diff --git a/build-logic/build.gradle.kts b/build-logic/build.gradle.kts
new file mode 100644
index 0000000..6a3cff1
--- /dev/null
+++ b/build-logic/build.gradle.kts
@@ -0,0 +1,18 @@
+plugins {
+    `kotlin-dsl`
+}
+
+dependencies {
+    compileOnly(libs.plugins.kotlinMultiplatform.asDependency())
+    compileOnly(libs.plugins.androidApplication.asDependency())
+    compileOnly(libs.plugins.composeMultiplatform.asDependency())
+    compileOnly(libs.plugins.composeCompiler.asDependency())
+    compileOnly(libs.plugins.composeHotReload.asDependency())
+    compileOnly(libs.plugins.kotlinJvm.asDependency())
+    compileOnly(libs.plugins.ktor.asDependency())
+    compileOnly(libs.plugins.spotless.asDependency())
+    compileOnly(libs.plugins.flywayPlugin.asDependency())
+}
+
+fun Provider<PluginDependency>.asDependency(): Provider<String> =
+    map { "${it.pluginId}:${it.pluginId}.gradle.plugin:${it.version.requiredVersion}" }
diff --git a/build-logic/settings.gradle.kts b/build-logic/settings.gradle.kts
new file mode 100644
index 0000000..011684d
--- /dev/null
+++ b/build-logic/settings.gradle.kts
@@ -0,0 +1,14 @@
+dependencyResolutionManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+    versionCatalogs {
+        create("libs") {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}
+
+rootProject.name = "build-logic"
diff --git a/build-logic/src/main/kotlin/recipe.android.application.gradle.kts b/build-logic/src/main/kotlin/recipe.android.application.gradle.kts
new file mode 100644
index 0000000..bce88da
--- /dev/null
+++ b/build-logic/src/main/kotlin/recipe.android.application.gradle.kts
@@ -0,0 +1,35 @@
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.kotlin.dsl.getByType
+
+plugins {
+    id("com.android.application")
+}
+
+val libs = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+android {
+    namespace = "dev.ulfrx.recipe"
+    compileSdk = libs.findVersion("android-compileSdk").get().toString().toInt()
+
+    defaultConfig {
+        applicationId = "dev.ulfrx.recipe"
+        minSdk = libs.findVersion("android-minSdk").get().toString().toInt()
+        targetSdk = libs.findVersion("android-targetSdk").get().toString().toInt()
+        versionCode = 1
+        versionName = "1.0"
+    }
+    packaging {
+        resources {
+            excludes += "/META-INF/{AL2.0,LGPL2.1}"
+        }
+    }
+    buildTypes {
+        getByName("release") {
+            isMinifyEnabled = false
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+}
diff --git a/build-logic/src/main/kotlin/recipe.compose.multiplatform.gradle.kts b/build-logic/src/main/kotlin/recipe.compose.multiplatform.gradle.kts
new file mode 100644
index 0000000..f8dd887
--- /dev/null
+++ b/build-logic/src/main/kotlin/recipe.compose.multiplatform.gradle.kts
@@ -0,0 +1,27 @@
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.kotlin.dsl.getByType
+
+plugins {
+    id("recipe.kotlin.multiplatform")
+    id("org.jetbrains.compose")
+    id("org.jetbrains.kotlin.plugin.compose")
+    id("org.jetbrains.compose.hot-reload")
+}
+
+val libs = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+kotlin {
+    sourceSets {
+        commonMain.dependencies {
+            implementation(libs.findLibrary("compose-runtime").get())
+            implementation(libs.findLibrary("compose-foundation").get())
+            implementation(libs.findLibrary("compose-material3").get())
+            implementation(libs.findLibrary("compose-ui").get())
+            implementation(libs.findLibrary("compose-components-resources").get())
+            implementation(libs.findLibrary("androidx-lifecycle-viewmodelCompose").get())
+            implementation(libs.findLibrary("androidx-lifecycle-runtimeCompose").get())
+            implementation(libs.findLibrary("koin-compose").get())
+            implementation(libs.findLibrary("koin-composeViewmodel").get())
+        }
+    }
+}
diff --git a/build-logic/src/main/kotlin/recipe.jvm.server.gradle.kts b/build-logic/src/main/kotlin/recipe.jvm.server.gradle.kts
new file mode 100644
index 0000000..bb2aeb5
--- /dev/null
+++ b/build-logic/src/main/kotlin/recipe.jvm.server.gradle.kts
@@ -0,0 +1,41 @@
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.kotlin.dsl.getByType
+
+plugins {
+    id("org.jetbrains.kotlin.jvm")
+    id("io.ktor.plugin")
+    id("org.flywaydb.flyway")
+    application
+}
+
+val libs = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+kotlin {
+    jvmToolchain(21)
+    compilerOptions {
+        allWarningsAsErrors.set(true)
+    }
+}
+
+dependencies {
+    "implementation"(libs.findLibrary("ktor-serverCore").get())
+    "implementation"(libs.findLibrary("ktor-serverNetty").get())
+    "implementation"(libs.findLibrary("ktor-serverContentNegotiation").get())
+    "implementation"(libs.findLibrary("ktor-serializationKotlinxJson").get())
+    "implementation"(libs.findLibrary("logback").get())
+    "implementation"(libs.findLibrary("flyway-core").get())
+    "implementation"(libs.findLibrary("flyway-database-postgresql").get())
+    "implementation"(libs.findLibrary("postgresql").get())
+    "testImplementation"(libs.findLibrary("ktor-serverTestHost").get())
+    "testImplementation"(libs.findLibrary("kotlin-testJunit").get())
+}
+
+flyway {
+    url = System.getenv("DATABASE_URL") ?: "jdbc:postgresql://localhost:5432/recipe"
+    user = System.getenv("DATABASE_USER") ?: "recipe"
+    password = System.getenv("DATABASE_PASSWORD") ?: "recipe"
+    locations = arrayOf("classpath:db/migration")
+    cleanDisabled = true
+    baselineOnMigrate = true
+    validateOnMigrate = true
+}
diff --git a/build-logic/src/main/kotlin/recipe.kotlin.multiplatform.gradle.kts b/build-logic/src/main/kotlin/recipe.kotlin.multiplatform.gradle.kts
new file mode 100644
index 0000000..9cc76d2
--- /dev/null
+++ b/build-logic/src/main/kotlin/recipe.kotlin.multiplatform.gradle.kts
@@ -0,0 +1,55 @@
+// build-logic/src/main/kotlin/recipe.kotlin.multiplatform.gradle.kts
+// Establishes the D-05 target matrix + JVM toolchain + common deps.
+// Android bytecode is JVM 11 (D-08); server + desktop + shared/jvm are JVM 21.
+
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.kotlin.dsl.getByType
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    id("org.jetbrains.kotlin.multiplatform")
+}
+
+val libs = extensions.getByType<VersionCatalogsExtension>().named("libs")
+
+kotlin {
+    jvmToolchain(21)
+
+    androidTarget {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_11)
+        }
+    }
+
+    listOf(iosArm64(), iosSimulatorArm64()).forEach { iosTarget ->
+        iosTarget.binaries.framework {
+            baseName = "ComposeApp"
+            isStatic = true
+        }
+    }
+
+    jvm {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_21)
+        }
+    }
+
+    @OptIn(ExperimentalWasmDsl::class)
+    wasmJs { browser() }
+
+    compilerOptions {
+        allWarningsAsErrors.set(true)
+    }
+
+    sourceSets {
+        commonMain.dependencies {
+            implementation(project.dependencies.platform(libs.findLibrary("koin-bom").get()))
+            implementation(libs.findLibrary("koin-core").get())
+            implementation(libs.findLibrary("kermit").get())
+        }
+        commonTest.dependencies {
+            implementation(libs.findLibrary("kotlin-test").get())
+        }
+    }
+}
diff --git a/build-logic/src/main/kotlin/recipe.quality.gradle.kts b/build-logic/src/main/kotlin/recipe.quality.gradle.kts
new file mode 100644
index 0000000..18fa24d
--- /dev/null
+++ b/build-logic/src/main/kotlin/recipe.quality.gradle.kts
@@ -0,0 +1,40 @@
+plugins {
+    id("com.diffplug.spotless")
+}
+
+spotless {
+    kotlin {
+        target("src/**/*.kt")
+        targetExclude("**/build/**", "**/generated/**")
+        ktlint()
+    }
+    kotlinGradle {
+        target("*.gradle.kts")
+        ktlint()
+    }
+    format("markdown") {
+        target("*.md", "docs/**/*.md")
+        endWithNewline()
+        trimTrailingWhitespace()
+    }
+}
+
+// D-11 redundancy guard: if a module applies recipe.quality alongside a Kotlin plugin
+// (multiplatform or jvm), ensure allWarningsAsErrors still applies even if the module
+// build didn't already configure it. Guarded with plugins.withId so this plugin is
+// safely composable even when applied alone (no KotlinCompilationTask type available
+// on the classpath until a Kotlin plugin is present).
+plugins.withId("org.jetbrains.kotlin.multiplatform") {
+    tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask<*>>().configureEach {
+        compilerOptions {
+            allWarningsAsErrors.set(true)
+        }
+    }
+}
+plugins.withId("org.jetbrains.kotlin.jvm") {
+    tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask<*>>().configureEach {
+        compilerOptions {
+            allWarningsAsErrors.set(true)
+        }
+    }
+}
diff --git a/build.gradle.kts b/build.gradle.kts
index 0116bfc..b628fb1 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -9,4 +9,6 @@ plugins {
     alias(libs.plugins.kotlinJvm) apply false
     alias(libs.plugins.kotlinMultiplatform) apply false
     alias(libs.plugins.ktor) apply false
+    alias(libs.plugins.spotless) apply false
+    alias(libs.plugins.flywayPlugin) apply false
 }
\ No newline at end of file
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 1be7746..31dbd58 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -2,6 +2,7 @@ rootProject.name = "recipe"
 enableFeaturePreview("TYPESAFE_PROJECT_ACCESSORS")
 
 pluginManagement {
+    includeBuild("build-logic")
     repositories {
         google {
             mavenContent {