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+# TODO: Lizenzserver Konfiguration Implementation
+
+## Overview
+Implement client configuration management and single-session enforcement for Account Forger software.
+
+## Current State
+- License activation works (consumes device slots)
+- Basic verification exists at `/api/license/verify`
+- No heartbeat system
+- No single-session enforcement
+- Admin panel has UI for "Lizenzserver Konfiguration" but backend is missing
+
+## Requirements
+1. **Single Session Enforcement**: Only one device can run the software at a time (even if activated on multiple devices)
+2. **Heartbeat System**: 30-second heartbeats to track active sessions
+3. **Version Management**: Control minimum supported version and update notifications
+4. **Client Configuration**: Manage Account Forger settings from admin panel
+
+## Implementation Tasks
+
+### 1. Database Schema
+
+#### Admin Panel Database
+```sql
+-- Client configuration (one row for Account Forger)
+CREATE TABLE client_configs (
+    id SERIAL PRIMARY KEY,
+    client_name VARCHAR(100) NOT NULL DEFAULT 'Account Forger',
+    api_key VARCHAR(255) NOT NULL,
+    heartbeat_interval INTEGER DEFAULT 30, -- seconds
+    session_timeout INTEGER DEFAULT 60, -- seconds (2x heartbeat)
+    current_version VARCHAR(20) NOT NULL,
+    minimum_version VARCHAR(20) NOT NULL,
+    download_url TEXT,
+    whats_new TEXT,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+-- Active sessions tracking
+CREATE TABLE active_sessions (
+    id SERIAL PRIMARY KEY,
+    license_id INTEGER REFERENCES licenses(id) ON DELETE CASCADE,
+    hardware_id VARCHAR(255) NOT NULL,
+    ip_address INET,
+    client_version VARCHAR(20),
+    session_token VARCHAR(255) UNIQUE NOT NULL,
+    started_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    last_heartbeat TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(license_id) -- Only one active session per license
+);
+
+-- Session history for debugging
+CREATE TABLE session_history (
+    id SERIAL PRIMARY KEY,
+    license_id INTEGER REFERENCES licenses(id) ON DELETE CASCADE,
+    hardware_id VARCHAR(255) NOT NULL,
+    ip_address INET,
+    client_version VARCHAR(20),
+    started_at TIMESTAMP,
+    ended_at TIMESTAMP,
+    end_reason VARCHAR(50) -- 'normal', 'timeout', 'forced', 'replaced'
+);
+```
+
+### 2. License Server Endpoints
+
+#### New endpoints needed in `/v2_lizenzserver/app/api/license.py`:
+
+1. **POST /api/license/session/start**
+   - Input: license_key, machine_id, hardware_hash, version
+   - Check: License valid? Already active session?
+   - If active session exists: Return error "Es ist nur eine Sitzung erlaubt, stelle sicher, dass nirgendwo sonst das Programm läuft"
+   - If no session: Create session, return session_token and version info
+   - Response includes: session_token, whats_new (if newer version), download_url
+
+2. **POST /api/license/session/heartbeat**
+   - Input: session_token, license_key
+   - Update last_heartbeat timestamp
+   - Return: success status
+
+3. **POST /api/license/session/end**
+   - Input: session_token
+   - Mark session as ended
+   - Log to session_history
+
+4. **Background job**: Clean up sessions older than 60 seconds without heartbeat
+
+### 3. Admin Panel Implementation
+
+#### Routes needed in `/v2_adminpanel/routes/admin_routes.py`:
+
+1. **GET /lizenzserver/config**
+   - Show current client configuration
+   - Display active sessions count
+
+2. **POST /lizenzserver/config/update**
+   - Update version, download URL, what's new
+   - Update minimum supported version
+
+3. **GET /lizenzserver/sessions**
+   - List all active sessions
+   - Show: License key, Customer name, Hardware ID, IP, Started at, Last heartbeat
+
+4. **POST /lizenzserver/sessions/{session_id}/terminate**
+   - Force close a session (admin only: rac00n, w@rh@mm3r)
+
+5. **GET /lizenzserver/config/client/new** (currently 404)
+   - This is what's missing and causing the error
+   - Should handle creating initial client config
+
+### 4. Security
+
+- API key required for all client requests
+- License key validates ownership  
+- Hardware ID ensures device authenticity
+- Session tokens prevent replay attacks
+
+### 5. Client Flow
+
+1. **Startup**:
+   ```
+   POST /api/license/session/start
+   -> Get session_token or error
+   -> Show version update if available
+   ```
+
+2. **Running** (every 30 seconds):
+   ```
+   POST /api/license/session/heartbeat
+   -> Keep session alive
+   ```
+
+3. **Shutdown**:
+   ```
+   POST /api/license/session/end
+   -> Clean session exit
+   ```
+
+### 6. Error Handling
+
+- Network interruption: Session expires after 60s
+- Software crash: Session expires after 60s
+- Multiple launch attempts: Show error message
+- Version too old: Block with message to update
+
+### 7. Admin Features
+
+- View active sessions
+- Force terminate sessions
+- Update version requirements
+- View session history (last 24h)
+- Manage client configuration
+
+## Implementation Order
+
+1. Create database tables
+2. Implement session management in license server
+3. Add heartbeat endpoint
+4. Create admin panel routes for configuration
+5. Implement session viewing/management
+6. Add background cleanup job
+7. Test with Account Forger client
+
+## Notes
+- YAGNI: One global config for all Account Forger instances
+- No per-customer settings
+- No grace period for session reclaim
+- Generic error messages (no "who's using it" info)
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