feat(tenancies-p6): module-gate entity tabs (berth / client / yacht)

- PortProvider exposes tenanciesModuleByPort + a useTenanciesModuleEnabled()
  hook that returns the flag for the currently-active port. Synchronous
  read off context (server-resolved in the dashboard layout), so no
  fetch latency / hydration flicker when the rep flips ports.
- buildBerthTabs / getClientTabs / getYachtTabs gain a
  tenanciesModuleEnabled option. When false, the Tenancies tab is
  filtered out entirely. When true, it slots into the entity-specific
  position (after Interests on berth + yacht; after Companies on client).
- BerthDetail / ClientDetail / YachtDetail pass the hook value through.
  Hook call ordered above the early-return so React's rules-of-hooks
  stays satisfied. Existing read-only tab content (Active tenancy card
  + History + the berth-side BerthReserveDialog "Create tenancy" CTA
  from P2) stays untouched — it just becomes visible when the module
  is on.

Deferred (separate ship): generic TenancyCreateDialog that pre-fills
clientId / yachtId from the parent entity context, so client / yacht
tabs can mint a tenancy without bouncing through the berth detail page.
Today client/yacht Tenancies tabs are read-only (the create entry-point
is the berth tab); the generic dialog will land alongside the Edit /
Renew / Transfer / End dialogs (design § P6 sub-tasks).

Verified: tsc clean, 1493/1493 vitest.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/(dashboard)/layout.tsx

@@ -91,7 +91,11 @@ export default async function DashboardLayout({ children }: { children: React.Re
 
   return (
     <QueryProvider>
-      <PortProvider ports={ports} defaultPortId={ports[0]?.id ?? null}>
+      <PortProvider
+        ports={ports}
+        defaultPortId={ports[0]?.id ?? null}
+        tenanciesModuleByPort={tenanciesModuleByPort}
+      >
         <PermissionsProvider>
           <SocketProvider>
             <RealtimeToasts />

src/components/berths/berth-detail.tsx

@@ -8,6 +8,7 @@ import { DetailLayout } from '@/components/shared/detail-layout';
 import { DetailNotFound } from '@/components/shared/detail-not-found';
 import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
 import { apiFetch } from '@/lib/api/client';
+import { useTenanciesModuleEnabled } from '@/providers/port-provider';
 import { useRealtimeInvalidation } from '@/hooks/use-realtime-invalidation';
 import { BerthDetailHeader, type BerthDetailData } from './berth-detail-header';
 import { BerthForm } from './berth-form';
@@ -20,6 +21,7 @@ interface BerthDetailProps {
 export function BerthDetail({ berthId }: BerthDetailProps) {
   const params = useParams<{ portSlug: string }>();
   const portSlug = params?.portSlug ?? '';
+  const tenanciesModuleEnabled = useTenanciesModuleEnabled();
 
   const { data, isLoading, error } = useQuery<BerthDetailData>({
     queryKey: ['berth', berthId],
@@ -84,7 +86,7 @@ export function BerthDetail({ berthId }: BerthDetailProps) {
       <DetailLayout
         isLoading={isLoading}
         header={berth ? <BerthDetailHeader berth={berth} /> : null}
-        tabs={berth ? buildBerthTabs(berth) : []}
+        tabs={berth ? buildBerthTabs(berth, { tenanciesModuleEnabled }) : []}
         defaultTab="overview"
       />
       {berth ? <BerthForm berth={berth} open={editOpen} onOpenChange={setEditOpen} /> : null}

src/components/berths/berth-tabs.tsx

@@ -419,8 +419,11 @@ function OverviewTab({ berth }: { berth: BerthData }) {
   );
 }
 
-export function buildBerthTabs(berth: BerthData): DetailTab[] {
+export function buildBerthTabs(
-  return [
+  berth: BerthData,
+  opts: { tenanciesModuleEnabled: boolean } = { tenanciesModuleEnabled: false },
+): DetailTab[] {
+  const tabs: DetailTab[] = [
     {
       id: 'overview',
       label: 'Overview',
@@ -431,11 +434,20 @@ export function buildBerthTabs(berth: BerthData): DetailTab[] {
       label: 'Interests',
       content: <BerthInterestsTab berthId={berth.id} />,
     },
-    {
+  ];
+  if (opts.tenanciesModuleEnabled) {
+    tabs.push({
       id: 'tenancies',
       label: 'Tenancies',
       content: <BerthTenanciesTab berthId={berth.id} />,
-    },
+    });
+  }
+  tabs.push(...buildBerthDetailRemainder(berth));
+  return tabs;
+}
+
+function buildBerthDetailRemainder(berth: BerthData): DetailTab[] {
+  return [
     {
       id: 'spec',
       label: 'Spec',

src/components/clients/client-detail.tsx

@@ -9,6 +9,7 @@ import { DetailNotFound } from '@/components/shared/detail-not-found';
 import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
 import { ClientDetailHeader } from '@/components/clients/client-detail-header';
 import { getClientTabs } from '@/components/clients/client-tabs';
+import { useTenanciesModuleEnabled } from '@/providers/port-provider';
 import { useRealtimeInvalidation } from '@/hooks/use-realtime-invalidation';
 import { useBreadcrumbHint } from '@/hooks/use-breadcrumb-hint';
 import { apiFetch } from '@/lib/api/client';
@@ -118,6 +119,8 @@ export function ClientDetail({ clientId, currentUserId }: ClientDetailProps) {
     'berth_tenancy:cancelled': [['clients', clientId]],
   });
 
+  const tenanciesModuleEnabled = useTenanciesModuleEnabled();
+
   if (error && !isLoading) {
     const status = (error as { status?: number } | null | undefined)?.status;
     return (
@@ -130,7 +133,9 @@ export function ClientDetail({ clientId, currentUserId }: ClientDetailProps) {
     );
   }
 
-  const tabs = data ? getClientTabs({ clientId, currentUserId, client: data }) : [];
+  const tabs = data
+    ? getClientTabs({ clientId, currentUserId, client: data, tenanciesModuleEnabled })
+    : [];
 
   return (
     <DetailLayout

src/components/clients/client-tabs.tsx

@@ -250,8 +250,13 @@ function OverviewTab({
   );
 }
 
-export function getClientTabs({ clientId, currentUserId, client }: ClientTabsOptions): DetailTab[] {
+export function getClientTabs({
-  return [
+  clientId,
+  currentUserId,
+  client,
+  tenanciesModuleEnabled = false,
+}: ClientTabsOptions & { tenanciesModuleEnabled?: boolean }): DetailTab[] {
+  const tabs: DetailTab[] = [
     {
       id: 'overview',
       label: 'Overview',
@@ -275,12 +280,6 @@ export function getClientTabs({ clientId, currentUserId, client }: ClientTabsOpt
       badge: client.companies.length,
       content: <ClientCompaniesTab clientId={clientId} companies={client.companies} />,
     },
-    {
-      id: 'tenancies',
-      label: 'Tenancies',
-      badge: client.activeTenancies.length,
-      content: <ClientTenanciesTab clientId={clientId} activeTenancies={client.activeTenancies} />,
-    },
     {
       id: 'addresses',
       label: 'Addresses',
@@ -323,4 +322,15 @@ export function getClientTabs({ clientId, currentUserId, client }: ClientTabsOpt
       ),
     },
   ];
+  if (tenanciesModuleEnabled) {
+    // Insert the Tenancies tab after Companies (index 4) so the entity
+    // ordering reads: Overview → Interests → Yachts → Companies → Tenancies.
+    tabs.splice(4, 0, {
+      id: 'tenancies',
+      label: 'Tenancies',
+      badge: client.activeTenancies.length,
+      content: <ClientTenanciesTab clientId={clientId} activeTenancies={client.activeTenancies} />,
+    });
+  }
+  return tabs;
 }

src/components/yachts/yacht-detail.tsx

@@ -9,6 +9,7 @@ import { DetailNotFound } from '@/components/shared/detail-not-found';
 import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
 import { YachtDetailHeader } from '@/components/yachts/yacht-detail-header';
 import { getYachtTabs } from '@/components/yachts/yacht-tabs';
+import { useTenanciesModuleEnabled } from '@/providers/port-provider';
 import { useRealtimeInvalidation } from '@/hooks/use-realtime-invalidation';
 import { useBreadcrumbHint } from '@/hooks/use-breadcrumb-hint';
 import { apiFetch } from '@/lib/api/client';
@@ -79,6 +80,8 @@ export function YachtDetail({ yachtId, currentUserId }: YachtDetailProps) {
     ],
   });
 
+  const tenanciesModuleEnabled = useTenanciesModuleEnabled();
+
   if (error && !isLoading) {
     const status = (error as { status?: number } | null | undefined)?.status;
     return (
@@ -91,7 +94,9 @@ export function YachtDetail({ yachtId, currentUserId }: YachtDetailProps) {
     );
   }
 
-  const tabs = data ? getYachtTabs({ yachtId, currentUserId, yacht: data }) : [];
+  const tabs = data
+    ? getYachtTabs({ yachtId, currentUserId, yacht: data, tenanciesModuleEnabled })
+    : [];
 
   return (
     <DetailLayout

src/components/yachts/yacht-tabs.tsx

@@ -355,8 +355,13 @@ function YachtTenanciesTab({ yachtId }: { yachtId: string }) {
   );
 }
 
-export function getYachtTabs({ yachtId, currentUserId, yacht }: YachtTabsOptions): DetailTab[] {
+export function getYachtTabs({
-  return [
+  yachtId,
+  currentUserId,
+  yacht,
+  tenanciesModuleEnabled = false,
+}: YachtTabsOptions & { tenanciesModuleEnabled?: boolean }): DetailTab[] {
+  const tabs: DetailTab[] = [
     {
       id: 'overview',
       label: 'Overview',
@@ -372,11 +377,6 @@ export function getYachtTabs({ yachtId, currentUserId, yacht }: YachtTabsOptions
       label: 'Interests',
       content: <YachtInterestsTab yachtId={yachtId} />,
     },
-    {
-      id: 'tenancies',
-      label: 'Tenancies',
-      content: <YachtTenanciesTab yachtId={yachtId} />,
-    },
     {
       id: 'notes',
       label: 'Notes',
@@ -401,4 +401,14 @@ export function getYachtTabs({ yachtId, currentUserId, yacht }: YachtTabsOptions
       ),
     },
   ];
+  if (tenanciesModuleEnabled) {
+    // Insert after Interests (index 3) so the ordering reads:
+    // Overview → Ownership History → Interests → Tenancies.
+    tabs.splice(3, 0, {
+      id: 'tenancies',
+      label: 'Tenancies',
+      content: <YachtTenanciesTab yachtId={yachtId} />,
+    });
+  }
+  return tabs;
 }

src/providers/port-provider.tsx

@@ -12,6 +12,10 @@ interface PortContextValue {
   currentPort: Port | null;
   currentPortId: string | null;
   currentPortSlug: string | null;
+  /** Per-port feature-flag map — currently just the Tenancies module.
+   *  Resolved server-side in the dashboard layout. Consumers read via
+   *  `useTenanciesModuleEnabled()`. */
+  tenanciesModuleByPort: Record<string, boolean>;
 }
 
 const PortContext = createContext<PortContextValue>({
@@ -19,15 +23,22 @@ const PortContext = createContext<PortContextValue>({
   currentPort: null,
   currentPortId: null,
   currentPortSlug: null,
+  tenanciesModuleByPort: {},
 });
 
 interface PortProviderProps {
   children: ReactNode;
   ports: Port[];
   defaultPortId: string | null;
+  tenanciesModuleByPort?: Record<string, boolean>;
 }
 
-export function PortProvider({ children, ports, defaultPortId }: PortProviderProps) {
+export function PortProvider({
+  children,
+  ports,
+  defaultPortId,
+  tenanciesModuleByPort = {},
+}: PortProviderProps) {
   const params = useParams();
   const portSlugFromUrl = params?.portSlug as string | undefined;
 
@@ -75,6 +86,7 @@ export function PortProvider({ children, ports, defaultPortId }: PortProviderPro
         currentPort: currentPort ?? null,
         currentPortId: currentPort?.id ?? null,
         currentPortSlug: currentPort?.slug ?? null,
+        tenanciesModuleByPort,
       }}
     >
       {children}
@@ -85,3 +97,12 @@ export function PortProvider({ children, ports, defaultPortId }: PortProviderPro
 export function usePortContext(): PortContextValue {
   return useContext(PortContext);
 }
+
+/** Read the tenancies-module-enabled flag for the currently-active port.
+ *  Server-side resolved in the dashboard layout, so this is a synchronous
+ *  read with no fetch latency or hydration flicker. */
+export function useTenanciesModuleEnabled(): boolean {
+  const { currentPortId, tenanciesModuleByPort } = useContext(PortContext);
+  if (!currentPortId) return false;
+  return tenanciesModuleByPort[currentPortId] ?? false;
+}