fix: Tier-2 UX robustness — action guards, in-progress guards, input trimming

The app-wide "import-key pattern" fixes (missing guards / untrimmed input / no
re-entrancy protection), from the robustness audit:

- Import-key dialog: unify the type indicator and the RPC dispatch on one
  classifier (classifyPrivateKey is now prefix-aware — an "SK..." shielded key no
  longer misroutes to the transparent RPC), trim manual input (not just Paste),
  and gate both the indicator and the Import button on a shared
  isRecognizedPrivateKey() so unrecognized/empty input can't be submitted.
- Shield: guard the submit button on connected + !syncing (like Send), with a
  disabled tooltip, instead of firing into a raw daemon error.
- Mining: disable the pool Mine button when the payout address is empty
  ("enter a payout address first"), and trim the pool URL/worker on persist.
- Console: track in-flight RPC commands (atomic counter + busy() override) so the
  input is disabled while a command runs instead of piling up on the worker.
- Maintenance (rescan/repair/delete-chain/reinstall-daemon): re-entrancy guard —
  bail with "already in progress" instead of launching a duplicate destructive op.
- Bootstrap dialog: re-attach to an in-flight download on reopen instead of
  resetting state and orphaning the running worker.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app.cpp

@@ -2650,20 +2650,24 @@ void App::renderImportKeyDialog()
         memset(import_key_input_, 0, sizeof(import_key_input_));
     }
     
+    // Trimmed view for validation (importPrivateKey trims again before the RPC). The indicator and the
+    // Import-button guard below both derive from the SAME shared classifier, so they can't disagree.
+    std::string keyTrim(import_key_input_);
+    while (!keyTrim.empty() && (keyTrim.front()==' '||keyTrim.front()=='\t'||keyTrim.front()=='\n'||keyTrim.front()=='\r')) keyTrim.erase(keyTrim.begin());
+    while (!keyTrim.empty() && (keyTrim.back()==' '||keyTrim.back()=='\t'||keyTrim.back()=='\n'||keyTrim.back()=='\r')) keyTrim.pop_back();
+    bool keyRecognized = services::WalletSecurityController::isRecognizedPrivateKey(keyTrim);
+    bool keyIsZ = services::WalletSecurityController::classifyPrivateKey(keyTrim)
+                  == services::WalletSecurityController::KeyKind::Shielded;
+
     // Key validation indicator
-    if (import_key_input_[0] != '\0') {
-        std::string k(import_key_input_);
-        bool isZKey = (k.substr(0, 20) == "secret-extended-key-") ||
-                      (k.length() >= 2 && k[0] == 'S' && k[1] == 'K');
-        bool isTKey = (k.length() >= 51 && k.length() <= 52 &&
-                      (k[0] == '5' || k[0] == 'K' || k[0] == 'L' || k[0] == 'U'));
-        if (isZKey || isTKey) {
+    if (!keyTrim.empty()) {
+        if (keyRecognized) {
             ImGui::PushFont(ui::material::Type().iconSmall());
             ImGui::TextColored(ImVec4(0.3f, 0.8f, 0.3f, 1.0f), ICON_MD_CHECK_CIRCLE);
             ImGui::PopFont();
             ImGui::SameLine(0, 4.0f);
             ImGui::TextColored(ImVec4(0.3f, 0.8f, 0.3f, 1.0f), "%s",
-                               isZKey ? "Shielded spending key" : "Transparent private key");
+                               keyIsZ ? "Shielded spending key" : "Transparent private key");
         } else {
             ImGui::PushFont(ui::material::Type().iconSmall());
             ImGui::TextColored(ImVec4(0.8f, 0.6f, 0.0f, 1.0f), ICON_MD_HELP);
@@ -2686,18 +2690,17 @@ void App::renderImportKeyDialog()
     ImGui::Spacing();
     ImGui::Separator();
     
+    ImGui::BeginDisabled(!keyRecognized);   // only a recognized Z/T key can be imported
     if (ui::material::StyledButton("Import", ImVec2(btnW, 0), ui::material::resolveButtonFont(btnFont))) {
-        std::string key(import_key_input_);
-        if (!key.empty()) {
-            importPrivateKey(key, [this](bool success, const std::string& msg) {
-                import_success_ = success;
-                import_status_ = msg;
-                if (success) {
-                    memset(import_key_input_, 0, sizeof(import_key_input_));
-                }
-            });
-        }
+        importPrivateKey(std::string(import_key_input_), [this](bool success, const std::string& msg) {
+            import_success_ = success;
+            import_status_ = msg;
+            if (success) {
+                memset(import_key_input_, 0, sizeof(import_key_input_));
+            }
+        });
     }
+    ImGui::EndDisabled();
     ImGui::SameLine();
     if (ui::material::StyledButton("Close", ImVec2(btnW, 0), ui::material::resolveButtonFont(btnFont))) {
         show_import_key_ = false;
@@ -3187,6 +3190,13 @@ void App::rescanBlockchain()
         return;
     }
 
+    // Re-entrancy guard: a rescan/repair (both drive state_.sync.rescanning) or this exact task already
+    // running would stomp each other — a second confirm must not launch a duplicate operation.
+    if (state_.sync.rescanning || async_tasks_.isRunning(decision.taskName)) {
+        ui::Notifications::instance().warning("A blockchain maintenance operation is already in progress.");
+        return;
+    }
+
     DEBUG_LOGF("[App] Starting blockchain rescan - stopping daemon first\n");
     ui::Notifications::instance().info("Restarting daemon with -rescan flag...");
     
@@ -3229,6 +3239,11 @@ void App::repairWallet()
         return;
     }
 
+    if (state_.sync.rescanning || async_tasks_.isRunning(decision.taskName)) {
+        ui::Notifications::instance().warning("A blockchain maintenance operation is already in progress.");
+        return;
+    }
+
     DEBUG_LOGF("[App] Starting wallet repair (-zapwallettxes=2) - stopping daemon first\n");
     ui::Notifications::instance().info("Restarting daemon with -zapwallettxes=2 (wallet repair)...");
 
@@ -3270,6 +3285,11 @@ void App::reinstallBundledDaemon()
         return;
     }
 
+    if (async_tasks_.isRunning("reinstall-daemon")) {
+        ui::Notifications::instance().warning("The daemon reinstall is already in progress.");
+        return;
+    }
+
     DEBUG_LOGF("[App] Reinstalling bundled daemon binary — stopping daemon first\n");
     ui::Notifications::instance().info("Installing bundled daemon — the node will stop, update, and restart...");
 
@@ -3309,6 +3329,11 @@ void App::deleteBlockchainData()
         return;
     }
 
+    if (state_.sync.rescanning || async_tasks_.isRunning(decision.taskName)) {
+        ui::Notifications::instance().warning("A blockchain maintenance operation is already in progress.");
+        return;
+    }
+
     DEBUG_LOGF("[App] Deleting blockchain data - stopping daemon first\n");
     ui::Notifications::instance().info("Stopping daemon and deleting blockchain data...");