make deconstruction its own system

src/lib/sim/BuildingSystem.cpp

@@ -181,7 +181,7 @@ int BuildingSystem::deconstruct(FactoryState& state, BuildingId id, Tick current
         state.deconstructionQueue.push_back(std::move(entry));
         if (wasEmpty)
         {
-            startFrontDeconstruction(state, currentTick);
+            startFrontDeconstruction(state, m_config, currentTick);
         }
         return 0;
     }
@@ -189,17 +189,6 @@ int BuildingSystem::deconstruct(FactoryState& state, BuildingId id, Tick current
     return 0;
 }
 
-void BuildingSystem::startFrontDeconstruction(FactoryState& state, Tick currentTick)
-{
-    if (state.deconstructionQueue.empty()) { return; }
-    DeconstructionEntry& front = state.deconstructionQueue.front();
-    if (front.completesAt == 0)
-    {
-        front.completesAt =
-            currentTick + secondsToTicks(m_config.world.deconstructionTimeSeconds);
-    }
-}
-
 // ---------------------------------------------------------------------------
 // Set recipe
 // ---------------------------------------------------------------------------
@@ -334,53 +323,6 @@ void BuildingSystem::setSiteSplitterFilters(FactoryState& state, BuildingId id,
 // Tick hooks
 // ---------------------------------------------------------------------------
 
-void BuildingSystem::tickDeconstruction(FactoryState& state, Tick currentTick)
-{
-    TRACE();
-    if (state.deconstructionQueue.empty())
-    {
-        return;
-    }
-
-    DeconstructionEntry& front = state.deconstructionQueue.front();
-
-    // Guard: if the front entry's timer was never started, start it now.
-    if (front.completesAt == 0)
-    {
-        startFrontDeconstruction(state, currentTick);
-        return;
-    }
-
-    if (currentTick < front.completesAt)
-    {
-        return;
-    }
-
-    // Remove the building from the world and credit its refund (REQ-BLD-DECONSTRUCT).
-    // Belt/tunnel/splitter tiles were already unregistered when the building was
-    // queued (see deconstruct), so only tile occupancy and the record remain.
-    for (std::vector<Building>::iterator it = state.buildings.begin();
-         it != state.buildings.end();
-         ++it)
-    {
-        if (it->id != front.id) { continue; }
-
-        const BuildingDef* def = m_config.buildings.findBuildingDef(it->type);
-        state.grid.release(it->bodyCells);
-        state.buildings.erase(it);
-        if (def)
-        {
-            m_addBuildingBlocks(def->cost * m_config.world.refundPercentage / 100);
-        }
-        break;
-    }
-
-    state.deconstructionQueue.pop_front();
-
-    // Start the next queued deconstruction, if any.
-    startFrontDeconstruction(state, currentTick);
-}
-
 void BuildingSystem::cancelDeconstruction(FactoryState& state, BuildingId id)
 {
     for (std::deque<DeconstructionEntry>::iterator it = state.deconstructionQueue.begin();

src/lib/sim/BuildingSystem.h

@@ -17,6 +17,7 @@
 #include "Building.h"
 #include "FactoryState.h"
 #include "BuildingBuffers.h"
+#include "DeconstructionSystem.h"
 #include "PlacementRules.h"
 #include "ProductionRules.h"
 #include "BuildingType.h"
@@ -107,7 +108,6 @@ public:
     // Advances the deconstruction queue (REQ-BLD-DECON-QUEUE): one building at a
     // time, in parallel with tickConstruction. Removes the front building and
     // credits its refund when its timer elapses.
-    void tickDeconstruction(FactoryState& state, Tick currentTick);
     void tickBeltPull(FactoryState& state);
     void tickProduction(FactoryState& state, Tick currentTick);
     void tickShipyardProduction(FactoryState& state, Tick currentTick);
@@ -183,7 +183,6 @@ public:
 private:
     // Starts the front deconstruction-queue entry's timer if not yet started
     // (mirrors how tickConstruction starts a queued construction site).
-    void                 startFrontDeconstruction(FactoryState& state, Tick currentTick);
 
     // Registers a belt/splitter/tunnel building's tile with the belt subsystem
     // (on construction completion, or when un-queuing a deconstruction). No-op for

src/lib/sim/CMakeLists.txt

@@ -14,6 +14,7 @@ SET(HDRS
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingConfig.h
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingGrid.h
     ${CMAKE_CURRENT_SOURCE_DIR}/ConstructionSystem.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/DeconstructionSystem.h
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingBuffers.h
     ${CMAKE_CURRENT_SOURCE_DIR}/FactoryState.h
     ${CMAKE_CURRENT_SOURCE_DIR}/FactoryQueries.h
@@ -45,6 +46,7 @@ SET(SRCS
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingConfig.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingGrid.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/ConstructionSystem.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/DeconstructionSystem.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildingBuffers.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/FactoryQueries.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/ProductionRules.cpp

src/lib/sim/DeconstructionSystem.cpp

@@ -0,0 +1,67 @@
+#include "DeconstructionSystem.h"
+
+#include <vector>
+
+#include "Building.h"
+#include "tracing.h"
+
+void startFrontDeconstruction(FactoryState& state, const GameConfig& config,
+                              Tick currentTick)
+{
+    if (state.deconstructionQueue.empty()) { return; }
+    DeconstructionEntry& front = state.deconstructionQueue.front();
+    if (front.completesAt == 0)
+    {
+        front.completesAt =
+            currentTick + secondsToTicks(config.world.deconstructionTimeSeconds);
+    }
+}
+
+
+void DeconstructionSystem::tick(FactoryState& state, Tick currentTick)
+{
+    TRACE();
+    if (state.deconstructionQueue.empty())
+    {
+        return;
+    }
+
+    DeconstructionEntry& front = state.deconstructionQueue.front();
+
+    // Guard: if the front entry's timer was never started, start it now.
+    if (front.completesAt == 0)
+    {
+        startFrontDeconstruction(state, m_config, currentTick);
+        return;
+    }
+
+    if (currentTick < front.completesAt)
+    {
+        return;
+    }
+
+    // Remove the building from the world and credit its refund (REQ-BLD-DECONSTRUCT).
+    // Belt/tunnel/splitter tiles were already unregistered when the building was
+    // queued (see deconstruct), so only tile occupancy and the record remain.
+    for (std::vector<Building>::iterator it = state.buildings.begin();
+         it != state.buildings.end();
+         ++it)
+    {
+        if (it->id != front.id) { continue; }
+
+        const BuildingDef* def = m_config.buildings.findBuildingDef(it->type);
+        state.grid.release(it->bodyCells);
+        state.buildings.erase(it);
+        if (def)
+        {
+            m_addBuildingBlocks(def->cost * m_config.world.refundPercentage / 100);
+        }
+        break;
+    }
+
+    state.deconstructionQueue.pop_front();
+
+    // Start the next queued deconstruction, if any.
+    startFrontDeconstruction(state, m_config, currentTick);
+}
+

src/lib/sim/DeconstructionSystem.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <functional>
+
+#include "FactoryState.h"
+#include "GameConfig.h"
+#include "Tick.h"
+
+// The queue timer for pending demolitions (REQ-BLD-DECON-QUEUE): one building at a
+// time, in parallel with construction. When the front entry's timer elapses the
+// building is removed from the world, its tiles are released, and its partial refund
+// is credited.
+//
+// It needs no BeltSystem: a belt, splitter or tunnel end is unregistered the moment
+// it is queued (see BuildingSystem::deconstruct), not when the timer completes.
+//
+// Holds the config and the refund sink; the world arrives per tick.
+class DeconstructionSystem
+{
+public:
+    DeconstructionSystem(const GameConfig& config,
+                         std::function<void(int)> addBuildingBlocks)
+        : m_config(config), m_addBuildingBlocks(std::move(addBuildingBlocks)) {}
+
+    void tick(FactoryState& state, Tick currentTick);
+
+private:
+    const GameConfig&        m_config;
+    std::function<void(int)> m_addBuildingBlocks;
+};
+
+// Starts the timer on the front entry of the deconstruction queue, if it has one and
+// it has not started yet. Shared: BuildingSystem::deconstruct starts the timer when it
+// queues the first entry, and DeconstructionSystem restarts it after each completion.
+void startFrontDeconstruction(FactoryState& state, const GameConfig& config,
+                              Tick currentTick);

src/lib/sim/Simulation.cpp

@@ -2,6 +2,7 @@
 
 #include "FactoryQueries.h"
 #include "ConstructionSystem.h"
+#include "DeconstructionSystem.h"
 #include "PlacementRules.h"
 
 #include <algorithm>
@@ -125,6 +126,8 @@ void Simulation::initializeSubsystems()
         [this](const std::string& itemId) -> bool { return isItemUnlocked(itemId); },
         m_rng);
     m_constructionSystem = std::make_unique<ConstructionSystem>(m_config);
+    m_deconstructionSystem = std::make_unique<DeconstructionSystem>(
+        m_config, [this](int amount) { m_buildingBlocksStock += amount; });
     m_shipSystem     = std::make_unique<ShipSystem>(m_config, m_admin);
     m_aiSystem       = std::make_unique<AiSystem>(m_config);
     m_movementIntentSystem = std::make_unique<MovementIntentSystem>();
@@ -246,7 +249,7 @@ void Simulation::tick()
 
     // Construction + production pipeline
     m_constructionSystem->tick(m_factoryState, m_beltSystem, m_currentTick);
-    m_buildingSystem->tickDeconstruction(m_factoryState, m_currentTick); // parallel to construction
+    m_deconstructionSystem->tick(m_factoryState, m_currentTick);        // parallel to construction
     m_buildingSystem->tickBeltPull(m_factoryState);                    // step 3
     m_buildingSystem->tickProduction(m_factoryState, m_currentTick);     // step 4
     m_buildingSystem->tickShipyardProduction(m_factoryState, m_currentTick); // step 4b

src/lib/sim/Simulation.h

@@ -26,6 +26,7 @@
 class AiSystem;
 class BuildingSystem;
 class ConstructionSystem;
+class DeconstructionSystem;
 struct Command;
 class Hasher;
 class CombatSystem;
@@ -220,6 +221,7 @@ private:
     BeltSystem                        m_beltSystem;
     std::unique_ptr<BuildingSystem>   m_buildingSystem;
     std::unique_ptr<ConstructionSystem> m_constructionSystem;
+    std::unique_ptr<DeconstructionSystem> m_deconstructionSystem;
     std::unique_ptr<ShipSystem>       m_shipSystem;
     std::unique_ptr<AiSystem>         m_aiSystem;
     std::unique_ptr<MovementIntentSystem> m_movementIntentSystem;

src/test/BuildingTest.cpp

@@ -16,6 +16,7 @@
 #include "Building.h"
 #include "BuildingSystem.h"
 #include "ConstructionSystem.h"
+#include "DeconstructionSystem.h"
 #include "FactoryState.h"
 #include "BuildingType.h"
 #include "ConfigLoader.h"
@@ -55,12 +56,12 @@ static Port westPort(QPoint tile)
 
 // Run N full sim ticks: construction, belt-pull, production, belt-push, belt tick.
 static void runTicks(BuildingSystem& bs, const GameConfig& cfg, FactoryState& state_bs,
-                     BeltSystem& belts, int n, Tick& tick)
+                     BeltSystem& belts, int& stock, int n, Tick& tick)
 {
     for (int i = 0; i < n; ++i)
     {
         ConstructionSystem(cfg).tick(state_bs, belts, tick);
-        bs.tickDeconstruction(state_bs, tick);
+        DeconstructionSystem(cfg, [&stock](int n) { stock += n; }).tick(state_bs, tick);
         bs.tickBeltPull(state_bs);
         bs.tickProduction(state_bs, tick);
         bs.tickOutputBelts(state_bs);
@@ -241,7 +242,7 @@ TEST_CASE("BuildingSystem: placing a belt registers it with BeltSystem after con
 
     // Complete construction (1 s).
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
 
     REQUIRE(belts.tryPutItem(QPoint(5, 5), makeItem("iron_ore"), Rotation::East));
     REQUIRE(getAllBuildings(state_bs).size() == 1);
@@ -354,7 +355,7 @@ TEST_CASE("BuildingSystem: construction completes after configured duration", "[
     // Miner construction_time_seconds = 10.  completesAt = secondsToTicks(10) = 300.
     // We need to process tick 300 itself, so run 301 ticks (ticks 0..300).
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
 
     REQUIRE(getAllSites(state_bs).empty());
     REQUIRE(findBuilding(state_bs, id) != nullptr);
@@ -369,7 +370,7 @@ static void runUntilBuilt(PlacementFixture& f, BuildingId id, Tick& tick)
 {
     for (int i = 0; i < 100000 && findBuilding(f.state, id) == nullptr; ++i)
     {
-        runTicks(f.bs, f.cfg, f.state, f.belts, 1, tick);
+        runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, 1, tick);
     }
     REQUIRE(findBuilding(f.state, id) != nullptr);
 }
@@ -394,7 +395,7 @@ TEST_CASE("BuildingSystem: deconstructing a built building queues it; refund cre
 
     // After the deconstruction time (0.1s = 3 ticks) it is removed and the partial
     // refund (15 * 75 / 100 = 11) is credited exactly once.
-    runTicks(f.bs, f.cfg, f.state, f.belts, static_cast<int>(secondsToTicks(0.1)) + 1, tick);
+    runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, static_cast<int>(secondsToTicks(0.1)) + 1, tick);
     REQUIRE(findBuilding(f.state, id) == nullptr);
     REQUIRE_FALSE(isTileOccupied(f.state, QPoint(0, 0)));
     REQUIRE(f.stock == 15 * f.cfg.world.refundPercentage / 100);
@@ -418,14 +419,14 @@ TEST_CASE("BuildingSystem: deconstruction queue removes one building at a time",
 
     // After one deconstruction interval only the front building is gone; the
     // second is still queued and its refund not yet credited.
-    runTicks(f.bs, f.cfg, f.state, f.belts, static_cast<int>(secondsToTicks(0.1)) + 1, tick);
+    runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, static_cast<int>(secondsToTicks(0.1)) + 1, tick);
     REQUIRE(findBuilding(f.state, a) == nullptr);
     REQUIRE(findBuilding(f.state, b) != nullptr);
     REQUIRE(isQueuedForDeconstruction(f.state, b));
     REQUIRE(f.stock == 15 * f.cfg.world.refundPercentage / 100);
 
     // The second drains next.
-    runTicks(f.bs, f.cfg, f.state, f.belts, static_cast<int>(secondsToTicks(0.1)) + 2, tick);
+    runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, static_cast<int>(secondsToTicks(0.1)) + 2, tick);
     REQUIRE(findBuilding(f.state, b) == nullptr);
     REQUIRE(f.stock == 2 * (15 * f.cfg.world.refundPercentage / 100));
 }
@@ -451,7 +452,7 @@ TEST_CASE("BuildingSystem: cancelling deconstruction resumes the building with n
     REQUIRE(f.stock == 0);
 
     // It is never removed even after more than a deconstruction interval passes.
-    runTicks(f.bs, f.cfg, f.state, f.belts, static_cast<int>(secondsToTicks(0.1)) + 5, tick);
+    runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, static_cast<int>(secondsToTicks(0.1)) + 5, tick);
     REQUIRE(findBuilding(f.state, id) != nullptr);
     REQUIRE(f.stock == 0);
 }
@@ -521,7 +522,7 @@ TEST_CASE("BuildingSystem: second building starts after first completes", "[buil
 
     // Process through tick 300 to complete first miner's construction.
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
 
     REQUIRE(getAllSites(state_bs).size() == 1);
     REQUIRE(getAllSites(state_bs).front().id == id2);
@@ -553,7 +554,7 @@ TEST_CASE("BuildingSystem: miner produces iron_ore after recipe duration", "[bui
     Tick tick = 0;
     // Construction completes on tick 300; production cycle starts tick 300,
     // completes on tick 330.  Process through tick 330: 331 ticks total.
-    runTicks(bs, cfg, state_bs, belts,
+    runTicks(bs, cfg, state_bs, belts, stock,
              static_cast<int>(secondsToTicks(10.0)) + static_cast<int>(secondsToTicks(1.0)) + 1,
              tick);
 
@@ -590,7 +591,7 @@ TEST_CASE("BuildingSystem: miner output buffer stalls when full", "[building]")
     // Cycle 2 starts at tick 331 (completesAt=361).
     // Cycle 2 completes at tick 361: deposit item → buffer=2, cycle 3 stalls.
     // Need to process through tick 361: 362 ticks total.
-    runTicks(bs, cfg, state_bs, belts,
+    runTicks(bs, cfg, state_bs, belts, stock,
              static_cast<int>(secondsToTicks(10.0))
              + 2 * static_cast<int>(secondsToTicks(1.0)) + 2,
              tick);
@@ -632,10 +633,10 @@ TEST_CASE("BuildingSystem: productionBuildingCount excludes construction sites",
 
     // The queue builds one at a time: miner (10s) completes at tick 300, then
     // the smelter (15s) starts and completes at tick 300 + 450 = 750.
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
     REQUIRE(getProductionBuildingCount(state_bs) == 1);
 
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(15.0)), tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(15.0)), tick);
     REQUIRE(getProductionBuildingCount(state_bs) == 2);
 
     // Neither is producing yet: the miner has no recipe selected, and the
@@ -643,7 +644,7 @@ TEST_CASE("BuildingSystem: productionBuildingCount excludes construction sites",
     REQUIRE(getActiveProductionBuildingCount(state_bs) == 0);
 
     bs.setRecipe(state_bs, minerId, "mine_iron_ore");
-    runTicks(bs, cfg, state_bs, belts, 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, 1, tick);
     REQUIRE(getActiveProductionBuildingCount(state_bs) == 1);
 }
 
@@ -671,12 +672,12 @@ TEST_CASE("BuildingSystem: activeProductionBuildingCount tracks production cycle
     REQUIRE(getActiveProductionBuildingCount(state_bs) == 0);
 
     // Construction completes at tick 300; cycle 1 starts the same tick (completesAt=330).
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(10.0)) + 1, tick);
     REQUIRE(getActiveProductionBuildingCount(state_bs) == 1);
 
     // Run cycles 1 and 2 to completion (1s each); cycle 3 stalls once the
     // output buffer (capacity 2) is full (REQ-MAT-OUTPUT-BUFFER).
-    runTicks(bs, cfg, state_bs, belts, 2 * static_cast<int>(secondsToTicks(1.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, 2 * static_cast<int>(secondsToTicks(1.0)) + 1, tick);
 
     const Building* b = findBuilding(state_bs, id);
     REQUIRE(b != nullptr);
@@ -714,7 +715,7 @@ TEST_CASE("BuildingSystem: smelter input buffer fills from adjacent west-flowing
 
     // Complete construction (15s → tick 450+1 = 451 ticks).
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
 
     // Place west-flowing belt at (2,0): belt flows West, delivers to smelter.
     belts.placeBelt(QPoint(2, 0), Rotation::West);
@@ -751,7 +752,7 @@ TEST_CASE("BuildingSystem: accepted input travels inward before entering the buf
 
     const BuildingId sid = bs.place(state_bs, BuildingType::Smelter, QPoint(0, 0), Rotation::East, 0).value();
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
 
     belts.placeBelt(QPoint(2, 0), Rotation::West);
     belts.tryPutItem(QPoint(2, 0), makeItem("iron_ore"));
@@ -794,7 +795,7 @@ TEST_CASE("BuildingSystem: input reservation caps buffered plus in-transit at th
     const BuildingId id = bs.place(state_bs, BuildingType::ReprocessingPlant,
                                   QPoint(0, 0), Rotation::East, 0).value();
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
 
     // Feed scrap via an input belt without ever running production (only pull), so
     // the buffer fills and stays full. Try to over-fill it well past the cap.
@@ -837,7 +838,7 @@ TEST_CASE("BuildingSystem: smelter auto-smelts ore without a recipe selection",
     const BuildingId sid = bs.place(state_bs, BuildingType::Smelter, QPoint(0, 0), Rotation::East, 0).value();
 
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
 
     // Feed 2 iron_ore (the test-config iron_ingot recipe needs 2) via a
     // west-flowing belt at input port (2,0).
@@ -850,7 +851,7 @@ TEST_CASE("BuildingSystem: smelter auto-smelts ore without a recipe selection",
     }
 
     // iron_ingot recipe cycle is 2s; run to completion.
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(2.0)) + 2, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(2.0)) + 2, tick);
 
     const Building* b = findBuilding(state_bs, sid);
     REQUIRE(b != nullptr);
@@ -884,7 +885,7 @@ TEST_CASE("BuildingSystem: smelter runs a satisfiable recipe while an incomplete
     const BuildingId sid = bs.place(state_bs, BuildingType::Smelter, QPoint(0, 0), Rotation::East, 0).value();
 
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(15.0)) + 1, tick);
 
     // Feed 1 iron_ore (iron_ingot needs 2 — incomplete) then 2 copper_ore
     // (copper_ingot needs 2 — satisfiable) via the west-flowing input belt.
@@ -898,7 +899,7 @@ TEST_CASE("BuildingSystem: smelter runs a satisfiable recipe while an incomplete
     }
 
     // copper_ingot cycle is 2.5s; run to completion.
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(2.5)) + 2, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(2.5)) + 2, tick);
 
     const Building* b = findBuilding(state_bs, sid);
     REQUIRE(b != nullptr);
@@ -944,13 +945,13 @@ TEST_CASE("BuildingSystem: miner output buffer drains onto adjacent belt", "[bui
 
     Tick tick = 0;
     // Construction (10s) + 1 production cycle (1s) + 1 extra tick.
-    runTicks(bs, cfg, state_bs, belts,
+    runTicks(bs, cfg, state_bs, belts, stock,
              static_cast<int>(secondsToTicks(10.0)) + static_cast<int>(secondsToTicks(1.0)) + 1,
              tick);
 
     // Item should have been pushed onto the belt this tick or a subsequent one.
     // Run one more tick to ensure tickBeltPush fires after the deposit tick.
-    runTicks(bs, cfg, state_bs, belts, 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, 1, tick);
 
     const std::optional<Item> item = belts.tryTakeItem(eastPort(QPoint(1, 1)));
     REQUIRE(item.has_value());
@@ -986,7 +987,7 @@ TEST_CASE("BuildingSystem: output port couples directly into an adjacent input p
 
     Tick tick = 0;
     // Smelter build (15s) + margin for coupling and a smelt cycle.
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(30.0)), tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(30.0)), tick);
 
     const Building* smelter = findBuilding(state_bs, smelterId);
     REQUIRE(smelter != nullptr);
@@ -1026,7 +1027,7 @@ TEST_CASE("BuildingSystem: direct coupling to a non-consumer leaves the item stu
 
     Tick tick = 0;
     // Both miners build sequentially (10s each), then the producer runs and jams.
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(25.0)), tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(25.0)), tick);
 
     const Building* miner = findBuilding(state_bs, minerId);
     const Building* sink  = findBuilding(state_bs, sinkId);
@@ -1062,7 +1063,7 @@ TEST_CASE("BuildingSystem: setRecipe clears output buffer and active production"
 
     Tick tick = 0;
     // Run until first item is in output buffer.
-    runTicks(bs, cfg, state_bs, belts,
+    runTicks(bs, cfg, state_bs, belts, stock,
              static_cast<int>(secondsToTicks(10.0)) + static_cast<int>(secondsToTicks(1.0)) + 1,
              tick);
 
@@ -1108,7 +1109,7 @@ TEST_CASE("BuildingSystem: reprocessing plant output buffer capacity equals max
 
     // Complete construction (25s).
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
 
     const Building* b = findBuilding(state_bs, id);
     REQUIRE(b != nullptr);
@@ -1141,7 +1142,7 @@ TEST_CASE("BuildingSystem: reprocessing plant produces one cycle output then sta
 
     // Complete construction (25s).
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(25.0)) + 1, tick);
 
     // Feed 5 scrap into the building via a belt at an input port.
     // Reprocessing plant body (East rotation) = 3×3 at (0,0).
@@ -1163,7 +1164,7 @@ TEST_CASE("BuildingSystem: reprocessing plant produces one cycle output then sta
     }
 
     // Run production cycle (3s = 90 ticks + 1 for the completion tick).
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(3.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(3.0)) + 1, tick);
 
     const Building* b = findBuilding(state_bs, id);
     REQUIRE(b != nullptr);
@@ -1240,7 +1241,7 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns the building id for a
     const BuildingId id = bs.place(state_bs, BuildingType::Belt, QPoint(0, 0), Rotation::East, 0).value();
 
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
     REQUIRE(getAllSites(state_bs).empty());
 
     const std::optional<BuildingId> result =
@@ -1422,7 +1423,7 @@ TEST_CASE("BuildingSystem: rotateInPlace updates rotation and output port direct
     const BuildingId id = bs.place(state_bs, BuildingType::Belt, QPoint(0, 0), Rotation::East, 0).value();
 
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
     REQUIRE(findBuilding(state_bs, id) != nullptr);
 
     const Building& before = *findBuilding(state_bs, id);
@@ -1454,7 +1455,7 @@ TEST_CASE("BuildingSystem: rotateInPlace re-registers a belt tile with BeltSyste
     const BuildingId id = bs.place(state_bs, BuildingType::Belt, QPoint(0, 0), Rotation::East, 0).value();
 
     Tick tick = 0;
-    runTicks(bs, cfg, state_bs, belts, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
+    runTicks(bs, cfg, state_bs, belts, stock, static_cast<int>(secondsToTicks(1.0)) + 1, tick);
 
     bs.rotateInPlace(state_bs, id, Rotation::North);
 
@@ -1474,7 +1475,7 @@ TEST_CASE("BuildingSystem: rotateInPlace preserves the output filters of a split
     Tick tick = 0;
     while (getAllBuildings(f.state).empty() && tick < 100000)
     {
-        runTicks(f.bs, f.cfg, f.state, f.belts, 1, tick);
+        runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, 1, tick);
     }
     REQUIRE(getAllBuildings(f.state).size() == 1);
 
@@ -1519,7 +1520,7 @@ TEST_CASE("BuildingSystem: splitter filters configured on a construction site ca
     Tick tick = 0;
     while (getAllBuildings(f.state).empty() && tick < 100000)
     {
-        runTicks(f.bs, f.cfg, f.state, f.belts, 1, tick);
+        runTicks(f.bs, f.cfg, f.state, f.belts, f.stock, 1, tick);
     }
     REQUIRE(getAllBuildings(f.state).size() == 1);
     REQUIRE(getAllBuildings(f.state)[0].type == BuildingType::Splitter);
@@ -1674,11 +1675,11 @@ namespace
     // Advances the sim until the given site becomes an operational building, or a
     // safety cap is reached.
     void buildToCompletion(BuildingSystem& bs, const GameConfig& cfg, FactoryState& state,
-                           BeltSystem& belts, BuildingId id, Tick& tick)
+                           BeltSystem& belts, int& stock, BuildingId id, Tick& tick)
     {
         for (int i = 0; i < 20000 && findBuilding(state, id) == nullptr; ++i)
         {
-            runTicks(bs, cfg, state, belts, 1, tick);
+            runTicks(bs, cfg, state, belts, stock, 1, tick);
         }
     }
 }
@@ -1713,7 +1714,7 @@ TEST_CASE("BuildingSystem: getInputPorts matches between a site and the built bu
     const BuildingId id = f.bs.place(f.state, BuildingType::Miner, QPoint(0, 0), Rotation::East, 0).value();
 
     const std::vector<Port> sitePorts = getInputPorts(f.state, f.cfg, id);
-    buildToCompletion(f.bs, f.cfg, f.state, f.belts, id, tick);
+    buildToCompletion(f.bs, f.cfg, f.state, f.belts, f.stock, id, tick);
     REQUIRE(findBuilding(f.state, id) != nullptr);
     const std::vector<Port> builtPorts = getInputPorts(f.state, f.cfg, id);