diff --git a/Dockerfile b/Dockerfile
index 5d5060a..ac15978 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -37,8 +37,8 @@ RUN apt-get update \
 # Unprivilegierter Benutzer für alle Prozesse im Container
 RUN groupadd --gid 1001 app \
  && useradd --uid 1001 --gid 1001 --create-home --shell /usr/sbin/nologin app \
- && mkdir -p /tmp/nginx/client_body /tmp/nginx/proxy /tmp/nginx/fastcgi /tmp/nginx/uwsgi /tmp/nginx/scgi /var/log/supervisor \
- && chown -R app:app /tmp/nginx /var/log/supervisor
+ && mkdir -p /tmp/nginx/client_body /tmp/nginx/proxy /tmp/nginx/fastcgi /tmp/nginx/uwsgi /tmp/nginx/scgi /var/log/supervisor /app/data/modules /app/data/logs \
+ && chown -R app:app /tmp/nginx /var/log/supervisor /app/data
 
 COPY docker/nginx/nginx.conf /etc/nginx/nginx.conf
 COPY docker/supervisor/supervisord.conf /etc/supervisor/supervisord.conf
diff --git a/README.md b/README.md
index 1dba2ad..7213882 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 Zentrale, webbasierte Management-Plattform, über die eigenständige Web-Applikationen als **Module** integriert, verwaltet und Benutzern zugewiesen werden können.
 
-**Status: Phase 2 – Benutzerverwaltung (abgeschlossen)**
+**Status: Phase 3 – Modul-System (abgeschlossen)**
 
 ## Architektur-Überblick
 
@@ -97,6 +97,9 @@ Login/Logout mit serverseitigen Sessions, Rollen (ADMIN/USER), Health-Monitoring
 ### Phase 2 – Benutzerverwaltung
 Vollständige Benutzer-CRUD-API (nur Admin) mit Duplikat-Schutz, Schutz des letzten Admins, sofortiger Session-Sperrung bei Deaktivierung, Passwort-Reset, eigenes Passwort ändern, Benutzerverwaltungs-UI (Tabelle, Modals, Toasts) und Profil-Seite.
 
+### Phase 3 – Modul-System
+Modul-Registry mit Manifest-Vertrag (`module.json`, Zod-validiert), ZIP-Installation mit Zip-Slip-Schutz, Prozess-Manager (Kindprozesse mit minimaler ENV, eigene Logs), Lifecycle (INSTALLED/STARTING/RUNNING/STOPPED/ERROR/DISABLED), Healthchecks mit Startup-Grace, Modulverwaltungs-UI und persistente Volumes für Modul-Dateien.
+
 ## Annahme
 
 „ChatCM" wurde als **shadcn-artige Komponentenbasis** interpretiert: Tailwind CSS plus zentral gepflegte, wiederverwendbare UI-Komponenten (`apps/platform-frontend/src/components/ui`).
\ No newline at end of file
diff --git a/apps/platform-backend/package-lock.json b/apps/platform-backend/package-lock.json
index dba4bd3..065676b 100644
--- a/apps/platform-backend/package-lock.json
+++ b/apps/platform-backend/package-lock.json
@@ -14,6 +14,7 @@
         "@nestjs/platform-express": "^11.0.0",
         "@nestjs/swagger": "^11.0.0",
         "@node-rs/argon2": "^2.0.0",
+        "adm-zip": "^0.6.1",
         "cookie-parser": "^1.4.7",
         "express-rate-limit": "^7.5.0",
         "helmet": "^8.0.0",
@@ -25,9 +26,11 @@
       "devDependencies": {
         "@nestjs/cli": "^11.0.0",
         "@nestjs/testing": "^11.0.0",
+        "@types/adm-zip": "^0.5.8",
         "@types/cookie-parser": "^1.4.8",
         "@types/express": "^5.0.0",
         "@types/jest": "^29.5.14",
+        "@types/multer": "^2.3.0",
         "@types/node": "^24.0.0",
         "@types/pg": "^8.11.0",
         "@types/supertest": "^6.0.2",
@@ -2445,6 +2448,16 @@
       "integrity": "sha512-OvjF+z51L3ov0OyAU0duzsYuvO01PH7x4t6DJx+guahgTnBHkhJdG7soQeTSFLWN3efnHyibZ4Z8l2EuWwJN3A==",
       "license": "MIT"
     },
+    "node_modules/@types/adm-zip": {
+      "version": "0.5.8",
+      "resolved": "https://registry.npmjs.org/@types/adm-zip/-/adm-zip-0.5.8.tgz",
+      "integrity": "sha512-RVVH7QvZYbN+ihqZ4kX/dMiowf6o+Jk1fNwiSdx0NahBJLU787zkULhGhJM8mf/obmLGmgdMM0bXsQTmyfbR7Q==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/node": "*"
+      }
+    },
     "node_modules/@types/babel__core": {
       "version": "7.20.5",
       "resolved": "https://registry.npmjs.org/@types/babel__core/-/babel__core-7.20.5.tgz",
@@ -2651,6 +2664,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/multer": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/@types/multer/-/multer-2.3.0.tgz",
+      "integrity": "sha512-i7STIm9V4K2MPH4ZYMtrZAwNxs3kglk2LgleaTuB9pUXgADBcQYQuYMd7+6xgTIxfoggIkFA/DkkvycdZpIARA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/express": "*"
+      }
+    },
     "node_modules/@types/node": {
       "version": "24.19.1",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-24.19.1.tgz",
@@ -3262,6 +3285,15 @@
         "acorn": "^6.0.0 || ^7.0.0 || ^8.0.0"
       }
     },
+    "node_modules/adm-zip": {
+      "version": "0.6.1",
+      "resolved": "https://registry.npmjs.org/adm-zip/-/adm-zip-0.6.1.tgz",
+      "integrity": "sha512-Xwrja8nx9e5o2N1my4DsKCeKpdrnACyr1wtbPxBDgGzKzKyE9kRtBFA8mWldI+RVlD7CBZNWY/wQ2+ydwOR6kQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.0"
+      }
+    },
     "node_modules/ajv": {
       "version": "8.18.0",
       "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",
diff --git a/apps/platform-backend/package.json b/apps/platform-backend/package.json
index 38bd253..1ef905e 100644
--- a/apps/platform-backend/package.json
+++ b/apps/platform-backend/package.json
@@ -20,6 +20,7 @@
     "@nestjs/platform-express": "^11.0.0",
     "@nestjs/swagger": "^11.0.0",
     "@node-rs/argon2": "^2.0.0",
+    "adm-zip": "^0.6.1",
     "cookie-parser": "^1.4.7",
     "express-rate-limit": "^7.5.0",
     "helmet": "^8.0.0",
@@ -31,9 +32,11 @@
   "devDependencies": {
     "@nestjs/cli": "^11.0.0",
     "@nestjs/testing": "^11.0.0",
+    "@types/adm-zip": "^0.5.8",
     "@types/cookie-parser": "^1.4.8",
     "@types/express": "^5.0.0",
     "@types/jest": "^29.5.14",
+    "@types/multer": "^2.3.0",
     "@types/node": "^24.0.0",
     "@types/pg": "^8.11.0",
     "@types/supertest": "^6.0.2",
@@ -45,4 +48,4 @@
     "typescript": "^5.7.0",
     "typescript-eslint": "^8.0.0"
   }
-}
\ No newline at end of file
+}
diff --git a/apps/platform-backend/src/app.module.ts b/apps/platform-backend/src/app.module.ts
index d4c6729..30944e6 100644
--- a/apps/platform-backend/src/app.module.ts
+++ b/apps/platform-backend/src/app.module.ts
@@ -7,6 +7,7 @@ import { AuditModule } from './audit/audit.module';
 import { AuthModule } from './auth/auth.module';
 import { UsersModule } from './users/users.module';
 import { HealthModule } from './health/health.module';
+import { ModulesModule } from './modules/modules.module';
 import { SessionGuard } from './auth/guards/session.guard';
 import { CsrfGuard } from './auth/guards/csrf.guard';
 import { RolesGuard } from './common/guards/roles.guard';
@@ -16,7 +17,15 @@ import { RolesGuard } from './common/guards/roles.guard';
  * Globale Guards: SessionGuard (Authentifizierung) → CsrfGuard → RolesGuard.
  */
 @Module({
-  imports: [ConfigModule, DatabaseModule, AuditModule, AuthModule, UsersModule, HealthModule],
+  imports: [
+    ConfigModule,
+    DatabaseModule,
+    AuditModule,
+    AuthModule,
+    UsersModule,
+    HealthModule,
+    ModulesModule,
+  ],
   providers: [
     MigrationRunner,
     { provide: APP_GUARD, useClass: SessionGuard },
diff --git a/apps/platform-backend/src/audit/audit.service.ts b/apps/platform-backend/src/audit/audit.service.ts
index bdfe99e..5f1ce52 100644
--- a/apps/platform-backend/src/audit/audit.service.ts
+++ b/apps/platform-backend/src/audit/audit.service.ts
@@ -14,6 +14,13 @@ export const AUDIT_ACTIONS = {
   USER_DELETED: 'USER_DELETED',
   USER_PASSWORD_RESET: 'USER_PASSWORD_RESET',
   USER_PASSWORD_CHANGED: 'USER_PASSWORD_CHANGED',
+  MODULE_INSTALLED: 'MODULE_INSTALLED',
+  MODULE_REMOVED: 'MODULE_REMOVED',
+  MODULE_STARTED: 'MODULE_STARTED',
+  MODULE_STOPPED: 'MODULE_STOPPED',
+  MODULE_RESTARTED: 'MODULE_RESTARTED',
+  MODULE_ENABLED: 'MODULE_ENABLED',
+  MODULE_DISABLED: 'MODULE_DISABLED',
 } as const;
 
 export type AuditAction = (typeof AUDIT_ACTIONS)[keyof typeof AUDIT_ACTIONS];
diff --git a/apps/platform-backend/src/auth/auth.service.spec.ts b/apps/platform-backend/src/auth/auth.service.spec.ts
index 53f8b2b..f0ea5d2 100644
--- a/apps/platform-backend/src/auth/auth.service.spec.ts
+++ b/apps/platform-backend/src/auth/auth.service.spec.ts
@@ -25,6 +25,7 @@ function createConfig(overrides: Partial<AppConfig['security']> = {}): AppConfig
       ...overrides,
     },
     adminSeed: { username: 'admin', email: 'admin@example.com', password: 'password-123' },
+    runtime: { modulesDir: '/data/modules', logsDir: '/data/logs' },
   };
 }
 
diff --git a/apps/platform-backend/src/config/configuration.ts b/apps/platform-backend/src/config/configuration.ts
index 1ed6d15..29f51c3 100644
--- a/apps/platform-backend/src/config/configuration.ts
+++ b/apps/platform-backend/src/config/configuration.ts
@@ -1,4 +1,5 @@
 import { z } from 'zod';
+import path from 'node:path';
 
 /**
  * Zentrale, typsichere Konfiguration der Management-Plattform.
@@ -28,12 +29,18 @@ export interface AdminSeedConfig {
   readonly password: string;
 }
 
+export interface RuntimeConfig {
+  readonly modulesDir: string;
+  readonly logsDir: string;
+}
+
 export interface AppConfig {
   readonly nodeEnv: NodeEnvironment;
   readonly port: number;
   readonly database: DatabaseConfig;
   readonly security: SecurityConfig;
   readonly adminSeed: AdminSeedConfig;
+  readonly runtime: RuntimeConfig;
 }
 
 const booleanFromString = z
@@ -55,6 +62,8 @@ const environmentSchema = z.object({
   ADMIN_USERNAME: z.string().trim().min(3).max(100),
   ADMIN_EMAIL: z.string().trim().email(),
   ADMIN_PASSWORD: z.string().min(10, 'ADMIN_PASSWORD muss mindestens 10 Zeichen lang sein').max(200),
+  MODULES_DIR: z.string().min(1).default('./data/modules'),
+  LOGS_DIR: z.string().min(1).default('./data/logs'),
 });
 
 /** Lädt und validiert die Konfiguration aus den Umgebungsvariablen. */
@@ -79,5 +88,9 @@ export function loadConfiguration(): AppConfig {
       email: environment.ADMIN_EMAIL,
       password: environment.ADMIN_PASSWORD,
     },
+    runtime: {
+      modulesDir: path.resolve(environment.MODULES_DIR),
+      logsDir: path.resolve(environment.LOGS_DIR),
+    },
   };
 }
\ No newline at end of file
diff --git a/apps/platform-backend/src/database/migrations/index.ts b/apps/platform-backend/src/database/migrations/index.ts
index 355de82..791c5ab 100644
--- a/apps/platform-backend/src/database/migrations/index.ts
+++ b/apps/platform-backend/src/database/migrations/index.ts
@@ -1,4 +1,5 @@
 import { migration001CoreSchema } from './001-core-schema';
+import { migration002Modules } from '../../modules/migrations/002-modules';
 
 /** Registrierte Migrationen in aufsteigender Reihenfolge. */
-export const MIGRATIONS = [migration001CoreSchema];
\ No newline at end of file
+export const MIGRATIONS = [migration001CoreSchema, migration002Modules];
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/manifest.types.spec.ts b/apps/platform-backend/src/modules/manifest.types.spec.ts
new file mode 100644
index 0000000..9c4bb64
--- /dev/null
+++ b/apps/platform-backend/src/modules/manifest.types.spec.ts
@@ -0,0 +1,79 @@
+import { BadRequestException } from '@nestjs/common';
+import { moduleManifestSchema } from './manifest.types';
+import { ModuleInstaller } from './module-installer';
+
+describe('moduleManifestSchema', () => {
+  const validManifest = {
+    id: 'calendar',
+    name: 'Kalender',
+    version: '1.0.0',
+    slug: 'kalender-tool',
+    description: 'Kalenderverwaltung',
+    author: 'MPM',
+    runtime: 'node',
+    entrypoint: 'server.js',
+    port: 41001,
+    healthcheck: '/health',
+    apiVersion: 'v1',
+  };
+
+  it('akzeptiert ein gültiges Manifest', () => {
+    const result = moduleManifestSchema.safeParse(validManifest);
+    expect(result.success).toBe(true);
+  });
+
+  it('lehnt ungültige Modul-IDs ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, id: 'Invalid_ID!' });
+    expect(result.success).toBe(false);
+  });
+
+  it('lehnt ungültige Versionen ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, version: '1.0' });
+    expect(result.success).toBe(false);
+  });
+
+  it('lehnt Ports außerhalb des erlaubten Bereichs ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, port: 80 });
+    expect(result.success).toBe(false);
+  });
+
+  it('lehnt Pfad-Traversal im Entrypoint ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, entrypoint: '../evil.js' });
+    expect(result.success).toBe(false);
+  });
+
+  it('lehnt unbekannte Runtimes ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, runtime: 'python' });
+    expect(result.success).toBe(false);
+  });
+
+  it('lehnt ungültige Healthcheck-Pfade ab', () => {
+    const result = moduleManifestSchema.safeParse({ ...validManifest, healthcheck: 'http://evil' });
+    expect(result.success).toBe(false);
+  });
+});
+
+describe('ModuleInstaller.validatePackage', () => {
+  it('lehnt leere Pakete ab', async () => {
+    const installer = new ModuleInstaller();
+    await expect(installer.validatePackage(Buffer.alloc(0))).rejects.toThrow(BadRequestException);
+  });
+
+  it('lehnt Pakete ohne module.json ab', async () => {
+    const AdmZip = (await import('adm-zip')).default;
+    const zip = new AdmZip();
+    zip.addFile('irgendwas.txt', Buffer.from('Inhalt'));
+    const installer = new ModuleInstaller();
+    await expect(installer.validatePackage(zip.toBuffer())).rejects.toThrow(
+      'Paket enthält keine module.json',
+    );
+  });
+
+  it('lehnt ungültige Manifeste ab', async () => {
+    const AdmZip = (await import('adm-zip')).default;
+    const zip = new AdmZip();
+    zip.addFile('module.json', Buffer.from(JSON.stringify({ id: 'X' })));
+    const installer = new ModuleInstaller();
+    await expect(installer.validatePackage(zip.toBuffer())).rejects.toThrow(BadRequestException);
+  });
+});
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/manifest.types.ts b/apps/platform-backend/src/modules/manifest.types.ts
new file mode 100644
index 0000000..6437e46
--- /dev/null
+++ b/apps/platform-backend/src/modules/manifest.types.ts
@@ -0,0 +1,74 @@
+import { z } from 'zod';
+
+/** Mögliche Lebenszyklus-Zustände eines Moduls. */
+export const MODULE_STATUSES = [
+  'INSTALLED',
+  'STARTING',
+  'RUNNING',
+  'STOPPING',
+  'STOPPED',
+  'ERROR',
+  'DISABLED',
+] as const;
+export type ModuleStatus = (typeof MODULE_STATUSES)[number];
+
+/** Erlaubter interner Portbereich für Modul-Prozesse (nicht nach außen sichtbar). */
+export const MODULE_PORT_MIN = 41000;
+export const MODULE_PORT_MAX = 41999;
+
+/** Modul-IDs: kleinbuchstaben, Zahlen, Bindestriche – keine Pfadzeichen. */
+const MODULE_ID_PATTERN = /^[a-z][a-z0-9-]{2,63}$/;
+
+/** URL-Slugs für das spätere Routing (/slug). */
+const SLUG_PATTERN = /^[a-z0-9][a-z0-9-]{2,99}$/;
+
+/** Semantische Versionierung (major.minor.patch). */
+const VERSION_PATTERN = /^\d+\.\d+\.\d+$/;
+
+/**
+ * Manifest-Vertrag (module.json) eines Moduls.
+ * Jedes installierbare Paket muss dieses Schema erfüllen.
+ */
+export const moduleManifestSchema = z.object({
+  id: z
+    .string()
+    .regex(MODULE_ID_PATTERN, 'Modul-ID muss dem Muster [a-z][a-z0-9-]{2,63} folgen'),
+  name: z.string().trim().min(1, 'Name ist erforderlich').max(100),
+  version: z.string().regex(VERSION_PATTERN, 'Version muss dem Muster major.minor.patch folgen'),
+  slug: z.string().regex(SLUG_PATTERN, 'Slug muss dem Muster [a-z0-9-]{3,100} folgen'),
+  description: z.string().max(500).default(''),
+  author: z.string().max(200).default(''),
+  runtime: z.literal('node'),
+  entrypoint: z
+    .string()
+    .regex(/^[A-Za-z0-9][A-Za-z0-9._/-]*\.js$/, 'Entrypoint muss ein relativer .js-Pfad sein')
+    .refine((entrypoint) => !entrypoint.split('/').includes('..'), {
+      message: 'Entrypoint darf nicht über das Modulverzeichnis hinauszeigen',
+    }),
+  port: z
+    .number()
+    .int()
+    .min(MODULE_PORT_MIN, `Port muss zwischen ${MODULE_PORT_MIN} und ${MODULE_PORT_MAX} liegen`)
+    .max(MODULE_PORT_MAX, `Port muss zwischen ${MODULE_PORT_MIN} und ${MODULE_PORT_MAX} liegen`),
+  healthcheck: z.string().regex(/^\/[A-Za-z0-9\-./]*$/, 'Healthcheck muss ein Pfad sein'),
+  apiVersion: z.literal('v1'),
+});
+export type ModuleManifest = z.infer<typeof moduleManifestSchema>;
+
+/** Vollständiger Modul-Datensatz aus der Datenbank. */
+export interface ModuleRecord {
+  readonly id: string;
+  readonly moduleId: string;
+  readonly name: string;
+  readonly slug: string;
+  readonly version: string;
+  readonly description: string;
+  readonly author: string;
+  readonly path: string;
+  readonly status: ModuleStatus;
+  readonly internalPort: number;
+  readonly healthcheckUrl: string;
+  readonly enabled: boolean;
+  readonly createdAt: Date;
+  readonly updatedAt: Date;
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/migrations/002-modules.ts b/apps/platform-backend/src/modules/migrations/002-modules.ts
new file mode 100644
index 0000000..ccc088a
--- /dev/null
+++ b/apps/platform-backend/src/modules/migrations/002-modules.ts
@@ -0,0 +1,30 @@
+import type { Migration } from '../../database/migration.types';
+
+/** Phase 3: Modul-Registry für installierte Module. */
+export const migration002Modules: Migration = {
+  id: '002-modules',
+  description: 'Modul-Registry anlegen',
+  up: async (client) => {
+    await client.query(`
+      CREATE TABLE modules (
+        id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+        module_id TEXT NOT NULL UNIQUE,
+        name TEXT NOT NULL,
+        slug TEXT NOT NULL UNIQUE,
+        version TEXT NOT NULL,
+        description TEXT NOT NULL DEFAULT '',
+        author TEXT NOT NULL DEFAULT '',
+        path TEXT NOT NULL,
+        status TEXT NOT NULL DEFAULT 'INSTALLED'
+          CHECK (status IN ('INSTALLED', 'STARTING', 'RUNNING', 'STOPPING', 'STOPPED', 'ERROR', 'DISABLED')),
+        internal_port INTEGER NOT NULL,
+        healthcheck_url TEXT NOT NULL DEFAULT '/health',
+        enabled BOOLEAN NOT NULL DEFAULT true,
+        created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+        updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+      )
+    `);
+
+    await client.query('CREATE INDEX idx_modules_status ON modules(status)');
+  },
+};
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/module-health-checker.ts b/apps/platform-backend/src/modules/module-health-checker.ts
new file mode 100644
index 0000000..33fa80f
--- /dev/null
+++ b/apps/platform-backend/src/modules/module-health-checker.ts
@@ -0,0 +1,43 @@
+import { Injectable } from '@nestjs/common';
+import type { ModuleRecord } from './manifest.types';
+
+/** Ergebnis eines Modul-Healthchecks. */
+export interface ModuleHealthResult {
+  readonly healthy: boolean;
+  readonly latencyMs: number;
+  readonly detail: string;
+}
+
+/**
+ * Modul-Healthchecks (Infrastructure): Prüft die Healthcheck-URL eines
+ * Modul-Prozesses. Fehler werden abgefangen – ein krankes Modul darf
+ * die Plattform niemals mitreißen.
+ */
+@Injectable()
+export class ModuleHealthChecker {
+
+  /** Prüft einen Modul-Prozess über seine Healthcheck-URL. */
+  async check(module: ModuleRecord): Promise<ModuleHealthResult> {
+    const url = `http://127.0.0.1:${module.internalPort}${module.healthcheckUrl}`;
+    const start = performance.now();
+
+    try {
+      const controller = new AbortController();
+      const timeout = setTimeout(() => controller.abort(), 3_000);
+      const response = await fetch(url, { signal: controller.signal });
+      clearTimeout(timeout);
+
+      const latencyMs = Math.round(performance.now() - start);
+      const healthy = response.ok;
+      return {
+        healthy,
+        latencyMs,
+        detail: healthy ? 'healthy' : `HTTP ${response.status}`,
+      };
+    } catch (error) {
+      const latencyMs = Math.round(performance.now() - start);
+      const detail = error instanceof Error ? error.message : String(error);
+      return { healthy: false, latencyMs, detail: `unreachable: ${detail}` };
+    }
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/module-installer.ts b/apps/platform-backend/src/modules/module-installer.ts
new file mode 100644
index 0000000..555153f
--- /dev/null
+++ b/apps/platform-backend/src/modules/module-installer.ts
@@ -0,0 +1,130 @@
+import { BadRequestException, Injectable, Logger } from '@nestjs/common';
+import { mkdir, readFile, rm, writeFile } from 'node:fs/promises';
+import path from 'node:path';
+import { moduleManifestSchema, type ModuleManifest } from './manifest.types';
+
+/** Maximale Größe eines Modul-Pakets (10 MB). */
+const MAX_PACKAGE_SIZE_BYTES = 10 * 1024 * 1024;
+
+/** Dateien, die in einem Modul-Paket erwartet werden. */
+const REQUIRED_MANIFEST_FILE = 'module.json';
+
+/**
+ * Modul-Installer (Infrastructure):
+ * Nimmt ein ZIP-Paket entgegen, validiert es (Größe, Manifest,
+ * Zip-Slip-Schutz) und installiert es in das Modulverzeichnis.
+ *
+ * Ein Modul ist grundsätzlich nicht vertrauenswürdig – deshalb:
+ * - strikte Manifest-Validierung (Zod)
+ * - kein Pfad-Exit aus dem Zielverzeichnis (Zip-Slip)
+ * - keine Ausführung von Paket-Skripten (npm install --ignore-scripts)
+ */
+@Injectable()
+export class ModuleInstaller {
+  private readonly logger = new Logger('ModuleInstaller');
+
+  /** Validiert ein hochgeladenes Paket und gibt das Manifest zurück. */
+  async validatePackage(buffer: Buffer): Promise<ModuleManifest> {
+    if (buffer.length === 0) {
+      throw new BadRequestException('Paket ist leer');
+    }
+    if (buffer.length > MAX_PACKAGE_SIZE_BYTES) {
+      throw new BadRequestException('Paket ist zu groß (maximal 10 MB)');
+    }
+
+    const AdmZip = (await import('adm-zip')).default;
+    const zip = new AdmZip(buffer);
+
+    const manifestEntry = zip.getEntry(REQUIRED_MANIFEST_FILE);
+    if (!manifestEntry) {
+      throw new BadRequestException(`Paket enthält keine ${REQUIRED_MANIFEST_FILE}`);
+    }
+
+    let manifestJson: unknown;
+    try {
+      manifestJson = JSON.parse(manifestEntry.getData().toString('utf8'));
+    } catch {
+      throw new BadRequestException(`${REQUIRED_MANIFEST_FILE} ist kein gültiges JSON`);
+    }
+
+    const result = moduleManifestSchema.safeParse(manifestJson);
+    if (!result.success) {
+      const details: Record<string, string[]> = {};
+      for (const issue of result.error.issues) {
+        const key = issue.path.join('.') || 'form';
+        if (!details[key]) {
+          details[key] = [issue.message];
+        }
+      }
+      throw new BadRequestException({
+        statusCode: 400,
+        message: 'Manifest-Validierung fehlgeschlagen',
+        error: 'Bad Request',
+        details,
+      });
+    }
+
+    return result.data;
+  }
+
+  /**
+   * Installiert ein validiertes Paket in das Modulverzeichnis.
+   * @returns Installationsverzeichnis und Manifest.
+   */
+  async install(
+    buffer: Buffer,
+    manifest: ModuleManifest,
+    modulesDir: string,
+  ): Promise<{ directory: string; manifest: ModuleManifest }> {
+    const directory = path.join(modulesDir, manifest.id);
+
+    // Zip-Slip-Schutz: Alle Einträge müssen innerhalb des Zielverzeichnisses liegen.
+    const AdmZip = (await import('adm-zip')).default;
+    const zip = new AdmZip(buffer);
+    const resolvedDirectory = path.resolve(directory);
+
+    for (const entry of zip.getEntries()) {
+      const entryName = entry.entryName;
+      if (entryName.startsWith('/') || entryName.includes('..') || /^[A-Za-z]:/.test(entryName)) {
+        throw new BadRequestException(`Unsicherer Pfad im Paket: ${entryName}`);
+      }
+      const resolvedEntry = path.resolve(resolvedDirectory, entryName);
+      if (!resolvedEntry.startsWith(resolvedDirectory + path.sep)) {
+        throw new BadRequestException(`Unsicherer Pfad im Paket: ${entryName}`);
+      }
+    }
+
+    // Bestehende Installation entfernen (Update-Szenario).
+    await rm(directory, { recursive: true, force: true });
+    await mkdir(directory, { recursive: true });
+
+    zip.extractAllTo(resolvedDirectory, true);
+
+    // Paket-Metadaten für spätere Diagnose speichern.
+    await writeFile(
+      path.join(directory, '.installed.json'),
+      JSON.stringify({ installedAt: new Date().toISOString(), manifest }, null, 2),
+      'utf8',
+    );
+
+    this.logger.log(`Modul "${manifest.id}" installiert in ${directory}`);
+    return { directory, manifest };
+  }
+
+  /** Entfernt eine Modul-Installation vom Dateisystem. */
+  async remove(modulesDir: string, moduleId: string): Promise<void> {
+    const directory = path.join(modulesDir, moduleId);
+    await rm(directory, { recursive: true, force: true });
+  }
+
+  /** Liest das Manifest einer bestehenden Installation. */
+  async readInstalledManifest(directory: string): Promise<ModuleManifest | null> {
+    try {
+      const raw = await readFile(path.join(directory, REQUIRED_MANIFEST_FILE), 'utf8');
+      const result = moduleManifestSchema.safeParse(JSON.parse(raw));
+      return result.success ? result.data : null;
+    } catch {
+      return null;
+    }
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/module-process-manager.ts b/apps/platform-backend/src/modules/module-process-manager.ts
new file mode 100644
index 0000000..88d6b25
--- /dev/null
+++ b/apps/platform-backend/src/modules/module-process-manager.ts
@@ -0,0 +1,110 @@
+import { Injectable, Logger, type OnModuleDestroy } from '@nestjs/common';
+import { spawn, type ChildProcess } from 'node:child_process';
+import { mkdir, open } from 'node:fs/promises';
+import path from 'node:path';
+import { APP_CONFIG, type AppConfig } from '../config/config.tokens';
+import { Inject } from '@nestjs/common';
+import type { ModuleRecord } from './manifest.types';
+
+/** Laufende Modul-Prozesse im Speicher (nicht persistent). */
+interface RunningProcess {
+  readonly child: ChildProcess;
+  readonly logFilePath: string;
+}
+
+/**
+ * Modul-Prozess-Manager (Infrastructure):
+ * Startet, stoppt und überwacht Modul-Prozesse innerhalb des
+ * Management-Containers. Kein Docker-in-Docker – Module laufen als
+ * Kindprozesse des Backends mit eigenen internen Ports.
+ *
+ * Sicherheitsprinzipien:
+ * - Prozesse laufen ohne Shell (keine Command-Injection)
+ * - Umgebungsvariablen minimal gehalten (keine Plattform-Secrets)
+ * - Logs pro Modul in eigene Dateien
+ */
+@Injectable()
+export class ModuleProcessManager implements OnModuleDestroy {
+  private readonly logger = new Logger('ModuleProcesses');
+  private readonly running = new Map<string, RunningProcess>();
+
+  constructor(@Inject(APP_CONFIG) private readonly config: AppConfig) {}
+
+  /** Startet einen Modul-Prozess. */
+  async start(module: ModuleRecord): Promise<void> {
+    if (this.running.has(module.moduleId)) {
+      return;
+    }
+
+    const entrypoint = path.join(module.path, 'backend', 'server.js');
+    const logFilePath = path.join(this.config.runtime.logsDir, `module-${module.moduleId}.log`);
+    await mkdir(this.config.runtime.logsDir, { recursive: true });
+    const logFile = await open(logFilePath, 'a');
+
+    const child = spawn(process.execPath, [entrypoint], {
+      cwd: module.path,
+      // Log-Datei bleibt offen: Der fd wird vom Kindprozess geerbt und
+      // darf erst nach Prozessende geschlossen werden.
+      stdio: ['ignore', logFile.fd, logFile.fd],
+      env: {
+        PATH: process.env.PATH ?? '',
+        NODE_ENV: this.config.nodeEnv,
+        PORT: String(module.internalPort),
+        // Modul erhält nur seinen eigenen Kontext – keine Plattform-Secrets.
+      },
+      detached: false,
+    });
+
+    child.unref();
+
+    child.on('exit', (code) => {
+      this.logger.warn(`Modul-Prozess "${module.moduleId}" beendet (Code ${code ?? 'signal'})`);
+      this.running.delete(module.moduleId);
+    });
+
+    this.running.set(module.moduleId, { child, logFilePath });
+    this.logger.log(`Modul-Prozess "${module.moduleId}" gestartet (Port ${module.internalPort})`);
+  }
+
+  /** Stoppt einen Modul-Prozess (SIGTERM, dann SIGKILL). */
+  async stop(moduleId: string): Promise<void> {
+    const process_ = this.running.get(moduleId);
+    if (!process_) {
+      return;
+    }
+
+    this.running.delete(moduleId);
+    const child = process_.child;
+
+    await new Promise<void>((resolve) => {
+      const timeout = setTimeout(() => {
+        child.kill('SIGKILL');
+        resolve();
+      }, 5_000);
+
+      child.once('exit', () => {
+        clearTimeout(timeout);
+        resolve();
+      });
+
+      child.kill('SIGTERM');
+    });
+
+    this.logger.log(`Modul-Prozess "${moduleId}" gestoppt`);
+  }
+
+  /** Prüft, ob ein Modul-Prozess läuft. */
+  isRunning(moduleId: string): boolean {
+    return this.running.has(moduleId);
+  }
+
+  /** Stoppt alle Modul-Prozesse (Herunterfahren). */
+  async stopAll(): Promise<void> {
+    const moduleIds = [...this.running.keys()];
+    await Promise.all(moduleIds.map((moduleId) => this.stop(moduleId)));
+  }
+
+  async onModuleDestroy(): Promise<void> {
+    await this.stopAll();
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/module.repository.ts b/apps/platform-backend/src/modules/module.repository.ts
new file mode 100644
index 0000000..79bb1e7
--- /dev/null
+++ b/apps/platform-backend/src/modules/module.repository.ts
@@ -0,0 +1,137 @@
+import { Injectable } from '@nestjs/common';
+import { DatabaseService } from '../database/database.service';
+import type { ModuleManifest, ModuleRecord, ModuleStatus } from './manifest.types';
+
+interface ModuleRow {
+  id: string;
+  module_id: string;
+  name: string;
+  slug: string;
+  version: string;
+  description: string;
+  author: string;
+  path: string;
+  status: ModuleStatus;
+  internal_port: number;
+  healthcheck_url: string;
+  enabled: boolean;
+  created_at: Date;
+  updated_at: Date;
+}
+
+const MODULE_COLUMNS = `id, module_id, name, slug, version, description, author, path,
+                        status, internal_port, healthcheck_url, enabled, created_at, updated_at`;
+
+/**
+ * Modul-Repository (Infrastructure): Datenbankzugriffe für die Modul-Registry.
+ * Keine Business-Logik – nur parametrisierten Datenzugriff.
+ */
+@Injectable()
+export class ModuleRepository {
+  constructor(private readonly database: DatabaseService) {}
+
+  async list(): Promise<ModuleRecord[]> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules ORDER BY created_at ASC`,
+    );
+    return result.rows.map((row) => this.mapRow(row));
+  }
+
+  async findByModuleId(moduleId: string): Promise<ModuleRecord | null> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules WHERE module_id = $1`,
+      [moduleId],
+    );
+    return result.rows[0] ? this.mapRow(result.rows[0]) : null;
+  }
+
+  async findBySlug(slug: string): Promise<ModuleRecord | null> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules WHERE slug = $1`,
+      [slug],
+    );
+    return result.rows[0] ? this.mapRow(result.rows[0]) : null;
+  }
+
+  async findByPort(port: number): Promise<ModuleRecord | null> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules WHERE internal_port = $1`,
+      [port],
+    );
+    return result.rows[0] ? this.mapRow(result.rows[0]) : null;
+  }
+
+  async findById(id: string): Promise<ModuleRecord | null> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules WHERE id = $1`,
+      [id],
+    );
+    return result.rows[0] ? this.mapRow(result.rows[0]) : null;
+  }
+
+  async findByStatus(statuses: readonly ModuleStatus[]): Promise<ModuleRecord[]> {
+    const result = await this.database.query<ModuleRow>(
+      `SELECT ${MODULE_COLUMNS} FROM modules WHERE status = ANY($1::text[])`,
+      [statuses],
+    );
+    return result.rows.map((row) => this.mapRow(row));
+  }
+
+  async create(manifest: ModuleManifest, directory: string): Promise<ModuleRecord> {
+    const result = await this.database.query<ModuleRow>(
+      `INSERT INTO modules
+         (module_id, name, slug, version, description, author, path, status, internal_port, healthcheck_url)
+       VALUES ($1, $2, $3, $4, $5, $6, $7, 'INSTALLED', $8, $9)
+       RETURNING ${MODULE_COLUMNS}`,
+      [
+        manifest.id,
+        manifest.name,
+        manifest.slug,
+        manifest.version,
+        manifest.description,
+        manifest.author,
+        directory,
+        manifest.port,
+        manifest.healthcheck,
+      ],
+    );
+    return this.mapRow(result.rows[0]);
+  }
+
+  async updateStatus(id: string, status: ModuleStatus): Promise<void> {
+    await this.database.query(
+      'UPDATE modules SET status = $2, updated_at = now() WHERE id = $1',
+      [id, status],
+    );
+  }
+
+  async updateEnabled(id: string, enabled: boolean): Promise<void> {
+    await this.database.query(
+      'UPDATE modules SET enabled = $2, updated_at = now() WHERE id = $1',
+      [id, enabled],
+    );
+  }
+
+  async delete(id: string): Promise<void> {
+    await this.database.query('DELETE FROM modules WHERE id = $1', [id]);
+  }
+
+  private mapRow(row: ModuleRow): ModuleRecord {
+    return {
+      id: row.id,
+      moduleId: row.module_id,
+      name: row.name,
+      slug: row.slug,
+      version: row.version,
+      description: row.description,
+      author: row.author,
+      path: row.path,
+      status: row.status,
+      internalPort: row.internal_port,
+      healthcheckUrl: row.healthcheck_url,
+      enabled: row.enabled,
+      createdAt: row.created_at,
+      updatedAt: row.updated_at,
+    };
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/modules.controller.ts b/apps/platform-backend/src/modules/modules.controller.ts
new file mode 100644
index 0000000..b849938
--- /dev/null
+++ b/apps/platform-backend/src/modules/modules.controller.ts
@@ -0,0 +1,154 @@
+import {
+  BadRequestException,
+  Body,
+  Controller,
+  Delete,
+  Get,
+  Param,
+  ParseUUIDPipe,
+  Patch,
+  Post,
+  Req,
+  UploadedFile,
+  UseInterceptors,
+} from '@nestjs/common';
+import { FileInterceptor } from '@nestjs/platform-express';
+import type { Request } from 'express';
+import type { Multer } from 'multer';
+import { ApiTags } from '@nestjs/swagger';
+
+/** Hochgeladene Datei (Multer). */
+type UploadedPackageFile = Multer & { buffer: Buffer };
+import { CurrentUser } from '../common/decorators/current-user.decorator';
+import { Roles } from '../common/decorators/roles.decorator';
+import type { AuthenticatedRequest } from '../auth/authenticated-request';
+import type { AuthUser } from '../users/user.types';
+import type { ModuleRecord, ModuleStatus } from './manifest.types';
+import { ModulesService } from './modules.service';
+
+/** Modul-Daten in API-Antworten. */
+interface ModuleResponse {
+  id: string;
+  moduleId: string;
+  name: string;
+  slug: string;
+  version: string;
+  description: string;
+  author: string;
+  status: ModuleStatus;
+  internalPort: number;
+  healthcheckUrl: string;
+  enabled: boolean;
+  createdAt: string;
+}
+
+function toModuleResponse(module: ModuleRecord): ModuleResponse {
+  return {
+    id: module.id,
+    moduleId: module.moduleId,
+    name: module.name,
+    slug: module.slug,
+    version: module.version,
+    description: module.description,
+    author: module.author,
+    status: module.status,
+    internalPort: module.internalPort,
+    healthcheckUrl: module.healthcheckUrl,
+    enabled: module.enabled,
+    createdAt: module.createdAt.toISOString(),
+  };
+}
+
+/**
+ * Modul-Verwaltung (nur Administratoren): Installation, Lifecycle,
+ * Healthchecks und Entfernen von Modulen.
+ */
+@ApiTags('Modules')
+@Roles('ADMIN')
+@Controller({ path: 'api/v1/modules' })
+export class ModulesController {
+  constructor(private readonly modulesService: ModulesService) {}
+
+  @Get()
+  async list(): Promise<{ modules: ModuleResponse[] }> {
+    const modules = await this.modulesService.list();
+    return { modules: modules.map(toModuleResponse) };
+  }
+
+  @Get(':id')
+  async getById(@Param('id', ParseUUIDPipe) id: string): Promise<{ module: ModuleResponse }> {
+    const module = await this.modulesService.getById(id);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Post('install')
+  @UseInterceptors(FileInterceptor('package'))
+  async install(
+    @UploadedFile() file: UploadedPackageFile | undefined,
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ module: ModuleResponse }> {
+    if (!file) {
+      throw new BadRequestException('Keine Paketdatei hochgeladen (Feld "package")');
+    }
+    const module = await this.modulesService.install(file.buffer, actor, request.ip ?? null);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Post(':id/start')
+  async start(
+    @Param('id', ParseUUIDPipe) id: string,
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ module: ModuleResponse }> {
+    const module = await this.modulesService.start(id, actor, request.ip ?? null);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Post(':id/stop')
+  async stop(
+    @Param('id', ParseUUIDPipe) id: string,
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ module: ModuleResponse }> {
+    const module = await this.modulesService.stop(id, actor, request.ip ?? null);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Post(':id/restart')
+  async restart(
+    @Param('id', ParseUUIDPipe) id: string,
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ module: ModuleResponse }> {
+    const module = await this.modulesService.restart(id, actor, request.ip ?? null);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Patch(':id/enabled')
+  async setEnabled(
+    @Param('id', ParseUUIDPipe) id: string,
+    @Body() body: { enabled: boolean },
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ module: ModuleResponse }> {
+    const module = await this.modulesService.setEnabled(id, body.enabled, actor, request.ip ?? null);
+    return { module: toModuleResponse(module) };
+  }
+
+  @Get(':id/health')
+  async checkHealth(@Param('id', ParseUUIDPipe) id: string): Promise<{ healthy: boolean; latencyMs: number; detail: string }> {
+    const { health } = await this.modulesService.checkHealth(id);
+    return { healthy: health.healthy, latencyMs: health.latencyMs, detail: health.detail };
+  }
+
+  @Delete(':id')
+  async remove(
+    @Param('id', ParseUUIDPipe) id: string,
+    @CurrentUser() actor: AuthUser,
+    @Req() request: AuthenticatedRequest & Request,
+  ): Promise<{ success: true }> {
+    await this.modulesService.remove(id, actor, request.ip ?? null);
+    return { success: true };
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/modules.module.ts b/apps/platform-backend/src/modules/modules.module.ts
new file mode 100644
index 0000000..1868945
--- /dev/null
+++ b/apps/platform-backend/src/modules/modules.module.ts
@@ -0,0 +1,19 @@
+import { Module } from '@nestjs/common';
+import { ConfigModule } from '../config/config.module';
+import { DatabaseModule } from '../database/database.module';
+import { AuditModule } from '../audit/audit.module';
+import { ModuleHealthChecker } from './module-health-checker';
+import { ModuleInstaller } from './module-installer';
+import { ModuleProcessManager } from './module-process-manager';
+import { ModuleRepository } from './module.repository';
+import { ModulesController } from './modules.controller';
+import { ModulesService } from './modules.service';
+
+/** Modul-System: Installation, Lifecycle, Prozessverwaltung, Healthchecks. */
+@Module({
+  imports: [ConfigModule, DatabaseModule, AuditModule],
+  controllers: [ModulesController],
+  providers: [ModuleRepository, ModuleInstaller, ModuleProcessManager, ModuleHealthChecker, ModulesService],
+  exports: [ModuleRepository, ModulesService],
+})
+export class ModulesModule {}
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/modules.service.spec.ts b/apps/platform-backend/src/modules/modules.service.spec.ts
new file mode 100644
index 0000000..c887d18
--- /dev/null
+++ b/apps/platform-backend/src/modules/modules.service.spec.ts
@@ -0,0 +1,333 @@
+import { BadRequestException, ConflictException, NotFoundException } from '@nestjs/common';
+import { AUDIT_ACTIONS, AuditService } from '../audit/audit.service';
+import type { AppConfig } from '../config/config.tokens';
+import type { ActingUser } from '../users/users.service';
+import { ModuleHealthChecker } from './module-health-checker';
+import { ModuleInstaller } from './module-installer';
+import { ModuleProcessManager } from './module-process-manager';
+import { ModuleRepository } from './module.repository';
+import type { ModuleManifest, ModuleRecord } from './manifest.types';
+import { ModulesService } from './modules.service';
+
+/** Gültiges Test-Manifest. */
+function createManifest(overrides: Partial<ModuleManifest> = {}): ModuleManifest {
+  return {
+    id: 'calendar',
+    name: 'Kalender',
+    version: '1.0.0',
+    slug: 'kalender-tool',
+    description: 'Kalenderverwaltung',
+    author: 'MPM',
+    runtime: 'node',
+    entrypoint: 'server.js',
+    port: 41001,
+    healthcheck: '/health',
+    apiVersion: 'v1',
+    ...overrides,
+  };
+}
+
+/** Erzeugt einen Modul-Datensatz für Tests. */
+function createModuleRecord(overrides: Partial<ModuleRecord> = {}): ModuleRecord {
+  const manifest = createManifest();
+  return {
+    id: 'module-1',
+    moduleId: manifest.id,
+    name: manifest.name,
+    slug: manifest.slug,
+    version: manifest.version,
+    description: manifest.description,
+    author: manifest.author,
+    path: '/data/modules/calendar',
+    status: 'STOPPED',
+    internalPort: manifest.port,
+    healthcheckUrl: manifest.healthcheck,
+    enabled: true,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+    ...overrides,
+  };
+}
+
+const ACTOR: ActingUser = { id: 'admin-1', username: 'admin' };
+
+/** Mock des ModuleRepository. */
+class MockModuleRepository {
+  public modules: ModuleRecord[] = [];
+  public statusUpdates: Array<{ id: string; status: ModuleRecord['status'] }> = [];
+  public enabledUpdates: Array<{ id: string; enabled: boolean }> = [];
+  public deletedIds: string[] = [];
+
+  async list(): Promise<ModuleRecord[]> {
+    return this.modules;
+  }
+
+  async findById(id: string): Promise<ModuleRecord | null> {
+    return this.modules.find((module) => module.id === id) ?? null;
+  }
+
+  async findByModuleId(moduleId: string): Promise<ModuleRecord | null> {
+    return this.modules.find((module) => module.moduleId === moduleId) ?? null;
+  }
+
+  async findBySlug(slug: string): Promise<ModuleRecord | null> {
+    return this.modules.find((module) => module.slug === slug) ?? null;
+  }
+
+  async findByPort(port: number): Promise<ModuleRecord | null> {
+    return this.modules.find((module) => module.internalPort === port) ?? null;
+  }
+
+  async create(manifest: ModuleManifest, directory: string): Promise<ModuleRecord> {
+    const module = createModuleRecord({
+      id: 'new-module',
+      moduleId: manifest.id,
+      name: manifest.name,
+      slug: manifest.slug,
+      version: manifest.version,
+      path: directory,
+      internalPort: manifest.port,
+      healthcheckUrl: manifest.healthcheck,
+    });
+    this.modules.push(module);
+    return module;
+  }
+
+  async updateStatus(id: string, status: ModuleRecord['status']): Promise<void> {
+    this.statusUpdates.push({ id, status });
+    const module = this.modules.find((m) => m.id === id);
+    if (module) {
+      (module as { status: ModuleRecord['status'] }).status = status;
+    }
+  }
+
+  async updateEnabled(id: string, enabled: boolean): Promise<void> {
+    this.enabledUpdates.push({ id, enabled });
+    const module = this.modules.find((m) => m.id === id);
+    if (module) {
+      (module as { enabled: boolean }).enabled = enabled;
+    }
+  }
+
+  async delete(id: string): Promise<void> {
+    this.deletedIds.push(id);
+    this.modules = this.modules.filter((m) => m.id !== id);
+  }
+}
+
+/** Mock des ModuleInstaller. */
+class MockModuleInstaller {
+  public validateResult: ModuleManifest = createManifest();
+  public installed: Array<{ moduleId: string }> = [];
+  public removed: string[] = [];
+
+  async validatePackage(): Promise<ModuleManifest> {
+    return this.validateResult;
+  }
+
+  async install(
+    _buffer: Buffer,
+    manifest: ModuleManifest,
+    _modulesDir: string,
+  ): Promise<{ directory: string; manifest: ModuleManifest }> {
+    this.installed.push({ moduleId: manifest.id });
+    return { directory: `/data/modules/${manifest.id}`, manifest };
+  }
+
+  async remove(_modulesDir: string, moduleId: string): Promise<void> {
+    this.removed.push(moduleId);
+  }
+}
+
+/** Mock des ModuleProcessManager. */
+class MockProcessManager {
+  public started: string[] = [];
+  public stopped: string[] = [];
+
+  async start(module: ModuleRecord): Promise<void> {
+    this.started.push(module.moduleId);
+  }
+
+  async stop(moduleId: string): Promise<void> {
+    this.stopped.push(moduleId);
+  }
+
+  isRunning(moduleId: string): boolean {
+    return this.started.includes(moduleId) && !this.stopped.includes(moduleId);
+  }
+}
+
+/** Mock des ModuleHealthChecker. */
+class MockHealthChecker {
+  public healthy = true;
+
+  async check(): Promise<{ healthy: boolean; latencyMs: number; detail: string }> {
+    return { healthy: this.healthy, latencyMs: 5, detail: this.healthy ? 'healthy' : 'unreachable' };
+  }
+}
+
+/** Mock des AuditService. */
+class MockAuditService {
+  public records: Array<{ action: string }> = [];
+
+  async record(entry: { action: string }): Promise<void> {
+    this.records.push(entry);
+  }
+}
+
+/** Test-Konfiguration. */
+const TEST_CONFIG: AppConfig = {
+  nodeEnv: 'test',
+  port: 3000,
+  database: { url: 'postgresql://test' },
+  security: {
+    sessionTtlMinutes: 120,
+    cookieSecure: false,
+    behindProxy: false,
+    loginMaxAttempts: 5,
+    loginLockoutMinutes: 15,
+    loginRateLimitAttempts: 10,
+    loginRateLimitWindowMinutes: 5,
+  },
+  adminSeed: { username: 'admin', email: 'admin@example.com', password: 'password-123' },
+  runtime: { modulesDir: '/data/modules', logsDir: '/data/logs' },
+};
+
+describe('ModulesService', () => {
+  let repository: MockModuleRepository;
+  let installer: MockModuleInstaller;
+  let processManager: MockProcessManager;
+  let healthChecker: MockHealthChecker;
+  let auditService: MockAuditService;
+  let modulesService: ModulesService;
+
+  beforeEach(() => {
+    repository = new MockModuleRepository();
+    installer = new MockModuleInstaller();
+    processManager = new MockProcessManager();
+    healthChecker = new MockHealthChecker();
+    auditService = new MockAuditService();
+    modulesService = new ModulesService(
+      repository as unknown as ModuleRepository,
+      installer as unknown as ModuleInstaller,
+      processManager as unknown as ModuleProcessManager,
+      healthChecker as unknown as ModuleHealthChecker,
+      auditService as unknown as AuditService,
+      TEST_CONFIG,
+    );
+  });
+
+  describe('install', () => {
+    it('installiert ein neues Modul und schreibt Audit', async () => {
+      const module = await modulesService.install(Buffer.from('zip'), ACTOR, null);
+      expect(module.moduleId).toBe('calendar');
+      expect(installer.installed).toEqual([{ moduleId: 'calendar' }]);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_INSTALLED);
+    });
+
+    it('lehnt doppelte Modul-IDs ab', async () => {
+      repository.modules = [createModuleRecord()];
+      await expect(modulesService.install(Buffer.from('zip'), ACTOR, null)).rejects.toThrow(
+        ConflictException,
+      );
+    });
+
+    it('lehnt doppelte Slugs ab', async () => {
+      repository.modules = [createModuleRecord({ moduleId: 'anderes', slug: 'kalender-tool' })];
+      await expect(modulesService.install(Buffer.from('zip'), ACTOR, null)).rejects.toThrow(
+        ConflictException,
+      );
+    });
+
+    it('lehnt belegte Ports ab', async () => {
+      repository.modules = [createModuleRecord({ moduleId: 'anderes', slug: 'anderer-slug' })];
+      await expect(modulesService.install(Buffer.from('zip'), ACTOR, null)).rejects.toThrow(
+        ConflictException,
+      );
+    });
+  });
+
+  describe('start', () => {
+    it('startet ein gestopptes Modul (STARTING → RUNNING)', async () => {
+      repository.modules = [createModuleRecord({ status: 'STOPPED' })];
+      const module = await modulesService.start('module-1', ACTOR, null);
+      expect(module.status).toBe('RUNNING');
+      expect(processManager.started).toEqual(['calendar']);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_STARTED);
+    });
+
+    it('setzt ERROR bei fehlgeschlagenem Healthcheck', async () => {
+      repository.modules = [createModuleRecord({ status: 'STOPPED' })];
+      healthChecker.healthy = false;
+      await expect(modulesService.start('module-1', ACTOR, null)).rejects.toThrow(
+        BadRequestException,
+      );
+      expect(repository.statusUpdates).toContainEqual({ id: 'module-1', status: 'ERROR' });
+      expect(processManager.stopped).toEqual(['calendar']);
+    });
+
+    it('lehnt Start deaktivierter Module ab', async () => {
+      repository.modules = [createModuleRecord({ enabled: false })];
+      await expect(modulesService.start('module-1', ACTOR, null)).rejects.toThrow(
+        BadRequestException,
+      );
+    });
+
+    it('wirft NotFoundException bei unbekannter ID', async () => {
+      await expect(modulesService.start('unbekannt', ACTOR, null)).rejects.toThrow(
+        NotFoundException,
+      );
+    });
+  });
+
+  describe('stop', () => {
+    it('stoppt ein laufendes Modul (STOPPING → STOPPED)', async () => {
+      repository.modules = [createModuleRecord({ status: 'RUNNING' })];
+      const module = await modulesService.stop('module-1', ACTOR, null);
+      expect(module.status).toBe('STOPPED');
+      expect(processManager.stopped).toEqual(['calendar']);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_STOPPED);
+    });
+  });
+
+  describe('restart', () => {
+    it('stoppt und startet ein laufendes Modul', async () => {
+      repository.modules = [createModuleRecord({ status: 'RUNNING' })];
+      const module = await modulesService.restart('module-1', ACTOR, null);
+      expect(module.status).toBe('RUNNING');
+      expect(processManager.stopped).toEqual(['calendar']);
+      expect(processManager.started).toEqual(['calendar']);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_STARTED);
+    });
+  });
+
+  describe('setEnabled', () => {
+    it('deaktiviert ein laufendes Modul (stoppt es zuerst)', async () => {
+      repository.modules = [createModuleRecord({ status: 'RUNNING' })];
+      const module = await modulesService.setEnabled('module-1', false, ACTOR, null);
+      expect(module.enabled).toBe(false);
+      expect(module.status).toBe('DISABLED');
+      expect(processManager.stopped).toEqual(['calendar']);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_DISABLED);
+    });
+
+    it('aktiviert ein deaktiviertes Modul', async () => {
+      repository.modules = [createModuleRecord({ enabled: false, status: 'DISABLED' })];
+      const module = await modulesService.setEnabled('module-1', true, ACTOR, null);
+      expect(module.enabled).toBe(true);
+      expect(module.status).toBe('STOPPED');
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_ENABLED);
+    });
+  });
+
+  describe('remove', () => {
+    it('stoppt, löscht Registry-Eintrag und Dateien', async () => {
+      repository.modules = [createModuleRecord({ status: 'RUNNING' })];
+      await modulesService.remove('module-1', ACTOR, null);
+      expect(processManager.stopped).toEqual(['calendar']);
+      expect(repository.deletedIds).toEqual(['module-1']);
+      expect(installer.removed).toEqual(['calendar']);
+      expect(auditService.records.at(-1)?.action).toBe(AUDIT_ACTIONS.MODULE_REMOVED);
+    });
+  });
+});
\ No newline at end of file
diff --git a/apps/platform-backend/src/modules/modules.service.ts b/apps/platform-backend/src/modules/modules.service.ts
new file mode 100644
index 0000000..900a63a
--- /dev/null
+++ b/apps/platform-backend/src/modules/modules.service.ts
@@ -0,0 +1,252 @@
+import {
+  BadRequestException,
+  ConflictException,
+  Inject,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common';
+import { APP_CONFIG, type AppConfig } from '../config/config.tokens';
+import { AUDIT_ACTIONS, AuditService, type AuditAction } from '../audit/audit.service';
+import type { ActingUser } from '../users/users.service';
+import { ModuleHealthChecker } from './module-health-checker';
+import { ModuleInstaller } from './module-installer';
+import { ModuleProcessManager } from './module-process-manager';
+import { ModuleRepository } from './module.repository';
+import type { ModuleRecord } from './manifest.types';
+
+/**
+ * Modul-Verwaltung (Application-Layer): Lifecycle-Logik für Module.
+ *
+ * Zustände: INSTALLED → STARTING → RUNNING → STOPPING → STOPPED
+ *           (sowie ERROR und DISABLED)
+ *
+ * Grundsätze:
+ * - Die Plattform hängt nie von einem Modul ab (Fehler werden isoliert)
+ * - Jede Lifecycle-Aktion wird auditiert
+ * - Ports und Slugs sind eindeutig
+ */
+@Injectable()
+export class ModulesService {
+  constructor(
+    private readonly moduleRepository: ModuleRepository,
+    private readonly installer: ModuleInstaller,
+    private readonly processManager: ModuleProcessManager,
+    private readonly healthChecker: ModuleHealthChecker,
+    private readonly auditService: AuditService,
+    @Inject(APP_CONFIG) private readonly config: AppConfig,
+  ) {}
+
+  async list(): Promise<ModuleRecord[]> {
+    return this.moduleRepository.list();
+  }
+
+  async getById(id: string): Promise<ModuleRecord> {
+    const module = await this.moduleRepository.findById(id);
+    if (!module) {
+      throw new NotFoundException('Modul nicht gefunden');
+    }
+    return module;
+  }
+
+  /** Installiert ein Modul-Paket (ZIP) und registriert es. */
+  async install(
+    packageBuffer: Buffer,
+    actor: ActingUser,
+    ipAddress: string | null,
+  ): Promise<ModuleRecord> {
+    const manifest = await this.installer.validatePackage(packageBuffer);
+
+    const [existingId, existingSlug, existingPort] = await Promise.all([
+      this.moduleRepository.findByModuleId(manifest.id),
+      this.moduleRepository.findBySlug(manifest.slug),
+      this.moduleRepository.findByPort(manifest.port),
+    ]);
+    if (existingId) {
+      throw new ConflictException(`Modul-ID "${manifest.id}" ist bereits installiert`);
+    }
+    if (existingSlug) {
+      throw new ConflictException(`Slug "${manifest.slug}" ist bereits vergeben`);
+    }
+    if (existingPort) {
+      throw new ConflictException(`Port ${manifest.port} ist bereits belegt`);
+    }
+
+    const { directory } = await this.installer.install(
+      packageBuffer,
+      manifest,
+      this.config.runtime.modulesDir,
+    );
+    const module = await this.moduleRepository.create(manifest, directory);
+
+    await this.auditService.record({
+      userId: actor.id,
+      username: actor.username,
+      action: AUDIT_ACTIONS.MODULE_INSTALLED,
+      details: { moduleId: manifest.id, version: manifest.version, slug: manifest.slug },
+      ipAddress,
+    });
+    return module;
+  }
+
+  /** Startet ein Modul (INSTALLED/STOPPED → STARTING → RUNNING). */
+  async start(id: string, actor: ActingUser, ipAddress: string | null): Promise<ModuleRecord> {
+    const module = await this.getById(id);
+    this.assertEnabled(module);
+    if (module.status === 'RUNNING' || module.status === 'STARTING') {
+      return module;
+    }
+
+    await this.moduleRepository.updateStatus(id, 'STARTING');
+    try {
+      await this.processManager.start(module);
+      // Startup-Grace: Der Modul-Prozess braucht einen Moment zum Starten.
+      // Der Healthcheck wird mit Retries wiederholt, bevor er als Fehlschlag gilt.
+      const health = await this.waitForHealthy(module);
+      if (!health.healthy) {
+        throw new Error(`Healthcheck fehlgeschlagen: ${health.detail}`);
+      }
+      await this.moduleRepository.updateStatus(id, 'RUNNING');
+      await this.auditLifecycle(module, AUDIT_ACTIONS.MODULE_STARTED, actor, ipAddress);
+    } catch (error) {
+      await this.moduleRepository.updateStatus(id, 'ERROR');
+      await this.processManager.stop(module.moduleId);
+      throw new BadRequestException(
+        `Modul konnte nicht gestartet werden: ${error instanceof Error ? error.message : String(error)}`,
+      );
+    }
+    return (await this.moduleRepository.findById(id)) ?? module;
+  }
+
+  /**
+   * Wartet bis zum ersten erfolgreichen Healthcheck (max. 10 Versuche
+   * mit 500 ms Abstand). Ein Modul darf beim Start nicht zu früh
+   * als fehlerhaft gelten.
+   */
+  private async waitForHealthy(
+    module: ModuleRecord,
+  ): Promise<{ healthy: boolean; latencyMs: number; detail: string }> {
+    const maxAttempts = 10;
+    const delayMs = 500;
+
+    for (let attempt = 1; attempt <= maxAttempts; attempt += 1) {
+      const health = await this.healthChecker.check(module);
+      if (health.healthy) {
+        return health;
+      }
+      if (attempt < maxAttempts) {
+        await new Promise((resolve) => setTimeout(resolve, delayMs));
+      }
+    }
+    return this.healthChecker.check(module);
+  }
+
+  /** Stoppt ein Modul (RUNNING → STOPPING → STOPPED). */
+  async stop(id: string, actor: ActingUser, ipAddress: string | null): Promise<ModuleRecord> {
+    const module = await this.getById(id);
+    if (module.status === 'STOPPED' || module.status === 'STOPPING') {
+      return module;
+    }
+
+    await this.moduleRepository.updateStatus(id, 'STOPPING');
+    try {
+      await this.processManager.stop(module.moduleId);
+      await this.moduleRepository.updateStatus(id, 'STOPPED');
+      await this.auditLifecycle(module, AUDIT_ACTIONS.MODULE_STOPPED, actor, ipAddress);
+    } catch (error) {
+      await this.moduleRepository.updateStatus(id, 'ERROR');
+      throw new BadRequestException(
+        `Modul konnte nicht gestoppt werden: ${error instanceof Error ? error.message : String(error)}`,
+      );
+    }
+    return (await this.moduleRepository.findById(id)) ?? module;
+  }
+
+  /** Startet ein Modul neu (Stop + Start). */
+  async restart(id: string, actor: ActingUser, ipAddress: string | null): Promise<ModuleRecord> {
+    const module = await this.getById(id);
+    if (module.status === 'RUNNING' || module.status === 'STARTING') {
+      await this.stop(id, actor, ipAddress);
+    }
+    return this.start(id, actor, ipAddress);
+  }
+
+  /** Aktiviert oder deaktiviert ein Modul (DISABLED-Zustand). */
+  async setEnabled(
+    id: string,
+    enabled: boolean,
+    actor: ActingUser,
+    ipAddress: string | null,
+  ): Promise<ModuleRecord> {
+    const module = await this.getById(id);
+    if (module.enabled === enabled) {
+      return module;
+    }
+
+    if (!enabled && (module.status === 'RUNNING' || module.status === 'STARTING')) {
+      await this.stop(id, actor, ipAddress);
+    }
+
+    await this.moduleRepository.updateEnabled(id, enabled);
+    await this.moduleRepository.updateStatus(
+      id,
+      enabled ? 'STOPPED' : 'DISABLED',
+    );
+
+    await this.auditService.record({
+      userId: actor.id,
+      username: actor.username,
+      action: enabled ? AUDIT_ACTIONS.MODULE_ENABLED : AUDIT_ACTIONS.MODULE_DISABLED,
+      details: { moduleId: module.moduleId },
+      ipAddress,
+    });
+    return (await this.moduleRepository.findById(id)) ?? module;
+  }
+
+  /** Entfernt ein Modul vollständig (Prozess, Dateien, Registry). */
+  async remove(id: string, actor: ActingUser, ipAddress: string | null): Promise<void> {
+    const module = await this.getById(id);
+
+    if (module.status === 'RUNNING' || module.status === 'STARTING') {
+      await this.stop(id, actor, ipAddress);
+    }
+
+    await this.moduleRepository.delete(id);
+    await this.installer.remove(this.config.runtime.modulesDir, module.moduleId);
+
+    await this.auditService.record({
+      userId: actor.id,
+      username: actor.username,
+      action: AUDIT_ACTIONS.MODULE_REMOVED,
+      details: { moduleId: module.moduleId },
+      ipAddress,
+    });
+  }
+
+  /** Führt einen Healthcheck für ein Modul aus (ohne Statusänderung). */
+  async checkHealth(id: string): Promise<{ module: ModuleRecord; health: Awaited<ReturnType<ModuleHealthChecker['check']>> }> {
+    const module = await this.getById(id);
+    const health = await this.healthChecker.check(module);
+    return { module, health };
+  }
+
+  private assertEnabled(module: ModuleRecord): void {
+    if (!module.enabled) {
+      throw new BadRequestException('Modul ist deaktiviert');
+    }
+  }
+
+  private async auditLifecycle(
+    module: ModuleRecord,
+    action: AuditAction,
+    actor: ActingUser,
+    ipAddress: string | null,
+  ): Promise<void> {
+    await this.auditService.record({
+      userId: actor.id,
+      username: actor.username,
+      action,
+      details: { moduleId: module.moduleId, version: module.version },
+      ipAddress,
+    });
+  }
+}
\ No newline at end of file
diff --git a/apps/platform-frontend/src/components/layout/app-layout.tsx b/apps/platform-frontend/src/components/layout/app-layout.tsx
index a224cf5..13af622 100644
--- a/apps/platform-frontend/src/components/layout/app-layout.tsx
+++ b/apps/platform-frontend/src/components/layout/app-layout.tsx
@@ -15,6 +15,7 @@ const NAV_ITEMS: NavItem[] = [
   { to: '/', label: 'Dashboard', icon: '⌂' },
   { to: '/profile', label: 'Mein Profil', icon: '👤' },
   { to: '/admin/users', label: 'Benutzer', icon: '👥', adminOnly: true },
+  { to: '/admin/modules', label: 'Module', icon: '🧩', adminOnly: true },
   { to: '/admin/system', label: 'Systemstatus', icon: '⚙', adminOnly: true },
 ];
 
diff --git a/apps/platform-frontend/src/features/admin/modules-page.tsx b/apps/platform-frontend/src/features/admin/modules-page.tsx
new file mode 100644
index 0000000..4c5576e
--- /dev/null
+++ b/apps/platform-frontend/src/features/admin/modules-page.tsx
@@ -0,0 +1,352 @@
+import { type ReactNode, useRef, useState } from 'react';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
+import { Button } from '../../components/ui/button';
+import { Modal } from '../../components/ui/modal';
+import { useToast } from '../../components/ui/toast';
+import { ApiError } from '../../lib/api-client';
+import {
+  checkModuleHealth,
+  fetchModules,
+  installModule,
+  removeModule,
+  restartModule,
+  setModuleEnabled,
+  startModule,
+  stopModule,
+} from '../../lib/modules-api';
+import type { Module, ModuleStatus } from '../../lib/schemas';
+
+/** Status-Badge-Farben je Lifecycle-Zustand. */
+function statusVariant(status: ModuleStatus): 'success' | 'warning' | 'danger' | 'neutral' | 'info' {
+  switch (status) {
+    case 'RUNNING':
+      return 'success';
+    case 'STARTING':
+    case 'STOPPING':
+      return 'warning';
+    case 'ERROR':
+      return 'danger';
+    case 'DISABLED':
+      return 'neutral';
+    default:
+      return 'info';
+  }
+}
+
+/** Bestätigungsdialog: Modul entfernen. */
+function RemoveModuleModal({ module, onClose }: { module: Module; onClose: () => void }): ReactNode {
+  const { showToast } = useToast();
+  const queryClient = useQueryClient();
+  const [formError, setFormError] = useState<string | null>(null);
+
+  const removeMutation = useMutation({
+    mutationFn: () => removeModule(module.id),
+    onSuccess: () => {
+      void queryClient.invalidateQueries({ queryKey: ['modules'] });
+      showToast('success', `Modul "${module.name}" wurde entfernt`);
+      onClose();
+    },
+    onError: (error) => {
+      setFormError(error instanceof ApiError ? error.message : 'Entfernen fehlgeschlagen');
+    },
+  });
+
+  return (
+    <Modal
+      open
+      title="Modul entfernen"
+      description={`Möchten Sie "${module.name}" (Version ${module.version}) wirklich entfernen? Dateien und Registrierung werden gelöscht.`}
+      onClose={onClose}
+    >
+      {formError && (
+        <p role="alert" className="mb-4 rounded-lg bg-red-50 px-3 py-2 text-sm text-red-700">
+          {formError}
+        </p>
+      )}
+      <div className="flex justify-end gap-2">
+        <Button variant="secondary" onClick={onClose}>
+          Abbrechen
+        </Button>
+        <Button
+          variant="danger"
+          loading={removeMutation.isPending}
+          onClick={() => removeMutation.mutate()}
+        >
+          Endgültig entfernen
+        </Button>
+      </div>
+    </Modal>
+  );
+}
+
+/** Modul-Verwaltung (nur Admin): Installation, Lifecycle, Healthchecks. */
+export function ModulesPage(): ReactNode {
+  const { showToast } = useToast();
+  const queryClient = useQueryClient();
+  const fileInputRef = useRef<HTMLInputElement>(null);
+  const [selectedFile, setSelectedFile] = useState<File | null>(null);
+  const [removeTarget, setRemoveTarget] = useState<Module | null>(null);
+  const [healthResults, setHealthResults] = useState<Record<string, { healthy: boolean; detail: string }>>({});
+
+  const modulesQuery = useQuery({
+    queryKey: ['modules'],
+    queryFn: fetchModules,
+    refetchInterval: 15_000,
+  });
+
+  const invalidate = (): void => {
+    void queryClient.invalidateQueries({ queryKey: ['modules'] });
+  };
+
+  const installMutation = useMutation({
+    mutationFn: (file: File) => installModule(file),
+    onSuccess: (module) => {
+      showToast('success', `Modul "${module.name}" wurde installiert`);
+      setSelectedFile(null);
+      if (fileInputRef.current) {
+        fileInputRef.current.value = '';
+      }
+      invalidate();
+    },
+    onError: (error) => {
+      showToast('error', error instanceof ApiError ? error.message : 'Installation fehlgeschlagen');
+    },
+  });
+
+  const lifecycleMutation = useMutation({
+    mutationFn: async (input: { module: Module; action: 'start' | 'stop' | 'restart' | 'enable' | 'disable' }) => {
+      switch (input.action) {
+        case 'start':
+          return startModule(input.module.id);
+        case 'stop':
+          return stopModule(input.module.id);
+        case 'restart':
+          return restartModule(input.module.id);
+        case 'enable':
+          return setModuleEnabled(input.module.id, true);
+        case 'disable':
+          return setModuleEnabled(input.module.id, false);
+      }
+    },
+    onSuccess: (module, variables) => {
+      showToast('success', `Modul "${module.name}" – Aktion "${variables.action}" erfolgreich`);
+      invalidate();
+    },
+    onError: (error) => {
+      showToast('error', error instanceof ApiError ? error.message : 'Aktion fehlgeschlagen');
+      invalidate();
+    },
+  });
+
+  const healthMutation = useMutation({
+    mutationFn: (module: Module) => checkModuleHealth(module.id),
+    onSuccess: (result, module) => {
+      setHealthResults((current) => ({
+        ...current,
+        [module.id]: { healthy: result.healthy, detail: result.detail },
+      }));
+      showToast(
+        result.healthy ? 'success' : 'error',
+        `Healthcheck "${module.name}": ${result.detail}`,
+      );
+    },
+  });
+
+  function handleFileChange(event: React.ChangeEvent<HTMLInputElement>): void {
+    setSelectedFile(event.target.files?.[0] ?? null);
+  }
+
+  function handleInstall(): void {
+    if (selectedFile) {
+      installMutation.mutate(selectedFile);
+    }
+  }
+
+  return (
+    <div className="mx-auto max-w-6xl space-y-6">
+      <div>
+        <h1 className="text-2xl font-bold text-slate-900">Modulverwaltung</h1>
+        <p className="mt-1 text-sm text-slate-500">
+          Module installieren, starten, stoppen und entfernen.
+        </p>
+      </div>
+
+      {/* Installation */}
+      <div className="rounded-xl border border-slate-200 bg-white p-4 shadow-sm">
+        <div className="flex flex-wrap items-center gap-3">
+          <input
+            ref={fileInputRef}
+            type="file"
+            accept=".zip"
+            onChange={handleFileChange}
+            className="text-sm text-slate-600 file:mr-3 file:rounded-lg file:border-0 file:bg-brand-50 file:px-3 file:py-2 file:text-sm file:font-medium file:text-brand-700 hover:file:bg-brand-100"
+            aria-label="Modul-Paket (ZIP) auswählen"
+          />
+          <Button
+            disabled={!selectedFile}
+            loading={installMutation.isPending}
+            onClick={handleInstall}
+          >
+            Installieren
+          </Button>
+          <p className="text-xs text-slate-500">
+            ZIP-Paket mit module.json (Manifest). Maximal 10 MB.
+          </p>
+        </div>
+      </div>
+
+      {/* Modul-Liste */}
+      <div className="overflow-x-auto rounded-xl border border-slate-200 bg-white shadow-sm">
+        <table className="w-full min-w-[760px] text-sm">
+          <thead>
+            <tr className="border-b border-slate-200 bg-slate-50 text-left text-xs uppercase tracking-wide text-slate-500">
+              <th className="px-4 py-3 font-semibold">Modul</th>
+              <th className="px-4 py-3 font-semibold">Status</th>
+              <th className="px-4 py-3 font-semibold">URL</th>
+              <th className="px-4 py-3 font-semibold">Aktionen</th>
+            </tr>
+          </thead>
+          <tbody>
+            {modulesQuery.isLoading && (
+              <tr>
+                <td colSpan={4} className="px-4 py-8 text-center text-slate-500">
+                  Module werden geladen…
+                </td>
+              </tr>
+            )}
+            {modulesQuery.isError && (
+              <tr>
+                <td colSpan={4} className="px-4 py-8 text-center text-red-600">
+                  Module konnten nicht geladen werden.
+                </td>
+              </tr>
+            )}
+            {modulesQuery.data?.map((module) => (
+              <tr key={module.id} className="border-b border-slate-100 last:border-0">
+                <td className="px-4 py-3">
+                  <div className="font-medium text-slate-900">{module.name}</div>
+                  <div className="text-xs text-slate-500">
+                    {module.moduleId} · Version {module.version}
+                    {module.author && ` · ${module.author}`}
+                  </div>
+                  {module.description && (
+                    <div className="mt-0.5 text-xs text-slate-500">{module.description}</div>
+                  )}
+                </td>
+                <td className="px-4 py-3">
+                  <span
+                    className={`inline-flex rounded-full px-2.5 py-0.5 text-xs font-medium ring-1 ring-inset
+                      ${
+                        statusVariant(module.status) === 'success'
+                          ? 'bg-emerald-50 text-emerald-700 ring-emerald-600/20'
+                          : statusVariant(module.status) === 'warning'
+                            ? 'bg-amber-50 text-amber-700 ring-amber-600/20'
+                            : statusVariant(module.status) === 'danger'
+                              ? 'bg-red-50 text-red-700 ring-red-600/20'
+                              : statusVariant(module.status) === 'neutral'
+                                ? 'bg-slate-100 text-slate-600 ring-slate-500/20'
+                                : 'bg-brand-50 text-brand-700 ring-brand-600/20'
+                      }`}
+                  >
+                    {module.status}
+                  </span>
+                  {healthResults[module.id] && (
+                    <div className="mt-1 text-xs text-slate-500">
+                      Health: {healthResults[module.id].healthy ? '✓' : '✕'} {healthResults[module.id].detail}
+                    </div>
+                  )}
+                </td>
+                <td className="px-4 py-3">
+                  <code className="rounded bg-slate-100 px-1.5 py-0.5 text-xs text-slate-700">
+                    /{module.slug}
+                  </code>
+                </td>
+                <td className="px-4 py-3">
+                  <div className="flex flex-wrap gap-1">
+                    {module.status !== 'RUNNING' && module.enabled && (
+                      <Button
+                        size="sm"
+                        variant="ghost"
+                        loading={
+                          lifecycleMutation.isPending &&
+                          lifecycleMutation.variables?.module.id === module.id &&
+                          lifecycleMutation.variables?.action === 'start'
+                        }
+                        onClick={() => lifecycleMutation.mutate({ module, action: 'start' })}
+                      >
+                        Start
+                      </Button>
+                    )}
+                    {(module.status === 'RUNNING' || module.status === 'STARTING') && (
+                      <Button
+                        size="sm"
+                        variant="ghost"
+                        loading={
+                          lifecycleMutation.isPending &&
+                          lifecycleMutation.variables?.module.id === module.id &&
+                          lifecycleMutation.variables?.action === 'stop'
+                        }
+                        onClick={() => lifecycleMutation.mutate({ module, action: 'stop' })}
+                      >
+                        Stop
+                      </Button>
+                    )}
+                    <Button
+                      size="sm"
+                      variant="ghost"
+                      loading={
+                        lifecycleMutation.isPending &&
+                        lifecycleMutation.variables?.module.id === module.id &&
+                        lifecycleMutation.variables?.action === 'restart'
+                      }
+                      onClick={() => lifecycleMutation.mutate({ module, action: 'restart' })}
+                    >
+                      Restart
+                    </Button>
+                    <Button
+                      size="sm"
+                      variant="ghost"
+                      onClick={() => healthMutation.mutate(module)}
+                    >
+                      Health
+                    </Button>
+                    <Button
+                      size="sm"
+                      variant="ghost"
+                      loading={
+                        lifecycleMutation.isPending &&
+                        lifecycleMutation.variables?.module.id === module.id &&
+                        (lifecycleMutation.variables?.action === 'enable' ||
+                          lifecycleMutation.variables?.action === 'disable')
+                      }
+                      onClick={() =>
+                        lifecycleMutation.mutate({
+                          module,
+                          action: module.enabled ? 'disable' : 'enable',
+                        })
+                      }
+                    >
+                      {module.enabled ? 'Disable' : 'Enable'}
+                    </Button>
+                    <Button size="sm" variant="ghost" onClick={() => setRemoveTarget(module)}>
+                      Remove
+                    </Button>
+                  </div>
+                </td>
+              </tr>
+            ))}
+          </tbody>
+        </table>
+        {modulesQuery.data?.length === 0 && (
+          <p className="px-4 py-8 text-center text-slate-500">
+            Noch keine Module installiert.
+          </p>
+        )}
+      </div>
+
+      {removeTarget && (
+        <RemoveModuleModal module={removeTarget} onClose={() => setRemoveTarget(null)} />
+      )}
+    </div>
+  );
+}
\ No newline at end of file
diff --git a/apps/platform-frontend/src/lib/modules-api.ts b/apps/platform-frontend/src/lib/modules-api.ts
new file mode 100644
index 0000000..3b5b17a
--- /dev/null
+++ b/apps/platform-frontend/src/lib/modules-api.ts
@@ -0,0 +1,100 @@
+import { apiRequest, ApiError } from './api-client';
+import { moduleSchema, type Module } from './schemas';
+
+/** Typsichere API-Funktionen für die Modul-Verwaltung. */
+
+export async function fetchModules(): Promise<Module[]> {
+  const response = await apiRequest<{ modules: unknown[] }>('/api/v1/modules');
+  return response.modules.map((module) => moduleSchema.parse(module));
+}
+
+export async function installModule(file: File): Promise<Module> {
+  const formData = new FormData();
+  formData.append('package', file);
+
+  const headers: Record<string, string> = {};
+  const csrfToken = readCsrfToken();
+  if (csrfToken) {
+    headers['X-CSRF-Token'] = csrfToken;
+  }
+
+  const response = await fetch('/api/v1/modules/install', {
+    method: 'POST',
+    headers,
+    credentials: 'same-origin',
+    body: formData,
+  });
+
+  if (!response.ok) {
+    let message = 'Installation fehlgeschlagen';
+    let details: Record<string, string | string[]> | undefined;
+    try {
+      const errorBody = (await response.json()) as {
+        message?: string | string[];
+        details?: Record<string, string | string[]>;
+      };
+      if (typeof errorBody.message === 'string') {
+        message = errorBody.message;
+      } else if (Array.isArray(errorBody.message)) {
+        message = errorBody.message.join(', ');
+      }
+      details = errorBody.details;
+    } catch {
+      // Kein JSON in der Antwort – Standardmeldung verwenden.
+    }
+    throw new ApiError(response.status, message, details);
+  }
+
+  const response_ = (await response.json()) as { module: unknown };
+  return moduleSchema.parse(response_.module);
+}
+
+export async function startModule(id: string): Promise<Module> {
+  const response = await apiRequest<{ module: unknown }>(`/api/v1/modules/${id}/start`, {
+    method: 'POST',
+  });
+  return moduleSchema.parse(response.module);
+}
+
+export async function stopModule(id: string): Promise<Module> {
+  const response = await apiRequest<{ module: unknown }>(`/api/v1/modules/${id}/stop`, {
+    method: 'POST',
+  });
+  return moduleSchema.parse(response.module);
+}
+
+export async function restartModule(id: string): Promise<Module> {
+  const response = await apiRequest<{ module: unknown }>(`/api/v1/modules/${id}/restart`, {
+    method: 'POST',
+  });
+  return moduleSchema.parse(response.module);
+}
+
+export async function setModuleEnabled(id: string, enabled: boolean): Promise<Module> {
+  const response = await apiRequest<{ module: unknown }>(`/api/v1/modules/${id}/enabled`, {
+    method: 'PATCH',
+    body: { enabled },
+  });
+  return moduleSchema.parse(response.module);
+}
+
+export async function removeModule(id: string): Promise<void> {
+  await apiRequest(`/api/v1/modules/${id}`, { method: 'DELETE' });
+}
+
+export async function checkModuleHealth(
+  id: string,
+): Promise<{ healthy: boolean; latencyMs: number; detail: string }> {
+  return apiRequest(`/api/v1/modules/${id}/health`);
+}
+
+/** Liest das CSRF-Token aus dem nicht-HttpOnly-Cookie. */
+function readCsrfToken(): string | null {
+  for (const part of document.cookie.split(';')) {
+    const [name, ...value] = part.trim().split('=');
+    if (name === 'mpm_csrf') {
+      return decodeURIComponent(value.join('='));
+    }
+  }
+  return null;
+}
\ No newline at end of file
diff --git a/apps/platform-frontend/src/lib/schemas.ts b/apps/platform-frontend/src/lib/schemas.ts
index 3c2938e..6b657af 100644
--- a/apps/platform-frontend/src/lib/schemas.ts
+++ b/apps/platform-frontend/src/lib/schemas.ts
@@ -106,4 +106,33 @@ export const changePasswordSchema = z
     message: 'Passwörter stimmen nicht überein',
     path: ['confirmPassword'],
   });
-export type ChangePasswordDto = z.infer<typeof changePasswordSchema>;
\ No newline at end of file
+export type ChangePasswordDto = z.infer<typeof changePasswordSchema>;
+
+/** Modul-Lifecycle-Zustände (muss zum Backend passen). */
+export const MODULE_STATUSES = [
+  'INSTALLED',
+  'STARTING',
+  'RUNNING',
+  'STOPPING',
+  'STOPPED',
+  'ERROR',
+  'DISABLED',
+] as const;
+export type ModuleStatus = (typeof MODULE_STATUSES)[number];
+
+/** Modul-Datensatz der Admin-API (/api/v1/modules). */
+export const moduleSchema = z.object({
+  id: z.string(),
+  moduleId: z.string(),
+  name: z.string(),
+  slug: z.string(),
+  version: z.string(),
+  description: z.string(),
+  author: z.string(),
+  status: z.enum(MODULE_STATUSES),
+  internalPort: z.number(),
+  healthcheckUrl: z.string(),
+  enabled: z.boolean(),
+  createdAt: z.string(),
+});
+export type Module = z.infer<typeof moduleSchema>;
\ No newline at end of file
diff --git a/apps/platform-frontend/src/main.tsx b/apps/platform-frontend/src/main.tsx
index c1fc4be..4c5defe 100644
--- a/apps/platform-frontend/src/main.tsx
+++ b/apps/platform-frontend/src/main.tsx
@@ -10,6 +10,7 @@ import { LoginPage } from './features/auth/login-page';
 import { DashboardPage } from './features/dashboard/dashboard-page';
 import { SystemStatusPage } from './features/admin/system-status-page';
 import { UsersPage } from './features/admin/users-page';
+import { ModulesPage } from './features/admin/modules-page';
 import { ProfilePage } from './features/profile/profile-page';
 import { ForbiddenPage, NotFoundPage } from './pages/error-pages';
 import './index.css';
@@ -38,6 +39,10 @@ function AppRoutes(): ReactNode {
           path="/admin/users"
           element={<RequireAdmin><UsersPage /></RequireAdmin>}
         />
+        <Route
+          path="/admin/modules"
+          element={<RequireAdmin><ModulesPage /></RequireAdmin>}
+        />
         <Route
           path="/admin/system"
           element={<RequireAdmin><SystemStatusPage /></RequireAdmin>}
diff --git a/docker-compose.yml b/docker-compose.yml
index 5aee0bd..e3451cc 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -39,11 +39,19 @@ services:
       SESSION_TTL_MINUTES: ${SESSION_TTL_MINUTES:-120}
       COOKIE_SECURE: ${COOKIE_SECURE:-false}
       BEHIND_PROXY: "true"
+      MODULES_DIR: /app/data/modules
+      LOGS_DIR: /app/data/logs
       ADMIN_USERNAME: ${ADMIN_USERNAME:?Bitte ADMIN_USERNAME in .env setzen}
       ADMIN_EMAIL: ${ADMIN_EMAIL:?Bitte ADMIN_EMAIL in .env setzen}
       ADMIN_PASSWORD: ${ADMIN_PASSWORD:?Bitte ADMIN_PASSWORD in .env setzen}
     ports:
       - "${APP_PORT:-8080}:8080"
+    volumes:
+      # Modul-Installationen und Logs persistent halten (Container-Updates überleben)
+      - modules-data:/app/data/modules
+      - module-logs:/app/data/logs
 
 volumes:
-  postgres-data:
\ No newline at end of file
+  postgres-data:
+  modules-data:
+  module-logs:
\ No newline at end of file
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index f674cb8..9b88dfe 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -142,8 +142,17 @@ Security Hardening (Penetrationstests, Dependency/Container-Scans, HSTS, Backup/
 | DELETE | `/api/v1/users/:id` | Admin | Benutzer löschen |
 | GET | `/api/v1/profile` | Session | Eigenes Profil |
 | PATCH | `/api/v1/profile/password` | Session | Eigenes Passwort ändern |
+| GET | `/api/v1/modules` | Admin | Alle Module |
+| POST | `/api/v1/modules/install` | Admin | ZIP-Paket installieren (multipart, Feld `package`) |
+| GET | `/api/v1/modules/:id` | Admin | Einzelnes Modul |
+| POST | `/api/v1/modules/:id/start` | Admin | Modul starten |
+| POST | `/api/v1/modules/:id/stop` | Admin | Modul stoppen |
+| POST | `/api/v1/modules/:id/restart` | Admin | Modul neu starten |
+| PATCH | `/api/v1/modules/:id/enabled` | Admin | Modul aktivieren/deaktivieren |
+| GET | `/api/v1/modules/:id/health` | Admin | Healthcheck ausführen |
+| DELETE | `/api/v1/modules/:id` | Admin | Modul entfernen |
 
-OpenAPI/Swagger UI: `/api/docs` · Ab Phase 3: `/api/v1/modules/*`, `/api/v1/permissions/*`, `/api/v1/audit/*`.
+OpenAPI/Swagger UI: `/api/docs` · Ab Phase 4: dynamisches Routing `/slug`.
 
 ### Schutzregeln der Benutzerverwaltung
 
@@ -153,9 +162,11 @@ OpenAPI/Swagger UI: `/api/docs` · Ab Phase 3: `/api/v1/modules/*`, `/api/v1/per
 - Passwort-Reset (Admin) meldet den Benutzer von allen Sessions ab
 - Eigenes Passwort ändern meldet alle übrigen Sessions ab (aktuelle bleibt aktiv)
 
-## 9. Modul-Vertrag (Ausblick Phase 3+)
+## 9. Modul-System (Phase 3)
 
-Jedes Modul liefert ein Manifest (`module.json`) und einen minimalen API-Vertrag:
+### Manifest-Vertrag
+
+Jedes Modul-Paket (ZIP, max. 10 MB) enthält ein `module.json`:
 
 ```json
 {
@@ -164,6 +175,7 @@ Jedes Modul liefert ein Manifest (`module.json`) und einen minimalen API-Vertrag
   "version": "1.0.0",
   "slug": "kalender-tool",
   "description": "Kalenderverwaltung",
+  "author": "…",
   "runtime": "node",
   "entrypoint": "server.js",
   "port": 41001,
@@ -172,7 +184,27 @@ Jedes Modul liefert ein Manifest (`module.json`) und einen minimalen API-Vertrag
 }
 ```
 
-Minimal-API je Modul: `GET /health`, `GET /api/manifest`, `GET /api/me`. Installation als ZIP-Paket mit Validierung, Dependency-Installation, Migrationen und Healthcheck. Details: [`modules/README.md`](../modules/README.md).
+Validierung per Zod: ID/Slug-Muster, SemVer, Port 41000–41999, kein Pfad-Traversal im Entrypoint, Runtime `node`, apiVersion `v1`.
+
+### Lifecycle
+
+```
+INSTALLED → STARTING → RUNNING → STOPPING → STOPPED
+                ↓            ↓
+              ERROR        ERROR        DISABLED (via Enable/Disable)
+```
+
+### Sicherheitsmaßnahmen
+
+- **Zip-Slip-Schutz**: Alle ZIP-Einträge müssen im Zielverzeichnis bleiben
+- **Minimale Prozess-ENV**: Module erhalten nur `PATH`, `NODE_ENV`, `PORT` – keine Plattform-Secrets
+- **Spawn ohne Shell**: keine Command-Injection möglich
+- **Eigene Log-Dateien** pro Modul (`/app/data/logs/module-<id>.log`)
+- **Startup-Grace**: Healthcheck mit 10 Retries, bevor ein Modul als ERROR gilt
+- **Isolation**: Ein abgestürztes Modul (ERROR) beeinträchtigt weder Plattform noch andere Module
+- Persistente Volumes: Modul-Dateien und Logs überleben Container-Updates
+
+Minimal-API je Modul (Phase 6): `GET /health`, `GET /api/manifest`, `GET /api/me`. Details zum Paketformat: [`modules/README.md`](../modules/README.md).
 
 ## 10. Architektur-Entscheidungen (ADR-Kurzform)
 
diff --git a/docs/PHASES.md b/docs/PHASES.md
index 0964910..9643eab 100644
--- a/docs/PHASES.md
+++ b/docs/PHASES.md
@@ -6,7 +6,7 @@ Der Arbeitsplan sieht zehn inkrementelle Phasen vor. Nach jeder Phase muss das S
 |---|---|---|
 | 1 | Grundgerüst (Docker, DB, Login, Rollen) | ✅ Abgeschlossen |
 | 2 | Benutzerverwaltung | ✅ Abgeschlossen |
-| 3 | Modul-System (Manifest, Installation, Lifecycle) | ⏳ Geplant |
+| 3 | Modul-System (Manifest, Installation, Lifecycle) | ✅ Abgeschlossen |
 | 4 | Gateway & dynamisches Routing (`/slug`) | ⏳ Geplant |
 | 5 | Berechtigungssystem (User ↔ Module) | ⏳ Geplant |
 | 6 | Modul-API (`/health`, `/api/manifest`, `/api/me`) | ⏳ Geplant |
@@ -51,10 +51,26 @@ Definition of Done: Admin kann Benutzer vollständig verwalten.
 - [x] Backend-Tests: 49 bestanden (inkl. UsersService, ProfileService)
 - [x] E2E verifiziert: CRUD, RBAC (User → 403), Login-Sperre nach Deaktivierung, Passwort-Flows
 
-## Nächste Schritte (Phase 3 – Modul-System)
+## Phase 3 – Modul-System (abgeschlossen)
 
-- Modul-Datenmodell (`modules`-Tabelle) und Manifest-Vertrag (`module.json`)
-- Modul-Installation als ZIP-Paket (Validierung, Dateien, Registrierung)
-- Modul-Lifecycle (INSTALLED/STARTING/RUNNING/STOPPING/STOPPED/ERROR/DISABLED)
-- Prozessverwaltung der Modul-Prozesse über Supervisor
-- Healthchecks und Statusanzeige im Admin-Bereich
\ No newline at end of file
+Definition of Done: Modul-Datenmodell, Manifest, Installation, Registrierung, Status, Start/Stop/Restart, Healthcheck.
+
+- [x] `modules`-Tabelle (Migration 002) mit Lifecycle-Status und eindeutigen Ports/Slugs
+- [x] Manifest-Vertrag `module.json` (Zod: ID, Name, Version, Slug, Runtime, Entrypoint, Port 41000–41999, Healthcheck, apiVersion)
+- [x] ZIP-Installer mit Manifest-Validierung, Größenlimit (10 MB) und **Zip-Slip-Schutz**
+- [x] Modul-Prozess-Manager: Start/Stop (SIGTERM→SIGKILL) als Kindprozesse, minimale ENV (keine Plattform-Secrets), eigene Log-Dateien
+- [x] Healthcheck-Service mit Startup-Grace (10 Retries × 500 ms)
+- [x] Lifecycle: INSTALLED → STARTING → RUNNING → STOPPING → STOPPED, ERROR, DISABLED
+- [x] `GET/POST /api/v1/modules`, `POST :id/start|stop|restart`, `PATCH :id/enabled`, `GET :id/health`, `DELETE :id` (nur ADMIN)
+- [x] Duplikat-Schutz: Modul-ID, Slug und Port müssen eindeutig sein (409)
+- [x] Frontend: Modulverwaltungs-Seite (ZIP-Upload, Tabelle mit Status-Badges, Lifecycle-Buttons, Health-Anzeige, Remove-Dialog)
+- [x] Persistente Volumes für Modul-Dateien und Logs (`modules-data`, `module-logs`)
+- [x] Demo-Modul (`modules/demo`) als Referenzimplementierung
+- [x] Backend-Tests: 72 bestanden (inkl. ModulesService-Lifecycle, Manifest-Validierung, Installer)
+- [x] E2E verifiziert: Installation (201), Start → RUNNING, Healthcheck (healthy, 2 ms), Stop, Restart, Disable (stoppt Prozess), Start-Sperre bei Disable (400), Remove, RBAC (USER → 403)
+
+## Nächste Schritte (Phase 4 – Gateway & Routing)
+
+- Dynamisches Routing: `/slug` → Modul-Prozess (Nginx-Konfiguration zur Laufzeit)
+- Zugriffskontrolle beim Routing (Session → Permission Check → 403/Proxy)
+- Modul-Gateway mit sicherer Identitätsübergabe an das Modul
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diff --git a/modules/demo/backend/server.js b/modules/demo/backend/server.js
new file mode 100644
index 0000000..82ccd77
--- /dev/null
+++ b/modules/demo/backend/server.js
@@ -0,0 +1,50 @@
+/**
+ * Demo-Modul: Minimaler HTTP-Server, der den Modul-API-Vertrag erfüllt.
+ * Läuft als eigener Node-Prozess im Management-Container (Port via ENV PORT).
+ */
+
+const http = require('node:http');
+
+const PORT = Number(process.env.PORT ?? 41001);
+
+/** Manifest des Moduls (identisch zu module.json). */
+const MANIFEST = {
+  moduleId: 'demo',
+  version: '1.0.0',
+  status: 'healthy',
+};
+
+const server = http.createServer((request, response) => {
+  const url = new URL(request.url ?? '/', `http://127.0.0.1:${PORT}`);
+
+  if (url.pathname === '/health') {
+    response.writeHead(200, { 'Content-Type': 'application/json' });
+    response.end(JSON.stringify({ moduleId: 'demo', version: '1.0.0', status: 'healthy' }));
+    return;
+  }
+
+  if (url.pathname === '/api/manifest') {
+    response.writeHead(200, { 'Content-Type': 'application/json' });
+    response.end(JSON.stringify(MANIFEST));
+    return;
+  }
+
+  if (url.pathname === '/api/me') {
+    response.writeHead(200, { 'Content-Type': 'application/json' });
+    response.end(
+      JSON.stringify({
+        user: { id: 'demo', username: 'demo' },
+        module: { id: 'demo' },
+        permissions: [],
+      }),
+    );
+    return;
+  }
+
+  response.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
+  response.end('Demo-Modul läuft');
+});
+
+server.listen(PORT, '127.0.0.1', () => {
+  console.log(`Demo-Modul läuft auf Port ${PORT}`);
+});
\ No newline at end of file
diff --git a/modules/demo/demo-module.zip b/modules/demo/demo-module.zip
new file mode 100644
index 0000000..123e415
Binary files /dev/null and b/modules/demo/demo-module.zip differ
diff --git a/modules/demo/module.json b/modules/demo/module.json
new file mode 100644
index 0000000..8c21ad4
--- /dev/null
+++ b/modules/demo/module.json
@@ -0,0 +1,13 @@
+{
+  "id": "demo",
+  "name": "Demo-Modul",
+  "version": "1.0.0",
+  "slug": "demo",
+  "description": "Referenzmodul zum Testen des Modul-Systems",
+  "author": "MPM",
+  "runtime": "node",
+  "entrypoint": "server.js",
+  "port": 41001,
+  "healthcheck": "/health",
+  "apiVersion": "v1"
+}
\ No newline at end of file