2023 18:46:14 +0200
Subject: [PATCH] [Observability] Buffer partial chunks when streaming
 (#160124)

---
 .../create_co_pilot_service.ts                | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/x-pack/plugins/observability/public/context/co_pilot_context/create_co_pilot_service.ts b/x-pack/plugins/observability/public/context/co_pilot_context/create_co_pilot_service.ts
index 07b1e3b33cf27..c493bff4e1df8 100644
--- a/x-pack/plugins/observability/public/context/co_pilot_context/create_co_pilot_service.ts
+++ b/x-pack/plugins/observability/public/context/co_pilot_context/create_co_pilot_service.ts
@@ -48,6 +48,8 @@ export function createCoPilotService({ enabled, http }: { enabled: boolean; http
 
             const chunks: CreateChatCompletionResponseChunk[] = [];
 
+            let prev: string = '';
+
             function read() {
               reader!.read().then(({ done, value }) => {
                 try {
@@ -61,10 +63,20 @@ export function createCoPilotService({ enabled, http }: { enabled: boolean; http
                     return;
                   }
 
-                  const lines = decoder
-                    .decode(value)
-                    .trim()
-                    .split('\n')
+                  let lines = (prev + decoder.decode(value)).split('\n');
+
+                  const lastLine = lines[lines.length - 1];
+
+                  const isPartialChunk = !!lastLine && lastLine !== 'data: [DONE]';
+
+                  if (isPartialChunk) {
+                    prev = lastLine;
+                    lines.pop();
+                  } else {
+                    prev = '';
+                  }
+
+                  lines = lines
                     .map((str) => str.substr(6))
                     .filter((str) => !!str && str !== '[DONE]');