fix: restore payment account details

internal/config/config_test.go

@@ -1,6 +1,10 @@
 package config
 
-import "testing"
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
 
 func TestDefaultConfigUsesOlonsAdmin(t *testing.T) {
 	cfg := defaultConfig()
@@ -17,6 +21,24 @@ func TestConfigRejectsOtherDatabase(t *testing.T) {
 	}
 }
 
+func TestLoadPreservesConfiguredFinanceKeyAsLegacyWhenEnvironmentOverridesIt(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "config.json")
+	data := []byte(`{"auth":{"finance_master_key":"legacy-finance-master-key-with-at-least-32-characters"}}`)
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("OLONS_SERVER_CONFIG", path)
+	t.Setenv("OLONS_SERVER_FINANCE_MASTER_KEY", "current-finance-master-key-with-at-least-32-characters")
+	cfg, err := Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cfg.Auth.FinanceLegacyMasterKeys) != 1 ||
+		cfg.Auth.FinanceLegacyMasterKeys[0] != "legacy-finance-master-key-with-at-least-32-characters" {
+		t.Fatalf("configured finance key was not retained for historical data: %#v", cfg.Auth.FinanceLegacyMasterKeys)
+	}
+}
+
 func TestApplyUploadSystemConfig(t *testing.T) {
 	cfg := UploadConfig{Driver: "local", Region: "us-east-1"}
 	ApplyUploadSystemConfig(&cfg, map[string]string{