From 4a2eb54dc6bf943196be4fb515e6a9407a4db143 Mon Sep 17 00:00:00 2001
From: Luis Pater <webmaster@idotorg.org>
Date: Wed, 29 Jul 2026 23:47:37 +0800
Subject: [PATCH] feat(translator): group consecutive tool results in Claude
 request conversion

- Added logic to merge consecutive tool responses into a single user message for better grouping.
- Updated `ConvertOpenAIRequestToClaude` to track previous roles and adjust message blocks accordingly.
- Introduced a comprehensive test to validate tool result grouping behavior and content preservation.

Closes: #4656
---
 .../chat-completions/claude_openai_request.go | 10 ++-
 .../claude_openai_request_test.go             | 64 +++++++++++++++++++
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/internal/translator/claude/openai/chat-completions/claude_openai_request.go b/internal/translator/claude/openai/chat-completions/claude_openai_request.go
index e0957b2d..9c483598 100644
--- a/internal/translator/claude/openai/chat-completions/claude_openai_request.go
+++ b/internal/translator/claude/openai/chat-completions/claude_openai_request.go
@@ -165,6 +165,7 @@ func ConvertOpenAIRequestToClaude(modelName string, inputRawJSON []byte, stream
 	if messages := root.Get("messages"); messages.Exists() && messages.IsArray() {
 		systemBlocks := make([][]byte, 0)
 		messageBlocks := make([][]byte, 0)
+		previousRole := ""
 		messages.ForEach(func(_, message gjson.Result) bool {
 			role := message.Get("role").String()
 			contentResult := message.Get("content")
@@ -274,8 +275,15 @@ func ConvertOpenAIRequestToClaude(modelName string, inputRawJSON []byte, stream
 					msg, _ = sjson.SetBytes(msg, "content.0.content", toolResultContent)
 				}
 				msg = common.AttachMessageCacheControl(msg, message)
-				messageBlocks = append(messageBlocks, msg)
+				if previousRole == "tool" && len(messageBlocks) > 0 {
+					toolResult := gjson.GetBytes(msg, "content.0")
+					lastIdx := len(messageBlocks) - 1
+					messageBlocks[lastIdx], _ = sjson.SetRawBytes(messageBlocks[lastIdx], "content.-1", []byte(toolResult.Raw))
+				} else {
+					messageBlocks = append(messageBlocks, msg)
+				}
 			}
+			previousRole = role
 			return true
 		})
 
diff --git a/internal/translator/claude/openai/chat-completions/claude_openai_request_test.go b/internal/translator/claude/openai/chat-completions/claude_openai_request_test.go
index 801b8e39..7c19f246 100644
--- a/internal/translator/claude/openai/chat-completions/claude_openai_request_test.go
+++ b/internal/translator/claude/openai/chat-completions/claude_openai_request_test.go
@@ -44,6 +44,70 @@ func TestConvertOpenAIRequestToClaude_SanitizesToolCallIDsForClaude(t *testing.T
 	}
 }
 
+func TestConvertOpenAIRequestToClaude_GroupsConsecutiveParallelToolResults(t *testing.T) {
+	inputJSON := `{
+		"model": "gpt-4.1",
+		"messages": [
+			{"role": "user", "content": "Use both tools."},
+			{
+				"role": "assistant",
+				"content": "",
+				"tool_calls": [
+					{"id": "call_1", "type": "function", "function": {"name": "tool_a", "arguments": "{}"}},
+					{"id": "call_2", "type": "function", "function": {"name": "tool_b", "arguments": "{}"}}
+				]
+			},
+			{
+				"role": "tool",
+				"tool_call_id": "call_1",
+				"content": "one",
+				"cache_control": {"type": "ephemeral"}
+			},
+			{"role": "tool", "tool_call_id": "call_2", "content": "two"},
+			{"role": "assistant", "content": "Done."}
+		]
+	}`
+
+	result := ConvertOpenAIRequestToClaude("claude-sonnet-4-5", []byte(inputJSON), false)
+	resultJSON := gjson.ParseBytes(result)
+	messages := resultJSON.Get("messages").Array()
+
+	if len(messages) != 4 {
+		t.Fatalf("Expected 4 messages, got %d. Messages: %s", len(messages), resultJSON.Get("messages").Raw)
+	}
+	if got := messages[2].Get("role").String(); got != "user" {
+		t.Fatalf("Expected grouped tool result role %q, got %q", "user", got)
+	}
+	toolResults := messages[2].Get("content").Array()
+	if len(toolResults) != 2 {
+		t.Fatalf("Expected 2 grouped tool results, got %d. Content: %s", len(toolResults), messages[2].Get("content").Raw)
+	}
+	wants := []struct {
+		id      string
+		content string
+	}{
+		{id: "call_1", content: "one"},
+		{id: "call_2", content: "two"},
+	}
+	for i, want := range wants {
+		if got := toolResults[i].Get("type").String(); got != "tool_result" {
+			t.Fatalf("tool result %d type = %q, want tool_result", i, got)
+		}
+		if got := toolResults[i].Get("tool_use_id").String(); got != want.id {
+			t.Fatalf("tool result %d tool_use_id = %q, want %q", i, got, want.id)
+		}
+		if got := toolResults[i].Get("content").String(); got != want.content {
+			t.Fatalf("tool result %d content = %q, want %q", i, got, want.content)
+		}
+	}
+	if got := toolResults[0].Get("cache_control.type").String(); got != "ephemeral" {
+		t.Fatalf("first tool result cache_control.type = %q, want ephemeral", got)
+	}
+	if got := messages[3].Get("content.0.text").String(); got != "Done." {
+		t.Fatalf("following assistant message text = %q, want Done.", got)
+	}
+}
+
 func TestConvertOpenAIRequestToClaude_DropsTemperature(t *testing.T) {
 	inputJSON := `{
 		"model": "gpt-4.1",
-- 
2.51.2