fix(session): repair the expiry warning and the gaps the review found

Review of 742f376 (Fable). Three defects made the feature not work for the
case it exists for:

- armExpiryWarning() cancelled the alarm before its own early return. Dart
  re-pushes the deadline every 60 s with no dedupe (rule 93's ">5 s" dedupe
  does not exist), so the first sync after the warning came due deleted the
  armed alarm and never re-armed it. Cancel now happens only on the branch
  that re-arms.
- cancelSessionWarningAlarm() built its PendingIntent with
  FLAG_UPDATE_CURRENT, rewriting the live alarm's RUNTIME_TOKEN to "" so a
  delivery in flight was dropped as a stale generation. It now looks the
  existing PendingIntent up with FLAG_NO_CREATE.
- SOCKS5 mode never requested POST_NOTIFICATIONS (requestPermission() is
  TUN-only because it also raises the VPN consent dialog), so on Android 13+
  both alerts were dropped. New plugin method requests it on its own.

Also:
- the native deadline wins the expiry race against the 1 s Dart tick, so the
  commonest session end reached _onVpnConnectionChanged as a bare tunnel
  drop with no message. It now reconciles and sets the expiry text, with
  postAlert false since the native side already posted.
- a resume reconnect no longer resets the support-ad claim: it re-attaches
  to the same server session, where the top-up has already been spent.
- RevoltAlerts sets setOnlyAlertOnce so a replacing post does not re-sound.
- AGENTS.md rule 93 described a setSessionExpiry/SESSION_EXPIRES_AT_MS path
  that no longer exists, dedupe included. Corrected; that stale text is what
  the warning bug was written against.
- CHANGELOG no longer claims the alert covers the tunnel stopping on its own.

flutter analyze clean; debug APK builds.

Co-Authored-By: Claude Opus 5 <[email protected]>

local_packages/flutter_vless_android-1.1.5/android/src/main/kotlin/com/github/tfox/flutter_vless/FlutterVlessPlugin.kt

@@ -240,6 +240,31 @@ class FlutterVlessPlugin : FlutterPlugin, ActivityAware, PluginRegistry.Activity
                 }
             }
 
+            // POST_NOTIFICATIONS on its own, without VpnService.prepare: SOCKS5
+            // mode never establishes a VPN interface, so it never called
+            // requestPermission and both session alerts were dropped unasked
+            // for on Android 13+.
+            "requestNotificationPermission" -> {
+                val currentActivity = activity
+                if (currentActivity == null) {
+                    result.error("NO_ACTIVITY", "Activity is not attached", null)
+                    return
+                }
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU &&
+                    ActivityCompat.checkSelfPermission(
+                        currentActivity,
+                        Manifest.permission.POST_NOTIFICATIONS,
+                    ) != PackageManager.PERMISSION_GRANTED
+                ) {
+                    ActivityCompat.requestPermissions(
+                        currentActivity,
+                        arrayOf(Manifest.permission.POST_NOTIFICATIONS),
+                        REQUEST_CODE_POST_NOTIFICATIONS,
+                    )
+                }
+                result.success(null)
+            }
+
             "requestPermission" -> {
                 val currentActivity = activity
                 if (currentActivity == null) {

local_packages/flutter_vless_android-1.1.5/android/src/main/kotlin/com/github/tfox/flutter_vless/xray/service/XrayVPNService.kt

@@ -473,15 +473,18 @@ class XrayVPNService : VpnService() {
     // scheduled must never stop a working tunnel, so nothing here fails closed.
     // Dart re-pushes the deadline on every sync, so this runs about once a minute.
     private fun armExpiryWarning(runtimeToken: String, expiresAtEpochMs: Long) {
-        cancelSessionWarningAlarm()
         if (runtimeToken.isEmpty()) return
 
         val warnAt = expiresAtEpochMs - RevoltAlerts.WARNING_LEAD_MS
         // Deadline already inside the warning window (or past): either the alarm
         // has fired and its notification should stay up, or this is the short
-        // bootstrap deadline at connect, which must not warn at all.
+        // bootstrap deadline at connect, which must not warn at all. Nothing is
+        // cancelled here - Dart re-pushes the same deadline every 60 s with no
+        // dedupe, so cancelling on this branch would reliably delete the armed
+        // warning on the first sync after it came due and never re-arm it.
         if (warnAt <= System.currentTimeMillis()) return
 
+        cancelSessionWarningAlarm()
         // More than the lead away, so any warning on screen belongs to an older
         // deadline - a support top-up just pushed it out.
         RevoltAlerts.cancelExpiryWarning(this)
@@ -691,12 +694,24 @@ class XrayVPNService : VpnService() {
     private fun cancelSessionWarningAlarm() {
         try {
             val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
-            alarmManager.cancel(sessionWarningPendingIntent(""))
+            // Look the existing PendingIntent up instead of building one: with
+            // FLAG_UPDATE_CURRENT, constructing it to cancel rewrites the live
+            // alarm's RUNTIME_TOKEN to "" first, and a delivery already in
+            // flight would then be dropped as a stale generation.
+            existingSessionWarningPendingIntent()?.let { alarmManager.cancel(it) }
         } catch (e: Exception) {
             Log.w(TAG, "Failed to cancel session-warning alarm", e)
         }
     }
 
+    private fun existingSessionWarningPendingIntent(): PendingIntent? {
+        val intent = Intent(this, XrayVPNService::class.java)
+            .putExtra(EXTRA_SESSION_WARNING, true)
+        val flags = PendingIntent.FLAG_NO_CREATE or
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) PendingIntent.FLAG_IMMUTABLE else 0
+        return PendingIntent.getService(this, SESSION_WARNING_REQUEST_CODE, intent, flags)
+    }
+
     // A PendingIntent is identified by component plus request code, not extras,
     // so the warning needs its own code or it would overwrite - and later
     // cancel - the expiry alarm.

local_packages/flutter_vless_android-1.1.5/android/src/main/kotlin/com/github/tfox/flutter_vless/xray/utils/RevoltAlerts.kt

@@ -97,6 +97,9 @@ object RevoltAlerts {
                 .setSmallIcon(icon)
                 .setAutoCancel(true)
                 .setOngoing(false)
+                // Both processes can post the disconnected alert; the second
+                // post replaces the first and must not sound again.
+                .setOnlyAlertOnce(true)
 
             launchIntent(context)?.let { builder.setContentIntent(it) }