fix: normalize web_search_preview for codex responses

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

@@ -39,6 +39,7 @@ func ConvertOpenAIResponsesRequestToCodex(modelName string, inputRawJSON []byte,
 
 	// Convert role "system" to "developer" in input array to comply with Codex API requirements.
 	rawJSON = convertSystemRoleToDeveloper(rawJSON)
+	rawJSON = normalizeCodexBuiltinTools(rawJSON)
 
 	return rawJSON
 }
@@ -82,3 +83,26 @@ func convertSystemRoleToDeveloper(rawJSON []byte) []byte {
 
 	return result
 }
+
+// normalizeCodexBuiltinTools rewrites legacy/preview built-in tool variants to the
+// stable names expected by the current Codex upstream.
+func normalizeCodexBuiltinTools(rawJSON []byte) []byte {
+	result := rawJSON
+
+	tools := gjson.GetBytes(result, "tools")
+	if tools.IsArray() {
+		toolArray := tools.Array()
+		for i := 0; i < len(toolArray); i++ {
+			typePath := fmt.Sprintf("tools.%d.type", i)
+			if gjson.GetBytes(result, typePath).String() == "web_search_preview" {
+				result, _ = sjson.SetBytes(result, typePath, "web_search")
+			}
+		}
+	}
+
+	if gjson.GetBytes(result, "tool_choice.type").String() == "web_search_preview" {
+		result, _ = sjson.SetBytes(result, "tool_choice.type", "web_search")
+	}
+
+	return result
+}

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

@@ -264,6 +264,26 @@ func TestConvertSystemRoleToDeveloper_AssistantRole(t *testing.T) {
 	}
 }
 
+func TestConvertOpenAIResponsesRequestToCodex_NormalizesWebSearchPreview(t *testing.T) {
+	inputJSON := []byte(`{
+		"model": "gpt-5.4-mini",
+		"input": "find latest OpenAI model news",
+		"tools": [
+			{"type": "web_search_preview"}
+		],
+		"tool_choice": {"type": "web_search_preview"}
+	}`)
+
+	output := ConvertOpenAIResponsesRequestToCodex("gpt-5.4-mini", inputJSON, false)
+
+	if got := gjson.GetBytes(output, "tools.0.type").String(); got != "web_search" {
+		t.Fatalf("tools.0.type = %q, want %q: %s", got, "web_search", string(output))
+	}
+	if got := gjson.GetBytes(output, "tool_choice.type").String(); got != "web_search" {
+		t.Fatalf("tool_choice.type = %q, want %q: %s", got, "web_search", string(output))
+	}
+}
+
 func TestUserFieldDeletion(t *testing.T) {
 	inputJSON := []byte(`{  
 		"model": "gpt-5.2",