feat(android-terminal): Phase F — kiosk, immersive, queued-action toast

Closes out the Android terminal plan (Phases A → F).

- MainActivity:
  * Immersive mode via WindowInsetsControllerCompat — hides status +
    navigation bars, swipe-to-reveal with auto-hide
    (BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE). Re-applied in onResume so
    a transient overlay can't leave the bars visible.
  * Lock Task Mode — startLockTask() in onResume. The manifest already
    declares lockTaskMode="if_whitelisted", so this enters kiosk on a
    properly MDM-provisioned tablet and is a silent no-op (caught
    SecurityException) on dev / unprovisioned devices.

- TerminalScreen:
  * SnackbarHost pinned at the bottom; LaunchedEffect(actionResult)
    shows "Queued — will sync when back online" whenever an offline
    action gets queued, so the cashier has explicit feedback beyond the
    top-bar pending pill.
  * 4 new locale strings (en/fr/de/lb) for the snackbar copy.

- Manifest cleanup: dropped redundant tools:replace from the debug
  AndroidManifest overlay (networkSecurityConfig isn't set in the main
  manifest, so the replace directive was a no-op + emitted a warning).

Skipped from the plan: a custom splash screen (the existing theme
background renders for the cold-start frame; adding the splashscreen
library is polish for a follow-up) and per-action success toasts
(the action sheet closing + balance refresh + recent-feed update are
adequate confirmation).

Verified by ./gradlew assembleDebug — clean build.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/terminal-android/app/src/debug/AndroidManifest.xml

@@ -1,10 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <!-- Debug-only manifest overlay. Merged onto the main manifest by AGP for
          debug builds; release builds skip this and keep the platform default
          (no cleartext HTTP). -->
     <application
-        android:networkSecurityConfig="@xml/network_security_config"
-        tools:replace="android:networkSecurityConfig" />
+        android:networkSecurityConfig="@xml/network_security_config" />
 </manifest>

clients/terminal-android/app/src/main/java/lu/rewardflow/terminal/MainActivity.kt

@@ -1,6 +1,9 @@
 package lu.rewardflow.terminal
 
+import android.app.ActivityManager
+import android.content.Context
 import android.os.Bundle
+import android.util.Log
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
@@ -8,6 +11,9 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.ui.Modifier
+import androidx.core.view.WindowCompat
+import androidx.core.view.WindowInsetsCompat
+import androidx.core.view.WindowInsetsControllerCompat
 import dagger.hilt.android.AndroidEntryPoint
 import lu.rewardflow.terminal.ui.RewardFlowNavHost
 import lu.rewardflow.terminal.ui.theme.RewardFlowTheme
@@ -18,6 +24,7 @@ class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
+        configureImmersiveMode()
 
         setContent {
             RewardFlowTheme {
@@ -30,4 +37,47 @@ class MainActivity : ComponentActivity() {
             }
         }
     }
+
+    override fun onResume() {
+        super.onResume()
+        // Re-apply immersive each time we come back from a transient overlay
+        // (action sheets, system dialogs) — they sometimes restore the bars.
+        configureImmersiveMode()
+        enterLockTaskIfPossible()
+    }
+
+    /** Hide both the status bar and the navigation bar; reveal them on
+     *  swipe and auto-hide again. Standard Android "immersive sticky"
+     *  behavior, expressed via the Compat APIs. */
+    private fun configureImmersiveMode() {
+        WindowCompat.setDecorFitsSystemWindows(window, false)
+        val controller = WindowInsetsControllerCompat(window, window.decorView)
+        controller.hide(WindowInsetsCompat.Type.systemBars())
+        controller.systemBarsBehavior =
+            WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
+    }
+
+    /**
+     * Promote the activity to Lock Task Mode (kiosk).
+     *
+     * Manifest has ``android:lockTaskMode="if_whitelisted"``, so this
+     * call is only honored when a Device Owner / DPC app has whitelisted
+     * our package. In dev — and on stock retail tablets without MDM
+     * provisioning — the call is a silent no-op, which is the right
+     * behavior. On a properly provisioned tablet, this prevents the
+     * cashier from leaving the app via Home / Recents / notifications.
+     */
+    private fun enterLockTaskIfPossible() {
+        val am = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
+        if (am.lockTaskModeState == ActivityManager.LOCK_TASK_MODE_NONE) {
+            try {
+                startLockTask()
+            } catch (e: SecurityException) {
+                // Whitelist isn't in place — fine, run as a regular app.
+                Log.d("MainActivity", "Lock task not whitelisted: ${e.message}")
+            } catch (e: IllegalStateException) {
+                Log.d("MainActivity", "Cannot enter lock task: ${e.message}")
+            }
+        }
+    }
 }

clients/terminal-android/app/src/main/java/lu/rewardflow/terminal/ui/terminal/TerminalScreen.kt

@@ -24,11 +24,16 @@ import androidx.compose.material3.FilledTonalButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Snackbar
+import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -95,6 +100,15 @@ private fun TerminalContent(
     onLockScreen: () -> Unit,
     viewModel: TerminalViewModel,
 ) {
+    val snackbarHostState = remember { SnackbarHostState() }
+    val queuedMessage = stringResource(R.string.snackbar_queued_for_sync)
+
+    LaunchedEffect(state.actionResult) {
+        if (state.actionResult is ActionResult.Queued) {
+            snackbarHostState.showSnackbar(message = queuedMessage)
+        }
+    }
+
     Column(modifier = Modifier.fillMaxSize()) {
         TopBar(
             staffName = staffName,
@@ -155,6 +169,19 @@ private fun TerminalContent(
             onCancel = viewModel::dismissScanner,
         )
     }
+
+    // Snackbar host pinned at the bottom — always present so it can fire
+    // over any of the dialogs/overlays above.
+    Box(modifier = Modifier.fillMaxSize()) {
+        SnackbarHost(
+            hostState = snackbarHostState,
+            modifier = Modifier
+                .align(Alignment.BottomCenter)
+                .padding(16.dp),
+        ) { data ->
+            Snackbar(snackbarData = data)
+        }
+    }
 }
 
 @Composable

clients/terminal-android/app/src/main/res/values-de/strings.xml

@@ -72,4 +72,8 @@
     <string name="generic_loading">Wird geladen…</string>
     <string name="generic_yes">Ja</string>
     <string name="generic_no">Nein</string>
+
+    <!-- Sync -->
+    <string name="snackbar_queued_for_sync">In der Warteschlange — synchronisiert, sobald wieder online</string>
+    <string name="snackbar_dismiss">Schließen</string>
 </resources>

clients/terminal-android/app/src/main/res/values-fr/strings.xml

@@ -72,4 +72,8 @@
     <string name="generic_loading">Chargement…</string>
     <string name="generic_yes">Oui</string>
     <string name="generic_no">Non</string>
+
+    <!-- Sync -->
+    <string name="snackbar_queued_for_sync">En file d\'attente — synchronisation au retour de la connexion</string>
+    <string name="snackbar_dismiss">Fermer</string>
 </resources>

clients/terminal-android/app/src/main/res/values-lb/strings.xml

@@ -72,4 +72,8 @@
     <string name="generic_loading">Lueden…</string>
     <string name="generic_yes">Jo</string>
     <string name="generic_no">Nee</string>
+
+    <!-- Sync -->
+    <string name="snackbar_queued_for_sync">An der Schlaang — synchroniséiert sou bal nees online</string>
+    <string name="snackbar_dismiss">Zoumaachen</string>
 </resources>

clients/terminal-android/app/src/main/res/values/strings.xml

@@ -72,4 +72,8 @@
     <string name="generic_loading">Loading…</string>
     <string name="generic_yes">Yes</string>
     <string name="generic_no">No</string>
+
+    <!-- Sync -->
+    <string name="snackbar_queued_for_sync">Queued — will sync when back online</string>
+    <string name="snackbar_dismiss">Dismiss</string>
 </resources>