From 70cb36852a507810f8b66baa16de5c09de06587e Mon Sep 17 00:00:00 2001
From: "a.bolonin" <andreybolonin1989@gmail.com>
Date: Mon, 2 Nov 2026 10:03:22 +0300
Subject: [PATCH] Avoid repeated array merges in prompt formatting

---
 .../Formatter/PromptResultFormatter.php       |  8 +++++++-
 .../Formatter/PromptResultFormatterTest.php   | 19 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/Capability/Formatter/PromptResultFormatter.php b/src/Capability/Formatter/PromptResultFormatter.php
index 207c7e26a..ad5356e4e 100644
--- a/src/Capability/Formatter/PromptResultFormatter.php
+++ b/src/Capability/Formatter/PromptResultFormatter.php
@@ -74,7 +74,13 @@ public function format(mixed $promptGenerationResult): array
                     if ($item instanceof PromptMessage) {
                         $result[] = $item;
                     } else {
-                        $result = array_merge($result, $this->format($item));
+                        foreach ($this->format($item) as $key => $message) {
+                            if (\is_int($key)) {
+                                $result[] = $message;
+                            } else {
+                                $result[$key] = $message;
+                            }
+                        }
                     }
                 }
 
diff --git a/tests/Unit/Capability/Formatter/PromptResultFormatterTest.php b/tests/Unit/Capability/Formatter/PromptResultFormatterTest.php
index 6a57c9907..6ac3a40fc 100644
--- a/tests/Unit/Capability/Formatter/PromptResultFormatterTest.php
+++ b/tests/Unit/Capability/Formatter/PromptResultFormatterTest.php
@@ -24,6 +24,25 @@
 
 class PromptResultFormatterTest extends TestCase
 {
+    public function testMixedMessagesPreserveNestedKeysAndOrder(): void
+    {
+        $first = new PromptMessage(Role::User, new TextContent('first'));
+        $second = new PromptMessage(Role::Assistant, new TextContent('second'));
+        $third = new PromptMessage(Role::User, new TextContent('third'));
+
+        $result = (new PromptResultFormatter())->format([
+            $first,
+            ['named' => $second, 8 => $first],
+            ['named' => $third, 5 => $second],
+        ]);
+
+        $this->assertSame([0, 'named', 1, 2], array_keys($result));
+        $this->assertSame($first, $result[0]);
+        $this->assertSame($third, $result['named']);
+        $this->assertSame($first, $result[1]);
+        $this->assertSame($second, $result[2]);
+    }
+
     public function testFormatPromptMessage(): void
     {
         $message = new PromptMessage(Role::User, new TextContent('hello'));