refactor(onboarding-wizard): migrate 10 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/onboarding/onboarding-wizard.tsx

@@ -12,6 +12,7 @@ import { clampWizardStep, getWizardSteps, stepIdAt } from '@/lib/onboarding-flow
 import { SecurityScanCard } from '@/components/onboarding/security-scan-card'
 // StepAgentRuntimes removed — runtime management moved to Settings page
 import { clearOnboardingReplayFromStart, markOnboardingDismissedThisSession, readOnboardingReplayFromStart } from '@/lib/onboarding-session'
+import { apiFetch } from '@/lib/api-client'
 
 interface StepInfo {
   id: string
@@ -94,8 +95,7 @@ export function OnboardingWizard() {
     const previousOverflow = document.body.style.overflow
     document.body.style.overflow = 'hidden'
 
-    fetch('/api/onboarding')
-      .then(r => r.ok ? r.json() : null)
+    apiFetch<OnboardingState>('/api/onboarding')
       .then(data => {
         if (data) {
           setState(data)
@@ -113,9 +113,9 @@ export function OnboardingWizard() {
 
     // Fetch system capabilities and runtime status in parallel
     Promise.allSettled([
-      fetch('/api/status?action=capabilities').then(r => r.ok ? r.json() : null),
-      fetch('/api/agents?limit=1').then(r => r.ok ? r.json() : null),
-      fetch('/api/agent-runtimes').then(r => r.ok ? r.json() : null),
+      apiFetch<any>('/api/status?action=capabilities').catch(() => null),
+      apiFetch<any>('/api/agents?limit=1').catch(() => null),
+      apiFetch<any>('/api/agent-runtimes').catch(() => null),
     ]).then(([statusResult, agentsResult, runtimesResult]) => {
       const statusData = statusResult.status === 'fulfilled' ? statusResult.value : null
       const agentsData = agentsResult.status === 'fulfilled' ? agentsResult.value : null
@@ -147,8 +147,7 @@ export function OnboardingWizard() {
 
   useEffect(() => {
     if (step !== credentialsStepIndex || credentialStatus) return
-    fetch('/api/diagnostics')
-      .then(r => r.ok ? r.json() : null)
+    apiFetch<{ security?: { checks?: DiagSecurityCheck[] } }>('/api/diagnostics')
       .then(data => {
         if (data?.security?.checks) {
           const checks = data.security.checks as DiagSecurityCheck[]
@@ -161,7 +160,7 @@ export function OnboardingWizard() {
   }, [step, credentialStatus, credentialsStepIndex])
 
   const completeStep = useCallback(async (stepId: string) => {
-    await fetch('/api/onboarding', {
+    await apiFetch<{ ok?: boolean }>('/api/onboarding', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ action: 'complete_step', step: stepId }),
@@ -170,7 +169,7 @@ export function OnboardingWizard() {
 
   const finish = useCallback(async () => {
     setCompletionMessage(true)
-    await fetch('/api/onboarding', {
+    await apiFetch<{ ok?: boolean }>('/api/onboarding', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ action: 'complete' }),
@@ -184,7 +183,7 @@ export function OnboardingWizard() {
 
   const skip = useCallback(async () => {
     setClosing(true)
-    await fetch('/api/onboarding', {
+    await apiFetch<{ ok?: boolean }>('/api/onboarding', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ action: 'skip' }),
@@ -457,7 +456,7 @@ function StepInterfaceMode({ isGateway, onNext, onBack }: {
     setSelected(mode)
     setInterfaceMode(mode)
     try {
-      await fetch('/api/settings', {
+      await apiFetch<{ ok?: boolean }>('/api/settings', {
         method: 'PUT',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ settings: { 'general.interface_mode': mode } }),
@@ -555,7 +554,7 @@ function StepGatewayLink({ isGateway, registration, onNext, onBack }: {
   const testConnection = async () => {
     setTesting(true)
     try {
-      const res = await fetch('/api/gateways/health', { method: 'POST' })
+      const res = await apiFetch<Response>('/api/gateways/health', { method: 'POST', raw: true })
       setHealthOk(res.ok)
     } catch {
       setHealthOk(false)

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()
+  })
+})