diff --git a/e2e/tests/50-multirealm.spec.ts b/e2e/tests/50-multirealm.spec.ts
new file mode 100644
index 0000000..ce3a20b
--- /dev/null
+++ b/e2e/tests/50-multirealm.spec.ts
@@ -0,0 +1,146 @@
+import { test, expect } from './fixtures/virtual-authenticator'
+import {
+  registerPasskey,
+  getSessionCookieName,
+  popDeviceToken,
+} from './fixtures/passkey-helpers'
+import {
+  startRemoteAuthRequest,
+  awaitRemoteAuthSession,
+  permitRemoteAuth,
+} from './fixtures/remote-auth'
+
+/**
+ * Multi-realm E2E tests.
+ *
+ * The server is bootstrapped with two realms: localhost (default) and
+ * test.localhost. Chrome resolves any *.localhost hostname to loopback, so
+ * both realms are reachable over real HTTP from the browser.
+ *
+ * Covers:
+ * - Host-based realm dispatch (settings, 421 for unknown hosts)
+ * - Related Origin Requests well-known endpoint + admin realm API
+ * - Cross-realm remote login: a passkey registered on localhost permits a
+ *   session on test.localhost via pairing code
+ * - The profile enrollment prompt on a realm where the user has no passkey
+ */
+
+test.describe('Multi-realm E2E', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
+  const realmUrl = 'http://test.localhost:4404'
+
+  test('dispatches realms by host header', async ({ page }) => {
+    // Browser navigation: Chrome maps *.localhost to loopback
+    const realmResp = await page.goto(`${realmUrl}/auth/api/settings`)
+    expect(realmResp?.status()).toBe(200)
+    const realmSettings = await realmResp?.json()
+    expect(realmSettings.rp_id).toBe('test.localhost')
+    expect(realmSettings.own_auth_host).toBeNull()
+
+    const defaultResp = await page.goto(`${baseUrl}/auth/api/settings`)
+    expect(defaultResp?.status()).toBe(200)
+    const defaultSettings = await defaultResp?.json()
+    expect(defaultSettings.rp_id).toBe('localhost')
+
+    // Unknown host is rejected with 421 Misdirected Request.
+    // page.request is Node-side, so target loopback with an explicit Host.
+    const unknownResp = await page.request.get(`${baseUrl}/auth/api/settings`, {
+      headers: { Host: 'unknown.example.org' },
+    })
+    expect(unknownResp.status()).toBe(421)
+  })
+
+  test('well-known webauthn endpoint reflects related origins', async ({ page }) => {
+    // No related origins configured initially → 404
+    const before = await page.request.get(`${baseUrl}/.well-known/webauthn`)
+    expect(before.status()).toBe(404)
+  })
+
+  test('master admin manages realms and related origins via API', async ({ page, virtualAuthenticator }) => {
+    // Fresh session via device token (realm writes require recent auth)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'No device tokens available')
+    await page.goto('/auth/')
+    const reg = await registerPasskey(page, baseUrl, { resetToken: deviceToken })
+    expect(reg.session_token).toBeTruthy()
+
+    const headers = { Cookie: `${getSessionCookieName()}=${reg.session_token}` }
+
+    // List realms
+    const list = await page.request.get(`${baseUrl}/auth/api/admin/realms/`, { headers })
+    expect(list.ok()).toBeTruthy()
+    const realms = await list.json()
+    expect(realms.map((r: any) => r.rp_id).sort()).toEqual(['localhost', 'test.localhost'])
+    const localhostRealm = realms.find((r: any) => r.rp_id === 'localhost')
+    expect(localhostRealm.is_default).toBe(true)
+
+    // Add a related origin (unrelated domain) to the localhost realm
+    const patch = await page.request.patch(`${baseUrl}/auth/api/admin/realms/localhost`, {
+      headers,
+      data: { rp_name: '', auth_host: '', origins: ['https://app.example.com'] },
+    })
+    expect(patch.ok()).toBeTruthy()
+
+    // The well-known endpoint now lists it
+    const wk = await page.request.get(`${baseUrl}/.well-known/webauthn`)
+    expect(wk.ok()).toBeTruthy()
+    const wkJson = await wk.json()
+    expect(wkJson.origins).toContain('https://app.example.com')
+
+    // Restore: remove origins again so later tests see the pristine state
+    const restore = await page.request.patch(`${baseUrl}/auth/api/admin/realms/localhost`, {
+      headers,
+      data: { rp_name: '', auth_host: '', origins: [] },
+    })
+    expect(restore.ok()).toBeTruthy()
+    const after = await page.request.get(`${baseUrl}/.well-known/webauthn`)
+    expect(after.status()).toBe(404)
+  })
+
+  test('cross-realm remote login via pairing code', async ({ page, virtualAuthenticator }) => {
+    // Register a fresh passkey on localhost (this test's virtual authenticator)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'No device tokens available')
+    await page.goto('/auth/')
+    const reg = await registerPasskey(page, baseUrl, { resetToken: deviceToken })
+    expect(reg.session_token).toBeTruthy()
+
+    // Requester page on the other realm (no session there)
+    const reqPage = await page.context().newPage()
+    await reqPage.goto(`${realmUrl}/auth/`)
+
+    const pairingCode = await startRemoteAuthRequest(reqPage)
+    expect(pairingCode.split('.')).toHaveLength(3)
+
+    // Approver permits with the localhost passkey; the "found" message names
+    // the requesting realm
+    const found = await permitRemoteAuth(page, pairingCode)
+    expect(found.rp_id).toBe('test.localhost')
+
+    // The requester redeems the exchange code on its own realm and the
+    // session validates there for the same user
+    const validation = await awaitRemoteAuthSession(reqPage)
+    expect(validation.ctx.user.uuid).toBe(reg.user)
+
+    // The session is recorded with the requesting host
+    const userInfo = await reqPage.evaluate(async () => {
+      const resp = await fetch('/auth/api/user-info')
+      if (!resp.ok) throw new Error(`user-info failed: ${resp.status}`)
+      return resp.json()
+    })
+    const current = Object.values(userInfo.sessions as any[]).find((s: any) => s.is_current) as any
+    expect(current.host).toContain('test.localhost')
+
+    // The profile on test.localhost prompts adding a passkey for this realm,
+    // and the existing localhost passkey carries a realm badge
+    await reqPage.goto(`${realmUrl}/auth/`)
+    const notice = reqPage.locator('.realm-enroll-notice')
+    await expect(notice).toBeVisible({ timeout: 15000 })
+    await expect(notice).toContainText('test.localhost')
+    await expect(reqPage.locator('.badge-realm').first()).toHaveText('localhost')
+
+    await reqPage.close()
+  })
+})
diff --git a/e2e/tests/fixtures/remote-auth.ts b/e2e/tests/fixtures/remote-auth.ts
new file mode 100644
index 0000000..b3f3957
--- /dev/null
+++ b/e2e/tests/fixtures/remote-auth.ts
@@ -0,0 +1,187 @@
+import { type Page } from '@playwright/test'
+
+/**
+ * Remote authentication (pairing code) helpers for E2E tests.
+ * These drive the /auth/ws/remote-auth/* protocol directly in browser context,
+ * so requests carry the page origin's cookies and Chrome's host resolution.
+ */
+
+// PBKDF2-SHA512 PoW solver; must match frontend/src/utils/pow.js.
+// Passed as source into page.evaluate and instantiated with eval there.
+const solvePoWSource = `async (challengeBytes, work) => {
+  const baseKey = await crypto.subtle.importKey('raw', challengeBytes, 'PBKDF2', false, ['deriveBits'])
+  const solution = new Uint8Array(8 * work)
+  const nonce = new Uint32Array(2)
+  const mask = 0x7FF
+  for (let i = 0; i < work; i++) {
+    let result
+    do {
+      if (++nonce[0] === 0x100000000) ++nonce[1]
+      result = new Uint32Array(await crypto.subtle.deriveBits(
+        { name: 'PBKDF2', salt: nonce, iterations: 128, hash: 'SHA-512' }, baseKey, 32))
+    } while (result[0] & mask)
+    solution.set(new Uint8Array(nonce.buffer), i * 8)
+  }
+  return solution
+}`
+
+const b64helpersSource = `
+  const b64dec = (s) => Uint8Array.from(atob(s.replace(/-/g, '+').replace(/_/g, '/')), c => c.charCodeAt(0))
+  const b64enc = (buf) => btoa(String.fromCharCode(...new Uint8Array(buf))).replace(/\\+/g, '-').replace(/\\//g, '_').replace(/=+$/, '')
+`
+
+/**
+ * Start a remote auth request on the given page (the device wanting to log in).
+ * The page must already be navigated to the requesting realm's origin.
+ * Keeps the WebSocket open on window.__raWs and collects later messages into
+ * window.__raMsgs; resolves with the pairing code.
+ */
+export async function startRemoteAuthRequest(page: Page): Promise<string> {
+  return page.evaluate(async ({ powSrc, b64src }) => {
+    const solvePoW = eval(`(${powSrc})`)
+    const { b64dec, b64enc } = eval(`(() => { ${b64src}; return { b64dec, b64enc } })()`)
+    const w = window as any
+    w.__raMsgs = []
+    return new Promise<string>((resolve, reject) => {
+      const ws = new WebSocket(`ws://${location.host}/auth/ws/remote-auth/request`)
+      w.__raWs = ws
+      ws.onmessage = async (event) => {
+        const data = JSON.parse(event.data)
+        w.__raMsgs.push(data)
+        if (typeof data.status === 'number' && data.status >= 400) {
+          ws.close()
+          reject(new Error(data.detail || `request failed: ${data.status}`))
+          return
+        }
+        if (data.pow && !data.pairing_code) {
+          const solution = await solvePoW(b64dec(data.pow.challenge), data.pow.work)
+          ws.send(JSON.stringify({ pow: b64enc(solution), action: 'login' }))
+          return
+        }
+        if (data.pairing_code) {
+          resolve(data.pairing_code)
+        }
+      }
+      ws.onerror = () => reject(new Error('WebSocket error during remote auth request'))
+      ws.onclose = (event) => {
+        if (!event.wasClean && event.code !== 1000) reject(new Error(`WebSocket closed unexpectedly: ${event.code}`))
+      }
+    })
+  }, { powSrc: solvePoWSource, b64src: b64helpersSource })
+}
+
+/**
+ * Wait for the remote auth request on the page to complete, redeem the
+ * exchange code via set-session, and return the /auth/api/validate response.
+ */
+export async function awaitRemoteAuthSession(page: Page, timeoutMs = 90000): Promise<any> {
+  return page.evaluate(async ({ timeoutMs }) => {
+    const w = window as any
+    const msgs: any[] = w.__raMsgs
+    if (!msgs) throw new Error('No remote auth request started on this page')
+    const exchangeCode: string = await new Promise((resolve, reject) => {
+      const timer = setTimeout(() => reject(new Error('Timed out waiting for remote auth completion')), timeoutMs)
+      const iv = setInterval(() => {
+        const done = msgs.find(m => m.status === 'authenticated' && m.exchange_code)
+        const failed = msgs.find(m => ['denied', 'expired', 'timeout', 'cancelled'].includes(m.status) || (typeof m.status === 'number' && m.status >= 400))
+        if (done) {
+          clearTimeout(timer); clearInterval(iv)
+          resolve(done.exchange_code)
+        } else if (failed) {
+          clearTimeout(timer); clearInterval(iv)
+          reject(new Error(failed.detail || `Remote auth ${failed.status}`))
+        }
+      }, 50)
+    })
+    const resp = await fetch('/auth/api/set-session', {
+      method: 'POST',
+      headers: { 'Authorization': `Bearer ${exchangeCode}` },
+    })
+    if (!resp.ok) throw new Error(`set-session failed: ${resp.status}`)
+    const validate = await fetch('/auth/api/validate', { method: 'POST' })
+    if (!validate.ok) throw new Error(`validate failed: ${validate.status}`)
+    return await validate.json()
+  }, { timeoutMs })
+}
+
+/**
+ * Permit a remote auth request from the given page (the authenticating device).
+ * The page must be on the approver's origin with a valid session cookie and a
+ * virtual authenticator holding a credential for that realm.
+ * Resolves with the "found" message (includes the requesting realm's rp_id).
+ */
+export async function permitRemoteAuth(page: Page, code: string): Promise<any> {
+  return page.evaluate(async ({ code, powSrc, b64src }) => {
+    const solvePoW = eval(`(${powSrc})`)
+    const { b64dec, b64enc } = eval(`(() => { ${b64src}; return { b64dec, b64enc } })()`)
+    return new Promise((resolve, reject) => {
+      const ws = new WebSocket(`ws://${location.host}/auth/ws/remote-auth/permit`)
+      let stage = 0
+      let foundMsg: any = null
+      ws.onmessage = async (event) => {
+        const data = JSON.parse(event.data)
+        try {
+          if (typeof data.status === 'number' && data.status >= 400) {
+            ws.close()
+            reject(new Error(data.detail || `permit failed: ${data.status}`))
+            return
+          }
+          if (data.pow && stage === 0) {
+            const solution = await solvePoW(b64dec(data.pow.challenge), data.pow.work)
+            stage = 1
+            ws.send(JSON.stringify({ code, pow: b64enc(solution) }))
+            return
+          }
+          if (data.status === 'found') {
+            foundMsg = data
+            const solution = await solvePoW(b64dec(data.pow.challenge), data.pow.work)
+            stage = 2
+            ws.send(JSON.stringify({ authenticate: true, pow: b64enc(solution) }))
+            return
+          }
+          if (data.optionsJSON) {
+            const opts = data.optionsJSON
+            const credential = await navigator.credentials.get({
+              publicKey: {
+                challenge: b64dec(opts.challenge),
+                rpId: opts.rpId,
+                timeout: opts.timeout,
+                userVerification: opts.userVerification,
+                allowCredentials: opts.allowCredentials?.map((cred: any) => ({
+                  type: cred.type,
+                  id: b64dec(cred.id),
+                  transports: cred.transports,
+                })) || [],
+              }
+            }) as PublicKeyCredential | null
+            if (!credential) throw new Error('Failed to get credential')
+            const response = credential.response as AuthenticatorAssertionResponse
+            ws.send(JSON.stringify({
+              id: credential.id,
+              rawId: b64enc(credential.rawId),
+              response: {
+                clientDataJSON: b64enc(response.clientDataJSON),
+                authenticatorData: b64enc(response.authenticatorData),
+                signature: b64enc(response.signature),
+                userHandle: response.userHandle ? b64enc(response.userHandle) : null,
+              },
+              type: credential.type,
+              clientExtensionResults: credential.getClientExtensionResults(),
+              authenticatorAttachment: (credential as any).authenticatorAttachment,
+            }))
+            return
+          }
+          if (data.status === 'success') {
+            ws.close()
+            resolve(foundMsg)
+            return
+          }
+        } catch (err: any) {
+          ws.close()
+          reject(new Error(err.message || 'Permit failed'))
+        }
+      }
+      ws.onerror = () => reject(new Error('WebSocket error during permit'))
+    })
+  }, { code, powSrc: solvePoWSource, b64src: b64helpersSource })
+}
diff --git a/e2e/tests/global-setup.ts b/e2e/tests/global-setup.ts
index fcceb0a..0a140b3 100644
--- a/e2e/tests/global-setup.ts
+++ b/e2e/tests/global-setup.ts
@@ -1,4 +1,4 @@
-import { execSync, spawn } from 'child_process'
+import { execFileSync, spawn, spawnSync } from 'child_process'
 import { join, dirname } from 'path'
 import { existsSync, mkdirSync, rmSync, writeFileSync } from 'fs'
 import { fileURLToPath } from 'url'
@@ -20,55 +20,73 @@ interface TestState {
 /**
  * Global setup for E2E tests.
  *
- * Uses in-memory SQLite database for fast, isolated tests.
- * Captures the bootstrap reset token for initial user registration.
+ * Bootstraps a fresh combined database (paskia.kantadb) with two realms —
+ * localhost (default) and test.localhost — then starts the server with the
+ * test data directory as its working directory. Captures the bootstrap reset
+ * token from 'paskia init' output for initial user registration.
  */
 export default async function globalSetup() {
   console.log('\n🔧 Setting up E2E test environment...\n')
 
-  // Create test data directory for state file
-  if (!existsSync(testDataDir)) {
-    mkdirSync(testDataDir, { recursive: true })
-  }
+  // Start from a clean slate: the test data directory doubles as the server
+  // working directory, so paskia.kantadb and paskia.data/ are created here
+  rmSync(testDataDir, { recursive: true, force: true })
+  mkdirSync(testDataDir, { recursive: true })
 
   // Build the package first
   console.log('  Building package with uv build...')
-  execSync('uv build', { cwd: projectRoot, stdio: 'inherit' })
+  execFileSync('uv', ['build'], { cwd: projectRoot, stdio: 'inherit' })
   console.log('  ✅ Build complete\n')
 
-  console.log('  Starting server with in-memory database...')
   if (COLLECT_COVERAGE) {
     console.log('  📊 Coverage collection enabled for Python backend')
   }
 
   const state: TestState = {}
 
-  // Build server command - with or without coverage
-  const serverArgs = COLLECT_COVERAGE
-    ? [
-        'run', 'coverage', 'run', '--parallel-mode',
-        '-m', 'paskia', '-l', 'localhost:4404',
-        '--rp-id', 'localhost'
-      ]
-    : [
-        'run', 'paskia', '-l', 'localhost:4404',
-        '--rp-id', 'localhost'
-      ]
-
-  // Use a fresh database file for tests
-  const testDbFile = join(testDataDir, 'test.paskiadb')
-
-  if (existsSync(testDbFile)) {
-    console.log('  Removing stale test database...')
-    rmSync(testDbFile, { force: true, recursive: true })
+  // Bootstrap the database: two realms, localhost (default) and test.localhost
+  console.log('  Bootstrapping database with paskia init...')
+  const initResult = spawnSync(
+    'uv',
+    [
+      'run', '--project', projectRoot,
+      'paskia', 'init', '-l', 'localhost:4404',
+      '--rp-id', 'localhost,test.localhost',
+    ],
+    { cwd: testDataDir, encoding: 'utf-8' }
+  )
+  const initOutput = `${initResult.stdout}${initResult.stderr}`
+  process.stdout.write(initOutput)
+  if (initResult.status !== 0) {
+    throw new Error(`paskia init failed with exit code ${initResult.status}`)
   }
 
-  // Start the server using Node's spawn
+  // Parse the reset token from init output
+  // Format: http://localhost:4404/auth/{token} where token is dot-separated words
+  const match = initOutput.match(/https?:\/\/localhost(?::\d+)?\/auth\/([a-z]+(?:\.[a-z]+)+)/)
+  if (!match) {
+    throw new Error('Failed to capture reset token from paskia init output')
+  }
+  state.resetToken = match[1]
+  console.log(`\n  ✅ Captured reset token: ${state.resetToken}\n`)
+
+  // Start the server (serve mode: all configuration comes from the database)
+  console.log('  Starting server...')
+  const serverArgs = COLLECT_COVERAGE
+    ? [
+        'run', '--project', projectRoot,
+        'coverage', 'run', '--parallel-mode',
+        '-m', 'paskia', '-l', 'localhost:4404'
+      ]
+    : [
+        'run', '--project', projectRoot,
+        'paskia', '-l', 'localhost:4404'
+      ]
+
   const serverProcess = spawn('uv', serverArgs, {
-    cwd: projectRoot,
+    cwd: testDataDir,
     env: {
       ...process.env,
-      PASKIA_DB: testDbFile,
       COVERAGE_FILE: join(projectRoot, '.coverage'),
     },
     stdio: ['ignore', 'pipe', 'pipe'],
@@ -76,66 +94,38 @@ export default async function globalSetup() {
 
   state.serverPid = serverProcess.pid
 
-  // Capture output to find reset token
-  const resetTokenPromise = new Promise<string>((resolve, reject) => {
-    const timeout = setTimeout(() => {
-      reject(new Error('Timed out waiting for server bootstrap (30s)'))
-    }, 30000)
+  serverProcess.stdout?.on('data', (data: Buffer) => process.stdout.write(data))
+  serverProcess.stderr?.on('data', (data: Buffer) => process.stderr.write(data))
 
-    let output = ''
-
-    const handleData = (data: Buffer) => {
-      const text = data.toString()
-      output += text
-      process.stdout.write(text) // Echo to console
-
-      // Look for the reset token URL in the output
-      // Format: https://localhost/auth/{token} or http://localhost:4404/auth/{token}
-      // where token is word.word.word.word.word (dot separated)
-      const match = output.match(/https?:\/\/localhost(?::\d+)?\/auth\/([a-z]+(?:\.[a-z]+)+)/)
-      if (match) {
-        clearTimeout(timeout)
-        // Wait a bit for server to fully start
-        setTimeout(() => resolve(match[1]), 1000)
-      }
+  serverProcess.on('exit', (code) => {
+    if (code !== 0 && code !== null) {
+      console.error(`Server exited unexpectedly with code ${code}`)
     }
-
-    serverProcess.stdout?.on('data', handleData)
-    serverProcess.stderr?.on('data', handleData)
-
-    serverProcess.on('error', (err) => {
-      clearTimeout(timeout)
-      reject(err)
-    })
-
-    serverProcess.on('exit', (code) => {
-      if (code !== 0 && code !== null) {
-        clearTimeout(timeout)
-        reject(new Error(`Server exited with code ${code}`))
-      }
-    })
   })
 
-  try {
-    state.resetToken = await resetTokenPromise
-    console.log(`\n  ✅ Captured reset token: ${state.resetToken}\n`)
-  } catch (err) {
-    console.error('Failed to capture reset token:', err)
-    serverProcess.kill()
-    throw err
+  // Wait for the server to become ready and fetch the session cookie name
+  console.log('  Waiting for server readiness...')
+  const deadline = Date.now() + 30000
+  let settings: any = null
+  while (Date.now() < deadline) {
+    try {
+      const response = await fetch('http://localhost:4404/auth/api/settings')
+      if (response.ok) {
+        settings = await response.json()
+        break
+      }
+    } catch {
+      // Not up yet
+    }
+    await new Promise(r => setTimeout(r, 250))
   }
-
-  // Fetch session cookie name from server settings
-  try {
-    const response = await fetch('http://localhost:4404/auth/api/settings')
-    const settings = await response.json()
-    state.sessionCookie = settings.session_cookie
-    console.log(`  ✅ Session cookie name: ${state.sessionCookie}\n`)
-  } catch (err) {
-    console.error('Failed to fetch settings:', err)
+  if (!settings) {
     serverProcess.kill()
-    throw err
+    throw new Error('Server did not become ready in time (30s)')
   }
+  state.sessionCookie = settings.session_cookie
+  console.log(`  ✅ Session cookie name: ${state.sessionCookie}`)
+  console.log(`  ✅ Realm: ${settings.rp_id} (${settings.rp_name})\n`)
 
   // Save state for tests
   writeFileSync(stateFile, JSON.stringify(state, null, 2))
diff --git a/e2e/tests/global-teardown.ts b/e2e/tests/global-teardown.ts
index 1570058..25ccdcb 100644
--- a/e2e/tests/global-teardown.ts
+++ b/e2e/tests/global-teardown.ts
@@ -59,11 +59,13 @@ export default async function globalTeardown() {
     rmSync(stateFile, { force: true })
   }
 
-  // Clean up test database
-  const testDbFile = join(testDataDir, 'test.paskiadb')
-  if (existsSync(testDbFile)) {
-    console.log('  Removing test database...')
-    rmSync(testDbFile, { force: true, recursive: true })
+  // Clean up test database and auxiliary data
+  for (const name of ['paskia.kantadb', 'paskia.data']) {
+    const p = join(testDataDir, name)
+    if (existsSync(p)) {
+      console.log(`  Removing ${name}...`)
+      rmSync(p, { force: true, recursive: true })
+    }
   }
 
   // Generate Python coverage report if coverage was collected