refactor(mining): surface inconclusive benchmark; dedup idle combo

- mining_benchmark: when a thread benchmark finishes with no nonzero
  hashrate sample (e.g. the pool never reported a rate), don't finish
  silently — set a new `inconclusive` flag on ThreadBenchmarkUpdate and
  let mining_tab warn. Keeps the state-machine core pure/no-I/O (it is
  unit-tested), rather than calling the Notifications singleton from it.
- mining_controls: fold the two byte-identical idle-delay combo blocks
  (non-scaling + thread-scaling branches) into one lambda parameterised
  by combo id; removes ~30 lines of duplication.
- request_payment: drop the dead s_selected_addr_idx state and write the
  address-selected comparisons as std::string == char* consistently.

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

src/ui/windows/mining_benchmark.cpp

@@ -189,6 +189,11 @@ ThreadBenchmarkUpdate AdvanceThreadBenchmark(ThreadBenchmark& benchmark,
                         update.startPoolMining = true;
                         update.startThreads = benchmark.optimal_threads;
                     }
+                } else {
+                    // No candidate produced a nonzero hashrate (e.g. a pool that never
+                    // reported a rate). Don't finish silently — flag the run as
+                    // inconclusive so the caller can surface it (keeps this core pure).
+                    update.inconclusive = true;
                 }
             }
             break;

src/ui/windows/mining_benchmark.h

@@ -56,6 +56,7 @@ struct ThreadBenchmarkUpdate {
     int startThreads = 0;
     bool saveOptimalThreads = false;
     int optimalThreads = 0;
+    bool inconclusive = false;  // finished with no nonzero hashrate sample — caller should warn
 };
 
 ThreadBenchmarkUpdate AdvanceThreadBenchmark(ThreadBenchmark& benchmark,

src/ui/windows/mining_controls.cpp

@@ -176,8 +176,9 @@ void RenderMiningControls(App* app, const WalletState& state, const MiningInfo&
                     idleRightEdge = gBtnX - 4.0f * dp;
                 }
 
-                // Idle delay combo (to the left, when idle is enabled and NOT in thread scaling mode)
+                // Idle delay combo renderer (shared by the non-scaling and thread-scaling
-                if (idleOn && !threadScaling) {
+                // branches below). Draws right-aligned at idleRightEdge and advances it.
+                auto renderIdleDelayCombo = [&](const char* comboId) {
                     struct DelayOption { int seconds; const char* label; };
                     static const DelayOption delays[] = {
                         {30, "30s"}, {60, "1m"}, {120, "2m"}, {300, "5m"}, {600, "10m"}
@@ -192,7 +193,7 @@ void RenderMiningControls(App* app, const WalletState& state, const MiningInfo&
                     float comboY = curY + (headerH - ImGui::GetFrameHeight()) * 0.5f;
                     ImGui::SetCursorScreenPos(ImVec2(comboX, comboY));
                     ImGui::SetNextItemWidth(comboW);
-                    if (ImGui::BeginCombo("##IdleDelay", previewLabel, ImGuiComboFlags_NoArrowButton)) {
+                    if (ImGui::BeginCombo(comboId, previewLabel, ImGuiComboFlags_NoArrowButton)) {
                         for (const auto& d : delays) {
                             bool selected = (d.seconds == curDelay);
                             if (ImGui::Selectable(d.label, selected)) {
@@ -206,6 +207,11 @@ void RenderMiningControls(App* app, const WalletState& state, const MiningInfo&
                     if (ImGui::IsItemHovered())
                         material::Tooltip("%s", TR("tt_idle_delay"));
                     idleRightEdge = comboX - 4.0f * dp;
+                };
+
+                // Idle delay combo (to the left, when idle is enabled and NOT in thread scaling mode)
+                if (idleOn && !threadScaling) {
+                    renderIdleDelayCombo("##IdleDelay");
                 }
 
                 // Thread scaling controls: idle delay + active threads / idle threads combos
@@ -213,36 +219,7 @@ void RenderMiningControls(App* app, const WalletState& state, const MiningInfo&
                     int hwThreads = std::max(1, (int)std::thread::hardware_concurrency());
 
                     // Idle delay combo
-                    {
+                    renderIdleDelayCombo("##IdleDelayScale");
-                        struct DelayOption { int seconds; const char* label; };
-                        static const DelayOption delays[] = {
-                            {30, "30s"}, {60, "1m"}, {120, "2m"}, {300, "5m"}, {600, "10m"}
-                        };
-                        int curDelay = app->settings()->getMineIdleDelay();
-                        const char* previewLabel = "2m";
-                        for (const auto& d : delays) {
-                            if (d.seconds == curDelay) { previewLabel = d.label; break; }
-                        }
-                        float comboW = schema::UI().drawElement("components.settings-page", "idle-combo-width").sizeOr(64.0f);
-                        float comboX = idleRightEdge - comboW;
-                        float comboY = curY + (headerH - ImGui::GetFrameHeight()) * 0.5f;
-                        ImGui::SetCursorScreenPos(ImVec2(comboX, comboY));
-                        ImGui::SetNextItemWidth(comboW);
-                        if (ImGui::BeginCombo("##IdleDelayScale", previewLabel, ImGuiComboFlags_NoArrowButton)) {
-                            for (const auto& d : delays) {
-                                bool selected = (d.seconds == curDelay);
-                                if (ImGui::Selectable(d.label, selected)) {
-                                    app->settings()->setMineIdleDelay(d.seconds);
-                                    app->settings()->save();
-                                }
-                                if (selected) ImGui::SetItemDefaultFocus();
-                            }
-                            ImGui::EndCombo();
-                        }
-                        if (ImGui::IsItemHovered())
-                            material::Tooltip("%s", TR("tt_idle_delay"));
-                        idleRightEdge = comboX - 4.0f * dp;
-                    }
 
                     // Idle threads combo (threads when system is idle)
                     {

src/ui/windows/mining_tab.cpp

@@ -248,6 +248,11 @@ static void RenderMiningTabContent(App* app)
         if (benchmarkUpdate.startPoolMining) {
             app->startPoolMining(benchmarkUpdate.startThreads);
         }
+        if (benchmarkUpdate.inconclusive) {
+            Notifications::instance().warning(
+                "Benchmark inconclusive: no hashrate samples were recorded. "
+                "Check the pool connection and try again.");
+        }
     }
 
     // ================================================================

src/ui/windows/request_payment_dialog.cpp

@@ -25,7 +25,6 @@ static char s_address[512] = "";
 static double s_amount = 0.0;
 static char s_memo[512] = "";
 static char s_label[128] = "";
-static int s_selected_addr_idx = -1;
 static std::string s_payment_uri;
 static uintptr_t s_qr_texture = 0;
 static int s_qr_width = 0;
@@ -45,7 +44,6 @@ void RequestPaymentDialog::show(const std::string& address)
     s_amount = 0.0;
     s_memo[0] = '\0';
     s_label[0] = '\0';
-    s_selected_addr_idx = -1;
     s_uri_dirty = true;
     
     if (!address.empty()) {
@@ -107,7 +105,7 @@ void RequestPaymentDialog::render(App* app)
                         label = label.substr(0, zAddrFrontLbl.truncate) + "..." + label.substr(label.length() - zAddrBackLbl.truncate);
                     }
                     
-                    if (ImGui::Selectable(label.c_str(), s_address == addr.address)) {
+                    if (ImGui::Selectable(label.c_str(), addr.address == s_address)) {
                         strncpy(s_address, addr.address.c_str(), sizeof(s_address) - 1);
                         s_uri_dirty = true;
                     }
@@ -124,7 +122,7 @@ void RequestPaymentDialog::render(App* app)
                         label = label.substr(0, tAddrFrontLbl.truncate) + "..." + label.substr(label.length() - tAddrBackLbl.truncate);
                     }
                     
-                    if (ImGui::Selectable(label.c_str(), s_address == addr.address)) {
+                    if (ImGui::Selectable(label.c_str(), addr.address == s_address)) {
                         strncpy(s_address, addr.address.c_str(), sizeof(s_address) - 1);
                         s_uri_dirty = true;
                     }