feat(mining): persistent start/stop error caption + timeout-aware pool status

- A mining start/stop/pool failure now sets a persistent App::mining_last_error_
  (cleared on the next attempt), rendered as a red caption with "Press Mine to
  try again" below the Mine button (plus a Dismiss, and a Windows-Defender
  "How to fix" on an AV block), so a crashed/blocked/failed miner is no longer
  just a button that "did nothing" once its toast faded. Two more hardcoded
  English strings (pool-payout-invalid, AV-blocked) moved to i18n.
- Pool connection status is now a persistent "Status" row in the pool stats
  card (PoolMiningState.running_since / last_error): it flips from "Connecting…"
  to "Can't reach pool — check the URL" after a 30s timeout instead of sitting
  on red forever, and no longer vanishes once logs arrive. The old transient
  banner in mining_tab.cpp was removed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ui/windows/mining_controls.cpp

@@ -991,6 +991,30 @@ void RenderMiningControls(App* app, const WalletState& state, const MiningInfo&
 
         ImGui::SetCursorScreenPos(ImVec2(cardMin.x, cardMax.y));
         ImGui::Dummy(ImVec2(availWidth, 0));
+
+        // Persistent error caption (a crashed/AV-blocked/failed miner otherwise leaves a button that
+        // "did nothing" once its toast faded). Normal ImGui flow, OUTSIDE the hand-drawn button card.
+        const std::string& merr = app->miningLastError();
+        if (!merr.empty() && !app->isMiningToggleInProgress()) {
+            ImGui::Dummy(ImVec2(0, Layout::spacingXs()));
+            ImGui::PushTextWrapPos(cardMin.x + availWidth);
+            ImGui::PushStyleColor(ImGuiCol_Text, ImGui::ColorConvertU32ToFloat4(Error()));
+            ImGui::TextWrapped("%s", merr.c_str());
+            ImGui::PopStyleColor();
+            ImGui::PushStyleColor(ImGuiCol_Text, ImGui::ColorConvertU32ToFloat4(OnSurfaceMedium()));
+            ImGui::TextUnformatted(TR("mining_error_retry_hint"));
+            ImGui::PopStyleColor();
+            ImGui::PopTextWrapPos();
+#ifdef _WIN32
+            if (app->miningErrorIsAntivirus()) {
+                ImGui::SameLine(0, Layout::spacingSm());
+                if (ImGui::SmallButton(TR("mining_error_av_help"))) app->showAntivirusHelp();
+            }
+#endif
+            ImGui::SameLine(0, Layout::spacingSm());
+            if (ImGui::SmallButton(TR("mining_error_dismiss"))) app->clearMiningError();
+        }
+
         ImGui::Dummy(ImVec2(0, gap));
 }
 

src/ui/windows/mining_stats.cpp

@@ -248,6 +248,21 @@ static void RenderLeftPoolCard(App* app, const WalletState& state, ImDrawList* d
         else                  snprintf(uptBuf, sizeof(uptBuf), "%lldh %lldm", (long long)(up / 3600), (long long)((up % 3600) / 60));
         metricRow(TR("mining_uptime"), uptBuf, OnSurface());
     }
+    // Connection status — replaces the old transient "Connecting" banner, with a timeout so a bad URL /
+    // blocked port flips from "Connecting" to "Can't reach pool" instead of spinning on red forever.
+    {
+        static constexpr int kPoolConnectTimeoutSec = 30;
+        const bool shares = pm.accepted + pm.rejected > 0;
+        const bool ok     = pm.connected || shares || pm.hashrate_10s > 0;
+        const bool failed = pm.xmrig_running && !ok && pm.running_since > 0 &&
+                            (std::time(nullptr) - pm.running_since) >= kPoolConnectTimeoutSec;
+        const char* stateText; ImU32 col;
+        if (ok)                    { stateText = TR("mining_status_connected");  col = Success(); }
+        else if (failed)           { stateText = TR("mining_pool_unreachable");  col = Error(); }
+        else if (pm.xmrig_running) { stateText = TR("mining_status_connecting"); col = Warning(); }
+        else                       { stateText = TR("mining_status_stopped");    col = OnSurfaceDisabled(); }
+        metricRow(TR("mining_status_label"), stateText, col);
+    }
     y += gap * 0.5f;
 
     // The pool list = official pools ∪ user-saved favorites ∪ the current custom pool.
@@ -397,7 +412,7 @@ void RenderMiningStats(const WalletState& state, const MiningInfo& mining,
             const float mRowH   = sub1->LegacySize + 7 * dp;
             const float listMinH = (capFont->LegacySize + 10 * dp) * 2.6f;  // ~2–3 rows before scroll
             float leftContentH = pad * 0.75f + toggleH + gap
-                               + mRowH * 4.0f + gap * 0.5f
+                               + mRowH * 5.0f + gap * 0.5f   // 4 metric rows + the connection-status row
                                + (ovFont->LegacySize + 4 * dp) + listMinH + pad * 0.75f;
             float cardH = std::max(leftContentH, statRowH + chartBudgetH + pad);
 

src/ui/windows/mining_tab.cpp

@@ -335,24 +335,9 @@ static void RenderMiningTabContent(App* app)
                          isMiningActive, s_pool_mode, availWidth, glassSpec, sHdr, gapOver);
 
     // ================================================================
-    // POOL CONNECTION STATUS — inline indicator (pool mode, no log)
-    // ================================================================
-    if (s_pool_mode && state.pool_mining.log_lines.empty() && state.pool_mining.xmrig_running) {
-        ImFont* iconFont = Type().iconSmall();
-        const char* dotIcon = ICON_MD_CIRCLE;
-        ImU32 dotCol = state.pool_mining.connected ? WithAlpha(Success(), 200) : WithAlpha(Error(), 200);
-        const char* statusText = state.pool_mining.connected
-            ? (state.pool_mining.pool_url.empty() ? TR("mining_connected") : state.pool_mining.pool_url.c_str())
-            : TR("mining_connecting");
-
-        ImVec2 pos = ImGui::GetCursorScreenPos();
-        ImVec2 dotSz = iconFont->CalcTextSizeA(iconFont->LegacySize, 1000.0f, 0.0f, dotIcon);
-        dl->AddText(iconFont, iconFont->LegacySize, pos, dotCol, dotIcon);
-        dl->AddText(capFont, capFont->LegacySize,
-                    ImVec2(pos.x + dotSz.x + 4 * dp, pos.y + (dotSz.y - capFont->LegacySize) * 0.5f),
-                    OnSurfaceMedium(), statusText);
-        ImGui::Dummy(ImVec2(availWidth, capFont->LegacySize + 4 * dp));
-    }
+    // (Pool connection status now lives as a persistent, timeout-aware row in RenderLeftPoolCard
+    //  (mining_stats.cpp) — the old transient "Connecting" banner that vanished once logs arrived and
+    //  sat on red forever on failure was removed.)
 }
 
 } // namespace ui