feat(fullnode): auto-reconcile wallet after bootstrap; runtime rescan for pruned nodes

A wallet bootstrapped from a snapshot keeps its wallet.dat but never rescans, so
its spent-state is stale and the first send tries to spend already-spent notes and
is rejected. The startup -rescan flag can't fix it either: the snapshot lacks the
pre-snapshot block history -rescan needs, so it errors. The working fix is a runtime
rescanblockchain RPC from a height the snapshot actually has.

- Add App::runtimeRescan(startHeight): runs rescanblockchain via the worker, drives
  the rescanning UI state, and owns completion via the RPC callback (getrescaninfo
  is unavailable on this daemon). Suppresses the per-second mining/rescan pollers
  and the Core/balance/tx refreshes while the daemon holds cs_main for the scan.
- Add App::detectLowestAvailableBlockHeight(): async binary search via getblock for
  the lowest height whose block data is on disk → the snapshot base, and whether the
  node still has full history.
- Auto-reconcile after bootstrap: both completion sites (wizard + Settings download
  dialog) mark a pending rescan; once the daemon is back up and the tip is known,
  detect the base and runtimeRescan() from it (or -rescan restart on a full node).
- Settings "Rescan Blockchain" now probes first: full-history nodes get the existing
  -rescan restart; bootstrapped/pruned nodes get a prompt pre-filled with the
  detected base height that runs the runtime rescan.

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

src/ui/pages/settings_page.cpp

@@ -148,6 +148,12 @@ struct SettingsPageState {
     bool confirm_clear_ztx = false;
     bool confirm_delete_blockchain = false;
     bool confirm_rescan = false;
+    // Rescan dialog: probe the node's available block range so a bootstrapped/pruned node gets a
+    // runtime rescan from a snapshot-available height instead of the (failing) -rescan-from-genesis.
+    bool rescan_height_detecting = false;
+    bool rescan_height_detected = false;
+    bool rescan_full_history = true;     // genesis present → traditional -rescan restart
+    int  rescan_start_height = 0;        // editable pre-fill for the runtime rescan
     bool confirm_repair_wallet = false;
     bool confirm_reinstall_daemon = false;
     // Cached daemon-binary status for the "daemon binary" panel (loaded once / on Refresh,
@@ -2241,6 +2247,9 @@ void RenderSettingsPage(App* app) {
                 ImGui::SameLine(0, Layout::spacingMd());
                 if (TactileButton(TR("rescan"), ImVec2(0, 0), dbBtnFont)) {
                     s_settingsState.confirm_rescan = true;
+                    // Re-probe the available block range each time the dialog is opened.
+                    s_settingsState.rescan_height_detecting = false;
+                    s_settingsState.rescan_height_detected = false;
                 }
                 if (ImGui::IsItemHovered(ImGuiHoveredFlags_AllowWhenDisabled)) ImGui::SetTooltip("%s", TR("tt_rescan"));
                 ImGui::EndDisabled();
@@ -2702,8 +2711,22 @@ void RenderSettingsPage(App* app) {
         }
     }
 
-    // Confirm: rescan blockchain (restarts the daemon, re-scans the whole chain — long but safe)
+    // Confirm: rescan blockchain. On a normal (full-history) node this restarts the daemon with
+    // -rescan; on a bootstrapped/pruned node that would fail (pre-snapshot blocks are absent), so we
+    // probe the lowest available block height and run a runtime rescanblockchain from a confirmed,
+    // editable height instead.
     if (s_settingsState.confirm_rescan) {
+        // Kick off the one-shot block-range probe the first frame the dialog is open.
+        if (!s_settingsState.rescan_height_detecting && !s_settingsState.rescan_height_detected) {
+            s_settingsState.rescan_height_detecting = true;
+            app->detectLowestAvailableBlockHeight([](bool ok, int lowest, bool fullHistory) {
+                s_settingsState.rescan_height_detecting = false;
+                s_settingsState.rescan_height_detected = true;
+                s_settingsState.rescan_full_history = (!ok) || fullHistory;
+                s_settingsState.rescan_start_height = (ok && !fullHistory) ? lowest : 0;
+            });
+        }
+
         if (BeginOverlayDialog(TR("confirm_rescan_title"), &s_settingsState.confirm_rescan, 500.0f, 0.94f)) {
             ImGui::PushFont(Type().iconLarge());
             ImGui::TextColored(ImVec4(1.0f, 0.8f, 0.2f, 1.0f), ICON_MD_WARNING);
@@ -2712,9 +2735,25 @@ void RenderSettingsPage(App* app) {
             ImGui::TextColored(ImVec4(1.0f, 0.8f, 0.2f, 1.0f), "%s", TR("warning"));
 
             ImGui::Spacing();
-            ImGui::TextWrapped("%s", TR("confirm_rescan_msg"));
-            ImGui::Spacing();
-            ImGui::TextColored(ImVec4(0.3f, 0.8f, 0.3f, 1.0f), "%s", TR("confirm_rescan_safe"));
+
+            const bool detecting = s_settingsState.rescan_height_detecting;
+            const bool bootstrapped = s_settingsState.rescan_height_detected && !s_settingsState.rescan_full_history;
+
+            if (detecting) {
+                ImGui::TextWrapped("%s", TR("rescan_detecting"));
+            } else if (bootstrapped) {
+                ImGui::TextWrapped("%s", TR("rescan_bootstrapped_msg"));
+                ImGui::Spacing();
+                ImGui::Text("%s", TR("rescan_from_height"));
+                ImGui::SetNextItemWidth(160.0f);
+                ImGui::InputInt("##rescanHeight", &s_settingsState.rescan_start_height);
+                if (s_settingsState.rescan_start_height < 0) s_settingsState.rescan_start_height = 0;
+            } else {
+                ImGui::TextWrapped("%s", TR("confirm_rescan_msg"));
+                ImGui::Spacing();
+                ImGui::TextColored(ImVec4(0.3f, 0.8f, 0.3f, 1.0f), "%s", TR("confirm_rescan_safe"));
+            }
+
             ImGui::Spacing();
             ImGui::Separator();
             ImGui::Spacing();
@@ -2724,10 +2763,16 @@ void RenderSettingsPage(App* app) {
                 s_settingsState.confirm_rescan = false;
             }
             ImGui::SameLine();
+            ImGui::BeginDisabled(detecting);
             if (ImGui::Button(TrId("rescan", "rescan_confirm").c_str(), ImVec2(btnW, 40))) {
-                app->rescanBlockchain();
+                if (bootstrapped) {
+                    app->runtimeRescan(s_settingsState.rescan_start_height);
+                } else {
+                    app->rescanBlockchain();
+                }
                 s_settingsState.confirm_rescan = false;
             }
+            ImGui::EndDisabled();
             EndOverlayDialog();
         }
     }

src/ui/windows/bootstrap_download_dialog.h

@@ -226,6 +226,8 @@ private:
         if (s_bootstrap->isDone()) {
             auto finalProg = s_bootstrap->getProgress();
             if (finalProg.state == util::Bootstrap::State::Completed) {
+                // Reconcile the preserved wallet.dat against the new chain once the daemon is back up.
+                s_app->markPostBootstrapRescanPending();
                 s_state = State::Done;
             } else {
                 s_errorMsg = finalProg.error;