refactor: standardize dataTag processing across response translators

- Unified `dataTag` initialization by removing spaces after `data:`.
- Replaced manual slicing with `bytes.TrimSpace` for consistent and robust handling of JSON payloads.

internal/translator/claude/gemini/claude_gemini_response.go

@@ -17,7 +17,7 @@ import (
 )
 
 var (
-	dataTag = []byte("data: ")
+	dataTag = []byte("data:")
 )
 
 // ConvertAnthropicResponseToGeminiParams holds parameters for response conversion
@@ -64,7 +64,7 @@ func ConvertClaudeResponseToGemini(_ context.Context, modelName string, original
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 	root := gjson.ParseBytes(rawJSON)
 	eventType := root.Get("type").String()
@@ -336,7 +336,7 @@ func ConvertClaudeResponseToGeminiNonStream(_ context.Context, modelName string,
 		line := scanner.Bytes()
 		// log.Debug(string(line))
 		if bytes.HasPrefix(line, dataTag) {
-			jsonData := line[6:]
+			jsonData := bytes.TrimSpace(line[5:])
 			streamingEvents = append(streamingEvents, jsonData)
 		}
 	}

internal/translator/claude/openai/chat-completions/claude_openai_response.go

@@ -18,7 +18,7 @@ import (
 )
 
 var (
-	dataTag = []byte("data: ")
+	dataTag = []byte("data:")
 )
 
 // ConvertAnthropicResponseToOpenAIParams holds parameters for response conversion
@@ -62,7 +62,7 @@ func ConvertClaudeResponseToOpenAI(_ context.Context, modelName string, original
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 	root := gjson.ParseBytes(rawJSON)
 	eventType := root.Get("type").String()
@@ -289,7 +289,7 @@ func ConvertClaudeResponseToOpenAINonStream(_ context.Context, _ string, origina
 		if !bytes.HasPrefix(line, dataTag) {
 			continue
 		}
-		chunks = append(chunks, line[6:])
+		chunks = append(chunks, bytes.TrimSpace(rawJSON[5:]))
 	}
 
 	// Base OpenAI non-streaming response template

internal/translator/claude/openai/responses/claude_openai-responses_response.go

@@ -34,7 +34,7 @@ type claudeToResponsesState struct {
 	ReasoningIndex     int
 }
 
-var dataTag = []byte("data: ")
+var dataTag = []byte("data:")
 
 func emitEvent(event string, payload string) string {
 	return fmt.Sprintf("event: %s\ndata: %s\n\n", event, payload)
@@ -51,7 +51,7 @@ func ConvertClaudeResponseToOpenAIResponses(ctx context.Context, modelName strin
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 	root := gjson.ParseBytes(rawJSON)
 	ev := root.Get("type").String()
 	var out []string

internal/translator/codex/claude/codex_claude_response.go

@@ -16,7 +16,7 @@ import (
 )
 
 var (
-	dataTag = []byte("data: ")
+	dataTag = []byte("data:")
 )
 
 // ConvertCodexResponseToClaude performs sophisticated streaming response format conversion.
@@ -45,7 +45,7 @@ func ConvertCodexResponseToClaude(_ context.Context, _ string, originalRequestRa
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 	output := ""
 	rootResult := gjson.ParseBytes(rawJSON)

internal/translator/codex/gemini/codex_gemini_response.go

@@ -16,7 +16,7 @@ import (
 )
 
 var (
-	dataTag = []byte("data: ")
+	dataTag = []byte("data:")
 )
 
 // ConvertCodexResponseToGeminiParams holds parameters for response conversion.
@@ -53,7 +53,7 @@ func ConvertCodexResponseToGemini(_ context.Context, modelName string, originalR
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 	rootResult := gjson.ParseBytes(rawJSON)
 	typeResult := rootResult.Get("type")
@@ -161,7 +161,7 @@ func ConvertCodexResponseToGeminiNonStream(_ context.Context, modelName string,
 		if !bytes.HasPrefix(line, dataTag) {
 			continue
 		}
-		rawJSON = line[6:]
+		rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 		rootResult := gjson.ParseBytes(rawJSON)
 

internal/translator/codex/openai/chat-completions/codex_openai_response.go

@@ -16,7 +16,7 @@ import (
 )
 
 var (
-	dataTag = []byte("data: ")
+	dataTag = []byte("data:")
 )
 
 // ConvertCliToOpenAIParams holds parameters for response conversion.
@@ -54,7 +54,7 @@ func ConvertCodexResponseToOpenAI(_ context.Context, modelName string, originalR
 	if !bytes.HasPrefix(rawJSON, dataTag) {
 		return []string{}
 	}
-	rawJSON = rawJSON[6:]
+	rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 	// Initialize the OpenAI SSE template.
 	template := `{"id":"","object":"chat.completion.chunk","created":12345,"model":"model","choices":[{"index":0,"delta":{"role":null,"content":null,"reasoning_content":null,"tool_calls":null},"finish_reason":null,"native_finish_reason":null}]}`
@@ -175,7 +175,7 @@ func ConvertCodexResponseToOpenAINonStream(_ context.Context, _ string, original
 		if !bytes.HasPrefix(line, dataTag) {
 			continue
 		}
-		rawJSON = line[6:]
+		rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 		rootResult := gjson.ParseBytes(rawJSON)
 		// Verify this is a response.completed event

internal/translator/codex/openai/responses/codex_openai-responses_response.go

@@ -13,8 +13,8 @@ import (
 // ConvertCodexResponseToOpenAIResponses converts OpenAI Chat Completions streaming chunks
 // to OpenAI Responses SSE events (response.*).
 func ConvertCodexResponseToOpenAIResponses(ctx context.Context, modelName string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, param *any) []string {
-	if bytes.HasPrefix(rawJSON, []byte("data: ")) {
-		rawJSON = rawJSON[6:]
+	if bytes.HasPrefix(rawJSON, []byte("data:")) {
+		rawJSON = bytes.TrimSpace(rawJSON[5:])
 		if typeResult := gjson.GetBytes(rawJSON, "type"); typeResult.Exists() {
 			typeStr := typeResult.String()
 			if typeStr == "response.created" || typeStr == "response.in_progress" || typeStr == "response.completed" {
@@ -32,14 +32,14 @@ func ConvertCodexResponseToOpenAIResponsesNonStream(_ context.Context, modelName
 	scanner := bufio.NewScanner(bytes.NewReader(rawJSON))
 	buffer := make([]byte, 10240*1024)
 	scanner.Buffer(buffer, 10240*1024)
-	dataTag := []byte("data: ")
+	dataTag := []byte("data:")
 	for scanner.Scan() {
 		line := scanner.Bytes()
 
 		if !bytes.HasPrefix(line, dataTag) {
 			continue
 		}
-		rawJSON = line[6:]
+		rawJSON = bytes.TrimSpace(rawJSON[5:])
 
 		rootResult := gjson.ParseBytes(rawJSON)
 		// Verify this is a response.completed event