v0.1.6 — audit fixes (critical, moderate, minor) + UX polish

Critical
--------
- DetectionService: subscribe to threatLevel + top event flows; rebuild the
  foreground notification on every change so a locked-screen user sees
  escalations. Vibrate on upward tier transitions (escalating waveforms for
  YELLOW/ORANGE/RED), gated by Settings.vibrateOnAlert (default on).
- DetectionService: only mark _running=true if at least one scanner started;
  stopSelf() if everything was disabled or denied. Switch START_STICKY →
  START_NOT_STICKY so a system-killed service doesn't re-create into a
  stuck "running but not scanning" state.
- DeflockClient: detect Overpass timeout-in-body (`{"remark": "...timed
  out..."}`) and treat as failure — previously these 200-with-empty-elements
  responses got cached for 24 h, hiding ALPRs in that 5×5 km cell for the
  next day.
- DeflockScanner: record lastFetch coords + timestamp on BOTH success and
  failure, with a 60 s backoff window after a failed attempt. Previously
  `lastFetchLat` was only set on Success, so every subsequent location
  update would re-trigger a 30 s POST that collectLatest then cancelled —
  we'd never finish a fetch under sustained Overpass slowness.
- LocationProvider: stale-lastLocation race fix. The async `lastLocation`
  callback now only seeds `_location` if it's still null and we're still
  running — previously it could overwrite a fresher fix from
  requestLocationUpdates, or fire after stop() and resurrect _location with
  stale data.

Moderate
--------
- CitizenScanner: wait for the first non-null location with .first { } before
  starting the poll/delay loop. First Citizen poll now fires within seconds
  of the location fix, not up to 60 s after.
- MainScreen: when not running, show a muted gray circle with "IDLE" text
  instead of the same solid green look as "scanning, all clear" — the
  pulse animation was the only differentiator before.
- Compose state: rememberSaveable for the screen enum + bottom-sheet open
  state, so SETTINGS survives rotation.
- MainActivity: detect permanently-denied permissions (the user picked
  "don't ask again") via shouldShowRequestPermissionRationale. UI swaps the
  call-to-action to "Open app settings" which fires
  Settings.ACTION_APPLICATION_DETAILS_SETTINGS. onResume re-checks so a
  user returning from app settings is reflected immediately.

Improvements
------------
- BLE/WiFi scanners record SourceHealth.OK on a successful start (and
  FAILED with a specific reason on every short-circuit — disabled adapter,
  missing permission, etc.) so the drill-down sheet is honest about radio
  state, not just network state.
- DetectionEvent gains optional lat/lon (populated by DEFLOCK and CITIZEN);
  SourceRow shows a tap-to-open-Maps icon next to events with coordinates,
  firing a `geo:lat,lon?q=lat,lon(label)` Intent.
- SettingsScreen sliders use onValueChangeFinished — only commit to
  SharedPreferences on drag-release, not on every pixel of movement.
- New Settings.vibrateOnAlert toggle (default on) wired to a SettingsScreen
  row under a new "Alerts" section.

Minor
-----
- BleScanner iterates ALL manufacturer-data entries to find XUNTONG; only
  falls back to the first entry if no XUNTONG match is present. Previously
  we only inspected the first entry.
- Drop dead `?.` on JSONArray.optString in CitizenClient (returns String,
  never null).
- Remove unused rememberCoroutineScope in MainScreen.
- Update stale Phase/Waze references in DetectionService comments.
- Add VIBRATE permission to manifest.

versionCode 6 → 7, versionName 0.1.5 → 0.1.6.

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

app/src/main/kotlin/org/soulstone/overwatch/MainActivity.kt

@@ -1,17 +1,22 @@
 package org.soulstone.overwatch
 
 import android.Manifest
+import android.app.Activity
+import android.content.Intent
 import android.content.pm.PackageManager
+import android.net.Uri
 import android.os.Build
 import android.os.Bundle
+import android.provider.Settings as AndroidSettings
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.core.app.ActivityCompat
 import androidx.core.content.ContextCompat
 import org.soulstone.overwatch.data.settings.Settings
 import org.soulstone.overwatch.service.DetectionService
@@ -44,6 +49,7 @@ class MainActivity : ComponentActivity() {
     ) { result ->
         val allGranted = result.all { it.value }
         permissionsGranted.value = allGranted
+        permanentlyDenied.value = !allGranted && !anyMissingCanStillAsk()
         if (allGranted) {
             // First-run path: user just granted everything, kick off scanning
             // immediately so they don't have to tap START a second time.
@@ -51,17 +57,22 @@ class MainActivity : ComponentActivity() {
         }
     }
 
-    private val permissionsGranted = androidx.compose.runtime.mutableStateOf(false)
+    private val permissionsGranted = mutableStateOf(false)
+    /** True when at least one required permission is denied AND the system says
+     *  we can no longer prompt for it (user picked "don't ask again"). The UI
+     *  swaps the START button's call-to-action for an "Open app settings" link. */
+    private val permanentlyDenied = mutableStateOf(false)
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         permissionsGranted.value = checkAllPermissions()
+        permanentlyDenied.value = false  // reset on activity create
         val settings = Settings.get(this)
 
         setContent {
             val themeMode by settings.themeMode.collectAsState()
             OverwatchTheme(mode = themeMode) {
-                var screen by remember { mutableStateOf(Screen.MAIN) }
+                var screen by rememberSaveable { mutableStateOf(Screen.MAIN) }
 
                 when (screen) {
                     Screen.MAIN -> {
@@ -70,6 +81,13 @@ class MainActivity : ComponentActivity() {
                         val threat by DetectionService.store.threatLevel.collectAsState()
                         val maxScore by DetectionService.store.maxScore.collectAsState()
                         val granted by permissionsGranted
+                        val denied by permanentlyDenied
+
+                        val message = when {
+                            granted -> null
+                            denied -> "Permissions permanently denied — open app settings to grant"
+                            else -> "Tap START to grant Bluetooth, WiFi + location permissions"
+                        }
 
                         MainScreen(
                             running = running,
@@ -77,13 +95,17 @@ class MainActivity : ComponentActivity() {
                             score = maxScore,
                             events = events,
                             canStart = true,
-                            permissionMessage = if (!granted) "Tap START to grant Bluetooth, WiFi + location permissions" else null,
+                            permissionMessage = message,
+                            showOpenAppSettings = denied && !granted,
+                            onOpenAppSettings = { openAppSettings() },
                             onStartStop = {
                                 if (running) {
                                     DetectionService.stop(this)
                                 } else {
                                     if (granted) {
                                         DetectionService.start(this)
+                                    } else if (denied) {
+                                        openAppSettings()
                                     } else {
                                         permissionLauncher.launch(requiredPermissions)
                                     }
@@ -111,7 +133,10 @@ class MainActivity : ComponentActivity() {
 
     override fun onResume() {
         super.onResume()
-        permissionsGranted.value = checkAllPermissions()
+        // User may have granted permissions in app settings while we were paused.
+        val nowGranted = checkAllPermissions()
+        permissionsGranted.value = nowGranted
+        if (nowGranted) permanentlyDenied.value = false
     }
 
     private fun checkAllPermissions(): Boolean =
@@ -119,5 +144,23 @@ class MainActivity : ComponentActivity() {
             ContextCompat.checkSelfPermission(this, it) == PackageManager.PERMISSION_GRANTED
         }
 
+    /** True if at least one missing permission is still askable via the system
+     *  prompt. False means everything missing was denied with "don't ask again". */
+    private fun anyMissingCanStillAsk(): Boolean {
+        val missing = requiredPermissions.filter {
+            ContextCompat.checkSelfPermission(this, it) != PackageManager.PERMISSION_GRANTED
+        }
+        if (missing.isEmpty()) return true
+        return missing.any { ActivityCompat.shouldShowRequestPermissionRationale(this, it) }
+    }
+
+    private fun openAppSettings() {
+        val intent = Intent(
+            AndroidSettings.ACTION_APPLICATION_DETAILS_SETTINGS,
+            Uri.fromParts("package", packageName, null)
+        ).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+        startActivity(intent)
+    }
+
     private enum class Screen { MAIN, SETTINGS }
 }