Add fail-open LSPosed notification probe

app/src/main/java/se/ajpanton/notificationsmaster/module/NotificationEnqueueProbe.kt

@@ -0,0 +1,54 @@
+package se.ajpanton.notificationsmaster.module
+
+import android.app.Notification
+import android.os.Bundle
+import android.util.Log
+import io.github.libxposed.api.XposedInterface
+import java.lang.reflect.Method
+
+/**
+ * Milestone-one probe for the system-server notification path.
+ *
+ * It deliberately observes only this repository's test helper and always
+ * calls through. No notification is modified, cancelled, or suppressed.
+ */
+internal class NotificationEnqueueProbe(private val framework: XposedInterface) {
+    fun install(classLoader: ClassLoader) {
+        val managerClass = Class.forName(NOTIFICATION_MANAGER_SERVICE, false, classLoader)
+        val method = managerClass.declaredMethods.singleOrNull {
+            it.name == ENQUEUE_NOTIFICATION &&
+                it.returnType == Boolean::class.javaPrimitiveType &&
+                it.parameterTypes.any { type -> type.name.endsWith("PostNotificationTracker") }
+        } ?: error("No final $ENQUEUE_NOTIFICATION implementation found")
+        hook(method)
+        Log.i(TAG, "Installed fail-open notification enqueue probe")
+    }
+
+    private fun hook(method: Method) {
+        method.isAccessible = true
+        framework.hook(method).intercept { chain ->
+            logHelperNotification(chain.args)
+            chain.proceed()
+        }
+    }
+
+    private fun logHelperNotification(args: List<Any?>) {
+        val notification = args.filterIsInstance<Notification>().firstOrNull() ?: return
+        val packageName = args.filterIsInstance<String>().firstOrNull() ?: return
+        if (packageName != TEST_HELPER_PACKAGE) return
+
+        val extras: Bundle = notification.extras ?: Bundle.EMPTY
+        Log.i(
+            TAG,
+            "Observed helper notification before enqueue: title=${extras.getCharSequence(Notification.EXTRA_TITLE)} " +
+                "text=${extras.getCharSequence(Notification.EXTRA_TEXT)}",
+        )
+    }
+
+    private companion object {
+        const val TAG = "NotificationsMaster"
+        const val NOTIFICATION_MANAGER_SERVICE = "com.android.server.notification.NotificationManagerService"
+        const val ENQUEUE_NOTIFICATION = "enqueueNotificationInternal"
+        const val TEST_HELPER_PACKAGE = "se.ajpanton.notificationsmaster.helper"
+    }
+}

app/src/main/java/se/ajpanton/notificationsmaster/module/NotificationsMasterModule.kt

@@ -0,0 +1,23 @@
+package se.ajpanton.notificationsmaster.module
+
+import android.util.Log
+import io.github.libxposed.api.XposedModule
+import io.github.libxposed.api.XposedModuleInterface
+
+/**
+ * Optional libxposed entry point. It is inert unless the user enables this APK
+ * in a compatible framework and grants it a system-server scope.
+ */
+class NotificationsMasterModule : XposedModule() {
+    override fun onSystemServerStarting(param: XposedModuleInterface.SystemServerStartingParam) {
+        runCatching {
+            NotificationEnqueueProbe(this).install(param.classLoader)
+        }.onFailure { error ->
+            Log.e(TAG, "Notification interception probe was not installed; leaving Android unchanged", error)
+        }
+    }
+
+    private companion object {
+        const val TAG = "NotificationsMaster"
+    }
+}