feat(learn,todo,meditate): dictate through the phone's voice input app (ADR 0038, D18)

On Android the microphone now opens the app handling
RECOGNIZE_SPEECH (FUTO Voice Input, Google's), the default the person
chose in Android, and puts the text it returns where the cursor stood,
as Dictation does; cancelled, nothing. Only where none is installed, or
it can't be opened, does speech_to_text listen in line as before.

halkyon_app: VoiceInputApp (one listen, an answer once closed) on the
channel app.halkyon/voice_input, which DeviceSpeechInput asks first at
every listen, answering SpeechStart.finished so that Dictation doesn't
listen again; speech_to_text isn't touched on that route, so our app
asks for no microphone. SpeechInput.listen and Dictation.start take the
prompt the voice input app shows (the field's hint).

Each app: VoiceInput.kt (queryIntentActivities, startActivityForResult,
the first of EXTRA_RESULTS) attached in MainActivity, which hands it
activity results, and RECOGNIZE_SPEECH among the manifest's queries.
The privacy pages of Learn and Meditate say so.

Our own Whisper and Meditate's dream recordings are dropped (D18).

Whats-New: The microphone now dictates through your phone's voice input app, such as FUTO Voice Input.
Whats-New-De: Das Mikrofon diktiert jetzt über die Spracheingabe-App deines Telefons, etwa FUTO Voice Input.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_flutter/android/app/src/main/AndroidManifest.xml

@@ -96,5 +96,10 @@
         <intent>
             <action android:name="android.speech.RecognitionService"/>
         </intent>
+        <!-- The voice input app dictation opens first (Meditate's ADR 0038, D18),
+             FUTO Voice Input or Google's, which records itself. -->
+        <intent>
+            <action android:name="android.speech.action.RECOGNIZE_SPEECH"/>
+        </intent>
     </queries>
 </manifest>

apps/learn/halkyon_learn_flutter/android/app/src/main/kotlin/app/halkyon/learn/MainActivity.kt

@@ -13,6 +13,9 @@ import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MethodChannel
 
 class MainActivity : FlutterActivity() {
+  /** The voice input app dictation opens (ADR 0038, D18). */
+  private val voiceInput = VoiceInput(this)
+
   private var askedToNotify = false
 
   override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
@@ -21,6 +24,7 @@ class MainActivity : FlutterActivity() {
     PomodoroService.appBack()
     ScreenGuard.attach(this, messenger)
     SensitiveClipboard.attach(this, messenger)
+    voiceInput.attach(messenger)
     // A question searched with the device's own web search (its default
     // browser or search app answers ACTION_WEB_SEARCH); false where none does,
     // and the app opens a search engine's address instead.
@@ -107,6 +111,12 @@ class MainActivity : FlutterActivity() {
     }
   }
 
+  override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+    if (!voiceInput.onActivityResult(requestCode, resultCode, data)) {
+      super.onActivityResult(requestCode, resultCode, data)
+    }
+  }
+
   private companion object {
     const val NOTIFY_REQUEST = 1
   }

apps/learn/halkyon_learn_flutter/android/app/src/main/kotlin/app/halkyon/learn/VoiceInput.kt

@@ -0,0 +1,84 @@
+package app.halkyon.learn
+
+import android.app.Activity
+import android.content.ActivityNotFoundException
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.os.Build
+import android.speech.RecognizerIntent
+import io.flutter.plugin.common.BinaryMessenger
+import io.flutter.plugin.common.MethodChannel
+
+/**
+ * The device's voice input app for halkyon_app's ChannelVoiceInputApp
+ * (Halkyon Meditate's ADR 0038, D18): whichever app handles
+ * ACTION_RECOGNIZE_SPEECH (FUTO Voice Input, Google's) opens over the app,
+ * records and returns text alone, so this app asks for no microphone.
+ * `installed` says whether one is (the manifest's <queries> lets Android 11
+ * on show it); `listen` opens it and answers once it is closed: its first
+ * result, empty where cancelled, an error where it couldn't be opened. The
+ * activity hands its results to [onActivityResult].
+ */
+class VoiceInput(private val activity: Activity) {
+  private var pending: MethodChannel.Result? = null
+
+  fun attach(messenger: BinaryMessenger) {
+    MethodChannel(messenger, "app.halkyon/voice_input").setMethodCallHandler { call, result ->
+      when (call.method) {
+        "installed" -> result.success(installed())
+        "listen" -> {
+          if (pending != null) {
+            result.error("busy", "The voice input app is open already", null)
+            return@setMethodCallHandler
+          }
+          val intent = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH)
+            .putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM)
+          call.argument<String>("language")?.let { intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE, it) }
+          call.argument<String>("prompt")?.let { intent.putExtra(RecognizerIntent.EXTRA_PROMPT, it) }
+          try {
+            pending = result
+            activity.startActivityForResult(intent, REQUEST)
+          } catch (error: ActivityNotFoundException) {
+            pending = null
+            result.error("noApp", error.message, null)
+          } catch (error: SecurityException) {
+            pending = null
+            result.error("refused", error.message, null)
+          }
+        }
+        else -> result.notImplemented()
+      }
+    }
+  }
+
+  private fun installed(): Boolean {
+    val intent = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH)
+    val packages = activity.packageManager
+    val found = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+      packages.queryIntentActivities(intent, PackageManager.ResolveInfoFlags.of(0))
+    } else {
+      @Suppress("DEPRECATION")
+      packages.queryIntentActivities(intent, 0)
+    }
+    return found.isNotEmpty()
+  }
+
+  /** Whether [requestCode] was the voice input app's, its text handed on. */
+  fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?): Boolean {
+    if (requestCode != REQUEST) return false
+    val result = pending ?: return true
+    pending = null
+    val text = if (resultCode == Activity.RESULT_OK) {
+      data?.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS)?.firstOrNull()
+    } else {
+      null
+    }
+    result.success(text ?: "")
+    return true
+  }
+
+  private companion object {
+    /** Any number the app's other activity results don't use. */
+    const val REQUEST = 0x766f
+  }
+}