# Kaizen & Authentik — Enterprise Identity & Access Management (IAM) Design Document

This design document outlines the architectural blueprint, security concepts, and native Android/Backend integration patterns to elevate **Kaizen** to a world-class, enterprise-grade AI assistant platform (comparable to ChatGPT Enterprise, Gemini Advanced, and Microsoft Copilot).

By leveraging **Authentik** as our central Identity Provider (IdP), we eliminate custom user-management development, guarantee enterprise-grade compliance (ISO 27001, SOC2, GDPR), and deliver a premium, high-performance, and friction-free user experience.

---

## 🏛️ 1. System Architecture

To achieve extreme scalability, security, and low-latency, we employ a decoupled, token-based, cloud-native architecture. 

```
                                  ┌───────────────────────────┐
                                  │      Authentik (IdP)      │
                                  │  - Master User Database   │
                                  │  - MFA, Passkeys, OAuth2  │
                                  │  - Exposes JWKS (Keys)    │
                                  └─────────────▲─────────────┘
                                                │
         ┌──────────────────────────────────────┼──────────────────────────────────────┐
         │ 1. Authenticate                      │ 3. Fetch public keys (JWKS)          │
         │    - OIDC / PKCE (Browser)           │    (Cached in memory, no DB lag)     │
         │    - OR Native ROPC (Direct API)     │                                      │
         ▼                                      ▼                                      ▼
┌──────────────────┐                  ┌──────────────────┐                    ┌──────────────────┐
│                  │                  │                  │                    │                  │
│    Kaizen App    │  2. API Request  │  Kaizen Backend  │  4. Read/Write     │    PostgreSQL    │
│     (Android)    ├─────────────────>│   (Next.js API)  ├───────────────────>│     Database     │
│                  │  (Bearer JWT)    │                  │  (User messages)   │   (Master/Repl)  │
└──────────────────┘                  └──────────────────┘                    └──────────────────┘
```

### Architectural Pillars:
1. **Single Source of Truth (SSOT):** Authentik manages all identities, credentials, MFA tokens, and group memberships. No passwords are saved or processed in the Kaizen Database.
2. **Offline JWT Verification (JWKS):** The Kaizen Backend does not query Authentik on every API request. Instead, it downloads Authentik's public keys (`/.well-known/jwks.json`) once, caches them, and validates incoming JWT signatures locally in microseconds.
3. **Database Scalability:** Since authentication is decoupled, the PostgreSQL database can be optimized with master-replica replication to handle high-frequency chat traffic seamlessly.

---

## 🔑 2. Identity Protocols & Flows (Zero-Friction UX)

To deliver a premium consumer feel while retaining strict enterprise security compliance, the system supports a dual-path authentication pipeline.

### Flow A: Direct Native Login (Resource Owner Password Credentials - ROPC)
*Best for: Daily personal use, family accounts, and initial setup where zero UI redirection is desired.*

```
┌─────────────────┐             POST /application/o/token/              ┌─────────────────┐
│   Kaizen App    ├────────────────────────────────────────────────────>│ Authentik (IdP) │
│ (Glassmorphic)  │<────────────────────────────────────────────────────┤                 │
└─────────────────┘             Returns Access & Refresh Token          └─────────────────┘
```
1. **Native UI:** The user enters their E-Mail and password inside Kaizen's premium glassmorphic native fields.
2. **Direct Secure API:** The app makes a secure background HTTPS call directly to Authentik’s OAuth token endpoint using the `password` grant type.
3. **Immediate Session:** Authentik returns a standard OIDC JSON payload (Access Token, Refresh Token, ID Token). The user transitions seamlessly into the chat with **zero browser redirects**.

---

### Flow B: Standard Authorization Code Flow with PKCE (RFC 7636)
*Best for: Corporate SSO (Microsoft Entra ID, Google Workspace, Okta), Multi-Factor Authentication (MFA), and passwordless Passkey registration.*

```
┌──────────────┐         1. Open Custom Tab (SAML/OIDC)         ┌──────────────┐
│  Kaizen App  ├───────────────────────────────────────────────>│  Authentik   │
│   (Native)   │<───────────────────────────────────────────────┤  Login Page  │
└──────┬───────┘          4. Redirect: kaizen://auth/callback   └──────────────┘
       │                                                               ▲
       │                                                               │
       │ 2. POST /token + PKCE Verifier                                │ 3. Authenticates
       └───────────────────────────────────────────────────────────────┘
```
1. **SSO Triggers:** The user clicks a branded button like **"Anmelden mit Microsoft"** or **"Anmelden mit Google"**.
2. **Secure Custom Tab:** The app opens an Android Custom Tab (not a vulnerable WebView) pointing to the Authentik flow.
3. **Corporate Handshake:** Authentik handles the redirect to Microsoft/Google, processes conditional access policies, checks MFA, and redirects back to the app via a custom scheme (`kaizen://auth/callback?code=XYZ`).
4. **Token Exchange:** The app exchanges the authorization code alongside the PKCE cryptographic verifier for security tokens.

---

### Flow C: Native Hardware-Backed Passkeys (FIDO2)
*Best for: High-end device users seeking instant passwordless convenience.*

1. **Android Credential Manager:** Kaizen implements Android's native Credential Manager API.
2. **Biometric Handshake:** When signing in, the OS slides up a native fingerprint/face unlock sheet.
3. **Cryptographic Validation:** The user touches the sensor. The secure enclave signs a challenge and Authentik validates it.
4. **No Redirection, No Passwords, Sub-Second Speed.**

---

## ⏳ 3. Token Lifecycle & Persistent Sessions (Silent Refresh)

Enterprise security mandates that API tokens must expire quickly (typically after 15 minutes). To prevent this security measure from destroying the user experience, Kaizen implements **Silent Background Refreshing**.

```
┌──────────────┐          1. Send API Call (Expired Token)           ┌────────────────┐
│              ├────────────────────────────────────────────────────>│                │
│              │<────────────────────────────────────────────────────┤                │
│              │                 2. Response: HTTP 401               │                │
│  Kaizen App  │                                                     │ Kaizen Backend │
│   (Android)  │          3. POST /token (Using Refresh Token)       │                │
│              ├───────────────────────────────────────────────┐     │                │
│              │<────────────────────────────────────────────┐ │     │                │
│              │       4. Store New Tokens & Retry Request   │ │     │                │
└──────────────┘                                             ▼ ▼     └────────────────┘
                                                       ┌─────────────┐
                                                       │  Authentik  │
                                                       └─────────────┘
```

1. **Token Storage:** Upon successful login, the **Access Token** and **Refresh Token** are saved in `SecureStore.kt` using `EncryptedSharedPreferences` (AES-256-GCM, hardware-bound to the StrongBox / Secure Enclave).
2. **The 401 Interceptor:** OkHttp's Interceptor mechanism intercepts any outgoing API request.
3. **Auto-Refresh:** If an API call fails with `HTTP 401 Unauthorized`, the interceptor pauses the request pipeline, makes a synchronous background call to Authentik using the langlebige `Refresh Token`, stores the new tokens, and retries the original request.
4. **Invisible to User:** The user's chat stream continues without interruption. They remain logged in for weeks or months (based on the Refresh Token validity configured in Authentik) without ever seeing a login screen.

---

## 👥 4. Hybrid User Management Architecture (Authentication vs. Authorization)

To deliver a world-class enterprise system with zero-friction, Kaizen decouples **Authentication & Lifecycle** (Identity, managed by Authentik) from **Authorization & Resource Allocation** (Application-specific, managed inside Kaizen).

```
         1. Authentication (MFA, Passwords, Passkeys)
   ┌───────────────────────┐
   │    Authentik (IdP)    │──────────► Overwrites/Provides Email & SSO status
   └───────────────────────┘
               │
               ▼ Just-In-Time (JIT) Provisioning
   ┌───────────────────────┐
   │  Kaizen PostgreSQL    │◄───────── Creates a local 'user' row on first OIDC callback
   └───────────┬───────────┘
               │
               ▼ Administrative Control
   ┌───────────────────────┐
   │   Kaizen Admin UI     │──────────► Manages app-specific settings (/admin/users):
   │    (/admin/users)     │           - Model Whitelisting (users.restrictions)
   └───────────────────────┘           - Monthly Spent Budgets (USD)
                                       - Built-in / MCP Tool whitelists
```

### Decoupling Rules:
1. **Authentik (Identity & Credential Master):**
   * Handles user creation, password policies, invitation links ("Magic Links"), MFA, and device registration (Passkeys).
   * Kaizen **never** stores or handles raw passwords when using Authentik OIDC or ROPC.
2. **Kaizen Admin Dashboard (App-Specific Authorization):**
   * Uses Kaizen's native `/admin/users` panel to configure PostgreSQL `users.restrictions` (Zod-validated JSONB schema).
   * **Model Whitelists:** Restrict a user to cheaper/faster models (e.g., Gemini 2.5 Flash only) or open powerful models (e.g., Gemini 1.5 Pro).
   * **Spending Limits (Budgets):** Enforce tight monthly, weekly, or lifetime spending limits (tested dynamically during the `/api/chat` preflight leg).
   * **Feature & Tool Whitelisting:** Enforce access control on built-in tools (`fetch_url`, `evaluate_math`, `get_weather`), MCP servers, document analysis (`analyze_document`), and generation engines.
3. **Just-In-Time (JIT) Provisioning:**
   * When a user successfully authenticates via Authentik OIDC for the first time, Auth.js on the backend automatically provisions a corresponding SQL record in the `users` table with default values, enabling a flawless onboarding experience.

---

## 🎨 5. Premium Enterprise Login Screen UI/UX

We transform the login screen into a luxury visual experience inspired by Gemini and Microsoft Copilot.

```
┌────────────────────────────────────────────────────────┐
│                                                        │
│                       [Kaizen]                         │
│                                                        │
│                      (KaizenOrb)                       │
│                        *Breaths*                       │
│                                                        │
│                    Willkommen zurück                   │
│                                                        │
│         ┌────────────────────────────────────┐         │
│         │     🟦  Mit Microsoft anmelden     │         │
│         └────────────────────────────────────┘         │
│         ┌────────────────────────────────────┘         │
│         │     ⬜  Mit Google anmelden        │         │
│         └────────────────────────────────────┘         │
│                                                        │
│               - oder per E-Mail anmelden -             │
│                                                        │
│         ┌────────────────────────────────────┐         │
│         │  E-Mail                            │         │
│         └────────────────────────────────────┘         │
│         ┌────────────────────────────────────┐         │
│         │  Passwort                          │         │
│         └────────────────────────────────────┘         │
│                                                        │
│         ┌────────────────────────────────────┐         │
│         │             Anmelden               │         │
│         └────────────────────────────────────┘         │
│                                                        │
└────────────────────────────────────────────────────────┘
```

### Visual Enhancements:
1. **SSO-First Layout:** The primary options are seidenmatte glassmorphic buttons for Microsoft Entra ID and Google Workspace, equipped with high-fidelity haptic clicks on touch.
2. **Responsive KaizenOrb States:**
   * **Idle:** Gentle breathing glow in standard Amber/Aurora.
   * **Domain Discovery (E-Mail entered):** The light ring around the Orb begins rotating elegantly as it checks the company's SSO endpoint.
   * **Redirecting:** A pulsing blue light when the Custom Tab or Passkey dialog is initiated.
   * **Success:** A single bright emerald flash paired with a short, precise tactile vibration, followed by a smooth screen transition.
3. **Workspace Switcher:** Once logged in, the sidebar displays a beautiful company logo/initials avatar, allowing users to switch between multiple logged-in accounts (e.g., Personal, Corporate) with standard enterprise isolation.

---

## 🛠️ 6. Implementation Roadmap

We can implement this architectural blueprint systematically over three clear phases:

### Phase 1: Backend OIDC / JWKS Setup
* Configure Authentik OAuth2 provider for Kaizen.
* Add JWT parsing & offline validation middleware to Next.js Backend (`kaizen/`).
* Extract user scopes and group mappings (e.g. `groups: ["kaizen-admins"]` -> `role = SUPER_ADMIN`).

### Phase 2: Android Native ROPC & Silent Refresh
* Refactor `SecureStore.kt` to handle standard JWT payloads (`accessToken`, `refreshToken`, `expiresAt`).
* Implement the OkHttp Interceptor in `KaizenApi` for silent background refreshing.
* Connect the existing glassmorphic email/password text fields directly to Authentik's `/application/o/token/` API endpoint.

### Phase 3: Premium SSO & Passkeys
* Implement OpenID AppAuth/Custom Tabs for standard SSO redirects.
* Integrate Android Credential Manager API for native hardware-backed FIDO2 Passkeys.
* Refactor `LoginScreen.kt` to show the beautiful SSO-First layout with animated `KaizenOrb` states.