diff --git a/src/app_network.cpp b/src/app_network.cpp
index c2ad22f..4e68bce 100644
--- a/src/app_network.cpp
+++ b/src/app_network.cpp
@@ -2765,6 +2765,7 @@ void App::resetChatSession()
     chat_db_.lock();
     chat_identity_provisioned_ = false;
     chat_identity_fetch_in_flight_ = false;
+    chat_fast_scan_in_flight_ = false;   // a stale in-flight fast-scan is dropped by its session guard
     chat_identity_unavailable_ = false;
     // Invalidate any in-flight identity fetch that captured the PREVIOUS wallet's secret, so its
     // completion callback can't provision that secret under the new wallet.
@@ -3178,7 +3179,8 @@ void App::fastScanChatMemos()
     if (addr.empty()) return;
 
     chat_fast_scan_in_flight_ = true;
-    worker_->post([this, addr]() -> rpc::RPCWorker::MainCb {
+    const int scanGen = chat_session_generation_;   // guard: drop the result if the wallet switches/locks
+    worker_->post([this, addr, scanGen]() -> rpc::RPCWorker::MainCb {
         std::vector<chat::HushChatTransactionMetadata> metadata;
         try {
             rpc::RPCClient::TraceScope trace("HushChat / 0-conf fast scan");
@@ -3208,7 +3210,11 @@ void App::fastScanChatMemos()
                 }
             }
         } catch (const std::exception&) {}
-        return [this, metadata = std::move(metadata)]() mutable {
+        return [this, scanGen, metadata = std::move(metadata)]() mutable {
+            // The wallet was switched/locked between post and now — this metadata belongs to the previous
+            // session. resetChatSession already reset the in-flight flag, so just drop; clearing it here
+            // would clobber a new session's own in-flight scan (mirrors the broadcast/identity guards).
+            if (scanGen != chat_session_generation_) return;
             chat_fast_scan_in_flight_ = false;
             if (metadata.empty()) return;
             // Skip HIDDEN conversations — the mempool fast path deliberately doesn't surface them; they