fix(settings): cache unset scheduling thresholds

backend/internal/service/backup_service_test.go

@@ -24,8 +24,10 @@ import (
 // ─── Mocks ───
 
 type mockSettingRepo struct {
-	mu   sync.Mutex
-	data map[string]string
+	mu            sync.Mutex
+	data          map[string]string
+	getValueErr   error
+	getValueCalls int
 }
 
 func newMockSettingRepo() *mockSettingRepo {
@@ -45,6 +47,10 @@ func (m *mockSettingRepo) Get(_ context.Context, key string) (*Setting, error) {
 func (m *mockSettingRepo) GetValue(_ context.Context, key string) (string, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
+	m.getValueCalls++
+	if m.getValueErr != nil {
+		return "", m.getValueErr
+	}
 	v, ok := m.data[key]
 	if !ok {
 		return "", nil

backend/internal/service/setting_features.go

@@ -1114,6 +1114,13 @@ func (s *SettingService) GetAccountSchedulingThresholds(ctx context.Context) map
 
 		raw, err := s.settingRepo.GetValue(dbCtx, SettingKeyAccountSchedulingThresholds)
 		if err != nil {
+			if errors.Is(err, ErrSettingNotFound) {
+				accountSchedulingThresholdsCache.Store(&cachedAccountSchedulingThresholds{
+					thresholds: cloneAccountSchedulingThresholds(thresholds),
+					expiresAt:  time.Now().Add(accountSchedulingThresholdsCacheTTL).UnixNano(),
+				})
+				return cloneAccountSchedulingThresholds(thresholds), nil
+			}
 			slog.Warn("failed to get account scheduling thresholds, falling back to defaults", "error", err)
 			accountSchedulingThresholdsCache.Store(&cachedAccountSchedulingThresholds{
 				thresholds: cloneAccountSchedulingThresholds(thresholds),

backend/internal/service/setting_service_platform_threshold_test.go

@@ -5,6 +5,7 @@ package service
 import (
 	"context"
 	"testing"
+	"time"
 
 	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/stretchr/testify/require"
@@ -108,6 +109,25 @@ func TestGetAccountSchedulingThresholds_ReadsStoredValue(t *testing.T) {
 	require.NotContains(t, got, "kiro")
 }
 
+func TestGetAccountSchedulingThresholds_MissingSettingUsesDefaultsAndNormalCacheTTL(t *testing.T) {
+	svc := newSettingServiceForPlatformThresholdTest(nil)
+	repo := svc.settingRepo.(*mockSettingRepo)
+	repo.getValueErr = ErrSettingNotFound
+
+	got := svc.GetAccountSchedulingThresholds(context.Background())
+	require.Equal(t, defaultAccountSchedulingThresholds(), got)
+	require.Equal(t, 1, repo.getValueCalls)
+
+	repo.data[SettingKeyAccountSchedulingThresholds] = `{"openai":91}`
+	got = svc.GetAccountSchedulingThresholds(context.Background())
+	require.Equal(t, 100, got[PlatformOpenAI], "missing-setting defaults should remain cached for the normal TTL")
+	require.Equal(t, 1, repo.getValueCalls)
+
+	cached, ok := accountSchedulingThresholdsCache.Load().(*cachedAccountSchedulingThresholds)
+	require.True(t, ok)
+	require.Greater(t, cached.expiresAt, time.Now().Add(accountSchedulingThresholdsCacheTTL-time.Second).UnixNano())
+}
+
 func TestUpdateSettings_OmittedAccountSchedulingThresholdsDoesNotCacheDefaults(t *testing.T) {
 	svc := newSettingServiceForPlatformThresholdTest(map[string]string{
 		SettingKeyAccountSchedulingThresholds: `{"openai":85,"grok":88,"kiro":87}`,