fix(auth): make DISABLE_AUTH work in web app

Return an anonymous session using the same response envelope as Better Auth's get-session endpoint, and make the session provider tolerant to both wrapped and raw session payloads.

Fixes #2524

Author: jayy-77

apps/sim/app/_shell/providers/session-provider.tsx

@@ -5,6 +5,7 @@ import { createContext, useCallback, useEffect, useMemo, useState } from 'react'
 import { useQueryClient } from '@tanstack/react-query'
 import posthog from 'posthog-js'
 import { client } from '@/lib/auth/auth-client'
+import { extractSessionDataFromAuthClientResult } from '@/lib/auth/session-response'
 
 export type AppSession = {
   user: {
@@ -45,7 +46,8 @@ export function SessionProvider({ children }: { children: React.ReactNode }) {
       const res = bypassCache
         ? await client.getSession({ query: { disableCookieCache: true } })
         : await client.getSession()
-      setData(res?.data ?? null)
+      const session = extractSessionDataFromAuthClientResult(res) as AppSession
+      setData(session)
     } catch (e) {
       setError(e instanceof Error ? e : new Error('Failed to fetch session'))
     } finally {

apps/sim/app/api/auth/[...all]/route.test.ts

@@ -0,0 +1,93 @@
+/**
+ * @vitest-environment node
+ */
+import { createMockRequest, setupCommonApiMocks } from '@sim/testing'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const handlerMocks = vi.hoisted(() => ({
+  betterAuthGET: vi.fn(),
+  betterAuthPOST: vi.fn(),
+  ensureAnonymousUserExists: vi.fn(),
+  createAnonymousGetSessionResponse: vi.fn(() => ({
+    data: {
+      user: { id: 'anon' },
+      session: { id: 'anon-session' },
+    },
+  })),
+}))
+
+vi.mock('better-auth/next-js', () => ({
+  toNextJsHandler: () => ({
+    GET: handlerMocks.betterAuthGET,
+    POST: handlerMocks.betterAuthPOST,
+  }),
+}))
+
+vi.mock('@/lib/auth', () => ({
+  auth: { handler: {} },
+}))
+
+vi.mock('@/lib/auth/anonymous', () => ({
+  ensureAnonymousUserExists: handlerMocks.ensureAnonymousUserExists,
+  createAnonymousGetSessionResponse: handlerMocks.createAnonymousGetSessionResponse,
+}))
+
+describe('auth catch-all route (DISABLE_AUTH get-session)', () => {
+  beforeEach(() => {
+    vi.resetModules()
+    setupCommonApiMocks()
+    handlerMocks.betterAuthGET.mockReset()
+    handlerMocks.betterAuthPOST.mockReset()
+    handlerMocks.ensureAnonymousUserExists.mockReset()
+    handlerMocks.createAnonymousGetSessionResponse.mockClear()
+  })
+
+  it('returns anonymous session in better-auth response envelope when auth is disabled', async () => {
+    vi.doMock('@/lib/core/config/feature-flags', () => ({ isAuthDisabled: true }))
+
+    const req = createMockRequest(
+      'GET',
+      undefined,
+      {},
+      'http://localhost:3000/api/auth/get-session'
+    )
+    const { GET } = await import('@/app/api/auth/[...all]/route')
+
+    const res = await GET(req as any)
+    const json = await res.json()
+
+    expect(handlerMocks.ensureAnonymousUserExists).toHaveBeenCalledTimes(1)
+    expect(handlerMocks.betterAuthGET).not.toHaveBeenCalled()
+    expect(json).toEqual({
+      data: {
+        user: { id: 'anon' },
+        session: { id: 'anon-session' },
+      },
+    })
+  })
+
+  it('delegates to better-auth handler when auth is enabled', async () => {
+    vi.doMock('@/lib/core/config/feature-flags', () => ({ isAuthDisabled: false }))
+
+    handlerMocks.betterAuthGET.mockResolvedValueOnce(
+      new (await import('next/server')).NextResponse(JSON.stringify({ data: { ok: true } }), {
+        headers: { 'content-type': 'application/json' },
+      }) as any
+    )
+
+    const req = createMockRequest(
+      'GET',
+      undefined,
+      {},
+      'http://localhost:3000/api/auth/get-session'
+    )
+    const { GET } = await import('@/app/api/auth/[...all]/route')
+
+    const res = await GET(req as any)
+    const json = await res.json()
+
+    expect(handlerMocks.ensureAnonymousUserExists).not.toHaveBeenCalled()
+    expect(handlerMocks.betterAuthGET).toHaveBeenCalledTimes(1)
+    expect(json).toEqual({ data: { ok: true } })
+  })
+})

apps/sim/app/api/auth/[...all]/route.ts

@@ -1,7 +1,7 @@
 import { toNextJsHandler } from 'better-auth/next-js'
 import { type NextRequest, NextResponse } from 'next/server'
 import { auth } from '@/lib/auth'
-import { createAnonymousSession, ensureAnonymousUserExists } from '@/lib/auth/anonymous'
+import { createAnonymousGetSessionResponse, ensureAnonymousUserExists } from '@/lib/auth/anonymous'
 import { isAuthDisabled } from '@/lib/core/config/feature-flags'
 
 export const dynamic = 'force-dynamic'
@@ -14,7 +14,7 @@ export async function GET(request: NextRequest) {
 
   if (path === 'get-session' && isAuthDisabled) {
     await ensureAnonymousUserExists()
-    return NextResponse.json(createAnonymousSession())
+    return NextResponse.json(createAnonymousGetSessionResponse())
   }
 
   return betterAuthGET(request)

apps/sim/lib/auth/anonymous.ts

@@ -102,3 +102,7 @@ export function createAnonymousSession(): AnonymousSession {
     },
   }
 }
+
+export function createAnonymousGetSessionResponse(): { data: AnonymousSession } {
+  return { data: createAnonymousSession() }
+}

apps/sim/lib/auth/session-response.test.ts

@@ -0,0 +1,31 @@
+/**
+ * @vitest-environment node
+ */
+import { describe, expect, it } from 'vitest'
+import { extractSessionDataFromAuthClientResult } from '@/lib/auth/session-response'
+
+describe('extractSessionDataFromAuthClientResult', () => {
+  it('returns null for non-objects', () => {
+    expect(extractSessionDataFromAuthClientResult(null)).toBeNull()
+    expect(extractSessionDataFromAuthClientResult(undefined)).toBeNull()
+    expect(extractSessionDataFromAuthClientResult('nope')).toBeNull()
+    expect(extractSessionDataFromAuthClientResult(123)).toBeNull()
+  })
+
+  it('prefers .data when present', () => {
+    expect(extractSessionDataFromAuthClientResult({ data: null })).toBeNull()
+
+    const session = { user: { id: 'u1' }, session: { id: 's1' } }
+    expect(extractSessionDataFromAuthClientResult({ data: session })).toEqual(session)
+  })
+
+  it('falls back to raw session payload shape', () => {
+    const raw = { user: { id: 'u1' }, session: { id: 's1' } }
+    expect(extractSessionDataFromAuthClientResult(raw)).toEqual(raw)
+  })
+
+  it('returns null for unknown object shapes', () => {
+    expect(extractSessionDataFromAuthClientResult({})).toBeNull()
+    expect(extractSessionDataFromAuthClientResult({ ok: true })).toBeNull()
+  })
+})

apps/sim/lib/auth/session-response.ts

@@ -0,0 +1,19 @@
+export function extractSessionDataFromAuthClientResult(result: unknown): unknown | null {
+  if (!result || typeof result !== 'object') {
+    return null
+  }
+
+  const record = result as Record<string, unknown>
+
+  // Expected shape from better-auth client: { data: <session> }
+  if ('data' in record) {
+    return (record as { data?: unknown }).data ?? null
+  }
+
+  // Fallback for raw session payloads: { user, session }
+  if ('user' in record) {
+    return record
+  }
+
+  return null
+}