diff --git a/.gitignore b/.gitignore
index 9f37740..ccc51e2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@
 Package.resolved
 xcuserdata/
 DerivedData/
+build/
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c657ed..30501d3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,198 @@ Alle Änderungen werden hier dokumentiert. Format orientiert an
 [Keep a Changelog](https://keepachangelog.com), Versionierung nach
 [Semver](https://semver.org).
 
+## [1.5.0] — 2026-05-14
+
+Minor — `getProfile()` + `ProfileInfo`. Apps können den 2FA-Status
+des eingeloggten Users lesen, damit AccountView entscheidet ob
+"Aktivieren" oder "Deaktivieren" angezeigt wird.
+
+### Neu
+
+- `ProfileInfo` (public struct) — `id`, `email`, `name`,
+  `emailVerified`, `twoFactorEnabled`.
+- `AuthClient.getProfile() -> ProfileInfo` — lädt aktuelles Profil
+  vom Server (`GET /api/v1/auth/profile` → Better Auths
+  `/api/auth/get-session`). Nutzt Session-Token als Bearer.
+
+### Tests
+
+- 4 neue Tests (twoFactor-on, twoFactor-off, ohne Session,
+  unauthorized). 70/70 grün.
+
+## [1.4.0] — 2026-05-14
+
+Minor — 2FA-Enrollment (Mini-Sprint B). Setzt Mini-Sprint A
+(`v1.3.0`) voraus. Komplett additiv.
+
+### ManaCore — 2FA-Enrollment
+
+- `TotpEnrollment` (public struct) — `totpURI` (für QR-Code-Display)
+  + `backupCodes` (Liste).
+- `AuthClient.enrollTotp(password:) -> TotpEnrollment` — aktiviert
+  TOTP-2FA; Server generiert Secret + Backup-Codes.
+- `AuthClient.disableTotp(password:)` — deaktiviert wieder.
+- `AuthClient.getTotpUri(password:) -> String` — Re-Display für
+  zweites Authenticator-Gerät.
+- `AuthClient.regenerateBackupCodes(password:) -> [String]` — neue
+  Codes, alte werden ungültig.
+
+Alle vier Methoden senden Bearer-Header mit Session-Token (Wire-
+Konvention für mana-auth-Account-Endpoints).
+
+### Server-Side Voraussetzung
+
+`mana-auth` ≥ Commit der Wrapper-Endpoints:
+- `POST /api/v1/auth/two-factor/enable`
+- `POST /api/v1/auth/two-factor/disable`
+- `POST /api/v1/auth/two-factor/get-totp-uri`
+- `POST /api/v1/auth/two-factor/generate-backup-codes`
+
+### Tests
+
+- 7 neue Tests (Success-Pfade aller vier Methoden, leeres Passwort,
+  ohne Session, falsches Passwort). 66/66 grün.
+
+## [1.3.0] — 2026-05-14
+
+Minor — 2FA-Login-Challenge (Mini-Sprint A). Apps mit aktiviertem
+TOTP-2FA können sich jetzt nativ einloggen. Komplett additiv.
+
+### ManaCore — 2FA-Login
+
+- `AuthClient.Status.twoFactorRequired(token: String, methods: [String], email: String)`
+  als neuer Case. Tritt nach `signIn(...)` auf, wenn der Account 2FA
+  aktiviert hat. `token` ist der opaque `two_factor`-Cookie-Wert vom
+  Server, den die App bei `verifyTotp(...)` zurückschickt.
+- `AuthClient.verifyTotp(code:trustDevice:)` — verifiziert 6-stelligen
+  TOTP-Code. Bei Erfolg `.signedIn`, bei Fehler bleibt der Status im
+  Challenge (User kann retry).
+- `AuthClient.verifyBackupCode(code:trustDevice:)` — Fallback wenn das
+  TOTP-Gerät verloren wurde. Backup-Codes sind einmalig.
+- `signIn(...)` erkennt den Server-Pfad `{twoFactorRequired: true, ...}`
+  und routet automatisch zu `.twoFactorRequired`.
+
+### Server-Side Voraussetzung
+
+Setzt zwei neue Custom-Endpoints in `mana-auth` voraus:
+- `POST /api/v1/auth/two-factor/verify-totp`
+- `POST /api/v1/auth/two-factor/verify-backup-code`
+
+Plus die `/api/v1/auth/login`-Erweiterung um den `twoFactorRequired`-
+Pfad. Siehe `mana/services/mana-auth/src/routes/auth.ts`.
+
+### Tests
+
+- 5 neue Tests (signIn-Redirect, verifyTotp-Success/-Fail, ohne-Challenge-
+  Guard, verifyBackupCode). 59/59 grün.
+
+### Bewusst NICHT in v1.3.0
+
+- 2FA-**Enrollment** (TOTP-Setup) — eigener Mini-Sprint B mit
+  `enrollTotp()`, `disableTotp()`, `regenerateBackupCodes()`.
+- Magic-Link, Passkey — eigene Sprints.
+
+## [1.2.0] — 2026-05-13
+
+Minor — Guest-Mode + Auth-Resilience. Native-Apps werden gegen mana-auth-
+Downtime gehärtet und können jetzt einen anonymen Local-First-Modus
+anbieten. Komplett additiv — keine Breaking Changes für bestehende
+Konsumenten (Memoro, Cards, Manaspur, Nutriphi).
+
+### ManaCore — Guest-Identität
+
+- `AuthClient.Status` um Case `.guest(id: String)` erweitert. Persistente
+  lokale UUID ohne Server-Account; gleichberechtigt mit `.signedIn` als
+  „App ist nutzbar"-Zustand. Apps können in diesem Modus alles Lokale
+  und alle unauthenticated-Server-Endpoints anbieten, schreibende
+  Endpoints poppen Auth-Sheet.
+- `AuthClient.enterGuestMode() throws -> String` — idempotent, erzeugt
+  oder reuse die Guest-UUID aus Keychain. Wechselt den Status nur,
+  wenn aktuell `.signedOut`/`.unknown` (eine aktive Session bleibt
+  unangetastet, App kann die Guest-ID parallel lesen).
+- `AuthClient.currentGuestId() -> String?` — Lookup unabhängig vom Status.
+  Genutzt z.B. um lokale Guest-Daten beim Sign-In dem neuen Server-
+  Account zuzuordnen.
+- `AuthClient.clearGuestId()` — entfernt die Guest-ID, etwa nach
+  erfolgreicher Migration der lokalen Daten auf einen Server-Account.
+- `AuthClient.signOut(keepGuestMode: Bool = false)` — Default-Verhalten
+  unverändert (`false` löscht alles, Status `.signedOut`). Mit `true`
+  bleibt die App im anonymen Modus weiter nutzbar.
+- `KeychainStore.Key.guestId` als neuer Key. `wipe()` löscht jetzt
+  *nur* Session-Felder (accessToken/refreshToken/email) — die Guest-ID
+  überlebt. Für komplettes Vergessen: neue `wipeAll()`.
+
+### ManaCore — Refresh-Resilience
+
+- `refreshAccessToken()` wipt nicht mehr blind den Keychain bei jedem
+  Nicht-200. Stattdessen Heuristik via `AuthError.invalidatesSession`:
+  - **Wipe** bei `.invalidCredentials`, `.unauthorized`, `.tokenExpired`,
+    `.tokenInvalid`, `.emailNotVerified` — Session ist tatsächlich tot.
+  - **Behalten** bei `.serviceUnavailable` (503), `.serverInternal`
+    (500), `.networkFailure`, `.rateLimited`, weiteren transienten
+    Fehlern. Apps werden bei mana-auth-Downtime nicht mehr in den
+    Login-Screen geworfen.
+- Beim Wipe-Pfad fällt der Status auf `.guest(id)` zurück, falls eine
+  Guest-Identität existiert; sonst auf `.signedOut`.
+- `AuthError.invalidatesSession: Bool` — public computed Property,
+  auch von Apps direkt nutzbar (z.B. um auf Transport-Fehler zu
+  reagieren).
+
+### Tests
+
+- 15 neue Tests: Guest-Mode (Idempotenz, Bootstrap-Priorität, Status-
+  Übergänge), signOut(keepGuestMode:) in beiden Modi, Refresh-Verhalten
+  bei 401/429/500/503/Network, invalidatesSession-Partitionierung.
+
+### Migration für Apps
+
+Bestehende Apps brauchen **keine** Änderung — Default-Verhalten ist
+identisch. Wer den anonymen Modus nutzen will:
+
+```swift
+// Beim App-Start nach bootstrap():
+auth.bootstrap()
+if case .signedOut = auth.status {
+    try? auth.enterGuestMode()  // Statt sofort Login-Screen
+}
+
+// In Aktionen, die einen Account brauchen:
+guard case .signedIn = auth.status else {
+    presentLoginSheet()
+    return
+}
+```
+
+## [1.1.1] — 2026-05-13
+
+Patch — Wire-Konvention für authenticated Account-Calls geklärt.
+
+### Geändert
+
+- `AuthClient.changeEmail`, `changePassword`, `deleteAccount` senden
+  jetzt den Session-Token (`refreshToken`-Feldwert) statt des JWT als
+  `Authorization: Bearer`. Hintergrund: Server-seitig wurde in
+  `mana-auth` Better Auths `bearer`-Plugin aktiviert
+  (`requireSignature: false`), das Session-Tokens zu Session-Cookies
+  konvertiert. Damit funktionieren `auth.api.changeEmail` etc. für
+  Native-Apps ohne Cookie-Container.
+- `AuthClient.currentSessionToken()` als public Helper hinzu. Symmetrisch
+  zu `currentAccessToken()`.
+
+### Trade-Off bewusst akzeptiert
+
+Session-Token wird bei jedem Account-Call versendet (vorher nur beim
+`/refresh`). Mit TLS-Baseline akzeptables Risiko; Compromise-Surface
+nicht relevant größer als JWT-Leak. Alternative wäre ein Custom-
+Bearer-JWT-to-Cookie-Resolver im Server (40+ Zeilen Hono-Middleware,
+HMAC-Cookie-Synthese) — bewusst nicht gewählt, weil der bearer-Plugin
+genau für diesen Use-Case existiert.
+
+### Tests
+
+- Test `changePassword schickt Bearer-Header` umbenannt auf
+  `schickt Session-Token als Bearer (nicht JWT)` und geupdated.
+
 ## [1.1.0] — 2026-05-13
 
 Phase 1 aus dem Native-Auth-Vollausbau-Plan (Option A — alles nativ,
diff --git a/Sources/ManaCore/Auth/AuthClient+Account.swift b/Sources/ManaCore/Auth/AuthClient+Account.swift
index d16b017..b717004 100644
--- a/Sources/ManaCore/Auth/AuthClient+Account.swift
+++ b/Sources/ManaCore/Auth/AuthClient+Account.swift
@@ -17,16 +17,19 @@ import Foundation
 /// - `POST /change-password` — Passwort ändern (current + new)
 /// - `DELETE /account` — Account löschen (App-Store-Pflicht 5.1.1(v))
 ///
-/// **Server-Limitation (Stand 2026-05-13):** `change-email`,
-/// `change-password` und `DELETE /account` forwarden Original-Request-
-/// Headers an Better Auth. Better Auth liest Session-Cookies. Der
-/// `bearer`-Plugin von Better Auth ist NICHT installiert, daher
-/// scheitern diese Endpoints heute mit reinem `Authorization: Bearer`.
-/// → Server-Fix in Phase 3 nötig (entweder `bearerPlugin()` in
-/// `better-auth.config.ts` aktivieren oder Custom-Bearer-Resolver in
-/// `mana-auth/src/routes/auth.ts` ergänzen). ManaCore sendet Bearer
-/// bereits korrekt — sobald der Server das akzeptiert, funktionieren
-/// die Methoden ohne Swift-Änderung.
+/// **Wire-Konvention für authenticated Account-Calls:**
+/// `change-email`, `change-password` und `DELETE /account` forwarden
+/// die Original-Request-Headers an Better Auth (`auth.api.changeEmail`
+/// etc.). Better Auth's `bearer`-Plugin (seit 2026-05-13 in mana-auth
+/// aktiv) konvertiert `Authorization: Bearer <session-token>` in
+/// einen synthetischen Session-Cookie. **Native-Apps senden hier den
+/// Session-Token (`refreshToken`-Feldwert aus /login bzw. /refresh),
+/// NICHT den JWT.** Der JWT bleibt für app-eigene Backends
+/// (memoro-api, cardecky-api etc.) der richtige Header.
+///
+/// Trade-Off: Session-Token wird häufiger versendet als der reine
+/// Refresh-Pfad. Bei TLS-only-Baseline akzeptabel; Compromise-Surface
+/// nicht relevant größer als JWT-Leak.
 public extension AuthClient {
     // MARK: - Registrierung
 
@@ -296,7 +299,9 @@ public extension AuthClient {
 
 extension AuthClient {
     /// Generischer JSON-POST/DELETE-Helper. Wenn `authenticated == true`,
-    /// wird der aktuelle Bearer-Token mitgeschickt.
+    /// wird der Session-Token (`refreshToken`-Feldwert, von Better Auth
+    /// als Session-ID interpretierbar via `bearer`-Plugin) als Bearer-
+    /// Header mitgeschickt — NICHT der JWT. Siehe Doc-Header dieser Datei.
     fileprivate func postJSON<Body: Encodable>(
         path: String,
         method: String = "POST",
@@ -308,7 +313,7 @@ extension AuthClient {
         request.httpMethod = method
         request.setValue("application/json", forHTTPHeaderField: "Content-Type")
         if authenticated {
-            let token = try currentAccessToken()
+            let token = try currentSessionToken()
             request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
         }
         do {
@@ -383,3 +388,348 @@ private struct ChangePasswordRequest: Encodable {
 private struct DeleteAccountRequest: Encodable {
     let password: String
 }
+
+// MARK: - Two-Factor (Login-Challenge)
+
+public extension AuthClient {
+    /// Verifiziert einen TOTP-Code im 2FA-Login-Flow. Vorbedingung:
+    /// Status ist ``Status/twoFactorRequired(token:methods:email:)``
+    /// (typisch nach `signIn(...)`).
+    ///
+    /// Bei Erfolg setzt der Server die Session, ManaCore persistiert
+    /// Tokens und der Status wird `.signedIn(email:)`.
+    ///
+    /// - Parameters:
+    ///   - code: 6-stelliger TOTP-Code aus der Authenticator-App.
+    ///   - trustDevice: Wenn `true`, setzt der Server einen
+    ///     `trust_device`-Cookie. Bei Native heute ohne Effekt
+    ///     (Cookies werden nicht persistiert) — wir spiegeln das Flag
+    ///     trotzdem für künftige Erweiterungen.
+    ///
+    /// - Throws: ``AuthError/twoFactorFailed`` bei falschem Code,
+    ///   ``AuthError/tokenExpired`` wenn der Challenge-Token alt ist,
+    ///   plus Standard-Netzwerk-Fehler.
+    func verifyTotp(code: String, trustDevice: Bool = false) async throws {
+        try await verifyTwoFactor(
+            path: "/api/v1/auth/two-factor/verify-totp",
+            code: code,
+            trustDevice: trustDevice
+        )
+    }
+
+    /// Verifiziert einen Backup-Code im 2FA-Login-Flow. Same Pre-/
+    /// Postconditions wie ``verifyTotp(code:trustDevice:)`` — der
+    /// Server entscheidet anhand des Endpoints, welches Verfahren er
+    /// nutzt. Backup-Codes werden vom Server beim Setup generiert
+    /// und einmalig konsumiert.
+    func verifyBackupCode(code: String, trustDevice: Bool = false) async throws {
+        try await verifyTwoFactor(
+            path: "/api/v1/auth/two-factor/verify-backup-code",
+            code: code,
+            trustDevice: trustDevice
+        )
+    }
+
+    private func verifyTwoFactor(
+        path: String,
+        code: String,
+        trustDevice: Bool
+    ) async throws {
+        guard case let .twoFactorRequired(token, _, email) = status else {
+            throw AuthError.validation(
+                message: "Kein 2FA-Challenge aktiv — verifyTotp setzt eine vorherige signIn-Antwort mit .twoFactorRequired voraus"
+            )
+        }
+        guard !code.isEmpty else {
+            throw AuthError.validation(message: "Code ist erforderlich")
+        }
+
+        let body = TwoFactorVerifyRequest(
+            code: code,
+            twoFactorToken: token,
+            trustDevice: trustDevice
+        )
+        let (data, http) = try await postJSON(path: path, body: body)
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+
+        let token2 = try JSONDecoder().decode(TwoFactorVerifyResponse.self, from: data)
+        guard let access = token2.accessToken, let refresh = token2.refreshToken else {
+            // Server hat 200 zurück, aber keine Tokens. Sollte nicht
+            // passieren — UI bleibt im 2FA-Required-Zustand.
+            throw AuthError.decoding("Tokens fehlen in 2FA-Verify-Antwort")
+        }
+
+        try persistSession(email: email, accessToken: access, refreshToken: refresh)
+        CoreLog.auth.info("2FA verify successful — signed in")
+    }
+}
+
+private struct TwoFactorVerifyRequest: Encodable {
+    let code: String
+    let twoFactorToken: String
+    let trustDevice: Bool
+}
+
+private struct TwoFactorVerifyResponse: Decodable {
+    let success: Bool?
+    let accessToken: String?
+    let refreshToken: String?
+}
+
+// MARK: - Two-Factor (Enrollment)
+
+/// Ergebnis von ``AuthClient/enrollTotp(password:)``: enthält die
+/// otpauth-URI (für QR-Code-Display) und die Backup-Codes. Backup-
+/// Codes sind einmalig nutzbar und sollten dem User zum Sichern
+/// (Kopieren/Drucken) angeboten werden — der Server zeigt sie nie
+/// mehr.
+public struct TotpEnrollment: Sendable, Equatable {
+    /// `otpauth://totp/Issuer:email?secret=...&...`-URI. Direkt als
+    /// QR-Code rendern (z.B. via `CIFilter.qrCodeGenerator`).
+    public let totpURI: String
+
+    /// Liste der Backup-Codes (üblich 10 Stück). Der User sollte sie
+    /// sicher aufbewahren — bei Verlust des TOTP-Geräts sind sie der
+    /// einzige Fallback. Server merkt sich nur Hashes; bei Verbrauch
+    /// werden sie als consumed markiert.
+    public let backupCodes: [String]
+}
+
+public extension AuthClient {
+    /// Aktiviert TOTP-2FA für den aktuellen Account.
+    ///
+    /// Re-Auth via aktuellem Passwort. Bei Erfolg generiert der Server
+    /// ein TOTP-Secret und gibt die otpauth-URI + Backup-Codes zurück.
+    /// Die App rendert die URI als QR-Code, der User scannt mit
+    /// Authenticator-App und gibt zur Bestätigung den ersten Code ein —
+    /// dieser zweite Schritt läuft über die regulären
+    /// ``verifyTotp(code:trustDevice:)``-Methode oder einen Re-Auth
+    /// signIn → twoFactorRequired-Flow (der Server entscheidet).
+    ///
+    /// - Important: Nutzt den Session-Token als Bearer (Wire-Konvention
+    ///   für mana-auth-Account-Endpoints, siehe Doc-Header dieser Datei).
+    func enrollTotp(password: String) async throws -> TotpEnrollment {
+        guard !password.isEmpty else {
+            throw AuthError.validation(message: "Passwort ist erforderlich")
+        }
+
+        let body = TotpEnableRequest(password: password)
+        let (data, http) = try await postJSON(
+            path: "/api/v1/auth/two-factor/enable",
+            body: body,
+            authenticated: true
+        )
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+
+        let decoded = try JSONDecoder().decode(TotpEnableResponse.self, from: data)
+        guard let uri = decoded.totpURI else {
+            throw AuthError.decoding("totpURI fehlt in Enroll-Antwort")
+        }
+        CoreLog.auth.info("2FA TOTP enrollment initiated")
+        return TotpEnrollment(totpURI: uri, backupCodes: decoded.backupCodes ?? [])
+    }
+
+    /// Deaktiviert TOTP-2FA für den aktuellen Account. Re-Auth via
+    /// Passwort.
+    func disableTotp(password: String) async throws {
+        guard !password.isEmpty else {
+            throw AuthError.validation(message: "Passwort ist erforderlich")
+        }
+
+        let body = TotpEnableRequest(password: password)
+        let (data, http) = try await postJSON(
+            path: "/api/v1/auth/two-factor/disable",
+            body: body,
+            authenticated: true
+        )
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+        CoreLog.auth.info("2FA TOTP disabled")
+    }
+
+    /// Liefert die otpauth-URI des aktuellen TOTP-Secrets. Nützlich
+    /// wenn der User den QR-Code erneut sehen will (z.B. zweites
+    /// Gerät einrichten). Re-Auth via Passwort.
+    ///
+    /// - Returns: `otpauth://totp/…`-URI, direkt als QR-Code renderbar.
+    func getTotpUri(password: String) async throws -> String {
+        guard !password.isEmpty else {
+            throw AuthError.validation(message: "Passwort ist erforderlich")
+        }
+
+        let body = TotpEnableRequest(password: password)
+        let (data, http) = try await postJSON(
+            path: "/api/v1/auth/two-factor/get-totp-uri",
+            body: body,
+            authenticated: true
+        )
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+
+        let decoded = try JSONDecoder().decode(TotpEnableResponse.self, from: data)
+        guard let uri = decoded.totpURI else {
+            throw AuthError.decoding("totpURI fehlt in get-totp-uri-Antwort")
+        }
+        return uri
+    }
+
+    /// Regeneriert die Backup-Codes. Alte Codes werden ungültig. Der
+    /// User sollte die neuen direkt sichern.
+    func regenerateBackupCodes(password: String) async throws -> [String] {
+        guard !password.isEmpty else {
+            throw AuthError.validation(message: "Passwort ist erforderlich")
+        }
+
+        let body = TotpEnableRequest(password: password)
+        let (data, http) = try await postJSON(
+            path: "/api/v1/auth/two-factor/generate-backup-codes",
+            body: body,
+            authenticated: true
+        )
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+
+        let decoded = try JSONDecoder().decode(TotpEnableResponse.self, from: data)
+        guard let codes = decoded.backupCodes else {
+            throw AuthError.decoding("backupCodes fehlen in Antwort")
+        }
+        return codes
+    }
+}
+
+private struct TotpEnableRequest: Encodable {
+    let password: String
+}
+
+/// Antwort-Format für alle Enrollment-Endpoints. Felder sind optional
+/// damit derselbe Type für `enable` (beide), `get-totp-uri` (nur URI)
+/// und `generate-backup-codes` (nur Codes) dekodierbar ist.
+private struct TotpEnableResponse: Decodable {
+    let totpURI: String?
+    let backupCodes: [String]?
+}
+
+// MARK: - Profile
+
+/// Subset des Server-User-Profiles, das die Apps für UI-Entscheidungen
+/// brauchen. Wird von ``AuthClient/getProfile()`` geliefert.
+///
+/// Server-Quelle: `GET /api/v1/auth/profile` (→ Better Auths
+/// `/api/auth/get-session`). Returnt `{user: {…}, session: {…}}`.
+/// Wir nehmen nur die UI-relevanten Felder mit.
+public struct ProfileInfo: Sendable, Equatable {
+    public let id: String
+    public let email: String
+    public let name: String?
+    public let emailVerified: Bool
+    /// `true` wenn der User TOTP-2FA aktiviert hat. Apps zeigen
+    /// dann den Disable-/Regenerate-Pfad statt des Enroll-Wizards.
+    public let twoFactorEnabled: Bool
+
+    public init(
+        id: String,
+        email: String,
+        name: String?,
+        emailVerified: Bool,
+        twoFactorEnabled: Bool
+    ) {
+        self.id = id
+        self.email = email
+        self.name = name
+        self.emailVerified = emailVerified
+        self.twoFactorEnabled = twoFactorEnabled
+    }
+}
+
+public extension AuthClient {
+    /// Lädt das aktuelle Profil des eingeloggten Users vom Server.
+    ///
+    /// - Important: Nutzt den Session-Token als Bearer (Wire-Konvention
+    ///   für mana-auth-Endpoints, siehe Doc-Header dieser Datei).
+    ///
+    /// - Throws: ``AuthError/notSignedIn`` ohne Session,
+    ///   ``AuthError/unauthorized`` wenn Server den Token rejected,
+    ///   Netzwerk-Cases.
+    func getProfile() async throws -> ProfileInfo {
+        let token = try currentSessionToken()
+        let url = config.authBaseURL.appending(path: "/api/v1/auth/profile")
+        var request = URLRequest(url: url)
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
+
+        let (data, http): (Data, HTTPURLResponse)
+        do {
+            let (d, r) = try await session.data(for: request)
+            guard let h = r as? HTTPURLResponse else {
+                throw AuthError.networkFailure("Keine HTTP-Antwort")
+            }
+            data = d
+            http = h
+        } catch let error as URLError {
+            throw AuthError.networkFailure(error.localizedDescription)
+        }
+
+        guard http.statusCode == 200 else {
+            throw AuthError.classify(
+                status: http.statusCode,
+                data: data,
+                retryAfterHeader: http.retryAfterSeconds
+            )
+        }
+
+        let envelope = try JSONDecoder().decode(ProfileEnvelope.self, from: data)
+        guard let user = envelope.user else {
+            throw AuthError.decoding("user-Feld fehlt in profile-Antwort")
+        }
+
+        return ProfileInfo(
+            id: user.id,
+            email: user.email,
+            name: user.name,
+            emailVerified: user.emailVerified ?? false,
+            twoFactorEnabled: user.twoFactorEnabled ?? false
+        )
+    }
+}
+
+/// Wire-Format-Hülle für `GET /api/v1/auth/profile`. Better-Auth-
+/// `/api/auth/get-session` returnt `{user: {...}, session: {...}}`;
+/// wir lesen `user` und ignorieren `session`.
+private struct ProfileEnvelope: Decodable {
+    let user: ProfileUser?
+}
+
+private struct ProfileUser: Decodable {
+    let id: String
+    let email: String
+    let name: String?
+    let emailVerified: Bool?
+    let twoFactorEnabled: Bool?
+}
diff --git a/Sources/ManaCore/Auth/AuthClient.swift b/Sources/ManaCore/Auth/AuthClient.swift
index c11ab2e..264b317 100644
--- a/Sources/ManaCore/Auth/AuthClient.swift
+++ b/Sources/ManaCore/Auth/AuthClient.swift
@@ -15,9 +15,27 @@ import Observation
 @Observable
 public final class AuthClient {
     public enum Status: Equatable, Sendable {
+        /// Vor `bootstrap()` — Keychain noch nicht ausgewertet.
         case unknown
+        /// Kein Account, keine Guest-Identität. UI sollte Login/Sign-Up
+        /// anbieten oder via `enterGuestMode()` einen anonymen Modus
+        /// starten.
         case signedOut
+        /// Anonyme lokale Identität ohne Server-Account. Apps können
+        /// lokale Daten unter dieser UUID persistieren und sie später
+        /// beim Sign-In einem Server-Account zuordnen. Read-only-
+        /// Server-Endpoints, die keinen User brauchen, sind in diesem
+        /// Status erreichbar; schreibende Endpoints nicht.
+        case guest(id: String)
         case signingIn
+        /// Sign-In war erfolgreich aber der Account hat 2FA aktiviert.
+        /// UI fragt nun den TOTP-Code (oder einen Backup-Code) ab und
+        /// ruft `verifyTotp(code:trustDevice:)` / `verifyBackupCode(...)`
+        /// mit dem hier gespeicherten Token auf.
+        ///
+        /// `token` ist der Better-Auth-`two_factor`-Cookie-Wert, vom
+        /// Server in der Login-Response als `twoFactorToken` mitgeliefert.
+        case twoFactorRequired(token: String, methods: [String], email: String)
         case signedIn(email: String)
         case error(String)
     }
@@ -49,16 +67,73 @@ public final class AuthClient {
         return nil
     }
 
+    /// Liest den persistierten Auth-Zustand aus dem Keychain. Reihenfolge:
+    /// vollwertige Session > Guest-Identität > komplett ausgeloggt.
+    ///
+    /// Keine Server-Roundtrips — Apps starten offline-fähig und mana-auth-
+    /// Downtime kann den letzten gültigen Zustand nicht überschreiben.
+    /// Token-Gültigkeit wird erst beim nächsten authentifizierten Call
+    /// geprüft (siehe ``refreshAccessToken()``).
     public func bootstrap() {
         let email = keychain.getString(for: .email)
         let hasToken = keychain.getString(for: .accessToken) != nil
         if let email, hasToken {
             status = .signedIn(email: email)
+        } else if let guestId = keychain.getString(for: .guestId) {
+            status = .guest(id: guestId)
         } else {
             status = .signedOut
         }
     }
 
+    /// Aktive Guest-Identität, falls vorhanden. Persistiert über
+    /// App-Starts hinweg. Existiert sowohl im ``Status/guest(id:)`` als
+    /// auch parallel zu einer eingeloggten Session — letzteres erlaubt
+    /// es einer App, beim Sign-In die zuvor lokal gesammelten anonymen
+    /// Daten dem neuen Server-Account zuzuordnen.
+    public func currentGuestId() -> String? {
+        keychain.getString(for: .guestId)
+    }
+
+    /// Setzt die App in den anonymen Modus. Idempotent: liefert eine
+    /// bestehende Guest-ID zurück, wenn schon eine im Keychain liegt;
+    /// sonst wird eine neue UUID erzeugt und persistiert.
+    ///
+    /// Ändert den Status nur, wenn aktuell `.signedOut` oder `.unknown`
+    /// vorliegt. Bei aktiver Session (`.signedIn`/`.signingIn`) bleibt
+    /// der Status unverändert — die App kann trotzdem `currentGuestId()`
+    /// nutzen, um die anonyme ID zu lesen, ohne die Session zu stören.
+    ///
+    /// - Throws: ``AuthError/keychain(_:)`` wenn der Keychain-Write
+    ///   scheitert.
+    @discardableResult
+    public func enterGuestMode() throws -> String {
+        if let existing = keychain.getString(for: .guestId) {
+            if case .signedIn = status {} else if case .signingIn = status {} else {
+                status = .guest(id: existing)
+            }
+            return existing
+        }
+        let newId = UUID().uuidString
+        try keychain.setString(newId, for: .guestId)
+        if case .signedIn = status {} else if case .signingIn = status {} else {
+            status = .guest(id: newId)
+        }
+        CoreLog.auth.info("Entered guest mode")
+        return newId
+    }
+
+    /// Löscht die Guest-Identität aus dem Keychain. Genutzt nach einer
+    /// erfolgreichen Migration der lokalen Guest-Daten auf einen
+    /// Server-Account — die anonyme ID wird dann nicht mehr gebraucht.
+    /// Wenn der Status aktuell `.guest` ist, wechselt er auf `.signedOut`.
+    public func clearGuestId() {
+        keychain.remove(for: .guestId)
+        if case .guest = status {
+            status = .signedOut
+        }
+    }
+
     public func signIn(email: String, password: String) async {
         let trimmed = email.trimmingCharacters(in: .whitespacesAndNewlines)
         guard !trimmed.isEmpty, !password.isEmpty else {
@@ -93,6 +168,23 @@ public final class AuthClient {
                 return
             }
 
+            // 2FA-Pfad: Server hat statt Tokens einen
+            // `twoFactorRequired`-Response geliefert. UI muss jetzt
+            // den TOTP-Code abfragen und `verifyTotp(...)` aufrufen.
+            if let twoFactor = try? JSONDecoder().decode(TwoFactorChallenge.self, from: data),
+               twoFactor.twoFactorRequired == true,
+               let tfToken = twoFactor.twoFactorToken
+            {
+                status = .twoFactorRequired(
+                    token: tfToken,
+                    methods: twoFactor.twoFactorMethods ?? ["totp"],
+                    email: trimmed
+                )
+                lastError = nil
+                CoreLog.auth.info("Sign-in needs 2FA challenge")
+                return
+            }
+
             let token = try JSONDecoder().decode(TokenResponse.self, from: data)
             try keychain.setString(token.accessToken, for: .accessToken)
             try keychain.setString(token.refreshToken, for: .refreshToken)
@@ -113,7 +205,15 @@ public final class AuthClient {
         }
     }
 
-    public func signOut() async {
+    /// Logged den User aus. Versucht den Server zu informieren (Logout-
+    /// Endpoint), wischt den lokalen Keychain und setzt den Status.
+    ///
+    /// - Parameter keepGuestMode: Wenn `true`, bleibt die App in einem
+    ///   anonymen Local-First-Modus aktiv. Eine bestehende Guest-ID
+    ///   wird beibehalten oder eine neue erzeugt; der Status wechselt
+    ///   auf ``Status/guest(id:)``. Default `false` für strict-Logout
+    ///   (Status → `.signedOut`, auch Guest-ID gelöscht).
+    public func signOut(keepGuestMode: Bool = false) async {
         if let token = keychain.getString(for: .accessToken) {
             let url = config.authBaseURL.appending(path: "/api/v1/auth/logout")
             var request = URLRequest(url: url)
@@ -122,8 +222,20 @@ public final class AuthClient {
             _ = try? await session.data(for: request)
         }
         keychain.wipe()
-        status = .signedOut
-        CoreLog.auth.info("Signed out")
+        if keepGuestMode {
+            if let existing = keychain.getString(for: .guestId) {
+                status = .guest(id: existing)
+            } else {
+                let newId = UUID().uuidString
+                try? keychain.setString(newId, for: .guestId)
+                status = .guest(id: newId)
+            }
+            CoreLog.auth.info("Signed out — kept guest mode")
+        } else {
+            keychain.remove(for: .guestId)
+            status = .signedOut
+            CoreLog.auth.info("Signed out")
+        }
     }
 
     public func currentAccessToken() throws -> String {
@@ -133,6 +245,19 @@ public final class AuthClient {
         return token
     }
 
+    /// Liefert den Session-Token (das wire-protocol `refreshToken`-Feld).
+    /// Wird von Better-Auth-`auth.api.*`-Endpoints akzeptiert wenn der
+    /// `bearer`-Plugin server-seitig aktiv ist — z.B. für `changeEmail`,
+    /// `changePassword`, `deleteAccount`. Der App-eigene JWT (aus
+    /// `currentAccessToken`) gilt für app-spezifische Backends, der
+    /// Session-Token nur für mana-auths Account-Aktionen.
+    public func currentSessionToken() throws -> String {
+        guard let token = keychain.getString(for: .refreshToken) else {
+            throw AuthError.notSignedIn
+        }
+        return token
+    }
+
     /// Liefert einen Access-Token, der nicht innerhalb der nächsten
     /// `refreshLeeway` Sekunden abläuft. Refreshed proaktiv, wenn nötig.
     public func freshAccessToken(refreshLeeway: TimeInterval = 300) async throws -> String {
@@ -159,13 +284,30 @@ public final class AuthClient {
             throw AuthError.networkFailure("Keine HTTP-Antwort")
         }
         guard http.statusCode == 200 else {
-            keychain.wipe()
-            status = .signedOut
-            throw AuthError.classify(
+            let err = AuthError.classify(
                 status: http.statusCode,
                 data: data,
                 retryAfterHeader: http.retryAfterSeconds
             )
+            // Wipe nur bei tatsächlich invalidierter Session. Transiente
+            // Fehler (5xx, Rate-Limit) lassen den Token erhalten — sonst
+            // wirft jeder mana-auth-Downtime-Moment alle Apps in den
+            // Login-Screen. Falls eine Guest-Identität existiert, wird
+            // beim Wipe in den Guest-Status zurückgefallen statt in
+            // strict `.signedOut`.
+            if err.invalidatesSession {
+                keychain.wipe()
+                if let guestId = keychain.getString(for: .guestId) {
+                    status = .guest(id: guestId)
+                } else {
+                    status = .signedOut
+                }
+            } else {
+                CoreLog.auth.notice(
+                    "Refresh failed transiently (\(http.statusCode, privacy: .public)) — keeping session"
+                )
+            }
+            throw err
         }
 
         let token = try JSONDecoder().decode(TokenResponse.self, from: data)
@@ -189,10 +331,12 @@ public final class AuthClient {
         status = .signedIn(email: email)
     }
 
-    /// Setzt den Status auf `.signedOut` und wirft den Keychain leer.
-    /// Genutzt nach `deleteAccount()`.
+    /// Setzt den Status auf `.signedOut` und wirft den Keychain
+    /// vollständig leer — inklusive Guest-ID. Genutzt nach
+    /// `deleteAccount()`: Account ist gelöscht, also auch die
+    /// (potenziell verknüpfte) anonyme Identität.
     func clearSession() {
-        keychain.wipe()
+        keychain.wipeAll()
         status = .signedOut
     }
 }
@@ -220,6 +364,16 @@ struct TokenResponse: Decodable {
     let refreshToken: String
 }
 
+/// 2FA-Pfad aus `/api/v1/auth/login`. Wenn `twoFactorRequired == true`,
+/// kein Token-Paar — UI muss `verifyTotp(...)` / `verifyBackupCode(...)`
+/// aufrufen. `twoFactorToken` ist der Server-injecten `two_factor`-Cookie-
+/// Wert (opaque).
+struct TwoFactorChallenge: Decodable {
+    let twoFactorRequired: Bool?
+    let twoFactorMethods: [String]?
+    let twoFactorToken: String?
+}
+
 extension HTTPURLResponse {
     /// Liest `Retry-After` als Anzahl Sekunden. Server schickt Integer-
     /// Sekunden (siehe `lib/auth-errors.ts`). HTTP-Datum-Variante wird
diff --git a/Sources/ManaCore/Auth/AuthError.swift b/Sources/ManaCore/Auth/AuthError.swift
index 14ed675..073f578 100644
--- a/Sources/ManaCore/Auth/AuthError.swift
+++ b/Sources/ManaCore/Auth/AuthError.swift
@@ -126,6 +126,49 @@ public enum AuthError: Error, LocalizedError, Sendable, Equatable {
         }
     }
 
+    /// `true` wenn dieser Fehler bedeutet, dass die gespeicherten
+    /// Tokens nicht mehr gültig sind und die App den Nutzer ausloggen
+    /// muss. `false` für *transiente* Fehler (Server-Downtime, Netzwerk-
+    /// Fehler, Rate-Limiting), bei denen die Session erhalten bleiben
+    /// soll — die App sollte den Versuch nur wiederholen.
+    ///
+    /// Genutzt von ``AuthClient/refreshAccessToken()`` um zu entscheiden,
+    /// ob der Keychain gewiped werden muss. Apps können denselben
+    /// Test auf Fehler aus ``AuthenticatedTransport`` anwenden, um
+    /// zwischen "neuer Login nötig" und "später nochmal probieren" zu
+    /// unterscheiden.
+    public var invalidatesSession: Bool {
+        switch self {
+        case .invalidCredentials,
+             .unauthorized,
+             .tokenExpired,
+             .tokenInvalid,
+             .emailNotVerified:
+            true
+        case .notSignedIn,
+             .encoding,
+             .keychain,
+             .decoding,
+             .networkFailure,
+             .emailAlreadyRegistered,
+             .weakPassword,
+             .accountLocked,
+             .signupLimitReached,
+             .rateLimited,
+             .twoFactorRequired,
+             .twoFactorFailed,
+             .passkeyNotEnabled,
+             .passkeyCancelled,
+             .passkeyVerificationFailed,
+             .validation,
+             .notFound,
+             .serviceUnavailable,
+             .serverInternal,
+             .serverError:
+            false
+        }
+    }
+
     /// Klassifiziert eine `mana-auth`-Fehler-Antwort. `data` ist der
     /// Response-Body, `status` der HTTP-Status, `retryAfterHeader` der
     /// `Retry-After`-Header-Wert in Sekunden (falls vorhanden).
diff --git a/Sources/ManaCore/Auth/KeychainStore.swift b/Sources/ManaCore/Auth/KeychainStore.swift
index b6847c8..b9e953e 100644
--- a/Sources/ManaCore/Auth/KeychainStore.swift
+++ b/Sources/ManaCore/Auth/KeychainStore.swift
@@ -5,10 +5,18 @@ import Security
 /// pro `ManaAppConfig`.
 public final class KeychainStore: Sendable {
     /// Bekannte Keys für mana-auth-Tokens.
+    ///
+    /// `.guestId` ist eine lokal generierte anonyme UUID für Apps mit
+    /// Local-First-/Guest-Modus. Sie wird unabhängig von den Session-
+    /// Tokens persistiert und vom Default-``wipe()`` *nicht* gelöscht —
+    /// damit eine App nach einem Logout im Guest-Modus weiterlaufen
+    /// kann, ohne dass die lokalen anonymen Daten ihre Besitzer-Spur
+    /// verlieren. Vollständiger Reset über ``wipeAll()``.
     public enum Key: String, Sendable {
         case accessToken = "access_token"
         case refreshToken = "refresh_token"
         case email
+        case guestId = "guest_id"
     }
 
     private let service: String
@@ -64,12 +72,22 @@ public final class KeychainStore: Sendable {
         SecItemDelete(query as CFDictionary)
     }
 
+    /// Löscht Session-Daten (accessToken, refreshToken, email). Behält
+    /// die ``Key/guestId``, damit lokale Guest-Daten nach einem Logout
+    /// erhalten bleiben können.
     public func wipe() {
         remove(for: .accessToken)
         remove(for: .refreshToken)
         remove(for: .email)
     }
 
+    /// Löscht *alles* inklusive der Guest-Identität. Genutzt nach
+    /// `deleteAccount()` oder bei explizitem "anonyme Daten vergessen".
+    public func wipeAll() {
+        wipe()
+        remove(for: .guestId)
+    }
+
     private func baseQuery(for key: Key) -> [CFString: Any] {
         var query: [CFString: Any] = [
             kSecClass: kSecClassGenericPassword,
diff --git a/Tests/ManaCoreTests/AuthClientAccountTests.swift b/Tests/ManaCoreTests/AuthClientAccountTests.swift
index cd743c0..1118c17 100644
--- a/Tests/ManaCoreTests/AuthClientAccountTests.swift
+++ b/Tests/ManaCoreTests/AuthClientAccountTests.swift
@@ -2,27 +2,10 @@ import Foundation
 import Testing
 @testable import ManaCore
 
-@Suite("AuthClient+Account", .serialized)
+@Suite("AuthClient+Account")
 @MainActor
 struct AuthClientAccountTests {
-    // MARK: - Fixtures
-
-    private static func makeClient() -> (AuthClient, URLSession) {
-        let configuration = URLSessionConfiguration.ephemeral
-        configuration.protocolClasses = [MockURLProtocol.self]
-        let session = URLSession(configuration: configuration)
-
-        let config = DefaultManaAppConfig(
-            authBaseURL: URL(string: "https://auth.test")!,
-            keychainService: "ev.mana.test.\(UUID().uuidString)",
-            keychainAccessGroup: nil
-        )
-        return (AuthClient(config: config, session: session), session)
-    }
-
     private func recordedBody(_ request: URLRequest) -> [String: Any] {
-        // URLSession verschiebt den Body in den BodyStream wenn er nicht
-        // klein-genug ist — ephemeral-Session lässt ihn als httpBody.
         guard let body = request.httpBody ?? request.bodyStreamData(),
               let json = try? JSONSerialization.jsonObject(with: body) as? [String: Any]
         else { return [:] }
@@ -33,66 +16,62 @@ struct AuthClientAccountTests {
 
     @Test("register schickt POST /api/v1/auth/register mit JSON-Body")
     func registerSendsCorrectRequest() async throws {
-        let (client, _) = Self.makeClient()
-        MockURLProtocol.handler = { request in
+        let mocked = makeMockedAuth()
+        mocked.setHandler { request in
             #expect(request.httpMethod == "POST")
             #expect(request.url?.path == "/api/v1/auth/register")
             #expect(request.value(forHTTPHeaderField: "Content-Type") == "application/json")
             return (200, Data(#"{"user":{"id":"u1","email":"new@x.de"}}"#.utf8))
         }
 
-        try await client.register(
+        try await mocked.auth.register(
             email: "new@x.de",
             password: "Aa-123456789",
             name: "Neu",
             sourceAppUrl: URL(string: "https://cardecky.mana.how/auth/verify")
         )
-        // Mit requireEmailVerification:true gibt es noch keine Session.
-        if case .signedIn = client.status {
+        if case .signedIn = mocked.auth.status {
             Issue.record("Expected not-signed-in after register without tokens")
         }
     }
 
     @Test("register mit Token-Antwort führt direkt zu signedIn")
     func registerWithTokensSignsIn() async throws {
-        let (client, _) = Self.makeClient()
-        // gültiger HS256-Header.payload (exp 2_000_000_000).sig — JWT.expiry()
-        // läuft danach nicht in den Refresh-Pfad.
-        let access =
-            "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
+        let mocked = makeMockedAuth()
+        let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
         let refresh = "refresh-token-value"
-        MockURLProtocol.handler = { _ in
+        mocked.setHandler { _ in
             (200, Data(#"""
             {"user":{"id":"u1","email":"new@x.de"},"accessToken":"\#(access)","refreshToken":"\#(refresh)"}
             """#.utf8))
         }
 
-        try await client.register(email: "new@x.de", password: "Aa-123456789")
-        #expect(client.status == .signedIn(email: "new@x.de"))
+        try await mocked.auth.register(email: "new@x.de", password: "Aa-123456789")
+        #expect(mocked.auth.status == .signedIn(email: "new@x.de"))
     }
 
     @Test("register mit existierender Email wirft emailAlreadyRegistered")
     func registerEmailAlreadyRegistered() async {
-        let (client, _) = Self.makeClient()
-        MockURLProtocol.handler = { _ in
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
             (409, Data(#"{"error":"EMAIL_ALREADY_REGISTERED","status":409}"#.utf8))
         }
 
         await #expect(throws: AuthError.emailAlreadyRegistered) {
-            try await client.register(email: "old@x.de", password: "Aa-123456789")
+            try await mocked.auth.register(email: "old@x.de", password: "Aa-123456789")
         }
     }
 
     @Test("register mit leerer Email wirft validation ohne Server-Call")
     func registerValidatesEmptyEmail() async {
-        let (client, _) = Self.makeClient()
-        MockURLProtocol.handler = { _ in
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
             Issue.record("Server darf nicht aufgerufen werden")
             return (500, Data())
         }
 
         await #expect(throws: (any Error).self) {
-            try await client.register(email: "  ", password: "Aa-123456789")
+            try await mocked.auth.register(email: "  ", password: "Aa-123456789")
         }
     }
 
@@ -100,14 +79,14 @@ struct AuthClientAccountTests {
 
     @Test("forgotPassword schickt email + redirectTo")
     func forgotPasswordPayload() async throws {
-        let (client, _) = Self.makeClient()
+        let mocked = makeMockedAuth()
         let capturedURL = MockURLProtocol.Capture()
-        MockURLProtocol.handler = { request in
+        mocked.setHandler { request in
             capturedURL.store(request)
             return (200, Data(#"{"success":true}"#.utf8))
         }
 
-        try await client.forgotPassword(
+        try await mocked.auth.forgotPassword(
             email: "user@x.de",
             resetUniversalLink: URL(string: "https://cardecky.mana.how/auth/reset")!
         )
@@ -122,14 +101,14 @@ struct AuthClientAccountTests {
 
     @Test("resetPassword schickt token + newPassword")
     func resetPasswordPayload() async throws {
-        let (client, _) = Self.makeClient()
+        let mocked = makeMockedAuth()
         let captured = MockURLProtocol.Capture()
-        MockURLProtocol.handler = { request in
+        mocked.setHandler { request in
             captured.store(request)
             return (200, Data(#"{"success":true}"#.utf8))
         }
 
-        try await client.resetPassword(token: "tok123", newPassword: "Neu-987654321")
+        try await mocked.auth.resetPassword(token: "tok123", newPassword: "Neu-987654321")
         let request = try #require(captured.request)
         let json = recordedBody(request)
         #expect(json["token"] as? String == "tok123")
@@ -139,13 +118,13 @@ struct AuthClientAccountTests {
 
     @Test("resetPassword mit abgelaufenem Token wirft tokenExpired")
     func resetPasswordTokenExpired() async {
-        let (client, _) = Self.makeClient()
-        MockURLProtocol.handler = { _ in
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
             (400, Data(#"{"error":"TOKEN_EXPIRED","status":400}"#.utf8))
         }
 
         await #expect(throws: AuthError.tokenExpired) {
-            try await client.resetPassword(token: "old", newPassword: "Neu-987654321")
+            try await mocked.auth.resetPassword(token: "old", newPassword: "Neu-987654321")
         }
     }
 
@@ -153,14 +132,14 @@ struct AuthClientAccountTests {
 
     @Test("resendVerification schickt email + sourceAppUrl")
     func resendVerificationPayload() async throws {
-        let (client, _) = Self.makeClient()
+        let mocked = makeMockedAuth()
         let captured = MockURLProtocol.Capture()
-        MockURLProtocol.handler = { request in
+        mocked.setHandler { request in
             captured.store(request)
             return (200, Data(#"{"success":true}"#.utf8))
         }
 
-        try await client.resendVerification(
+        try await mocked.auth.resendVerification(
             email: "user@x.de",
             sourceAppUrl: URL(string: "https://cardecky.mana.how/auth/verify")
         )
@@ -172,8 +151,8 @@ struct AuthClientAccountTests {
 
     @Test("resendVerification mit Rate-Limit liefert retryAfter")
     func resendVerificationRateLimited() async {
-        let (client, _) = Self.makeClient()
-        MockURLProtocol.handler = { _ in
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
             (
                 429,
                 Data(#"{"error":"RATE_LIMITED","retryAfterSec":42,"status":429}"#.utf8),
@@ -182,7 +161,7 @@ struct AuthClientAccountTests {
         }
 
         do {
-            try await client.resendVerification(email: "user@x.de")
+            try await mocked.auth.resendVerification(email: "user@x.de")
             Issue.record("Expected throw")
         } catch let AuthError.rateLimited(retryAfter) {
             #expect(retryAfter == 42)
@@ -195,126 +174,43 @@ struct AuthClientAccountTests {
 
     @Test("changeEmail ohne Login wirft notSignedIn")
     func changeEmailRequiresSession() async {
-        let (client, _) = Self.makeClient()
+        let mocked = makeMockedAuth()
         await #expect(throws: AuthError.notSignedIn) {
-            try await client.changeEmail(newEmail: "neu@x.de")
+            try await mocked.auth.changeEmail(newEmail: "neu@x.de")
         }
     }
 
-    @Test("changePassword schickt Bearer-Header wenn eingeloggt")
+    @Test("changePassword schickt Session-Token als Bearer (nicht JWT)")
     func changePasswordSendsBearer() async throws {
-        let (client, _) = Self.makeClient()
-        // Mock-Token im Keychain ablegen via persistSession-Helper.
+        let mocked = makeMockedAuth()
         let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
-        try client.persistSession(email: "u@x.de", accessToken: access, refreshToken: "r")
+        let session = "session-token-value"
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: access, refreshToken: session)
 
         let captured = MockURLProtocol.Capture()
-        MockURLProtocol.handler = { request in
+        mocked.setHandler { request in
             captured.store(request)
             return (200, Data(#"{"success":true}"#.utf8))
         }
 
-        try await client.changePassword(currentPassword: "alt", newPassword: "neu")
+        try await mocked.auth.changePassword(currentPassword: "alt", newPassword: "neu")
         let request = try #require(captured.request)
-        #expect(request.value(forHTTPHeaderField: "Authorization") == "Bearer \(access)")
+        #expect(request.value(forHTTPHeaderField: "Authorization") == "Bearer \(session)")
         #expect(request.url?.path == "/api/v1/auth/change-password")
     }
 
     @Test("deleteAccount wiped Session bei Erfolg")
     func deleteAccountClearsSession() async throws {
-        let (client, _) = Self.makeClient()
+        let mocked = makeMockedAuth()
         let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
-        try client.persistSession(email: "u@x.de", accessToken: access, refreshToken: "r")
-        #expect(client.status == .signedIn(email: "u@x.de"))
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: access, refreshToken: "r")
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
 
-        MockURLProtocol.handler = { request in
+        mocked.setHandler { request in
             #expect(request.httpMethod == "DELETE")
             return (200, Data(#"{"success":true}"#.utf8))
         }
-        try await client.deleteAccount(password: "pw")
-        #expect(client.status == .signedOut)
-    }
-}
-
-// MARK: - URLProtocol Mock
-
-final class MockURLProtocol: URLProtocol, @unchecked Sendable {
-    /// Antwort-Tuple: (status, body) oder (status, body, headers).
-    typealias Response = (status: Int, body: Data, headers: [String: String])
-    typealias Handler = @Sendable (URLRequest) -> Any  // (Int, Data) | (Int, Data, [String:String])
-
-    nonisolated(unsafe) static var handler: Handler?
-
-    /// Thread-safer Capture-Container — Tests können den Request darin
-    /// festhalten und nach dem await aus dem Test-Body lesen.
-    final class Capture: @unchecked Sendable {
-        private let lock = NSLock()
-        private var stored: URLRequest?
-
-        func store(_ r: URLRequest) {
-            lock.lock(); defer { lock.unlock() }
-            stored = r
-        }
-
-        var request: URLRequest? {
-            lock.lock(); defer { lock.unlock() }
-            return stored
-        }
-    }
-
-    override class func canInit(with request: URLRequest) -> Bool { true }
-    override class func canonicalRequest(for request: URLRequest) -> URLRequest { request }
-    override func stopLoading() {}
-
-    override func startLoading() {
-        guard let handler = MockURLProtocol.handler else {
-            client?.urlProtocol(
-                self,
-                didFailWithError: URLError(.unknown)
-            )
-            return
-        }
-
-        let result = handler(request)
-        let status: Int
-        let body: Data
-        let headers: [String: String]
-        if let tuple = result as? (Int, Data, [String: String]) {
-            status = tuple.0; body = tuple.1; headers = tuple.2
-        } else if let tuple = result as? (Int, Data) {
-            status = tuple.0; body = tuple.1; headers = [:]
-        } else {
-            client?.urlProtocol(self, didFailWithError: URLError(.unknown))
-            return
-        }
-
-        let response = HTTPURLResponse(
-            url: request.url!,
-            statusCode: status,
-            httpVersion: "HTTP/1.1",
-            headerFields: headers
-        )!
-        client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
-        client?.urlProtocol(self, didLoad: body)
-        client?.urlProtocolDidFinishLoading(self)
-    }
-}
-
-extension URLRequest {
-    /// Liest httpBodyStream in einen Data. URLSession ephemeral-Session
-    /// nutzt manchmal Streams statt httpBody.
-    func bodyStreamData() -> Data? {
-        guard let stream = httpBodyStream else { return nil }
-        stream.open(); defer { stream.close() }
-        var data = Data()
-        let bufferSize = 1024
-        let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
-        defer { buffer.deallocate() }
-        while stream.hasBytesAvailable {
-            let read = stream.read(buffer, maxLength: bufferSize)
-            if read <= 0 { break }
-            data.append(buffer, count: read)
-        }
-        return data
+        try await mocked.auth.deleteAccount(password: "pw")
+        #expect(mocked.auth.status == .signedOut)
     }
 }
diff --git a/Tests/ManaCoreTests/AuthClientGuestAndResilienceTests.swift b/Tests/ManaCoreTests/AuthClientGuestAndResilienceTests.swift
new file mode 100644
index 0000000..c322242
--- /dev/null
+++ b/Tests/ManaCoreTests/AuthClientGuestAndResilienceTests.swift
@@ -0,0 +1,230 @@
+import Foundation
+import Testing
+@testable import ManaCore
+
+@Suite("AuthClient Guest-Mode + Resilience")
+@MainActor
+struct AuthClientGuestAndResilienceTests {
+    // MARK: - enterGuestMode / currentGuestId
+
+    @Test("enterGuestMode aus signedOut erzeugt UUID und setzt .guest")
+    func enterGuestModeFromSignedOut() throws {
+        let mocked = makeMockedAuth()
+        mocked.auth.bootstrap()
+        #expect(mocked.auth.status == .signedOut)
+
+        let id = try mocked.auth.enterGuestMode()
+        #expect(!id.isEmpty)
+        #expect(mocked.auth.status == .guest(id: id))
+        #expect(mocked.auth.currentGuestId() == id)
+    }
+
+    @Test("enterGuestMode ist idempotent")
+    func enterGuestModeIdempotent() throws {
+        let mocked = makeMockedAuth()
+        let first = try mocked.auth.enterGuestMode()
+        let second = try mocked.auth.enterGuestMode()
+        #expect(first == second)
+        #expect(mocked.auth.status == .guest(id: first))
+    }
+
+    @Test("enterGuestMode stört aktive Session nicht")
+    func enterGuestModeKeepsSignedIn() throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+
+        let id = try mocked.auth.enterGuestMode()
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+        #expect(mocked.auth.currentGuestId() == id)
+    }
+
+    @Test("clearGuestId aus .guest fällt auf .signedOut")
+    func clearGuestIdFromGuest() throws {
+        let mocked = makeMockedAuth()
+        _ = try mocked.auth.enterGuestMode()
+        mocked.auth.clearGuestId()
+        #expect(mocked.auth.status == .signedOut)
+        #expect(mocked.auth.currentGuestId() == nil)
+    }
+
+    @Test("clearGuestId aus .signedIn behält Status")
+    func clearGuestIdKeepsSignedIn() throws {
+        let mocked = makeMockedAuth()
+        _ = try mocked.auth.enterGuestMode()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.auth.clearGuestId()
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+        #expect(mocked.auth.currentGuestId() == nil)
+    }
+
+    // MARK: - bootstrap
+
+    @Test("bootstrap erkennt nur-Guest-Keychain als .guest")
+    func bootstrapDetectsGuest() throws {
+        let mocked = makeMockedAuth()
+        _ = try mocked.auth.enterGuestMode()
+        mocked.auth.bootstrap()
+        if case let .guest(id) = mocked.auth.status {
+            #expect(!id.isEmpty)
+        } else {
+            Issue.record("Expected .guest after bootstrap, got \(mocked.auth.status)")
+        }
+    }
+
+    @Test("bootstrap priorisiert Session über Guest")
+    func bootstrapPrioritisesSession() throws {
+        let mocked = makeMockedAuth()
+        _ = try mocked.auth.enterGuestMode()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.auth.bootstrap()
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+    }
+
+    // MARK: - signOut(keepGuestMode:)
+
+    @Test("signOut Default löscht alles inkl. Guest-ID")
+    func signOutDefaultClearsGuest() async throws {
+        let mocked = makeMockedAuth()
+        _ = try mocked.auth.enterGuestMode()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in (200, Data()) }
+
+        await mocked.auth.signOut()
+        #expect(mocked.auth.status == .signedOut)
+        #expect(mocked.auth.currentGuestId() == nil)
+    }
+
+    @Test("signOut(keepGuestMode: true) behält existierende Guest-ID")
+    func signOutKeepsExistingGuest() async throws {
+        let mocked = makeMockedAuth()
+        let id = try mocked.auth.enterGuestMode()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in (200, Data()) }
+
+        await mocked.auth.signOut(keepGuestMode: true)
+        #expect(mocked.auth.status == .guest(id: id))
+        #expect(mocked.auth.currentGuestId() == id)
+    }
+
+    @Test("signOut(keepGuestMode: true) erzeugt neue Guest-ID wenn keine existiert")
+    func signOutCreatesGuestWhenMissing() async throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in (200, Data()) }
+
+        await mocked.auth.signOut(keepGuestMode: true)
+        if case let .guest(id) = mocked.auth.status {
+            #expect(!id.isEmpty)
+            #expect(mocked.auth.currentGuestId() == id)
+        } else {
+            Issue.record("Expected .guest after signOut(keepGuestMode:), got \(mocked.auth.status)")
+        }
+    }
+
+    // MARK: - refreshAccessToken Resilience
+
+    @Test("refresh 503 wirft serviceUnavailable, behält Session")
+    func refreshKeepsSessionOn503() async throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in
+            (503, Data(#"{"error":"SERVICE_UNAVAILABLE","status":503}"#.utf8))
+        }
+
+        do {
+            _ = try await mocked.auth.refreshAccessToken()
+            Issue.record("Expected throw on 503")
+        } catch let err as AuthError {
+            #expect(err == .serviceUnavailable)
+        }
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+    }
+
+    @Test("refresh 500 wirft serverInternal, behält Session")
+    func refreshKeepsSessionOn500() async throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in
+            (500, Data(#"{"error":"INTERNAL","status":500}"#.utf8))
+        }
+
+        do {
+            _ = try await mocked.auth.refreshAccessToken()
+            Issue.record("Expected throw on 500")
+        } catch let err as AuthError {
+            #expect(err == .serverInternal)
+        }
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+    }
+
+    @Test("refresh 429 wirft rateLimited, behält Session")
+    func refreshKeepsSessionOnRateLimit() async throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in
+            (429, Data(#"{"error":"RATE_LIMITED","retryAfterSec":30,"status":429}"#.utf8))
+        }
+
+        do {
+            _ = try await mocked.auth.refreshAccessToken()
+            Issue.record("Expected throw on 429")
+        } catch let err as AuthError {
+            if case let .rateLimited(retryAfter) = err {
+                #expect(retryAfter == 30)
+            } else {
+                Issue.record("Expected .rateLimited, got \(err)")
+            }
+        }
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+    }
+
+    @Test("refresh 401 invalidiert Session ohne Guest → .signedOut")
+    func refreshInvalidates401NoGuest() async throws {
+        let mocked = makeMockedAuth()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in
+            (401, Data(#"{"error":"UNAUTHORIZED","status":401}"#.utf8))
+        }
+
+        do {
+            _ = try await mocked.auth.refreshAccessToken()
+            Issue.record("Expected throw on 401")
+        } catch let err as AuthError {
+            #expect(err.invalidatesSession)
+        }
+        #expect(mocked.auth.status == .signedOut)
+    }
+
+    @Test("refresh 401 mit Guest-ID fällt auf .guest zurück")
+    func refreshInvalidates401WithGuest() async throws {
+        let mocked = makeMockedAuth()
+        let id = try mocked.auth.enterGuestMode()
+        try mocked.auth.persistSession(email: "u@x.de", accessToken: "a", refreshToken: "r")
+        mocked.setHandler { _ in
+            (401, Data(#"{"error":"UNAUTHORIZED","status":401}"#.utf8))
+        }
+
+        _ = try? await mocked.auth.refreshAccessToken()
+        #expect(mocked.auth.status == .guest(id: id))
+        #expect(mocked.auth.currentGuestId() == id)
+    }
+
+    // MARK: - AuthError.invalidatesSession
+
+    @Test("invalidatesSession unterscheidet Session-Tot vs. transient")
+    func invalidatesSessionPartitioning() {
+        // Tot — Session muss weg
+        #expect(AuthError.invalidCredentials.invalidatesSession)
+        #expect(AuthError.unauthorized.invalidatesSession)
+        #expect(AuthError.tokenExpired.invalidatesSession)
+        #expect(AuthError.tokenInvalid.invalidatesSession)
+
+        // Transient — Session bleibt
+        #expect(!AuthError.serviceUnavailable.invalidatesSession)
+        #expect(!AuthError.serverInternal.invalidatesSession)
+        #expect(!AuthError.networkFailure("offline").invalidatesSession)
+        #expect(!AuthError.rateLimited(retryAfter: 30).invalidatesSession)
+        #expect(!AuthError.accountLocked(retryAfter: nil).invalidatesSession)
+    }
+}
diff --git a/Tests/ManaCoreTests/AuthClientProfileTests.swift b/Tests/ManaCoreTests/AuthClientProfileTests.swift
new file mode 100644
index 0000000..69c0daf
--- /dev/null
+++ b/Tests/ManaCoreTests/AuthClientProfileTests.swift
@@ -0,0 +1,77 @@
+import Foundation
+import Testing
+@testable import ManaCore
+
+@Suite("AuthClient getProfile")
+@MainActor
+struct AuthClientProfileTests {
+    private func signedInAuth() async -> MockedAuth {
+        let mocked = makeMockedAuth()
+        let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
+        mocked.setHandler { _ in
+            (200, Data(#"{"accessToken":"\#(access)","refreshToken":"session-tok"}"#.utf8))
+        }
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+        return mocked
+    }
+
+    @Test("getProfile mit twoFactor on")
+    func profileTwoFactorOn() async throws {
+        let mocked = await signedInAuth()
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"""
+            {"user":{"id":"u1","email":"u@x.de","name":"Test","emailVerified":true,"twoFactorEnabled":true},
+             "session":{"id":"s1"}}
+            """#.utf8))
+        }
+
+        let profile = try await mocked.auth.getProfile()
+        #expect(profile.id == "u1")
+        #expect(profile.email == "u@x.de")
+        #expect(profile.name == "Test")
+        #expect(profile.emailVerified == true)
+        #expect(profile.twoFactorEnabled == true)
+
+        let request = try #require(captured.request)
+        #expect(request.httpMethod == "GET")
+        #expect(request.url?.path == "/api/v1/auth/profile")
+        // Bearer-Header trägt den Session-Token
+        #expect(request.value(forHTTPHeaderField: "Authorization") == "Bearer session-tok")
+    }
+
+    @Test("getProfile mit twoFactor off (Feld fehlt)")
+    func profileTwoFactorOff() async throws {
+        let mocked = await signedInAuth()
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"user":{"id":"u1","email":"u@x.de","name":null,"emailVerified":true}}
+            """#.utf8))
+        }
+
+        let profile = try await mocked.auth.getProfile()
+        #expect(profile.twoFactorEnabled == false)
+        #expect(profile.name == nil)
+    }
+
+    @Test("getProfile ohne Session → notSignedIn")
+    func profileNoSession() async {
+        let mocked = makeMockedAuth()
+        await #expect(throws: AuthError.notSignedIn) {
+            try await mocked.auth.getProfile()
+        }
+    }
+
+    @Test("getProfile mit abgelaufenem Token → unauthorized")
+    func profileUnauthorized() async {
+        let mocked = await signedInAuth()
+        mocked.setHandler { _ in
+            (401, Data(#"{"error":"UNAUTHORIZED","status":401}"#.utf8))
+        }
+
+        await #expect(throws: AuthError.unauthorized) {
+            try await mocked.auth.getProfile()
+        }
+    }
+}
diff --git a/Tests/ManaCoreTests/AuthClientTwoFactorEnrollmentTests.swift b/Tests/ManaCoreTests/AuthClientTwoFactorEnrollmentTests.swift
new file mode 100644
index 0000000..b749c28
--- /dev/null
+++ b/Tests/ManaCoreTests/AuthClientTwoFactorEnrollmentTests.swift
@@ -0,0 +1,119 @@
+import Foundation
+import Testing
+@testable import ManaCore
+
+@Suite("AuthClient 2FA-Enrollment")
+@MainActor
+struct AuthClientTwoFactorEnrollmentTests {
+    /// Bringt den AuthClient in den `.signedIn`-Status mit einem
+    /// Session-Token für authenticated Calls.
+    private func signedInAuth() async -> MockedAuth {
+        let mocked = makeMockedAuth()
+        let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
+        mocked.setHandler { _ in
+            (200, Data(#"{"accessToken":"\#(access)","refreshToken":"session-tok"}"#.utf8))
+        }
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+        return mocked
+    }
+
+    @Test("enrollTotp liefert URI + Backup-Codes")
+    func enrollSuccess() async throws {
+        let mocked = await signedInAuth()
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"""
+            {"totpURI":"otpauth://totp/Mana:u@x.de?secret=ABC&issuer=Mana","backupCodes":["a-b-c","d-e-f","g-h-i"]}
+            """#.utf8))
+        }
+
+        let enrollment = try await mocked.auth.enrollTotp(password: "pw")
+        #expect(enrollment.totpURI.hasPrefix("otpauth://totp/"))
+        #expect(enrollment.backupCodes == ["a-b-c", "d-e-f", "g-h-i"])
+
+        let request = try #require(captured.request)
+        #expect(request.url?.path == "/api/v1/auth/two-factor/enable")
+        // Bearer-Header trägt den Session-Token (nicht JWT)
+        #expect(request.value(forHTTPHeaderField: "Authorization") == "Bearer session-tok")
+    }
+
+    @Test("enrollTotp mit leerem Passwort → validation, kein Server-Call")
+    func enrollEmptyPassword() async {
+        let mocked = await signedInAuth()
+        mocked.setHandler { _ in
+            Issue.record("Server darf nicht aufgerufen werden")
+            return (500, Data())
+        }
+
+        await #expect(throws: AuthError.validation(message: "Passwort ist erforderlich")) {
+            try await mocked.auth.enrollTotp(password: "")
+        }
+    }
+
+    @Test("enrollTotp ohne Session → notSignedIn")
+    func enrollNoSession() async {
+        let mocked = makeMockedAuth()
+        await #expect(throws: AuthError.notSignedIn) {
+            try await mocked.auth.enrollTotp(password: "pw")
+        }
+    }
+
+    @Test("disableTotp success")
+    func disableSuccess() async throws {
+        let mocked = await signedInAuth()
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"{"success":true}"#.utf8))
+        }
+
+        try await mocked.auth.disableTotp(password: "pw")
+        let request = try #require(captured.request)
+        #expect(request.url?.path == "/api/v1/auth/two-factor/disable")
+    }
+
+    @Test("disableTotp mit falschem Passwort → invalidCredentials")
+    func disableWrongPassword() async {
+        let mocked = await signedInAuth()
+        mocked.setHandler { _ in
+            (401, Data(#"{"error":"INVALID_CREDENTIALS","status":401}"#.utf8))
+        }
+
+        await #expect(throws: AuthError.invalidCredentials) {
+            try await mocked.auth.disableTotp(password: "wrong")
+        }
+    }
+
+    @Test("getTotpUri liefert URI ohne Backup-Codes")
+    func getUriSuccess() async throws {
+        let mocked = await signedInAuth()
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"totpURI":"otpauth://totp/Mana:u@x.de?secret=XYZ&issuer=Mana"}
+            """#.utf8))
+        }
+
+        let uri = try await mocked.auth.getTotpUri(password: "pw")
+        #expect(uri.hasPrefix("otpauth://totp/"))
+        #expect(uri.contains("secret=XYZ"))
+    }
+
+    @Test("regenerateBackupCodes liefert neue Codes")
+    func regenerateSuccess() async throws {
+        let mocked = await signedInAuth()
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"""
+            {"backupCodes":["new-1","new-2","new-3","new-4","new-5"]}
+            """#.utf8))
+        }
+
+        let codes = try await mocked.auth.regenerateBackupCodes(password: "pw")
+        #expect(codes.count == 5)
+        #expect(codes.first == "new-1")
+        let request = try #require(captured.request)
+        #expect(request.url?.path == "/api/v1/auth/two-factor/generate-backup-codes")
+    }
+}
diff --git a/Tests/ManaCoreTests/AuthClientTwoFactorTests.swift b/Tests/ManaCoreTests/AuthClientTwoFactorTests.swift
new file mode 100644
index 0000000..54fca82
--- /dev/null
+++ b/Tests/ManaCoreTests/AuthClientTwoFactorTests.swift
@@ -0,0 +1,127 @@
+import Foundation
+import Testing
+@testable import ManaCore
+
+@Suite("AuthClient 2FA-Login-Challenge")
+@MainActor
+struct AuthClientTwoFactorTests {
+    @Test("signIn mit 2FA-Account → .twoFactorRequired statt .signedIn")
+    func signInRedirectsToTwoFactor() async {
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"twoFactorRequired":true,"twoFactorMethods":["totp"],"twoFactorToken":"tf-abc123"}
+            """#.utf8))
+        }
+
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+        if case let .twoFactorRequired(token, methods, email) = mocked.auth.status {
+            #expect(token == "tf-abc123")
+            #expect(methods == ["totp"])
+            #expect(email == "u@x.de")
+        } else {
+            Issue.record("Expected .twoFactorRequired, got \(mocked.auth.status)")
+        }
+    }
+
+    @Test("verifyTotp erfolgreich → .signedIn")
+    func verifyTotpSuccess() async throws {
+        let mocked = makeMockedAuth()
+        // Schritt 1: signIn liefert 2FA-Challenge.
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"twoFactorRequired":true,"twoFactorMethods":["totp"],"twoFactorToken":"tf-xyz"}
+            """#.utf8))
+        }
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+
+        // Schritt 2: verifyTotp liefert Tokens.
+        let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"""
+            {"success":true,"accessToken":"\#(access)","refreshToken":"r1"}
+            """#.utf8))
+        }
+
+        try await mocked.auth.verifyTotp(code: "123456")
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+
+        let request = try #require(captured.request)
+        #expect(request.url?.path == "/api/v1/auth/two-factor/verify-totp")
+        // Body trägt code + twoFactorToken aus dem Challenge-Status
+        let body = request.httpBody ?? request.bodyStreamData() ?? Data()
+        let json = try JSONSerialization.jsonObject(with: body) as? [String: Any] ?? [:]
+        #expect(json["code"] as? String == "123456")
+        #expect(json["twoFactorToken"] as? String == "tf-xyz")
+    }
+
+    @Test("verifyTotp ohne aktiven 2FA-Challenge wirft validation")
+    func verifyTotpRequiresChallenge() async {
+        let mocked = makeMockedAuth()
+        // Status ist initial .unknown — kein 2FA-Challenge.
+        do {
+            try await mocked.auth.verifyTotp(code: "123456")
+            Issue.record("Expected throw")
+        } catch let AuthError.validation(message) {
+            #expect(message?.contains("2FA-Challenge") == true)
+        } catch {
+            Issue.record("Unexpected error: \(error)")
+        }
+    }
+
+    @Test("verifyTotp mit falschem Code → twoFactorFailed, bleibt im Challenge")
+    func verifyTotpWrongCode() async {
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"twoFactorRequired":true,"twoFactorMethods":["totp"],"twoFactorToken":"tf-xyz"}
+            """#.utf8))
+        }
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+
+        mocked.setHandler { _ in
+            (401, Data(#"{"error":"TWO_FACTOR_FAILED","status":401}"#.utf8))
+        }
+
+        do {
+            try await mocked.auth.verifyTotp(code: "000000")
+            Issue.record("Expected throw")
+        } catch AuthError.twoFactorFailed {
+            // Status bleibt im Challenge — User kann erneut versuchen
+            if case .twoFactorRequired = mocked.auth.status {
+                #expect(Bool(true))
+            } else {
+                Issue.record("Status should remain .twoFactorRequired, got \(mocked.auth.status)")
+            }
+        } catch {
+            Issue.record("Unexpected error: \(error)")
+        }
+    }
+
+    @Test("verifyBackupCode erfolgreich → .signedIn")
+    func verifyBackupCodeSuccess() async throws {
+        let mocked = makeMockedAuth()
+        mocked.setHandler { _ in
+            (200, Data(#"""
+            {"twoFactorRequired":true,"twoFactorMethods":["totp"],"twoFactorToken":"tf-xyz"}
+            """#.utf8))
+        }
+        await mocked.auth.signIn(email: "u@x.de", password: "pw")
+
+        let access = "eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1MSIsImV4cCI6MjAwMDAwMDAwMH0.sig"
+        let captured = MockURLProtocol.Capture()
+        mocked.setHandler { request in
+            captured.store(request)
+            return (200, Data(#"""
+            {"success":true,"accessToken":"\#(access)","refreshToken":"r1"}
+            """#.utf8))
+        }
+
+        try await mocked.auth.verifyBackupCode(code: "abc-def-ghi")
+        #expect(mocked.auth.status == .signedIn(email: "u@x.de"))
+        let request = try #require(captured.request)
+        #expect(request.url?.path == "/api/v1/auth/two-factor/verify-backup-code")
+    }
+}
diff --git a/Tests/ManaCoreTests/MockURLProtocol.swift b/Tests/ManaCoreTests/MockURLProtocol.swift
new file mode 100644
index 0000000..289332b
--- /dev/null
+++ b/Tests/ManaCoreTests/MockURLProtocol.swift
@@ -0,0 +1,127 @@
+import Foundation
+@testable import ManaCore
+
+/// URLProtocol-Mock mit Pro-Test-Routing: jede Test-AuthClient-
+/// Instanz kriegt eine eigene Test-ID als HTTP-Header, der Mock
+/// routet nach ID zum richtigen Handler. Das löst die Cross-Suite-
+/// Pollution (mehrere `.serialized`-Suites laufen untereinander
+/// parallel, der globale Handler-Slot wäre sonst ein Race).
+///
+/// Identisches Pattern wie in mana-swift-ui — wenn weitere Test-
+/// Helper hier hinzukommen, beide Pakete parallel halten.
+final class MockURLProtocol: URLProtocol, @unchecked Sendable {
+    typealias Handler = @Sendable (URLRequest) -> Any
+
+    nonisolated(unsafe) static var handlersStorage: [String: Handler] = [:]
+    static let handlersLock = NSLock()
+
+    static func register(testID: String, handler: @escaping Handler) {
+        handlersLock.lock(); defer { handlersLock.unlock() }
+        handlersStorage[testID] = handler
+    }
+
+    static func unregister(testID: String) {
+        handlersLock.lock(); defer { handlersLock.unlock() }
+        handlersStorage.removeValue(forKey: testID)
+    }
+
+    private static func lookup(testID: String) -> Handler? {
+        handlersLock.lock(); defer { handlersLock.unlock() }
+        return handlersStorage[testID]
+    }
+
+    final class Capture: @unchecked Sendable {
+        private let lock = NSLock()
+        private var stored: URLRequest?
+
+        func store(_ r: URLRequest) {
+            lock.lock(); defer { lock.unlock() }
+            stored = r
+        }
+
+        var request: URLRequest? {
+            lock.lock(); defer { lock.unlock() }
+            return stored
+        }
+    }
+
+    override class func canInit(with request: URLRequest) -> Bool { true }
+    override class func canonicalRequest(for request: URLRequest) -> URLRequest { request }
+    override func stopLoading() {}
+
+    override func startLoading() {
+        let testID = request.value(forHTTPHeaderField: "X-Test-ID") ?? ""
+        guard let handler = MockURLProtocol.lookup(testID: testID) else {
+            client?.urlProtocol(self, didFailWithError: URLError(.unknown))
+            return
+        }
+
+        let result = handler(request)
+        let status: Int
+        let body: Data
+        let headers: [String: String]
+        if let tuple = result as? (Int, Data, [String: String]) {
+            status = tuple.0; body = tuple.1; headers = tuple.2
+        } else if let tuple = result as? (Int, Data) {
+            status = tuple.0; body = tuple.1; headers = [:]
+        } else {
+            client?.urlProtocol(self, didFailWithError: URLError(.unknown))
+            return
+        }
+
+        let response = HTTPURLResponse(
+            url: request.url!,
+            statusCode: status,
+            httpVersion: "HTTP/1.1",
+            headerFields: headers
+        )!
+        client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
+        client?.urlProtocol(self, didLoad: body)
+        client?.urlProtocolDidFinishLoading(self)
+    }
+}
+
+/// Bündelt einen `AuthClient` mit seiner Test-ID.
+@MainActor
+struct MockedAuth {
+    let auth: AuthClient
+    let testID: String
+
+    func setHandler(_ handler: @escaping MockURLProtocol.Handler) {
+        MockURLProtocol.register(testID: testID, handler: handler)
+    }
+}
+
+@MainActor
+func makeMockedAuth() -> MockedAuth {
+    let testID = UUID().uuidString
+    let configuration = URLSessionConfiguration.ephemeral
+    configuration.protocolClasses = [MockURLProtocol.self]
+    configuration.httpAdditionalHeaders = ["X-Test-ID": testID]
+    let session = URLSession(configuration: configuration)
+    let config = DefaultManaAppConfig(
+        authBaseURL: URL(string: "https://auth.test")!,
+        keychainService: "ev.mana.test.\(testID)",
+        keychainAccessGroup: nil
+    )
+    return MockedAuth(auth: AuthClient(config: config, session: session), testID: testID)
+}
+
+extension URLRequest {
+    /// Liest httpBodyStream in einen Data. URLSession ephemeral-Session
+    /// nutzt manchmal Streams statt httpBody.
+    func bodyStreamData() -> Data? {
+        guard let stream = httpBodyStream else { return nil }
+        stream.open(); defer { stream.close() }
+        var data = Data()
+        let bufferSize = 1024
+        let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
+        defer { buffer.deallocate() }
+        while stream.hasBytesAvailable {
+            let read = stream.read(buffer, maxLength: bufferSize)
+            if read <= 0 { break }
+            data.append(buffer, count: read)
+        }
+        return data
+    }
+}