Fix recipe button unclickable on construction site during play

A selected construction site rebuilt the entire panel on every
TickAdvancedEvent (~30x/s at 1x), because refreshSelectionDisplay() called
rebuild() for sites. Each rebuild runs buildSingle() -> hideAllWidgets(),
which hides and re-shows the recipe-select button. Hiding a QPushButton
mid-press clears its pressed state, so a rebuild landing between the user's
mouse press and release cancelled the click. While paused no tick advances,
so no rebuild occurred and the button worked -- matching the report.

Give sites a lightweight per-tick refresh that updates only the progress
label, mirroring refreshBuffers() for live buildings. The site progress
block is extracted from buildSingle() into refreshSiteProgress() (no
duplicated arithmetic). refreshSelectionDisplay() now takes a RefreshReason:
a PeriodicTick updates progress only, while a CommandApplied still rebuilds
so a site's newly chosen recipe/layout is reflected. The site -> completed
building transition remains handled by the existing "(Building) " title
branch.

No UI test added: the test target links only lib (no QtWidgets), per the
simulation/presentation split, so a widget-level test does not fit the
harness.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DyCu8vwChKMbLJQ3xosYEN

src/lib/eventsystem/event/CMakeLists.txt

@@ -31,6 +31,7 @@ SET(HDRS
 	${CMAKE_CURRENT_SOURCE_DIR}/BeamFiredEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/DebugDrawToggledEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/CommandRequestedEvent.h
+	${CMAKE_CURRENT_SOURCE_DIR}/PlayerCommandsAppliedEvent.h
 	PARENT_SCOPE
 )
 

src/lib/eventsystem/event/PlayerCommandsAppliedEvent.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "Event.h"
+
+// Emitted by GameWorldView once per frame after queued player commands have been
+// drained and applied to the simulation. It lets presentation widgets refresh
+// even while the game is paused (no tick advances, so no TickAdvancedEvent), for
+// example so a shipyard's layout preview appears immediately after its schematic
+// is chosen. It is a UI notification only and never feeds back into the command
+// queue, so it has no effect on replay recording or determinism.
+class PlayerCommandsAppliedEvent : public Event
+{
+};

src/ui/GameWorldView.cpp

@@ -62,6 +62,7 @@
 #include "ExpansionCostChangedEvent.h"
 #include "GameSpeedChangedEvent.h"
 #include "SchematicChoicesAvailableEvent.h"
+#include "PlayerCommandsAppliedEvent.h"
 #include "TickAdvancedEvent.h"
 
 namespace
@@ -212,6 +213,7 @@ void GameWorldView::onFrame()
         // Drain queued player commands once per frame, before the tick batch. This
         // runs even at 0x so a paused player sees placed construction sites
         // immediately, while staying deterministic (see docs/replay_design.md).
+        const bool commandsApplied = m_commandManager.hasPending();
         m_commandManager.drain();
 
         // A drained Reset reinitialized the simulation; reset the view to match.
@@ -221,6 +223,17 @@ void GameWorldView::onFrame()
             resetForNewGame();
         }
 
+        // Notify presentation widgets that queued commands were applied, so a
+        // paused player still sees the effect (e.g. a shipyard's layout preview
+        // after picking a schematic) even though no tick advances. UI-only: this
+        // does not touch the command queue or simulation, so replay recording
+        // and determinism are unaffected.
+        if (commandsApplied)
+        {
+            EventManager::getInstance()->sendEventImmediately(
+                std::make_shared<PlayerCommandsAppliedEvent>());
+        }
+
         const int ticks = m_tickDriver.advance(
             static_cast<double>(elapsed), m_gameSpeedMultiplier);
         for (int i = 0; i < ticks; ++i)

src/ui/SelectedBuildingPanel.cpp

@@ -33,6 +33,7 @@
 #include "ItemType.h"
 #include "LayoutDialogRequestedEvent.h"
 #include "ModulesConfig.h"
+#include "PlayerCommandsAppliedEvent.h"
 #include "RecipeSelectionDialog.h"
 #include "RecipeSelectionRequestedEvent.h"
 #include "Rotation.h"
@@ -294,38 +295,12 @@ void SelectedBuildingPanel::buildSingle(BuildingId id)
         }
         m_recipeSelectButton->show();
 
-        if (type == BuildingType::Shipyard && !recipeId.empty())
-        {
-            const ShipDef* sDef = findShipDef(recipeId);
-            if (sDef && !sDef->layout.empty())
-            {
-                ShipLayoutConfig layout;
-                if (shipLayout.has_value())
-                {
-                    layout = *shipLayout;
-                }
-                m_layoutPreview->setShipAndLayout(
-                    sDef->layout, layout, &m_config->modules.modules);
-                m_layoutPreview->show();
-                m_configureLayoutBtn->show();
-            }
-            else
-            {
-                m_layoutPreview->hide();
-                m_configureLayoutBtn->hide();
-            }
-        }
-        else
-        {
-            m_layoutPreview->hide();
-            m_configureLayoutBtn->hide();
-        }
+        updateShipyardLayoutWidgets(type, recipeId, shipLayout);
     }
     else
     {
         m_recipeSelectButton->hide();
-        m_layoutPreview->hide();
-        m_configureLayoutBtn->hide();
+        updateShipyardLayoutWidgets(type, recipeId, shipLayout);
     }
 
     // Belt "Clear" removes items from a live belt tile; a construction site has
@@ -362,6 +337,16 @@ void SelectedBuildingPanel::buildSingle(BuildingId id)
     }
 
     if (m_singleIsSite)
+    {
+        refreshSiteProgress(s);
+    }
+    else
+    {
+        refreshBuffers(b);
+    }
+}
+
+void SelectedBuildingPanel::refreshSiteProgress(const ConstructionSite* s)
 {
     QString progress;
     if (s->completesAt == 0)
@@ -390,11 +375,6 @@ void SelectedBuildingPanel::buildSingle(BuildingId id)
     }
     m_buffersLabel->setText(progress);
 }
-    else
-    {
-        refreshBuffers(b);
-    }
-}
 
 void SelectedBuildingPanel::refreshBuffers(const Building* b)
 {
@@ -530,15 +510,38 @@ void SelectedBuildingPanel::refreshBuffers(const Building* b)
 
     m_buffersLabel->setText(bufText);
 
-    if (b->type == BuildingType::Shipyard && shipDef && !shipDef->layout.empty())
+    // The recipe/schematic is applied via a queued command that only drains on a
+    // later frame, so the per-tick refresh must own the shipyard preview and the
+    // Configure Layout button's visibility; otherwise they stay hidden until the
+    // building is re-selected (which re-runs buildSingle).
+    updateShipyardLayoutWidgets(b->type, b->recipeId, b->shipLayout);
+}
+
+void SelectedBuildingPanel::updateShipyardLayoutWidgets(
+    BuildingType type,
+    const std::string& recipeId,
+    const std::optional<ShipLayoutConfig>& shipLayout)
+{
+    const ShipDef* shipDef = (type == BuildingType::Shipyard)
+        ? findShipDef(recipeId)
+        : nullptr;
+
+    if (shipDef && !shipDef->layout.empty())
     {
         ShipLayoutConfig layout;
-        if (b->shipLayout.has_value())
+        if (shipLayout.has_value())
         {
-            layout = *b->shipLayout;
+            layout = *shipLayout;
         }
         m_layoutPreview->setShipAndLayout(
             shipDef->layout, layout, &m_config->modules.modules);
+        m_layoutPreview->show();
+        m_configureLayoutBtn->show();
+    }
+    else
+    {
+        m_layoutPreview->hide();
+        m_configureLayoutBtn->hide();
     }
 }
 
@@ -563,6 +566,21 @@ const ShipDef* SelectedBuildingPanel::findShipDef(const std::string& id) const
 }
 
 void SelectedBuildingPanel::handleEvent(std::shared_ptr<const TickAdvancedEvent> /*event*/)
+{
+    refreshSelectionDisplay(RefreshReason::PeriodicTick);
+}
+
+void SelectedBuildingPanel::handleEvent(
+    std::shared_ptr<const PlayerCommandsAppliedEvent> /*event*/)
+{
+    // Player commands (e.g. choosing a shipyard schematic) are applied by a
+    // queued drain, not synchronously. When the game is paused no tick advances,
+    // so TickAdvancedEvent never fires; refresh here too, otherwise the panel
+    // would not reflect the change until the next tick or a re-selection.
+    refreshSelectionDisplay(RefreshReason::CommandApplied);
+}
+
+void SelectedBuildingPanel::refreshSelectionDisplay(RefreshReason reason)
 {
     if (m_selectedEntity.has_value())
     {
@@ -586,8 +604,19 @@ void SelectedBuildingPanel::handleEvent(std::shared_ptr<const TickAdvancedEvent>
     }
     const ConstructionSite* s = m_sim->buildings().findSite(m_singleBuildingId);
     if (s)
+    {
+        // A periodic tick only advances construction progress, so update just the
+        // progress label. Rebuilding every tick would hide/re-show all widgets and
+        // cancel any in-progress click on the recipe button. An applied command
+        // may have changed the site's recipe/layout, so rebuild in that case.
+        if (reason == RefreshReason::CommandApplied)
         {
             rebuild();
+        }
+        else
+        {
+            refreshSiteProgress(s);
+        }
         return;
     }
     buildEmpty();
@@ -647,9 +676,11 @@ void SelectedBuildingPanel::onSelectRecipeClicked()
         return;
     }
     // The emit is synchronous: MainWindow pauses the game, runs the modal
-    // selection dialog, applies the chosen recipe/schematic, and restores the
-    // speed before this returns. rebuild() then refreshes the button caption,
-    // tooltip, preview, and buffers for the new selection.
+    // selection dialog, and restores the speed before this returns. The chosen
+    // recipe/schematic is only *enqueued* as a command, though, and drains on a
+    // later frame -- so this rebuild() still sees the old recipe. The per-tick
+    // refreshBuffers() path picks up the new schematic (and shows the layout
+    // preview + Configure Layout button) once the command has been applied.
     EventManager::getInstance()->sendEventImmediately(
         std::make_shared<RecipeSelectionRequestedEvent>(m_singleBuildingId));
     rebuild();

src/ui/SelectedBuildingPanel.h

@@ -16,6 +16,7 @@
 #include "EntitySelectedEvent.h"
 #include "EventHandler.h"
 #include "GameConfig.h"
+#include "PlayerCommandsAppliedEvent.h"
 #include "RecipesConfig.h"
 #include "SelectionChangedEvent.h"
 #include "ShipLayout.h"
@@ -33,6 +34,7 @@ class QVBoxLayout;
 
 class SelectedBuildingPanel : public QWidget,
                                public CombinedEventHandler<TickAdvancedEvent,
+                                                           PlayerCommandsAppliedEvent,
                                                            EntitySelectedEvent,
                                                            SelectionChangedEvent,
                                                            DebugDrawToggledEvent>
@@ -46,6 +48,7 @@ public:
 
 private:
     void handleEvent(std::shared_ptr<const TickAdvancedEvent> event) override;
+    void handleEvent(std::shared_ptr<const PlayerCommandsAppliedEvent> event) override;
     void handleEvent(std::shared_ptr<const EntitySelectedEvent> event) override;
     void handleEvent(std::shared_ptr<const SelectionChangedEvent> event) override;
     void handleEvent(std::shared_ptr<const DebugDrawToggledEvent> event) override;
@@ -56,7 +59,18 @@ private slots:
     void onSplitterFilterChanged();
 
 private:
+    // Why the selection display is being refreshed. A periodic tick only needs a
+    // lightweight content update (e.g. a construction site's progress label),
+    // whereas an applied player command may have changed the configuration and
+    // needs a full structural rebuild.
+    enum class RefreshReason
+    {
+        PeriodicTick,
+        CommandApplied
+    };
+
     void onSelectionChanged(const std::vector<BuildingId>& ids);
+    void refreshSelectionDisplay(RefreshReason reason);
     void rebuild();
     void hideAllWidgets();
     void clearContent();
@@ -64,6 +78,10 @@ private:
     void buildSingle(BuildingId id);
     void buildMulti(const std::vector<BuildingId>& ids);
     void refreshBuffers(const Building* b);
+    void refreshSiteProgress(const ConstructionSite* s);
+    void updateShipyardLayoutWidgets(BuildingType type,
+                                     const std::string& recipeId,
+                                     const std::optional<ShipLayoutConfig>& shipLayout);
     void buildSplitterFilters(const std::optional<BeltSystem::SplitterInfo>& info);
     const RecipeDef* findRecipe(const Building* b) const;
     const ShipDef*   findShipDef(const std::string& id) const;