From b133a21914cc9d55f80ffd98b5d7e5243bb87cd5 Mon Sep 17 00:00:00 2001
From: Malte Langkabel <malte.langkabel@gmail.com>
Date: Mon, 3 Aug 2026 21:53:19 +0200
Subject: [PATCH] make BlueprintPanel read the block stock from the simulation

BlueprintPanel was the second panel caching BuildingBlocksChangedEvent's
payload as truth; it already held a Simulation*, so refreshButtonStates()
now re-reads getBuildingBlocksStock() at the point of use, per the "events
are refresh signals" rule.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YHcUerKAZKWNvSKJxYKbnG
---
 src/ui/BlueprintPanel.cpp | 8 ++++----
 src/ui/BlueprintPanel.h   | 3 ++-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/ui/BlueprintPanel.cpp b/src/ui/BlueprintPanel.cpp
index 8dcbdc3..f6b8c2a 100644
--- a/src/ui/BlueprintPanel.cpp
+++ b/src/ui/BlueprintPanel.cpp
@@ -27,7 +27,6 @@ BlueprintPanel::BlueprintPanel(Simulation* sim, const GameConfig* config, QWidge
     : QWidget(parent)
     , m_sim(sim)
     , m_config(config)
-    , m_currentBlocks(0)
 {
     QVBoxLayout* layout = new QVBoxLayout(this);
     layout->setContentsMargins(4, 4, 4, 4);
@@ -71,9 +70,8 @@ void BlueprintPanel::onSelectionChanged(const std::vector<BuildingId>& ids)
     refreshButtonStates();
 }
 
-void BlueprintPanel::handleEvent(std::shared_ptr<const BuildingBlocksChangedEvent> event)
+void BlueprintPanel::handleEvent(std::shared_ptr<const BuildingBlocksChangedEvent> /*event*/)
 {
-    m_currentBlocks = event->blocks;
     refreshButtonStates();
 }
 
@@ -247,10 +245,12 @@ void BlueprintPanel::refreshButtonStates()
     // A construction site counts the same as an operational building (REQ-UI-BLUEPRINT-CREATE).
     m_createBtn->setEnabled(selectionHasPlaceableBuilding(*m_sim, m_selectedBuildingIds));
 
+    const int blocks = m_sim->getBuildingBlocksStock();
+
     for (int i = 0; i < static_cast<int>(m_blueprintButtons.size()); ++i)
     {
         const int  cost      = computeBlueprintCost(m_blueprints[static_cast<std::size_t>(i)]);
-        const bool canAfford = m_currentBlocks >= cost;
+        const bool canAfford = blocks >= cost;
         m_blueprintButtons[static_cast<std::size_t>(i)]->setEnabled(
             canAfford || m_activeIndex == i);
     }
diff --git a/src/ui/BlueprintPanel.h b/src/ui/BlueprintPanel.h
index 513d0ef..ae4dd9c 100644
--- a/src/ui/BlueprintPanel.h
+++ b/src/ui/BlueprintPanel.h
@@ -53,10 +53,11 @@ private:
     void      loadFromDisk();
     void      saveToDisk() const;
 
+    // The simulation is the single source of truth for the block stock; the
+    // change event is only a refresh signal.
     Simulation*               m_sim;
     const GameConfig*         m_config;
     std::vector<BuildingId>     m_selectedBuildingIds;
-    int                       m_currentBlocks;
     std::optional<int>        m_activeIndex;  // nullopt = no blueprint selected
     std::vector<Blueprint>    m_blueprints;
     std::vector<QPushButton*> m_blueprintButtons;