fix: seq-based dedup prevents catch_up from duplicating messages

Matthias Nott

2026-03-22 798112d632b970ab1649af541a43de6912d2d43a

fix: seq-based dedup prevents catch_up from duplicating messages

 lib/screens/chat_screen.dart
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@@ -42,6 +42,7 @@
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   int _lastSeq = 0;
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   bool _isCatchingUp = false;
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   bool _screenshotForChat = false;
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+  final Set<int> _seenSeqs = {};
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   @override
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   void initState() {
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@@ -153,9 +154,19 @@
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   void _handleMessage(Map<String, dynamic> msg) {
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     // Track sequence numbers for catch_up protocol
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     final seq = msg['seq'] as int?;
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-    if (seq != null && seq > _lastSeq) {
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-      _lastSeq = seq;
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-      _saveLastSeq();
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+    if (seq != null) {
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+      // Dedup: skip messages we've already processed
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+      if (_seenSeqs.contains(seq)) return;
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+      _seenSeqs.add(seq);
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+      // Keep set bounded
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+      if (_seenSeqs.length > 500) {
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+        final sorted = _seenSeqs.toList()..sort();
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+        _seenSeqs.removeAll(sorted.sublist(0, sorted.length - 300));
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+      }
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+      if (seq > _lastSeq) {
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+        _lastSeq = seq;
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+        _saveLastSeq();
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+      }
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     }
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     final type = msg['type'] as String?;