fix: treat empty enabled list as default (all features) in useTenantFeatures

An empty features.enabled array is treated the same as an absent config —
fall back to all features. This avoids the inconsistency where defaultFeature
could resolve to a feature not present in the enabled set.

Author: bjcoombs

frontend/src/hooks/__tests__/use-tenant-features.test.ts

@@ -139,7 +139,7 @@ describe('useTenantFeatures', () => {
     expect(result.current.defaultFeature).toBe('accounts')
   })
 
-  it('returns empty string for defaultFeature when no features are enabled', () => {
+  it('falls back to all features when enabled list is empty', () => {
     vi.mocked(useTenantContext).mockReturnValue(
       makeContext({
         tenantConfig: {
@@ -152,8 +152,9 @@ describe('useTenantFeatures', () => {
 
     const { result } = renderHook(() => useTenantFeatures())
 
-    // No enabled features — defaultFeature must not point to a disabled feature
-    expect(result.current.defaultFeature).toBe('')
-    expect(result.current.isFeatureEnabled('dashboard')).toBe(false)
+    // Empty enabled list is treated as "use defaults" — all features enabled
+    expect(result.current.enabledFeatures).toEqual([...ALL_FEATURES])
+    expect(result.current.isFeatureEnabled('dashboard')).toBe(true)
+    expect(result.current.defaultFeature).toBe('dashboard')
   })
 })

frontend/src/hooks/use-tenant-features.ts

@@ -19,15 +19,18 @@ export function useTenantFeatures(): TenantFeaturesResult {
 
   return useMemo(() => {
     const config = tenantConfig ?? DEFAULT_UI_CONFIG
-    const enabledFeatures = config.features?.enabled ?? [...ALL_FEATURES]
+
+    // Treat an empty enabled list the same as an absent one — fall back to all features
+    const configuredEnabled = config.features?.enabled ?? [...ALL_FEATURES]
+    const enabledFeatures = configuredEnabled.length > 0 ? configuredEnabled : [...ALL_FEATURES]
     const enabledSet = new Set<string>(enabledFeatures)
 
-    // Fall back to the first enabled feature if the configured default is not in the enabled list.
-    // When no features are enabled at all, defaultFeature is an empty string (no valid default).
-    const configuredDefault = config.features?.defaultFeature ?? 'dashboard'
+    // Fall back to the first enabled feature if the configured default is not in the enabled list
+    const configuredDefault =
+      config.features?.defaultFeature ?? DEFAULT_UI_CONFIG.features!.defaultFeature!
     const defaultFeature = enabledSet.has(configuredDefault)
       ? configuredDefault
-      : (enabledFeatures[0] ?? '')
+      : enabledFeatures[0]
 
     return {
       isFeatureEnabled: (feature: string) => enabledSet.has(feature),