feat(translator): enhance content block handling and add stream-specific test

- Refactored content block start/stop logic into `startCodexTextBlock` and `stopCodexTextBlock` for better readability and reusability.
- Updated logic to ensure proper handling of "output_text" block events to avoid ghost stop emissions.
- Added `TestConvertCodexResponseToClaude_StreamTextBeforeToolCallsDoesNotEmitGhostStop` to validate content block start/stop behavior in streamed responses.

Author: luispater

internal/translator/codex/claude/codex_claude_response.go

@@ -104,25 +104,22 @@ func ConvertCodexResponseToClaude(_ context.Context, _ string, originalRequestRa
 	case "response.reasoning_summary_part.done":
 		params.ThinkingStopPending = true
 	case "response.content_part.added":
-		template = []byte(`{"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}`)
-		template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
-		params.TextBlockOpen = true
-
-		output = translatorcommon.AppendSSEEventBytes(output, "content_block_start", template, 2)
+		if rootResult.Get("part.type").String() == "output_text" {
+			output = append(output, startCodexTextBlock(params)...)
+		}
 	case "response.output_text.delta":
 		params.HasTextDelta = true
+		output = append(output, finalizeCodexThinkingBlock(params)...)
+		output = append(output, startCodexTextBlock(params)...)
 		template = []byte(`{"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":""}}`)
 		template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
 		template, _ = sjson.SetBytes(template, "delta.text", rootResult.Get("delta").String())
 
 		output = translatorcommon.AppendSSEEventBytes(output, "content_block_delta", template, 2)
 	case "response.content_part.done":
-		template = []byte(`{"type":"content_block_stop","index":0}`)
-		template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
-		params.TextBlockOpen = false
-		params.BlockIndex++
-
-		output = translatorcommon.AppendSSEEventBytes(output, "content_block_stop", template, 2)
+		if rootResult.Get("part.type").String() == "output_text" {
+			output = append(output, stopCodexTextBlock(params)...)
+		}
 	case "response.web_search_call.searching", "response.web_search_call.completed", "response.web_search_call.in_progress":
 		// Wait for populated web_search_call items on output_item.done.
 	case "response.completed", "response.incomplete":
@@ -145,6 +142,7 @@ func ConvertCodexResponseToClaude(_ context.Context, _ string, originalRequestRa
 		switch itemType {
 		case "function_call":
 			output = append(output, finalizeCodexThinkingBlock(params)...)
+			output = append(output, stopCodexTextBlock(params)...)
 			params.HasToolCall = true
 			params.HasReceivedArgumentsDelta = false
 			template = []byte(`{"type":"content_block_start","index":0,"content_block":{"type":"tool_use","id":"","name":"","input":{}}}`)
@@ -199,24 +197,15 @@ func ConvertCodexResponseToClaude(_ context.Context, _ string, originalRequestRa
 			}
 
 			output = append(output, finalizeCodexThinkingBlock(params)...)
-			if !params.TextBlockOpen {
-				template = []byte(`{"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}`)
-				template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
-				params.TextBlockOpen = true
-				output = translatorcommon.AppendSSEEventBytes(output, "content_block_start", template, 2)
-			}
+			output = append(output, startCodexTextBlock(params)...)
 
 			template = []byte(`{"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":""}}`)
 			template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
 			template, _ = sjson.SetBytes(template, "delta.text", text)
 			output = translatorcommon.AppendSSEEventBytes(output, "content_block_delta", template, 2)
 
-			template = []byte(`{"type":"content_block_stop","index":0}`)
-			template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
-			params.TextBlockOpen = false
-			params.BlockIndex++
+			output = append(output, stopCodexTextBlock(params)...)
 			params.HasTextDelta = true
-			output = translatorcommon.AppendSSEEventBytes(output, "content_block_stop", template, 2)
 		case "function_call":
 			template = []byte(`{"type":"content_block_stop","index":0}`)
 			template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
@@ -517,6 +506,31 @@ func ClaudeTokenCount(_ context.Context, count int64) []byte {
 	return translatorcommon.ClaudeInputTokensJSON(count)
 }
 
+func startCodexTextBlock(params *ConvertCodexResponseToClaudeParams) []byte {
+	if params.TextBlockOpen {
+		return nil
+	}
+
+	template := []byte(`{"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}`)
+	template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
+	params.TextBlockOpen = true
+
+	return translatorcommon.AppendSSEEventBytes(nil, "content_block_start", template, 2)
+}
+
+func stopCodexTextBlock(params *ConvertCodexResponseToClaudeParams) []byte {
+	if !params.TextBlockOpen {
+		return nil
+	}
+
+	template := []byte(`{"type":"content_block_stop","index":0}`)
+	template, _ = sjson.SetBytes(template, "index", params.BlockIndex)
+	params.TextBlockOpen = false
+	params.BlockIndex++
+
+	return translatorcommon.AppendSSEEventBytes(nil, "content_block_stop", template, 2)
+}
+
 func startCodexThinkingBlock(params *ConvertCodexResponseToClaudeParams) []byte {
 	if params.ThinkingBlockOpen {
 		return nil

internal/translator/codex/claude/codex_claude_response_test.go

@@ -472,6 +472,65 @@ func TestConvertCodexResponseToClaudeNonStream_ThinkingIncludesSignature(t *test
 	}
 }
 
+func TestConvertCodexResponseToClaude_StreamTextBeforeToolCallsDoesNotEmitGhostStop(t *testing.T) {
+	ctx := context.Background()
+	originalRequest := []byte(`{"tools":[{"name":"Read","description":"read"}]}`)
+	var param any
+
+	chunks := [][]byte{
+		[]byte(`data: {"type":"response.created","response":{"id":"resp_1","model":"grok-composer-2.5-fast"}}`),
+		[]byte(`data: {"type":"response.output_item.added","item":{"type":"message","status":"in_progress"},"output_index":1}`),
+		[]byte(`data: {"type":"response.content_part.added","part":{"type":"output_text"},"content_index":0,"output_index":1}`),
+		[]byte(`data: {"type":"response.output_text.delta","delta":"查看项目的 README 和核心入口，以便准确说明项目用途。\n","output_index":1}`),
+		[]byte(`data: {"type":"response.output_item.added","item":{"type":"function_call","call_id":"call_a","name":"Read","status":"in_progress"},"output_index":2}`),
+		[]byte(`data: {"type":"response.function_call_arguments.delta","delta":"{\"path\":\"/tmp/README.md\"}","output_index":2}`),
+		[]byte(`data: {"type":"response.function_call_arguments.done","arguments":"{\"path\":\"/tmp/README.md\"}","output_index":2}`),
+		[]byte(`data: {"type":"response.output_item.done","item":{"type":"function_call","call_id":"call_a","name":"Read","arguments":"{\"path\":\"/tmp/README.md\"}"},"output_index":2}`),
+		[]byte(`data: {"type":"response.output_item.added","item":{"type":"function_call","call_id":"call_b","name":"Read","status":"in_progress"},"output_index":3}`),
+		[]byte(`data: {"type":"response.function_call_arguments.delta","delta":"{\"path\":\"/tmp/main.go\"}","output_index":3}`),
+		[]byte(`data: {"type":"response.content_part.done","part":{"type":"output_text"},"content_index":0,"output_index":1}`),
+		[]byte(`data: {"type":"response.output_item.done","item":{"type":"message","status":"completed"},"output_index":1}`),
+		[]byte(`data: {"type":"response.function_call_arguments.done","arguments":"{\"path\":\"/tmp/main.go\"}","output_index":3}`),
+		[]byte(`data: {"type":"response.output_item.done","item":{"type":"function_call","call_id":"call_b","name":"Read","arguments":"{\"path\":\"/tmp/main.go\"}"},"output_index":3}`),
+		[]byte(`data: {"type":"response.completed","response":{"usage":{"input_tokens":1,"output_tokens":1}}}`),
+	}
+
+	var outputs [][]byte
+	for _, chunk := range chunks {
+		outputs = append(outputs, ConvertCodexResponseToClaude(ctx, "", originalRequest, nil, chunk, &param)...)
+	}
+
+	var startIndices []int64
+	var stopIndices []int64
+	for _, out := range outputs {
+		for _, line := range strings.Split(string(out), "\n") {
+			if !strings.HasPrefix(line, "data: ") {
+				continue
+			}
+			data := gjson.Parse(strings.TrimPrefix(line, "data: "))
+			switch data.Get("type").String() {
+			case "content_block_start":
+				startIndices = append(startIndices, data.Get("index").Int())
+			case "content_block_stop":
+				stopIndices = append(stopIndices, data.Get("index").Int())
+			}
+		}
+	}
+
+	if len(startIndices) != 3 {
+		t.Fatalf("expected 3 content_block_start events (text + 2 tools), got %v", startIndices)
+	}
+	if len(stopIndices) != 3 {
+		t.Fatalf("expected 3 content_block_stop events, got %v", stopIndices)
+	}
+	if startIndices[0] != 0 || startIndices[1] != 1 || startIndices[2] != 2 {
+		t.Fatalf("unexpected start indices: %v", startIndices)
+	}
+	if stopIndices[0] != 0 || stopIndices[1] != 1 || stopIndices[2] != 2 {
+		t.Fatalf("unexpected stop indices: %v", stopIndices)
+	}
+}
+
 func TestConvertCodexResponseToClaude_StreamEmptyOutputUsesOutputItemDoneMessageFallback(t *testing.T) {
 	ctx := context.Background()
 	originalRequest := []byte(`{"tools":[]}`)