diff --git a/backend/services/ping/ping-api/build.gradle.kts b/backend/services/ping/ping-api/build.gradle.kts
index b10588e4..e69de29b 100644
--- a/backend/services/ping/ping-api/build.gradle.kts
+++ b/backend/services/ping/ping-api/build.gradle.kts
@@ -1,39 +0,0 @@
-plugins {
-    alias(libs.plugins.kotlinMultiplatform)
-    alias(libs.plugins.kotlinSerialization)
-}
-
-group = "at.mocode"
-version = "1.0.0"
-
-kotlin {
-    // Toolchain is now handled centrally in the root build.gradle.kts
-
-    // JVM target for backend usage
-    jvm()
-
-    // JS target for frontend usage (Compose/Browser)
-    js {
-        browser()
-        // no need for binaries.executable() in a library
-    }
-
-    // Wasm enabled by default
-    @OptIn(org.jetbrains.kotlin.gradle.ExperimentalWasmDsl::class)
-    wasmJs {
-        browser()
-    }
-
-    sourceSets {
-        commonMain {
-            dependencies {
-                implementation(libs.kotlinx.serialization.json)
-            }
-        }
-        commonTest {
-            dependencies {
-                implementation(libs.kotlin.test)
-            }
-        }
-    }
-}
diff --git a/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt b/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt
index 56c0a256..e69de29b 100644
--- a/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt
+++ b/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt
@@ -1,7 +0,0 @@
-package at.mocode.ping.api
-
-interface PingApi {
-    suspend fun simplePing(): PingResponse
-    suspend fun enhancedPing(simulate: Boolean = false): EnhancedPingResponse
-    suspend fun healthCheck(): HealthResponse
-}
diff --git a/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt b/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt
index b2101614..e69de29b 100644
--- a/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt
+++ b/backend/services/ping/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt
@@ -1,23 +0,0 @@
-package at.mocode.ping.api
-
-import kotlinx.serialization.Serializable
-
-@Serializable
-data class PingResponse(val status: String, val timestamp: String, val service: String)
-
-@Serializable
-data class EnhancedPingResponse(
-    val status: String,
-    val timestamp: String,
-    val service: String,
-    val circuitBreakerState: String,
-    val responseTime: Long
-)
-
-@Serializable
-data class HealthResponse(
-    val status: String,
-    val timestamp: String,
-    val service: String,
-    val healthy: Boolean
-)
diff --git a/backend/services/ping/ping-service/build.gradle.kts b/backend/services/ping/ping-service/build.gradle.kts
index 1d23061f..3b1bd5fa 100644
--- a/backend/services/ping/ping-service/build.gradle.kts
+++ b/backend/services/ping/ping-service/build.gradle.kts
@@ -14,7 +14,7 @@ kotlin {
 
 dependencies {
     // === Project Dependencies ===
-    implementation(projects.backend.services.ping.pingApi)
+    implementation(projects.contracts.pingApi)
     implementation(projects.platform.platformDependencies)
     // NEU: Zugriff auf die verschobenen DatabaseUtils
     implementation(projects.backend.infrastructure.persistence)
diff --git a/backend/services/ping/ping-service/src/main/kotlin/at/mocode/ping/PingServiceApplication.kt b/backend/services/ping/ping-service/src/main/kotlin/at/mocode/ping/PingServiceApplication.kt
index 01fc1b21..80711032 100644
--- a/backend/services/ping/ping-service/src/main/kotlin/at/mocode/ping/PingServiceApplication.kt
+++ b/backend/services/ping/ping-service/src/main/kotlin/at/mocode/ping/PingServiceApplication.kt
@@ -2,33 +2,12 @@ package at.mocode.ping
 
 import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
-import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.EnableAspectJAutoProxy
-import org.springframework.web.servlet.config.annotation.WebMvcConfigurer
 
 @SpringBootApplication
 // Scannt explizit alle Sub-Packages (infrastructure, application, domain)
 @EnableAspectJAutoProxy
-class PingServiceApplication {
-
-    @Bean
-    fun corsConfigurer(): WebMvcConfigurer {
-        return object : WebMvcConfigurer {
-            override fun addCorsMappings(registry: org.springframework.web.servlet.config.annotation.CorsRegistry) {
-                registry.addMapping("/**")
-                    .allowedOriginPatterns("http://localhost:*")
-                    .allowedOrigins("http://localhost:8080",
-                        "http://localhost:8083",
-                        "http://localhost:4000"
-                    )
-                    .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")
-                    .allowedHeaders("*")
-                    .allowCredentials(true)
-                    .maxAge(3600)
-            }
-        }
-    }
-}
+class PingServiceApplication
 
 fun main(args: Array<String>) {
     runApplication<PingServiceApplication>(*args)
diff --git a/backend/services/ping/ping-service/src/main/resources/application.yaml b/backend/services/ping/ping-service/src/main/resources/application.yaml
index 00506c55..7efea199 100644
--- a/backend/services/ping/ping-service/src/main/resources/application.yaml
+++ b/backend/services/ping/ping-service/src/main/resources/application.yaml
@@ -42,6 +42,17 @@ spring:
         health-check-interval: 10s
         instance-id: ${spring.application.name}-${server.port}-${random.uuid}
 
+# CORS-Konfiguration ausgelagert aus dem Code
+web:
+  cors:
+    mappings:
+      "/**":
+        allowed-origin-patterns: "http://localhost:*,http://127.0.0.1:*"
+        allowed-methods: "GET,POST,PUT,DELETE,OPTIONS"
+        allowed-headers: "*"
+        allow-credentials: true
+        max-age: 3600
+
 management:
   endpoints:
     web:
diff --git a/build.gradle.kts b/build.gradle.kts
index beb3e839..2c8c2a66 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -10,7 +10,7 @@ import java.util.zip.GZIPOutputStream
 
 plugins {
   // Version management plugin for dependency updates
-  id("com.github.ben-manes.versions") version "0.51.0"
+  alias(libs.plugins.benManesVersions)
 
   // Kotlin plugins declared here with 'apply false' to centralize version management
   // This prevents "plugin loaded multiple times" errors in Gradle 9.2.1+
@@ -29,8 +29,8 @@ plugins {
   alias(libs.plugins.dokka)
 
   // Static analysis (enabled at root and inherited by subprojects)
-  id("io.gitlab.arturbosch.detekt") version "1.23.6"
-  id("org.jlleitschuh.gradle.ktlint") version "12.1.1"
+  alias(libs.plugins.detekt)
+  alias(libs.plugins.ktlint)
 }
 
 // ##################################################################
@@ -80,14 +80,6 @@ subprojects {
     // The agent configuration was causing Task.project access at execution time
   }
 
-  // Erzwinge eine stabile Version von kotlinx-serialization-json für alle Konfigurationen,
-  // um Auflösungsfehler (z.B. 1.10.2, nicht verfügbar auf Maven Central) zu vermeiden
-  configurations.configureEach {
-    resolutionStrategy {
-      force("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.3")
-    }
-  }
-
   // Dedicated performance test task per JVM subproject
   plugins.withId("java") {
     val javaExt = extensions.getByType<JavaPluginExtension>()
diff --git a/contracts/ping-api/build.gradle.kts b/contracts/ping-api/build.gradle.kts
new file mode 100644
index 00000000..b10588e4
--- /dev/null
+++ b/contracts/ping-api/build.gradle.kts
@@ -0,0 +1,39 @@
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.kotlinSerialization)
+}
+
+group = "at.mocode"
+version = "1.0.0"
+
+kotlin {
+    // Toolchain is now handled centrally in the root build.gradle.kts
+
+    // JVM target for backend usage
+    jvm()
+
+    // JS target for frontend usage (Compose/Browser)
+    js {
+        browser()
+        // no need for binaries.executable() in a library
+    }
+
+    // Wasm enabled by default
+    @OptIn(org.jetbrains.kotlin.gradle.ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+    }
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation(libs.kotlinx.serialization.json)
+            }
+        }
+        commonTest {
+            dependencies {
+                implementation(libs.kotlin.test)
+            }
+        }
+    }
+}
diff --git a/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt b/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt
new file mode 100644
index 00000000..56c0a256
--- /dev/null
+++ b/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt
@@ -0,0 +1,7 @@
+package at.mocode.ping.api
+
+interface PingApi {
+    suspend fun simplePing(): PingResponse
+    suspend fun enhancedPing(simulate: Boolean = false): EnhancedPingResponse
+    suspend fun healthCheck(): HealthResponse
+}
diff --git a/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt b/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt
new file mode 100644
index 00000000..b2101614
--- /dev/null
+++ b/contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt
@@ -0,0 +1,23 @@
+package at.mocode.ping.api
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class PingResponse(val status: String, val timestamp: String, val service: String)
+
+@Serializable
+data class EnhancedPingResponse(
+    val status: String,
+    val timestamp: String,
+    val service: String,
+    val circuitBreakerState: String,
+    val responseTime: Long
+)
+
+@Serializable
+data class HealthResponse(
+    val status: String,
+    val timestamp: String,
+    val service: String,
+    val healthy: Boolean
+)
diff --git a/docs/Ping-Service_Impl_01-2026.md b/docs/Ping-Service_Impl_01-2026.md
new file mode 100644
index 00000000..ca53cac5
--- /dev/null
+++ b/docs/Ping-Service_Impl_01-2026.md
@@ -0,0 +1,202 @@
+**An:** Senior Backend Developer
+**Von:** Lead Software Architect
+**Betreff:** Arbeitsauftrag: Implementierung des `ping-service` (Tracer Bullet)
+
+Guten Tag,
+
+deine nächste Aufgabe ist die Implementierung unseres ersten Microservices, des `ping-service`. Dieser Service ist von
+strategischer Bedeutung, da er als **"Tracer Bullet"** und **Blaupause** für alle zukünftigen fachlichen Services dient.
+
+Mit dieser Implementierung validieren wir die gesamte Kette: von der Service-Registrierung bei Consul über das
+Gateway-Routing und die Security mit Keycloak bis hin zur Observability mit Zipkin.
+
+Deine Expertise in Spring Boot, DDD und sauberer Architektur ist hier entscheidend, um eine qualitativ hochwertige und
+wiederverwendbare Vorlage zu schaffen.
+
+## Deine Aufgaben im Detail:
+
+1. Modulstruktur anlegen
+
+Bitte lege die folgende Modulstruktur unter backend/services/ping an. Beachte die neue, klarere Benennung des
+Implementierungsmoduls:
+
+- `:backend:services:ping:ping-api`: Enthält die KMP-kompatiblen DTOs.
+- `:backend:services:ping:ping-infrastructure`: Enthält die Spring Boot Anwendung, Controller und Konfiguration.
+
+Stelle sicher, dass die Module in der `settings.gradle.kts` registriert sind.
+
+  ```kotlin 
+  include(
+  ":platform:platform-bom",
+  ":platform:platform-testing",
+  ":backend:services:ping:ping-api",
+  ":backend:services:ping:ping-infrastructure",
+  ":backend:gateway",
+  // ":backend:services:registry:registry-api",
+  // ":backend:services:registry:registry-domain",
+  ```
+
+2. API-Definition in `:ping-api`
+
+Definiere in `ping-api/src/commonMain/kotlin` ein einfaches, serialisierbares DTO. Dieses Modul darf **keine
+JVM-spezifischen Abhängigkeiten** enthalten, um die KMP-Kompatibilität für das Frontend zu gewährleisten.
+
+  ```kotlin
+  PingResponse.kt
+  ```
+  ```kotlin
+  package de.meldestelle.api.ping
+  
+  import kotlinx . serialization . Serializable
+
+  @Serializable
+  data class PingResponse(
+    val message: String,
+    val principal: String? = null
+  )
+  ```
+
+3. Service-Implementierung in :ping-infrastructure
+   
+Implementiere die Spring Boot Anwendung.
+
+- **`PingController.kt`:**
+ - **`GET /api/ping`:** Ein öffentlicher Endpunkt, der eine `PingResponse("Pong", "anonymous")` zurückgibt.
+ - **`GET /api/ping/secure`:** Ein durch Spring Security geschützter Endpunkt. Er soll den `preferred_username` aus dem `Jwt` Principal extrahieren und in der `PingResponse` zurückgeben.
+
+Hier ist ein Implementierungsvorschlag für den Controller:
+
+  ```kotlin
+  // in backend/services/ping/ping-infrastructure/src/main/kotlin/.../PingController.kt
+  
+  @RestController
+  @RequestMapping("/api/ping")
+  class PingController {
+  
+      @GetMapping
+      fun pingPublic(): PingResponse {
+          return PingResponse(message = "Pong", principal = "anonymous")
+      }
+  
+      @GetMapping("/secure")
+      fun pingSecure(principal: Jwt): PingResponse {
+          val username = principal.getClaimAsString("preferred_username")
+          return PingResponse(message = "Pong (Secure)", principal = username)
+      }
+  }
+  ```
+
+4. **Konfiguration**
+
+Erstelle die `application.yml` für den Service. Sie muss die Anwendung für unsere Infrastruktur korrekt konfigurieren:
+
+- **Service Name:** ping-service
+- **Service Discovery:** Registrierung bei Consul.
+- **Security:** Konfiguration als Resource Server, der JWTs vom `issuer-uri` unseres Keycloak-Containers validiert.
+- **Observability:** Actuator-Endpunkte (`health`, `info`, `prometheus`) freigeben und Tracing aktivieren.
+
+  ```yaml
+  # in backend/services/ping/ping-infrastructure/src/main/resources/application.yml
+  
+  server:
+    port: 8081 # Eindeutiger Port für den Service
+  
+  spring:
+    application:
+      name: ping-service
+  
+    # --- Consul Discovery ---
+    cloud:
+      consul:
+        host: consul
+        port: 8500
+        discovery:
+          instance-id: \${spring.application.name}:\${random.value}
+          health-check-path: /actuator/health
+          health-check-interval: 10s
+  
+    # --- Security (Keycloak) ---
+    security:
+      oauth2:
+        resourceserver:
+          jwt:
+            issuer-uri: http://keycloak:8080/realms/meldestelle
+  
+  # --- Observability ---
+  management:
+    endpoints:
+      web:
+        exposure:
+          include: "health,info,prometheus"
+    tracing:
+      sampling:
+        probability: 1.0 # Trace every request
+  
+  logging:
+    pattern:
+      level: "%5p [${spring.application.name:},%X{traceId:-},%X{spanId:-}]"
+  ```
+  
+5. **Build-Konfiguration(`build.gradle.kts`)
+
+Achte auf die korrekte und saubere Definition der Abhängigkeiten.
+
+- `ping-api/build.gradle.kts`
+  ```kotlin
+      plugins {
+        alias(libs.plugins.kotlin.multiplatform)
+        alias(libs.plugins.kotlin.serialization)
+    }
+
+    kotlin {
+        jvm() // Für die Nutzung im Backend
+        js(IR) { browser() } // Für die Nutzung im Frontend
+        sourceSets {
+            commonMain.dependencies {
+                implementation(libs.kotlinx.serialization.json)
+            }
+        }
+    }
+  ```
+  
+- `ping-infrastructure/build.gradle.kts`
+  ```kotlin
+      plugins {
+        alias(libs.plugins.spring.boot)
+        alias(libs.plugins.kotlin.jvm)
+        alias(libs.plugins.kotlin.spring)
+    }
+
+    dependencies {
+        // API-Modul einbinden
+        implementation(project(":backend:services:ping:ping-api"))
+
+        // Unsere zentrale BOM für konsistente Versionen
+        implementation(platform(project(":platform:platform-bom")))
+
+        // Spring Boot Starter
+        implementation(libs.spring.boot.starter.web)
+        implementation(libs.spring.boot.starter.actuator)
+        implementation(libs.spring.boot.starter.security)
+        implementation(libs.spring.boot.starter.oauth2.resource.server)
+
+        // Spring Cloud (Consul, OpenFeign etc.)
+        implementation(libs.spring.cloud.starter.consul.discovery)
+
+        // Test-Abhängigkeiten
+        testImplementation(platform(project(":platform:platform-testing")))
+        testImplementation(libs.bundles.test.spring)
+    }
+  ```
+  
+## Definition of Done:
+
+Der Auftrag gilt als erledigt, wenn:
+1. Die Anwendung erfolgreich startet und sich im Consul UI als `UP` registriert.
+2. Ein `GET`-Request auf `http//localhost:8081/api/ping` (über das Gateway) den Status `200 OK` und die `{"message":"Pong", "principal":"anonymous"}` zurückgibt.
+3. Ein `GET`-Request auf `http//localhost:8081/api/ping/secure` ohne Token den Status `401 Unauthorized` zurückgibt.
+4. Ein `GET`-Request auf `http//localhost:8081/api/ping/secure` mit einem gültigen Keycloak-Token deb Status `200 OK` und eine Antwort mit dem korrekten Benutzernamen zurückgibt.
+5. Die Requests in der Zipkin UI als Trace sichtbar sind.
+
+Bei Fragen zur Konfiguration oder zur Architektur stehe ich dir zur Verfügung.
+
diff --git a/frontend/features/ping-feature/build.gradle.kts b/frontend/features/ping-feature/build.gradle.kts
index 2d2522e6..ce05f16b 100644
--- a/frontend/features/ping-feature/build.gradle.kts
+++ b/frontend/features/ping-feature/build.gradle.kts
@@ -39,7 +39,7 @@ kotlin {
   sourceSets {
     commonMain.dependencies {
       // Contract from backend
-      implementation(projects.backend.services.ping.pingApi)
+      implementation(projects.contracts.pingApi)
 
       // UI Kit (Design System)
       implementation(projects.frontend.core.designSystem)
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 1aebfb03..faee7f9d 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -88,6 +88,10 @@ testcontainersKafka = "1.21.4"
 
 # Gradle Plugins
 foojayResolver = "1.0.0"
+benManesVersions = "0.51.0"
+detekt = "1.23.6"
+ktlint = "12.1.1"
+dokka = "2.1.0"
 
 [libraries]
 # ==============================================================================
@@ -370,4 +374,7 @@ sqldelight = { id = "app.cash.sqldelight", version.ref = "sqldelight" }
 
 # --- Tools ---
 foojayResolver = { id = "org.gradle.toolchains.foojay-resolver-convention", version.ref = "foojayResolver" }
-dokka = { id = "org.jetbrains.dokka", version = "2.1.0" }
+dokka = { id = "org.jetbrains.dokka", version.ref = "dokka" }
+benManesVersions = { id = "com.github.ben-manes.versions", version.ref = "benManesVersions" }
+detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt" }
+ktlint = { id = "org.jlleitschuh.gradle.ktlint", version.ref = "ktlint" }
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 7b72c99a..fa6432d3 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -28,6 +28,11 @@ dependencyResolutionManagement {
   }
 }
 
+// ==========================================================================
+// CONTRACTS
+// ==========================================================================
+include(":contracts:ping-api")
+
 // ==========================================================================
 // Backend
 // ==========================================================================
@@ -89,7 +94,6 @@ include(":backend:services:entries:entries-service")
 // include(":backend:services:members:members-service")
 
 // --- PING (Ping Service) ---
-include(":backend:services:ping:ping-api")
 include(":backend:services:ping:ping-service")
 
 // --- REGISTRY (Single Source of Truth) ---