From 40a74ce393902087014671643bc02b4360aa745c Mon Sep 17 00:00:00 2001
From: Nash Aschenbath <wwh86696@163.com>
Date: Fri, 13 Nov 2026 10:02:48 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20=E4=BF=AE=E5=A4=8D=E4=B8=8B=E8=BD=BD?=
 =?UTF-8?q?=E8=BF=9B=E5=BA=A6=E5=9B=9E=E9=80=80=E5=8F=8A=E5=A4=B1=E8=B4=A5?=
 =?UTF-8?q?=E6=8F=90=E7=A4=BA=E4=B8=A2=E5=A4=B1?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 lib/services/download_service.dart | 37 +++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/lib/services/download_service.dart b/lib/services/download_service.dart
index 0dab022..8e9f436 100644
--- a/lib/services/download_service.dart
+++ b/lib/services/download_service.dart
@@ -32,6 +32,12 @@ class DownloadStopped implements Exception {
   const DownloadStopped();
 }
 
+/// Carries only the locally selected message from a failed permission preview.
+class _DownloadUnavailable implements Exception {
+  const _DownloadUnavailable(this.message);
+  final String message;
+}
+
 /// Cooperative cancellation also interrupts cooldowns. A backend must checkpoint
 /// before opening a request and between chunks, and close its response on stop.
 class DownloadControl {
@@ -1138,9 +1144,10 @@ class DownloadService {
           _automaticGuards[task.id] = allowed;
         }
       }
-      _tasks
-        ..clear()
-        ..addAll(next);
+      // Other workers can report progress while this snapshot is being saved.
+      for (final task in admitted) {
+        _tasks[task.id] = task;
+      }
       if (album != null) _albums[album.id] = album;
       _suspended = false;
       _notify();
@@ -1869,7 +1876,7 @@ class DownloadService {
       final prepared = batch.items.single;
       await control.checkpoint();
       if (prepared.error != null) {
-        throw XmlyException('download_unavailable', prepared.error!);
+        throw _DownloadUnavailable(prepared.error!);
       }
       final settings = Map<String, dynamic>.from(current.settings)
         ..remove('billingPreviewPending');
@@ -1928,20 +1935,23 @@ class DownloadService {
         if (claimed != null && claimed > 0) {
           await _updates.synchronized(() async {
             final next = Map<String, DownloadTask>.from(_tasks);
+            final balances = <String, int>{};
             for (final item in next.values.toList()) {
               if (item.accountIdentity == current.accountIdentity &&
                   item.expectedBalance != null &&
                   item.state != DownloadState.completed &&
                   !_hasDebit(item.accountIdentity, item.id, item.track.id)) {
+                balances[item.id] = item.expectedBalance! + claimed;
                 next[item.id] = item.copyWith(
-                  expectedBalance: item.expectedBalance! + claimed,
+                  expectedBalance: balances[item.id],
                 );
               }
             }
             await _save(next);
-            _tasks
-              ..clear()
-              ..addAll(next);
+            for (final entry in balances.entries) {
+              _tasks[entry.key] = task(entry.key)
+                  .copyWith(expectedBalance: entry.value);
+            }
           });
           expectedBalance = task(id).expectedBalance;
         }
@@ -2189,7 +2199,18 @@ class DownloadService {
         ),
       );
   static String _message(Object error) {
+    if (error is _DownloadUnavailable) return error.message;
     // Never persist third-party messages (they can contain signed URLs/secrets).
+    if (error is AccountException) {
+      switch (error.code) {
+        case 'missing':
+          return '原账号未登录，请重新登录原账号后重试';
+        case 'credential_missing':
+          return '原账号安全凭据缺失，请重新导入原账号后重试';
+        case 'paused':
+          return '账号正在切换，请稍后重试';
+      }
+    }
     if (error is XmlyException) {
       switch (error.code) {
         case 'original_account_required':