App 2.40.4: the recorder's listening works on Android 9

listenToProperties looked only for registerCallback (Android 10); the
car's car library has registerListener/unregisterListener. Take either,
unsubscribe property by property, and say why when it fails.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhzAVaUyqcw5PkGjz4mWW6

EVHardware/lib/src/main/java/com/evsuite/hardware/EVHardware.kt

@@ -324,6 +324,10 @@ object EVHardware {
     // Listening to properties (the app's signal recorder) — read only
     // -------------------------------------------------------------------------
 
+    /** Why the last [listenToProperties] returned null, in a few words; null after a success. */
+    @Volatile var listenProblem: String? = null
+        private set
+
     /** A subscription made by [listenToProperties]; [close] ends it. */
     class PropertyListening internal constructor(
         /** Properties subscribed to, and those the car service refused. */
@@ -342,19 +346,44 @@ object EVHardware {
      * may fill a property from the car network only while someone listens, so a poll alone can
      * read its default. ON_CHANGE properties are asked for every change, CONTINUOUS ones for
      * 1 Hz within their limits. Read only: nothing is set. Null when there is no
-     * CarPropertyManager or no way to subscribe; [PropertyListening.close] unsubscribes.
+     * CarPropertyManager or no way to subscribe, with the reason in [listenProblem];
+     * [PropertyListening.close] unsubscribes.
+     *
+     * Android 9's car library (the MG4's) names the calls `registerListener(CarPropertyEventListener,
+     * int, float)` and `unregisterListener`; Android 10 renamed them `registerCallback` and
+     * `unregisterCallback`. Both are looked for. Unsubscribing goes property by property: the
+     * one-argument `unregisterListener` of Android 9 removes entries from the list it walks and so
+     * leaves every other property subscribed.
      */
     fun listenToProperties(admit: (Int) -> Boolean, onEvent: (Int, Int, String) -> Unit): PropertyListening? {
-        val cpm = sCarPropertyManager ?: return null
+        listenProblem = null
+        val cpm = sCarPropertyManager ?: run {
+            listenProblem = "no car service"
+            return null
+        }
         return try {
-            val register = cpm.javaClass.methods.firstOrNull {
-                it.name == "registerCallback" && it.parameterCount == 3
-            } ?: return null
-            val unregister = cpm.javaClass.methods.firstOrNull {
-                it.name == "unregisterCallback" && it.parameterCount == 1
+            val methods = cpm.javaClass.methods
+            val register = methods.firstOrNull {
+                (it.name == "registerListener" || it.name == "registerCallback") && it.parameterCount == 3 &&
+                    it.parameterTypes[1] == Int::class.javaPrimitiveType &&
+                    it.parameterTypes[2] == Float::class.javaPrimitiveType
+            } ?: run {
+                listenProblem = "no way to subscribe"
+                return null
             }
             val callbackType = register.parameterTypes[0]
-            if (!callbackType.isInterface) return null
+            val unregister = methods.firstOrNull {
+                it.name == register.name.replaceFirst("register", "unregister") && it.parameterCount == 2 &&
+                    it.parameterTypes[0] == callbackType && it.parameterTypes[1] == Int::class.javaPrimitiveType
+            }
+            val unregisterAll = methods.firstOrNull {
+                it.name == register.name.replaceFirst("register", "unregister") && it.parameterCount == 1 &&
+                    it.parameterTypes[0] == callbackType
+            }
+            if (!callbackType.isInterface) {
+                listenProblem = "unexpected listener type ${callbackType.simpleName}"
+                return null
+            }
             val proxy = Proxy.newProxyInstance(callbackType.classLoader, arrayOf(callbackType)) { self, method, args ->
                 when (method.name) {
                     "onChangeEvent" -> {
@@ -385,7 +414,7 @@ object EVHardware {
                 }
             }
             val configs = cpm.javaClass.getMethod("getPropertyList").invoke(cpm) as? List<*> ?: return null
-            var subscribed = 0
+            val subscribedIds = ArrayList<Int>()
             var refused = 0
             for (config in configs) {
                 if (config == null) continue
@@ -399,21 +428,31 @@ object EVHardware {
                     1f.coerceIn(min, maxOf(min, max))
                 }
                 try {
-                    if (register.invoke(cpm, proxy, id, rate) == false) refused++ else subscribed++
+                    if (register.invoke(cpm, proxy, id, rate) == false) refused++ else subscribedIds.add(id)
                 } catch (e: Exception) {
                     refused++
                     AppLogger.d(TAG, "listen: 0x%08X refused: %s".format(id, e.readFailureReason()))
                 }
             }
-            AppLogger.i(TAG, "listening to $subscribed properties ($refused refused)")
-            PropertyListening(subscribed, refused) {
-                try {
-                    unregister?.invoke(cpm, proxy)
-                } catch (e: Exception) {
-                    AppLogger.d(TAG, "listen: unsubscribe failed: ${e.readFailureReason()}")
+            AppLogger.i(TAG, "listening to ${subscribedIds.size} properties ($refused refused) via ${register.name}")
+            PropertyListening(subscribedIds.size, refused) {
+                for (id in subscribedIds) {
+                    try {
+                        if (unregister != null) unregister.invoke(cpm, proxy, id)
+                    } catch (e: Exception) {
+                        AppLogger.d(TAG, "listen: unsubscribe 0x%08X failed: %s".format(id, e.readFailureReason()))
+                    }
+                }
+                if (unregister == null) {
+                    try {
+                        unregisterAll?.invoke(cpm, proxy)
+                    } catch (e: Exception) {
+                        AppLogger.d(TAG, "listen: unsubscribe failed: ${e.readFailureReason()}")
+                    }
                 }
             }
         } catch (e: Exception) {
+            listenProblem = e.readFailureReason()
             AppLogger.w(TAG, "listenToProperties: ${e.readFailureReason()}")
             null
         }

EVHardware/lib/src/test/java/com/evsuite/hardware/PropertyListeningTest.kt

@@ -0,0 +1,105 @@
+package com.evsuite.hardware
+
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class PropertyListeningTest {
+
+    class Config(val propertyId: Int, val changeMode: Int, val minSampleRate: Float, val maxSampleRate: Float)
+    class Value(val propertyId: Int, val areaId: Int, val value: Any)
+
+    /** Shaped like Android 9's CarPropertyManager, the car's: registerListener, and an
+     *  unregisterListener(listener) that skips every other property as the car's does. */
+    class Android9Manager(private val configs: List<Config>) {
+        interface CarPropertyEventListener {
+            fun onChangeEvent(value: Any?)
+            fun onErrorEvent(propertyId: Int, areaId: Int)
+        }
+
+        val active = LinkedHashMap<Int, MutableList<CarPropertyEventListener>>()
+        val rates = HashMap<Int, Float>()
+
+        fun getPropertyList(): List<Config> = configs
+
+        fun registerListener(listener: CarPropertyEventListener, propertyId: Int, rate: Float): Boolean {
+            active.getOrPut(propertyId) { ArrayList() }.add(listener)
+            rates[propertyId] = rate
+            return true
+        }
+
+        fun unregisterListener(listener: CarPropertyEventListener) {
+            val ids = active.keys.toMutableList()
+            var i = 0
+            while (i < ids.size) {
+                unregisterListener(listener, ids[i])
+                if (active[ids[i]] == null) ids.removeAt(i) // as SparseArray.remove under keyAt(i)
+                i++
+            }
+        }
+
+        fun unregisterListener(listener: CarPropertyEventListener, propertyId: Int) {
+            val list = active[propertyId] ?: return
+            list.remove(listener)
+            if (list.isEmpty()) active.remove(propertyId)
+        }
+
+        fun fire(propertyId: Int, value: Any) {
+            active[propertyId]?.toList()?.forEach { it.onChangeEvent(Value(propertyId, 0x01000000, value)) }
+        }
+    }
+
+    class NoListeners {
+        fun getPropertyList(): List<Config> = emptyList()
+    }
+
+    private val field = EVHardware::class.java.getDeclaredField("sCarPropertyManager").apply { isAccessible = true }
+
+    @After
+    fun reset() = field.set(null, null)
+
+    @Test
+    fun `subscribes through Android 9's registerListener and unsubscribes every property`() {
+        val manager = Android9Manager(listOf(
+            Config(0x2160A15B, 1, 0f, 0f),     // in the block, on change
+            Config(0x2140A15A, 1, 0f, 0f),
+            Config(0x2160A1A3, 2, 0f, 10f),    // continuous
+            Config(0x2140A101, 1, 0f, 0f),
+            Config(0x11400400, 1, 0f, 0f),     // outside the block
+        ))
+        field.set(null, manager)
+        val heard = ArrayList<String>()
+
+        val listening = EVHardware.listenToProperties(AssistBlock::contains) { id, area, value ->
+            heard += "%08X/%d=%s".format(id, area, value)
+        }
+
+        assertNotNull(EVHardware.listenProblem, listening)
+        assertEquals(4, listening!!.subscribed)
+        assertEquals(0, listening.refused)
+        assertEquals(setOf(0x2160A15B, 0x2140A15A, 0x2160A1A3, 0x2140A101), manager.active.keys)
+        assertEquals(0f, manager.rates[0x2160A15B])
+        assertEquals(1f, manager.rates[0x2160A1A3])
+
+        manager.fire(0x2160A15B, 90f)
+        assertEquals(1, heard.size)
+        assertTrue(heard[0], heard[0].startsWith("2160A15B/16777216="))
+
+        listening.close()
+        assertTrue(manager.active.toString(), manager.active.isEmpty())
+    }
+
+    @Test
+    fun `says why when there is no way to subscribe`() {
+        field.set(null, NoListeners())
+        assertNull(EVHardware.listenToProperties(AssistBlock::contains) { _, _, _ -> })
+        assertEquals("no way to subscribe", EVHardware.listenProblem)
+
+        field.set(null, null)
+        assertNull(EVHardware.listenToProperties(AssistBlock::contains) { _, _, _ -> })
+        assertEquals("no car service", EVHardware.listenProblem)
+    }
+}

SPECS.md

@@ -140,6 +140,20 @@ tyre pressures, GPS (lat, lon, elevation, heading) and the is_* flags. It does *
   confirmed car facts, app structure, UI conventions, build/test/ship, documents. It replaces
   upstream's EVABRPUploader text. The test emulator is now in the flake: `nix run .#car-emulator`
   (Android 9 AOSP at 1920×720, 160 dpi; the car build installs as the system user — checked).
+- 2026-10-27 — App 2.40.4: **the recorder's listening works on Android 9**. Both recordings
+  from the car (08:49 and 08:52, 2.40.3) said "listening to the assistance properties: not
+  possible": `listenToProperties` looked only for `registerCallback`, Android 10's name; the car's
+  car library (Android 9) has `registerListener(CarPropertyEventListener, int, float)` and
+  `unregisterListener`, as the app's `CarPropertyAdapter` already knew. It now takes either, and
+  unsubscribes property by property (Android 9's one-argument `unregisterListener` removes
+  entries from the list it walks and would leave every other property subscribed). A failure now
+  says why (`EVHardware.listenProblem`: no car service, no way to subscribe, or the exception).
+  Tested with a stand-in manager of Android 9's shape (`PropertyListeningTest`). Correction to
+  2.40.3: the ignition listener it was compared with also looks only for `registerCallback`, so
+  it most likely never subscribes on the car either (it reads the state once at start); left as
+  it is. What the polled part of the two recordings shows of the block: `0x2160A15B` (by name
+  the target speed) 0.0 throughout; `0x2140A15A` between 3 and 7 every few captures;
+  `0x2160A1A3`/`0x2160A1A4` counting up by 0.1; speeds 8–33 km/h. Not tried on the car.
 - 2026-10-27 — App 2.40.3 published (`car-2.40.3`; also carries 2.40.1 and 2.40.2).
 - 2026-10-27 — App 2.40.3: **the signal recorder listens** (owner: "is there really nothing we
   can do about the readout of the cruise control set point"). The 2.32.0 recording only polled.

app/build.gradle

@@ -34,8 +34,8 @@ android {
         applicationId "com.stinnesbeck.nilsmg4"
         minSdk 27
         targetSdk 36
-        versionCode 148
-        versionName "2.40.3"
+        versionCode 149
+        versionName "2.40.4"
 
         // Nothing about the server ships in the APK: its URL and ingest token are entered in
         // the app's Server tab (ServerConfig), and the database is only reachable by the server.

app/src/main/java/com/evsuite/abrp/SignalRecorder.java

@@ -103,7 +103,8 @@ final class SignalRecorder {
             rec.note(System.currentTimeMillis(), "listening failed: " + t.getClass().getSimpleName());
         }
         rec.note(System.currentTimeMillis(), listening == null
-                ? "listening to the assistance properties: not possible (no car service)"
+                ? "listening to the assistance properties: not possible ("
+                        + EVHardware.INSTANCE.getListenProblem() + ")"
                 : "listening to " + listening.getSubscribed() + " assistance properties ("
                         + listening.getRefused() + " refused)");
         try {