feat(stealth): earn and equip the Eye of True Seeing

Add independent eight-hour Night Vision progression, save-gated crafting and holder eligibility, authenticated helmet items and guarded inventory movement. Verify source attribution, native item/recipe/event adapters and actual plugin lifecycle. Drain final state asynchronously and reject stale lifecycle callbacks. Per-viewer revelation remains the next story; no deployment is included.

build.gradle.kts

@@ -1,3 +1,6 @@
+import java.net.URI
+import java.security.MessageDigest
+
 plugins {
     java
 }
@@ -43,6 +46,60 @@ tasks.test {
     systemProperty("distribution.version", project.version.toString())
 }
 
+// Exercise real potion events, item components and recipes without starting a listening server.
+val stealthRuntime = layout.buildDirectory.dir("stealth-runtime")
+val downloadStealthRuntime = tasks.register("downloadStealthRuntime") {
+    val launcher = stealthRuntime.map { it.file("purpur-26.2-2618.jar") }
+    outputs.file(launcher)
+    doLast {
+        val file = launcher.get().asFile
+        file.parentFile.mkdirs()
+        val connection = URI("https://api.purpurmc.org/v2/purpur/26.2/2618/download").toURL().openConnection()
+        connection.connectTimeout = 30_000
+        connection.readTimeout = 120_000
+        val bytes = connection.getInputStream().use { it.readBytes() }
+        val digest = MessageDigest.getInstance("SHA-256").digest(bytes).joinToString("") { "%02x".format(it) }
+        check(digest == "4a32d046a118804d89ca74ba89b798c98f6d8d1f310c18077ac573597049de31") {
+            "Purpur 2618 checksum mismatch"
+        }
+        file.writeBytes(bytes)
+    }
+}
+val prepareStealthRuntime = tasks.register<JavaExec>("prepareStealthRuntime") {
+    dependsOn(downloadStealthRuntime)
+    javaLauncher = javaToolchains.launcherFor { languageVersion = JavaLanguageVersion.of(25) }
+    classpath = files(stealthRuntime.map { it.file("purpur-26.2-2618.jar") })
+    mainClass = "io.papermc.paperclip.Main"
+    jvmArgs("-Dpaperclip.patchonly=true")
+    workingDir(stealthRuntime)
+    outputs.dir(stealthRuntime.map { it.dir("versions") })
+    outputs.dir(stealthRuntime.map { it.dir("libraries") })
+}
+val nativeTest = sourceSets.create("nativeTest")
+dependencies {
+    add(nativeTest.implementationConfigurationName, platform("org.junit:junit-bom:5.13.4"))
+    add(nativeTest.implementationConfigurationName, "org.junit.jupiter:junit-jupiter")
+    add(nativeTest.implementationConfigurationName, "org.mockito:mockito-core:5.18.0")
+    add(nativeTest.implementationConfigurationName, "net.dmulloy2:ProtocolLib:5.4.0")
+    add(nativeTest.compileOnlyConfigurationName, "org.jetbrains:annotations:26.0.2")
+    add(nativeTest.compileOnlyConfigurationName, "org.checkerframework:checker-qual:3.49.2")
+    add(nativeTest.runtimeOnlyConfigurationName, "org.junit.platform:junit-platform-launcher")
+}
+val nativeRuntimeJars = files(fileTree(stealthRuntime) {
+    include("versions/**/*.jar", "libraries/**/*.jar")
+}).builtBy(prepareStealthRuntime)
+nativeTest.compileClasspath += sourceSets.main.get().output + nativeRuntimeJars
+nativeTest.runtimeClasspath += sourceSets.main.get().output + nativeRuntimeJars
+val nativeStealthTest = tasks.register<Test>("nativeStealthTest") {
+    description = "Runs native Purpur adapter regressions without starting a server"
+    testClassesDirs = nativeTest.output.classesDirs
+    classpath = nativeTest.runtimeClasspath
+    useJUnitPlatform()
+    maxHeapSize = "1G"
+    workingDir(stealthRuntime)
+}
+tasks.check { dependsOn(nativeStealthTest) }
+
 val pluginVersion = version
 
 tasks.processResources {