refactor(multi-gateway-panel): migrate 12 bare fetch to apiFetch

eslint.config.mjs

@@ -18,6 +18,37 @@ const config = [
       'react-hooks/immutability': 'off',
     },
   },
+  // P1.5 — Discourage bare `fetch('/api/...')`.
+  // The team must migrate to `apiFetch<T>()` from `@/lib/api-client` so that
+  // 401 / 403 / 5xx / network failures are handled uniformly.
+  // Phase 1 (this PR): warn level, allow incremental migration.
+  // Phase 3 (final cleanup): upgrade to error and forbid merges that introduce
+  // new bare fetch('/api/...') sites.
+  // Selector rationale:
+  //   - covers single-quoted, double-quoted, and template-literal forms
+  //   - filters by /api prefix so cross-origin / external fetches stay untouched
+  //   - exempts api-client.ts itself (the one allowed implementer)
+  {
+    files: ['src/**/*.{ts,tsx,js,jsx}'],
+    ignores: ['src/lib/api-client.ts'],
+    rules: {
+      'no-restricted-syntax': [
+        'warn',
+        {
+          selector:
+            "CallExpression[callee.name='fetch'] > Literal[value=/^\\/api\\//]",
+          message:
+            "Use apiFetch<T>() from '@/lib/api-client' instead of bare fetch('/api/...'). It handles 401 redirect, 403/5xx typed errors, and network failures uniformly. See PR-api-client.md.",
+        },
+        {
+          selector:
+            "CallExpression[callee.name='fetch'] > TemplateLiteral.arguments:first-child[quasis.0.value.raw=/^\\/api\\//]",
+          message:
+            "Use apiFetch<T>() from '@/lib/api-client' instead of bare fetch(`/api/...`). It handles 401 redirect, 403/5xx typed errors, and network failures uniformly.",
+        },
+      ],
+    },
+  },
 ]
 
 export default config

src/app/layout.tsx

@@ -6,6 +6,7 @@ import { NextIntlClientProvider } from 'next-intl'
 import { getLocale, getMessages } from 'next-intl/server'
 import { THEME_IDS } from '@/lib/themes'
 import { ThemeBackground } from '@/components/ui/theme-background'
+import { AuthExpiredListener } from '@/components/auth-expired-listener'
 import './globals.css'
 
 const inter = Inter({
@@ -114,6 +115,7 @@ export default async function RootLayout({
             disableTransitionOnChange
           >
             <ThemeBackground />
+            <AuthExpiredListener />
             <div className="h-screen overflow-hidden bg-background text-foreground">
               {children}
             </div>

src/components/auth-expired-listener.tsx

@@ -0,0 +1,33 @@
+'use client'
+
+import { useEffect } from 'react'
+
+/**
+ * Listens for `mc:auth-expired` CustomEvent dispatched by `apiFetch()` when the
+ * server returns 401. The redirect to `/login?from=...` is already handled inside
+ * `apiFetch`; this listener exists so we have a single observability hook the
+ * team can extend (toast, telemetry, Sentry).
+ *
+ * Mounted once at the root layout. SSR-safe (effect runs only on the client).
+ *
+ * Why a separate component?
+ *   - layout.tsx is a server component (uses `await headers()`); we cannot
+ *     attach window listeners there directly.
+ *   - Co-locating the listener with the api-client keeps the auth-failure
+ *     contract in one place.
+ */
+export function AuthExpiredListener(): null {
+  useEffect(() => {
+    const onExpired = (e: Event) => {
+      const detail = (e as CustomEvent<{ path: string; status: number }>).detail
+      // No toast lib installed yet — log for now. Replace with sonner in next PR.
+      console.warn(
+        `[mc] session expired on ${detail?.path ?? 'unknown'} (status=${detail?.status ?? 401}), redirecting to /login`
+      )
+    }
+    window.addEventListener('mc:auth-expired', onExpired)
+    return () => window.removeEventListener('mc:auth-expired', onExpired)
+  }, [])
+
+  return null
+}

src/components/panels/multi-gateway-panel.tsx

@@ -5,6 +5,7 @@ import { useTranslations } from 'next-intl'
 import { Button } from '@/components/ui/button'
 import { useMissionControl } from '@/store'
 import { useWebSocket } from '@/lib/websocket'
+import { apiFetch } from '@/lib/api-client'
 
 interface Gateway {
   id: number
@@ -84,33 +85,29 @@ export function MultiGatewayPanel() {
 
   const fetchGateways = useCallback(async () => {
     try {
-      const res = await fetch('/api/gateways')
-      const data = await res.json()
+      const data = await apiFetch<{ gateways?: Gateway[] }>('/api/gateways')
       setGateways(data.gateways || [])
     } catch { /* ignore */ }
     setLoading(false)
   }, [])
 
   const fetchDirectConnections = useCallback(async () => {
     try {
-      const res = await fetch('/api/connect')
-      const data = await res.json()
+      const data = await apiFetch<{ connections?: DirectConnection[] }>('/api/connect')
       setDirectConnections(data.connections || [])
     } catch { /* ignore */ }
   }, [])
 
   const fetchDiscovered = useCallback(async () => {
     try {
-      const res = await fetch('/api/gateways/discover')
-      const data = await res.json()
+      const data = await apiFetch<{ gateways?: DiscoveredGateway[] }>('/api/gateways/discover')
       setDiscoveredGateways(data.gateways || [])
     } catch { /* ignore */ }
   }, [])
 
   const fetchHistory = useCallback(async () => {
     try {
-      const res = await fetch('/api/gateways/health/history')
-      const data = await res.json()
+      const data = await apiFetch<{ history?: GatewayHistory[] }>('/api/gateways/health/history')
       const map: Record<number, GatewayHistory> = {}
       for (const entry of data.history || []) {
         map[entry.gatewayId] = entry
@@ -141,40 +138,41 @@ export function MultiGatewayPanel() {
     !gateways.some(gatewayMatchesConnection)
 
   const setPrimary = async (gw: Gateway) => {
-    await fetch('/api/gateways', {
+    await apiFetch('/api/gateways', {
       method: 'PUT',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ id: gw.id, is_primary: 1 }),
-    })
+    }).catch(() => {})
     fetchGateways()
     fetchHistory()
   }
 
   const deleteGateway = async (id: number) => {
-    await fetch('/api/gateways', {
+    await apiFetch('/api/gateways', {
       method: 'DELETE',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ id }),
-    })
+    }).catch(() => {})
     fetchGateways()
     fetchHistory()
   }
 
   const updateToken = async (gw: Gateway, token: string) => {
-    await fetch('/api/gateways', {
+    await apiFetch('/api/gateways', {
       method: 'PUT',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ id: gw.id, token }),
-    })
+    }).catch(() => {})
     fetchGateways()
   }
 
   const connectTo = async (gw: Gateway) => {
     try {
-      const res = await fetch('/api/gateways/connect', {
+      const res = await apiFetch<Response>('/api/gateways/connect', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ id: gw.id }),
+        raw: true,
       })
       if (!res.ok) return
       const payload = await res.json()
@@ -192,8 +190,7 @@ export function MultiGatewayPanel() {
 
   const probeAll = async () => {
     try {
-      const res = await fetch("/api/gateways/health", { method: "POST" })
-      const data = await res.json().catch(() => ({}))
+      const data = await apiFetch<{ results?: GatewayHealthProbe[] }>("/api/gateways/health", { method: "POST" })
       const rows = Array.isArray(data?.results) ? data.results as GatewayHealthProbe[] : []
       const mapped = new Map<number, GatewayHealthProbe>()
       for (const row of rows) {
@@ -213,7 +210,7 @@ export function MultiGatewayPanel() {
 
   const disconnectCli = async (connectionId: string) => {
     try {
-      await fetch('/api/connect', {
+      await apiFetch('/api/connect', {
         method: 'DELETE',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ connection_id: connectionId }),
@@ -350,7 +347,7 @@ export function MultiGatewayPanel() {
                     </div>
                     <Button
                       onClick={async () => {
-                        await fetch('/api/gateways', {
+                        await apiFetch('/api/gateways', {
                           method: 'POST',
                           headers: { 'Content-Type': 'application/json' },
                           body: JSON.stringify({
@@ -359,7 +356,7 @@ export function MultiGatewayPanel() {
                             port: dg.port,
                             is_primary: false,
                           }),
-                        })
+                        }).catch(() => {})
                         fetchGateways()
                         fetchDiscovered()
                       }}
@@ -643,7 +640,7 @@ function AddGatewayForm({ onAdded, onCancel }: { onAdded: () => void; onCancel:
     setSaving(true)
 
     try {
-      const res = await fetch('/api/gateways', {
+      const res = await apiFetch<Response>('/api/gateways', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({
@@ -653,6 +650,7 @@ function AddGatewayForm({ onAdded, onCancel }: { onAdded: () => void; onCancel:
           token: form.token,
           is_primary: false,
         }),
+        raw: true,
       })
       const data = await res.json()
       if (!res.ok) {

src/lib/__tests__/api-client.test.ts

@@ -0,0 +1,114 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import { apiFetch, ApiError } from '../api-client'
+
+const realFetch = global.fetch
+const realLocation = window.location
+
+function mockResponse(status: number, body: unknown = {}, opts: { json?: boolean } = { json: true }) {
+  return new Response(opts.json ? JSON.stringify(body) : String(body), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  })
+}
+
+describe('apiFetch — global 401 / 403 / 5xx / network handling', () => {
+  let dispatched: CustomEvent[] = []
+  let originalHref = ''
+  let authExpiredListener: ((e: Event) => void) | null = null
+
+  beforeEach(() => {
+    dispatched = []
+    authExpiredListener = (e) => dispatched.push(e as CustomEvent)
+    window.addEventListener('mc:auth-expired', authExpiredListener)
+
+    // Stub location so redirect-to-login is observable
+    originalHref = window.location.href
+    Object.defineProperty(window, 'location', {
+      writable: true,
+      value: {
+        ...realLocation,
+        pathname: '/cost-tracker',
+        search: '',
+        href: 'http://127.0.0.1:3000/cost-tracker',
+      },
+    })
+  })
+
+  afterEach(() => {
+    if (authExpiredListener) {
+      window.removeEventListener('mc:auth-expired', authExpiredListener)
+      authExpiredListener = null
+    }
+    global.fetch = realFetch
+    Object.defineProperty(window, 'location', { writable: true, value: realLocation })
+    window.location.href = originalHref
+    vi.restoreAllMocks()
+  })
+
+  it('returns parsed JSON on 200', async () => {
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(200, { ok: true, count: 42 }))
+    const data = await apiFetch<{ ok: boolean; count: number }>('/api/tokens')
+    expect(data).toEqual({ ok: true, count: 42 })
+  })
+
+  it('emits mc:auth-expired and redirects to /login on 401', async () => {
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(401, { error: 'Authentication required' }))
+    await expect(apiFetch('/api/tokens')).rejects.toMatchObject({
+      code: 'UNAUTHENTICATED',
+      status: 401,
+    })
+    expect(dispatched).toHaveLength(1)
+    expect(dispatched[0].detail).toMatchObject({ path: '/api/tokens', status: 401 })
+    expect(window.location.href).toContain('/login?from=%2Fcost-tracker')
+  })
+
+  it('does NOT redirect when redirectOnUnauthenticated=false', async () => {
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(401, { error: 'Authentication required' }))
+    await expect(
+      apiFetch('/api/tokens', { redirectOnUnauthenticated: false })
+    ).rejects.toThrow(ApiError)
+    expect(window.location.href).toBe('http://127.0.0.1:3000/cost-tracker')
+  })
+
+  it('throws FORBIDDEN on 403 without redirecting', async () => {
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(403, { error: 'Requires admin role' }))
+    await expect(apiFetch('/api/tokens')).rejects.toMatchObject({
+      code: 'FORBIDDEN',
+      status: 403,
+    })
+    expect(window.location.href).toBe('http://127.0.0.1:3000/cost-tracker')
+  })
+
+  it('throws SERVER_ERROR on 500 with upstream message', async () => {
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(500, { error: 'database is locked' }))
+    await expect(apiFetch('/api/tokens')).rejects.toMatchObject({
+      code: 'SERVER_ERROR',
+      status: 500,
+      message: 'database is locked',
+    })
+  })
+
+  it('throws NETWORK_ERROR when fetch rejects', async () => {
+    global.fetch = vi.fn().mockRejectedValue(new TypeError('Failed to fetch'))
+    await expect(apiFetch('/api/tokens')).rejects.toMatchObject({
+      code: 'NETWORK_ERROR',
+      status: 0,
+    })
+  })
+
+  it('does not redirect when already on /login (avoid infinite loop)', async () => {
+    Object.defineProperty(window, 'location', {
+      writable: true,
+      value: { ...realLocation, pathname: '/login', search: '', href: 'http://127.0.0.1:3000/login' },
+    })
+    global.fetch = vi.fn().mockResolvedValue(mockResponse(401))
+    await expect(apiFetch('/api/auth/login', { method: 'POST' })).rejects.toThrow(ApiError)
+    expect(window.location.href).toBe('http://127.0.0.1:3000/login')
+  })
+
+  it('returns undefined for 204 No Content', async () => {
+    global.fetch = vi.fn().mockResolvedValue(new Response(null, { status: 204 }))
+    const data = await apiFetch('/api/sessions/123', { method: 'DELETE' })
+    expect(data).toBeUndefined()
+  })
+})