move FactoryState ownership out of BuildingSystem to Simulation

Simulation (and ArenaSimulation in the balancing tool) now owns the factory's world data; BuildingSystem holds a reference to it. This is what lets the systems that operate on the data be handed the same state — phase 3's construction and deconstruction systems, and later the ecs/system/ classes that today take a BuildingSystem& only to query it. reset() clears the state alongside m_admin and m_beltSystem, matching how the subsystems were already rebuilt from scratch. Falls short of the tick-argument form I sketched: BuildingSystem still reaches the data through a member reference rather than a parameter. Making it truly stateless means the const query surface has to find the data some other way, and that surface is large — findBuilding alone has 64 call sites, with findSite, getAllBuildings, getAllSites, isTileOccupied and the rest behind it. Doing that needs a queries facade behind Simulation::getBuildings() so the callers do not all move, which is its own decision rather than a side effect of this one. The constructor gains a parameter, so the four owners and the three test fixtures that build a BuildingSystem directly are updated; the 33 files that only use one are untouched. Verified with a golden-checksum capture before and after — all four sample ticks identical. Co-Authored-By: Claude <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01YHcUerKAZKWNvSKJxYKbnG
gather the factory's world data into FactoryState
2026-08-04 20:55:32 +02:00 · 2026-08-04 20:39:34 +02:00
11 changed files with 219 additions and 134 deletions
--- a/src/balancing/ArenaSimulation.cpp
+++ b/src/balancing/ArenaSimulation.cpp
@@ -48,6 +48,7 @@ ArenaSimulation::ArenaSimulation(const GameConfig& gameConfig,
 {
    m_buildingSystem = std::make_unique<BuildingSystem>(
        m_gameConfig,
+        m_factoryState,
        m_beltSystem,
        [this]() { return allocateBuildingId(); },
        [](int) {},
--- a/src/balancing/ArenaSimulation.h
+++ b/src/balancing/ArenaSimulation.h
@@ -10,6 +10,7 @@

 #include "BalancingConfig.h"
 #include "BeltSystem.h"
+#include "FactoryState.h"
 #include "EntityAdmin.h"
 #include "BuildingId.h"

@@ -107,6 +108,7 @@ private:
    BuildingId m_nextBuildingId;

    EntityAdmin m_admin;
+    FactoryState                      m_factoryState;
    BeltSystem m_beltSystem;
    std::unique_ptr<BuildingSystem> m_buildingSystem;
    std::unique_ptr<ShipSystem>     m_shipSystem;
--- a/src/lib/sim/BuildingSystem.cpp
+++ b/src/lib/sim/BuildingSystem.cpp
@@ -23,6 +23,7 @@ bool inputLaneEntryFree(const std::vector<BeltItemSlot>& lane)
 }  // namespace

 BuildingSystem::BuildingSystem(const GameConfig& config,
+                               FactoryState& state,
                               BeltSystem& belts,
                               std::function<BuildingId()> allocateBuildingId,
                               std::function<void(int)> addBuildingBlocks,
@@ -31,6 +32,7 @@ BuildingSystem::BuildingSystem(const GameConfig& config,
                               std::function<bool(const std::string&)> isItemUnlocked,
                               std::mt19937& rng)
    : m_config(config)
+    , m_state(state)
    , m_belts(belts)
    , m_allocateBuildingId(std::move(allocateBuildingId))
    , m_addBuildingBlocks(std::move(addBuildingBlocks))
@@ -308,7 +310,7 @@ std::optional<BuildingId> BuildingSystem::place(BuildingType type, QPoint anchor
    for (const QPoint& cell : mask.bodyCells)
    {
        const QPoint absCell = anchor + cell;
-        m_grid.occupy(absCell, id);
+        m_state.grid.occupy(absCell, id);
    }

    // Build construction site.
@@ -323,13 +325,13 @@ std::optional<BuildingId> BuildingSystem::place(BuildingType type, QPoint anchor
        site.bodyCells.push_back(anchor + cell);
    }

-    if (m_constructionQueue.empty())
+    if (m_state.constructionQueue.empty())
    {
        site.completesAt = currentTick + secondsToTicks(def->constructionTimeSeconds);
    }
    // else: completesAt remains 0 (queued, not yet started).

-    m_constructionQueue.push_back(std::move(site));
+    m_state.constructionQueue.push_back(std::move(site));
    return id;
 }

@@ -405,15 +407,15 @@ int BuildingSystem::deconstruct(BuildingId id, Tick currentTick)
 {
    // Construction site? Removed instantly with the full refund; never queued
    // for deconstruction (REQ-BLD-DECONSTRUCT).
-    for (std::deque<ConstructionSite>::iterator it = m_constructionQueue.begin();
-         it != m_constructionQueue.end();
+    for (std::deque<ConstructionSite>::iterator it = m_state.constructionQueue.begin();
+         it != m_state.constructionQueue.end();
         ++it)
    {
        if (it->id == id)
        {
            const BuildingDef* def = m_config.buildings.findBuildingDef(it->type);
-            m_grid.release(it->bodyCells);
-            m_constructionQueue.erase(it);
+            m_state.grid.release(it->bodyCells);
+            m_state.constructionQueue.erase(it);
            if (def)
            {
                return def->cost;
@@ -425,7 +427,7 @@ int BuildingSystem::deconstruct(BuildingId id, Tick currentTick)
    // Operational building? Append it to the deconstruction queue rather than
    // removing it now; the partial refund is credited on completion in
    // tickDeconstruction (REQ-BLD-DECON-QUEUE).
-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        if (building.id != id) { continue; }
        if (building.queuedForDeconstruction) { return 0; }  // already queued
@@ -453,8 +455,8 @@ int BuildingSystem::deconstruct(BuildingId id, Tick currentTick)
            m_belts.removeTile(building.anchor);
        }

-        const bool wasEmpty = m_deconstructionQueue.empty();
-        m_deconstructionQueue.push_back(std::move(entry));
+        const bool wasEmpty = m_state.deconstructionQueue.empty();
+        m_state.deconstructionQueue.push_back(std::move(entry));
        if (wasEmpty)
        {
            startFrontDeconstruction(currentTick);
@@ -467,8 +469,8 @@ int BuildingSystem::deconstruct(BuildingId id, Tick currentTick)

 void BuildingSystem::startFrontDeconstruction(Tick currentTick)
 {
-    if (m_deconstructionQueue.empty()) { return; }
-    DeconstructionEntry& front = m_deconstructionQueue.front();
+    if (m_state.deconstructionQueue.empty()) { return; }
+    DeconstructionEntry& front = m_state.deconstructionQueue.front();
    if (front.completesAt == 0)
    {
        front.completesAt =
@@ -483,7 +485,7 @@ void BuildingSystem::startFrontDeconstruction(Tick currentTick)
 void BuildingSystem::setRecipe(BuildingId id, const std::string& recipeId)
 {
    // Construction site: store recipe for when building completes.
-    for (ConstructionSite& site : m_constructionQueue)
+    for (ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id == id)
        {
@@ -506,7 +508,7 @@ void BuildingSystem::setRecipe(BuildingId id, const std::string& recipeId)
    }

    // Operational building: clear buffers and re-init.
-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        if (building.id == id)
        {
@@ -558,7 +560,7 @@ void BuildingSystem::setRecipe(BuildingId id, const std::string& recipeId)

 void BuildingSystem::setShipLayout(BuildingId id, const ShipLayoutConfig& layout)
 {
-    for (ConstructionSite& site : m_constructionQueue)
+    for (ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id == id)
        {
@@ -567,7 +569,7 @@ void BuildingSystem::setShipLayout(BuildingId id, const ShipLayoutConfig& layout
        }
    }

-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        if (building.id == id)
        {
@@ -594,7 +596,7 @@ void BuildingSystem::setShipLayout(BuildingId id, const ShipLayoutConfig& layout
 std::optional<BeltSystem::SplitterInfo>
 BuildingSystem::getSiteSplitterInfo(BuildingId id) const
 {
-    for (const ConstructionSite& site : m_constructionQueue)
+    for (const ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id != id) { continue; }
        if (site.type != BuildingType::Splitter) { return std::nullopt; }
@@ -618,7 +620,7 @@ void BuildingSystem::setSiteSplitterFilters(BuildingId id,
                                            const std::vector<ItemType>& filterA,
                                            const std::vector<ItemType>& filterB)
 {
-    for (ConstructionSite& site : m_constructionQueue)
+    for (ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id == id && site.type == BuildingType::Splitter)
        {
@@ -636,12 +638,12 @@ void BuildingSystem::setSiteSplitterFilters(BuildingId id,
 void BuildingSystem::tickConstruction(Tick currentTick)
 {
 	TRACE();
-    if (m_constructionQueue.empty())
+    if (m_state.constructionQueue.empty())
    {
        return;
    }

-    ConstructionSite& front = m_constructionQueue.front();
+    ConstructionSite& front = m_state.constructionQueue.front();

    // Guard: if somehow the front site was never started, start it now.
    if (front.completesAt == 0)
@@ -719,18 +721,18 @@ void BuildingSystem::tickConstruction(Tick currentTick)
    // filters configured while under construction carry over (REQ-BLD-SITE-CONFIG).
    reregisterBeltTile(building, front.splitterFilterA, front.splitterFilterB);

-    m_buildings.push_back(std::move(building));
+    m_state.buildings.push_back(std::move(building));

-    m_constructionQueue.pop_front();
+    m_state.constructionQueue.pop_front();

    // Start next queued site if present.
-    if (!m_constructionQueue.empty() && m_constructionQueue.front().completesAt == 0)
+    if (!m_state.constructionQueue.empty() && m_state.constructionQueue.front().completesAt == 0)
    {
        const BuildingDef* nextDef =
-            m_config.buildings.findBuildingDef(m_constructionQueue.front().type);
+            m_config.buildings.findBuildingDef(m_state.constructionQueue.front().type);
        if (nextDef)
        {
-            m_constructionQueue.front().completesAt =
+            m_state.constructionQueue.front().completesAt =
                currentTick + secondsToTicks(nextDef->constructionTimeSeconds);
        }
    }
@@ -767,12 +769,12 @@ void BuildingSystem::reregisterBeltTile(const Building& building,
 void BuildingSystem::tickDeconstruction(Tick currentTick)
 {
    TRACE();
-    if (m_deconstructionQueue.empty())
+    if (m_state.deconstructionQueue.empty())
    {
        return;
    }

-    DeconstructionEntry& front = m_deconstructionQueue.front();
+    DeconstructionEntry& front = m_state.deconstructionQueue.front();

    // Guard: if the front entry's timer was never started, start it now.
    if (front.completesAt == 0)
@@ -789,15 +791,15 @@ void BuildingSystem::tickDeconstruction(Tick currentTick)
    // 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 = m_buildings.begin();
-         it != m_buildings.end();
+    for (std::vector<Building>::iterator it = m_state.buildings.begin();
+         it != m_state.buildings.end();
         ++it)
    {
        if (it->id != front.id) { continue; }

        const BuildingDef* def = m_config.buildings.findBuildingDef(it->type);
-        m_grid.release(it->bodyCells);
-        m_buildings.erase(it);
+        m_state.grid.release(it->bodyCells);
+        m_state.buildings.erase(it);
        if (def)
        {
            m_addBuildingBlocks(def->cost * m_config.world.refundPercentage / 100);
@@ -805,7 +807,7 @@ void BuildingSystem::tickDeconstruction(Tick currentTick)
        break;
    }

-    m_deconstructionQueue.pop_front();
+    m_state.deconstructionQueue.pop_front();

    // Start the next queued deconstruction, if any.
    startFrontDeconstruction(currentTick);
@@ -813,8 +815,8 @@ void BuildingSystem::tickDeconstruction(Tick currentTick)

 void BuildingSystem::cancelDeconstruction(BuildingId id)
 {
-    for (std::deque<DeconstructionEntry>::iterator it = m_deconstructionQueue.begin();
-         it != m_deconstructionQueue.end();
+    for (std::deque<DeconstructionEntry>::iterator it = m_state.deconstructionQueue.begin();
+         it != m_state.deconstructionQueue.end();
         ++it)
    {
        if (it->id != id) { continue; }
@@ -828,7 +830,7 @@ void BuildingSystem::cancelDeconstruction(BuildingId id)
            reregisterBeltTile(*building, it->splitterFilterA, it->splitterFilterB);
        }

-        m_deconstructionQueue.erase(it);
+        m_state.deconstructionQueue.erase(it);
        // If the running front was removed, the new front (completesAt == 0) has
        // its timer started by the next tickDeconstruction guard.
        return;
@@ -848,7 +850,7 @@ void BuildingSystem::tickBeltPull()
    // (REQ-GW-BELT-SPEED, REQ-MAT-INPUT-INTAKE).
    const double progressPerTick = m_belts.getProgressPerTick_tpt();

-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        // A building queued for deconstruction stops operating (REQ-BLD-DECON-QUEUE).
        if (building.queuedForDeconstruction) { continue; }
@@ -932,7 +934,7 @@ bool BuildingSystem::tryDirectCoupleDeposit(BuildingId producerId,
                                            const Port& outputPort,
                                            const Item& item)
 {
-    const std::optional<BuildingId> ownerId = m_grid.findOwner(outputPort.tile);
+    const std::optional<BuildingId> ownerId = m_state.grid.findOwner(outputPort.tile);
    if (!ownerId.has_value() || *ownerId == producerId)
    {
        return false;
@@ -966,7 +968,7 @@ bool BuildingSystem::tryDirectCoupleDeposit(BuildingId producerId,
 void BuildingSystem::tickProduction(Tick currentTick)
 {
 	TRACE();
-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        // A building queued for deconstruction stops operating (REQ-BLD-DECON-QUEUE).
        if (building.queuedForDeconstruction) { continue; }
@@ -1069,7 +1071,7 @@ void BuildingSystem::tickProduction(Tick currentTick)
 void BuildingSystem::tickShipyardProduction(Tick currentTick)
 {
 	TRACE();
-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        // A building queued for deconstruction stops operating (REQ-BLD-DECON-QUEUE).
        if (building.queuedForDeconstruction) { continue; }
@@ -1169,7 +1171,7 @@ void BuildingSystem::tickOutputBelts()
    // same speed as real belts (REQ-GW-BELT-SPEED, REQ-MAT-OUTPUT-EMERGE).
    const double progressPerTick = m_belts.getProgressPerTick_tpt();

-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        // A building queued for deconstruction stops operating (REQ-BLD-DECON-QUEUE).
        if (building.queuedForDeconstruction) { continue; }
@@ -1215,7 +1217,7 @@ void BuildingSystem::tickOutputBelts()
 void BuildingSystem::forEachEmergingItem(
    const std::function<void(const ItemType&, QPointF)>& visit) const
 {
-    for (const Building& building : m_buildings)
+    for (const Building& building : m_state.buildings)
    {
        for (std::size_t p = 0; p < building.outputPorts.size(); ++p)
        {
@@ -1237,7 +1239,7 @@ void BuildingSystem::forEachEmergingItem(
 void BuildingSystem::forEachIncomingItem(
    const std::function<void(const ItemType&, QPointF)>& visit) const
 {
-    for (const Building& building : m_buildings)
+    for (const Building& building : m_state.buildings)
    {
        for (std::size_t p = 0; p < building.inputPorts.size(); ++p)
        {
@@ -1262,7 +1264,7 @@ void BuildingSystem::forEachIncomingItem(

 const Building* BuildingSystem::findBuilding(BuildingId id) const
 {
-    for (const Building& building : m_buildings)
+    for (const Building& building : m_state.buildings)
    {
        if (building.id == id)
        {
@@ -1274,7 +1276,7 @@ const Building* BuildingSystem::findBuilding(BuildingId id) const

 Building* BuildingSystem::findBuildingMutable(BuildingId id)
 {
-    for (Building& building : m_buildings)
+    for (Building& building : m_state.buildings)
    {
        if (building.id == id)
        {
@@ -1286,7 +1288,7 @@ Building* BuildingSystem::findBuildingMutable(BuildingId id)

 const ConstructionSite* BuildingSystem::findSite(BuildingId id) const
 {
-    for (const ConstructionSite& site : m_constructionQueue)
+    for (const ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id == id)
        {
@@ -1298,13 +1300,13 @@ const ConstructionSite* BuildingSystem::findSite(BuildingId id) const

 std::vector<Building> BuildingSystem::getAllBuildings() const
 {
-    return m_buildings;
+    return m_state.buildings;
 }

 std::vector<ConstructionSite> BuildingSystem::getAllSites() const
 {
-    return std::vector<ConstructionSite>(m_constructionQueue.begin(),
-                                         m_constructionQueue.end());
+    return std::vector<ConstructionSite>(m_state.constructionQueue.begin(),
+                                         m_state.constructionQueue.end());
 }

 namespace
@@ -1328,7 +1330,7 @@ bool isProductionBuildingType(BuildingType type)
 int BuildingSystem::getProductionBuildingCount() const
 {
    int count = 0;
-    for (const Building& b : m_buildings)
+    for (const Building& b : m_state.buildings)
    {
        if (isProductionBuildingType(b.type)) { ++count; }
    }
@@ -1338,7 +1340,7 @@ int BuildingSystem::getProductionBuildingCount() const
 int BuildingSystem::getActiveProductionBuildingCount() const
 {
    int count = 0;
-    for (const Building& b : m_buildings)
+    for (const Building& b : m_state.buildings)
    {
        if (isProductionBuildingType(b.type) && b.production.has_value()) { ++count; }
    }
@@ -1489,7 +1491,7 @@ BuildingSystem::getProductionStatus(const Building& building) const
 std::vector<BuildingSystem::BeltTileInfo> BuildingSystem::getAllBeltTiles() const
 {
    std::vector<BeltTileInfo> result;
-    for (const Building& b : m_buildings)
+    for (const Building& b : m_state.buildings)
    {
        if (b.type != BuildingType::Belt && b.type != BuildingType::Splitter)
        {
@@ -1520,7 +1522,7 @@ std::vector<BuildingSystem::BeltTileInfo> BuildingSystem::getAllBeltTiles() cons

 bool BuildingSystem::isTileOccupied(QPoint tile) const
 {
-    return m_grid.isOccupied(tile);
+    return m_state.grid.isOccupied(tile);
 }

 std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
@@ -1541,13 +1543,13 @@ std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(

    // All body cells must be occupied by the same entity.
    const QPoint firstAbs = anchor + mask.bodyCells[0];
-    const std::optional<BuildingId> firstOwner = m_grid.findOwner(firstAbs);
+    const std::optional<BuildingId> firstOwner = m_state.grid.findOwner(firstAbs);
    if (!firstOwner.has_value()) { return std::nullopt; }
    const BuildingId candidateId = *firstOwner;

    for (const QPoint& rel : mask.bodyCells)
    {
-        const std::optional<BuildingId> owner = m_grid.findOwner(anchor + rel);
+        const std::optional<BuildingId> owner = m_state.grid.findOwner(anchor + rel);
        if (!owner.has_value() || *owner != candidateId)
        {
            return std::nullopt;
@@ -1555,14 +1557,14 @@ std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
    }

    // Verify the candidate is the same building type with the same cell count.
-    for (const ConstructionSite& site : m_constructionQueue)
+    for (const ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id != candidateId) { continue; }
        if (site.type != type) { return std::nullopt; }
        if (site.bodyCells.size() != mask.bodyCells.size()) { return std::nullopt; }
        return candidateId;
    }
-    for (const Building& b : m_buildings)
+    for (const Building& b : m_state.buildings)
    {
        if (b.id != candidateId) { continue; }
        if (b.type != type) { return std::nullopt; }
@@ -1576,7 +1578,7 @@ std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
 void BuildingSystem::rotateInPlace(BuildingId id, Rotation newRotation)
 {
    // Construction site path — just update rotation; no ports to recompute.
-    for (ConstructionSite& site : m_constructionQueue)
+    for (ConstructionSite& site : m_state.constructionQueue)
    {
        if (site.id == id)
        {
@@ -1586,7 +1588,7 @@ void BuildingSystem::rotateInPlace(BuildingId id, Rotation newRotation)
    }

    // Operational building path.
-    for (Building& b : m_buildings)
+    for (Building& b : m_state.buildings)
    {
        if (b.id != id) { continue; }

@@ -1643,7 +1645,7 @@ const Building* BuildingSystem::findNearestBuilding(QVector2D worldPos,
 {
    const Building* best = nullptr;
    float bestDist = std::numeric_limits<float>::max();
-    for (const Building& b : m_buildings)
+    for (const Building& b : m_state.buildings)
    {
        if (b.type != type)
        {
@@ -1664,7 +1666,7 @@ const Building* BuildingSystem::findNearestBuilding(QVector2D worldPos,
 bool BuildingSystem::deliverScrapToSalvageBay(BuildingId bayId)
 {
    Building* bay = nullptr;
-    for (Building& b : m_buildings)
+    for (Building& b : m_state.buildings)
    {
        if (b.id == bayId)
        {
@@ -1708,7 +1710,7 @@ BuildingId BuildingSystem::placeImmediate(BuildingType type,
    {
        const QPoint absCell = anchor + cell;
        building.bodyCells.push_back(absCell);
-        m_grid.occupy(absCell, id);
+        m_state.grid.occupy(absCell, id);
    }
    for (const Port& port : mask.outputPorts)
    {
@@ -1726,14 +1728,14 @@ BuildingId BuildingSystem::placeImmediate(BuildingType type,
        initSalvageBayBuffer(building);
    }

-    m_buildings.push_back(std::move(building));
+    m_state.buildings.push_back(std::move(building));
    return id;
 }

 bool BuildingSystem::removeBuilding(BuildingId id)
 {
-    for (std::vector<Building>::iterator it = m_buildings.begin();
-         it != m_buildings.end();
+    for (std::vector<Building>::iterator it = m_state.buildings.begin();
+         it != m_state.buildings.end();
         ++it)
    {
        if (it->id == id)
@@ -1743,8 +1745,8 @@ bool BuildingSystem::removeBuilding(BuildingId id)
            {
                m_belts.removeTile(it->anchor);
            }
-            m_grid.release(it->bodyCells);
-            m_buildings.erase(it);
+            m_state.grid.release(it->bodyCells);
+            m_state.buildings.erase(it);
            return true;
        }
    }
@@ -1753,7 +1755,7 @@ bool BuildingSystem::removeBuilding(BuildingId id)

 void BuildingSystem::forEachBuilding(std::function<void(Building&)> fn)
 {
-    for (Building& b : m_buildings)
+    for (Building& b : m_state.buildings)
    {
        fn(b);
    }
@@ -1762,12 +1764,12 @@ void BuildingSystem::forEachBuilding(std::function<void(Building&)> fn)
 void BuildingSystem::registerTileOccupancy(const std::vector<QPoint>& cells,
                                            BuildingId ownerPlaceholder)
 {
-    m_grid.occupy(cells, ownerPlaceholder);
+    m_state.grid.occupy(cells, ownerPlaceholder);
 }

 void BuildingSystem::unregisterTileOccupancy(const std::vector<QPoint>& cells)
 {
-    m_grid.release(cells);
+    m_state.grid.release(cells);
 }

 namespace
@@ -1801,10 +1803,10 @@ void appendInputBuffer(Hasher& hasher, const InputBuffer& buffer)

 void BuildingSystem::appendChecksum(Hasher& hasher) const
 {
-    // m_buildings keeps a stable, deterministic order (append on build, swap-free
+    // m_state.buildings keeps a stable, deterministic order (append on build, swap-free
    // erase aside — both runs perform identical operations, so order matches).
-    hasher.append(m_buildings.size());
-    for (const Building& b : m_buildings)
+    hasher.append(m_state.buildings.size());
+    for (const Building& b : m_state.buildings)
    {
        hasher.append(b.id);
        hasher.append(b.anchor);
@@ -1847,8 +1849,8 @@ void BuildingSystem::appendChecksum(Hasher& hasher) const
        hasher.append(b.queuedForDeconstruction);
    }

-    hasher.append(m_constructionQueue.size());
-    for (const ConstructionSite& s : m_constructionQueue)
+    hasher.append(m_state.constructionQueue.size());
+    for (const ConstructionSite& s : m_state.constructionQueue)
    {
        hasher.append(s.id);
        hasher.append(s.anchor);
@@ -1865,8 +1867,8 @@ void BuildingSystem::appendChecksum(Hasher& hasher) const
        for (const ItemType& type : s.splitterFilterB) { hasher.append(type.id); }
    }

-    hasher.append(m_deconstructionQueue.size());
-    for (const DeconstructionEntry& e : m_deconstructionQueue)
+    hasher.append(m_state.deconstructionQueue.size());
+    for (const DeconstructionEntry& e : m_state.deconstructionQueue)
    {
        hasher.append(e.id);
        hasher.append(e.completesAt);
@@ -1876,5 +1878,5 @@ void BuildingSystem::appendChecksum(Hasher& hasher) const
        for (const ItemType& type : e.splitterFilterB) { hasher.append(type.id); }
    }

-    m_grid.appendChecksum(hasher);
+    m_state.grid.appendChecksum(hasher);
 }
--- a/src/lib/sim/BuildingSystem.h
+++ b/src/lib/sim/BuildingSystem.h
@@ -15,7 +15,7 @@

 #include "BeltSystem.h"
 #include "Building.h"
-#include "BuildingGrid.h"
+#include "FactoryState.h"
 #include "BuildingType.h"
 #include "BuildingId.h"
 #include "GameConfig.h"
@@ -47,6 +47,7 @@ class BuildingSystem
 {
 public:
    BuildingSystem(const GameConfig& config,
+                   FactoryState& state,
                   BeltSystem& belts,
                   std::function<BuildingId()> allocateBuildingId,
                   std::function<void(int)> addBuildingBlocks,
@@ -285,6 +286,11 @@ private:
                            QPoint anchor) const;

    const GameConfig&                              m_config;
+
+    // The factory's world data — buildings, queued work, tile ownership. Owned by
+    // Simulation, not by this system (see FactoryState.h).
+    FactoryState&                                  m_state;
+
    BeltSystem&                                    m_belts;
    std::function<BuildingId()>                      m_allocateBuildingId;
    std::function<void(int)>                       m_addBuildingBlocks;
@@ -293,24 +299,4 @@ private:
    std::function<bool(const std::string&)>        m_isItemUnlocked;
    std::mt19937&                                  m_rng;
    int                                            m_asteroidWidth_tiles;
-
-    std::vector<Building>           m_buildings;
-    std::deque<ConstructionSite>    m_constructionQueue;
-
-    // One pending demolition of a fully-built building (REQ-BLD-DECON-QUEUE).
-    // completesAt == 0 means "queued but its timer has not started yet"
-    // (mirrors ConstructionSite). For a Splitter, the filters it had are captured
-    // here so cancelDeconstruction can restore them on re-registration.
-    struct DeconstructionEntry
-    {
-        BuildingId            id          = kInvalidBuildingId;
-        Tick                  completesAt = 0;
-        std::vector<ItemType> splitterFilterA;
-        std::vector<ItemType> splitterFilterB;
-    };
-    std::deque<DeconstructionEntry> m_deconstructionQueue;
-
-    // The authority on which building owns which tile; every placement and removal
-    // path claims and releases its body cells here.
-    BuildingGrid m_grid;
 };
--- a/src/lib/sim/CMakeLists.txt
+++ b/src/lib/sim/CMakeLists.txt
@@ -13,6 +13,7 @@ SET(HDRS
    ${CMAKE_CURRENT_SOURCE_DIR}/Building.h
    ${CMAKE_CURRENT_SOURCE_DIR}/BuildingConfig.h
    ${CMAKE_CURRENT_SOURCE_DIR}/BuildingGrid.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/FactoryState.h
    ${CMAKE_CURRENT_SOURCE_DIR}/BuildingSystem.h
    ${CMAKE_CURRENT_SOURCE_DIR}/EntityHitTest.h
    ${CMAKE_CURRENT_SOURCE_DIR}/ShipLayout.h
--- a/src/lib/sim/FactoryState.h
+++ b/src/lib/sim/FactoryState.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include <deque>
+#include <vector>
+
+#include "Building.h"
+#include "BuildingGrid.h"
+#include "BuildingId.h"
+#include "ItemType.h"
+#include "Tick.h"
+
+// One pending demolition of a fully-built building (REQ-BLD-DECON-QUEUE).
+// completesAt == 0 means "queued but its timer has not started yet"
+// (mirrors ConstructionSite). For a Splitter, the filters it had are captured
+// here so cancelDeconstruction can restore them on re-registration.
+struct DeconstructionEntry
+{
+    BuildingId            id          = kInvalidBuildingId;
+    Tick                  completesAt = 0;
+    std::vector<ItemType> splitterFilterA;
+    std::vector<ItemType> splitterFilterB;
+};
+
+// The factory's world data: every building, the work queued on them, and the
+// tile ownership index. This is the buildings-side counterpart to EntityAdmin —
+// data with no behaviour of its own beyond what BuildingGrid encapsulates.
+//
+// Buildings deliberately stay a plain vector rather than becoming EnTT entities
+// (see docs/architecture.md). Separating this data from the systems that operate
+// on it is not a step toward putting them in the entity model; it is the same
+// data/behaviour split the ecs/system/ classes already follow, where world data
+// arrives as a tick argument instead of being owned by the system.
+//
+// Owned by Simulation (and by ArenaSimulation in the balancing tool), not by the
+// systems that operate on it. BuildingSystem holds a reference. The remaining step
+// is to pass this into the tick methods instead, so the systems become stateless
+// over it — that one is gated on the query surface, which today reaches the data
+// through BuildingSystem's ~180 const call sites.
+struct FactoryState
+{
+    std::vector<Building>           buildings;
+    std::deque<ConstructionSite>    constructionQueue;
+    std::deque<DeconstructionEntry> deconstructionQueue;
+
+    // The authority on which building owns which tile; every placement and removal
+    // path claims and releases its body cells here.
+    BuildingGrid                    grid;
+};
--- a/src/lib/sim/Simulation.cpp
+++ b/src/lib/sim/Simulation.cpp
@@ -94,6 +94,7 @@ void Simulation::reset(unsigned int seed)
    m_pendingSchematicChoices.clear();

    m_admin.clear();
+    m_factoryState = FactoryState{};
    m_beltSystem = BeltSystem(m_config.world.beltSpeed_tps);
    initializeSubsystems();

@@ -105,6 +106,7 @@ void Simulation::initializeSubsystems()
 {
    m_buildingSystem = std::make_unique<BuildingSystem>(
        m_config,
+        m_factoryState,
        m_beltSystem,
        [this]() { return allocateBuildingId(); },
        [this](int amount) { m_buildingBlocksStock += amount; },
--- a/src/lib/sim/Simulation.h
+++ b/src/lib/sim/Simulation.h
@@ -9,6 +9,7 @@
 #include <QPoint>

 #include "BeltSystem.h"
+#include "FactoryState.h"
 #include "EntityAdmin.h"
 #include "entt/entity/entity.hpp"
 #include "SchematicChoiceOption.h"
@@ -209,6 +210,9 @@ private:
    UnlockState m_unlockState;

    EntityAdmin                       m_admin;
+    // The factory's world data. Owned here, not by BuildingSystem, so the systems
+    // that operate on it can be handed the same state (see FactoryState.h).
+    FactoryState                      m_factoryState;
    BeltSystem                        m_beltSystem;
    std::unique_ptr<BuildingSystem>   m_buildingSystem;
    std::unique_ptr<ShipSystem>       m_shipSystem;
--- a/src/test/BehaviorSystemTest.cpp
+++ b/src/test/BehaviorSystemTest.cpp
@@ -14,6 +14,7 @@
 #include "BeltSystem.h"
 #include "Building.h"
 #include "BuildingSystem.h"
+#include "FactoryState.h"
 #include "BuildingType.h"
 #include "ConfigLoader.h"
 #include "DeliverScrapBehavior.h"
@@ -54,6 +55,7 @@
 struct Fixture
 {
    GameConfig     cfg;
+    FactoryState   state;
    BeltSystem     belts;
    BuildingId       nextBuildingId;
    int            stock;
@@ -76,7 +78,7 @@ struct Fixture
        , nextBuildingId(1)
        , stock(0)
        , rng(42)
-        , buildings(cfg, belts,
+        , buildings(cfg, state, belts,
                    [this]() { return nextBuildingId++; },
                    [this](int n) { stock += n; },
                    [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
--- a/src/test/BuildingTest.cpp
+++ b/src/test/BuildingTest.cpp
@@ -12,6 +12,7 @@
 #include "BeltSystem.h"
 #include "Building.h"
 #include "BuildingSystem.h"
+#include "FactoryState.h"
 #include "BuildingType.h"
 #include "ConfigLoader.h"
 #include "Item.h"
@@ -83,6 +84,7 @@ static std::vector<Item> outputSideItems(const Building& b)
 struct PlacementFixture
 {
    GameConfig     cfg = loadTestConfig();
+    FactoryState   state;
    BeltSystem     belts{cfg.world.beltSpeed_tps};
    int            stock = 0;
    std::mt19937   rng{0};
@@ -90,7 +92,7 @@ struct PlacementFixture
    BuildingSystem bs;

    PlacementFixture()
-        : bs(cfg, belts,
+        : bs(cfg, state, belts,
             [this]() { return nextBuildingId++; },
             [this](int n) { stock += n; },
             [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -111,7 +113,8 @@ TEST_CASE("BuildingSystem: place miner occupies expected body tiles", "[building
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -219,7 +222,8 @@ TEST_CASE("BuildingSystem: placing a belt registers it with BeltSystem after con
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -248,7 +252,8 @@ TEST_CASE("BuildingSystem: placed building enters construction queue", "[buildin
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -290,7 +295,8 @@ TEST_CASE("BuildingSystem: first queued building starts construction immediately
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -308,7 +314,8 @@ TEST_CASE("BuildingSystem: second queued building waits (completesAt == 0)", "[b
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -330,7 +337,8 @@ TEST_CASE("BuildingSystem: construction completes after configured duration", "[
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -496,7 +504,8 @@ TEST_CASE("BuildingSystem: second building starts after first completes", "[buil
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -526,7 +535,8 @@ TEST_CASE("BuildingSystem: miner produces iron_ore after recipe duration", "[bui
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -559,7 +569,8 @@ TEST_CASE("BuildingSystem: miner output buffer stalls when full", "[building]")
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -599,7 +610,8 @@ TEST_CASE("BuildingSystem: productionBuildingCount excludes construction sites",
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -639,7 +651,8 @@ TEST_CASE("BuildingSystem: activeProductionBuildingCount tracks production cycle
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -681,7 +694,8 @@ TEST_CASE("BuildingSystem: smelter input buffer fills from adjacent west-flowing
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -723,7 +737,8 @@ TEST_CASE("BuildingSystem: accepted input travels inward before entering the buf
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -764,7 +779,8 @@ TEST_CASE("BuildingSystem: input reservation caps buffered plus in-transit at th
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -806,7 +822,8 @@ TEST_CASE("BuildingSystem: smelter auto-smelts ore without a recipe selection",
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -852,7 +869,8 @@ TEST_CASE("BuildingSystem: smelter runs a satisfiable recipe while an incomplete
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -906,7 +924,8 @@ TEST_CASE("BuildingSystem: miner output buffer drains onto adjacent belt", "[bui
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -945,7 +964,8 @@ TEST_CASE("BuildingSystem: output port couples directly into an adjacent input p
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -985,7 +1005,8 @@ TEST_CASE("BuildingSystem: direct coupling to a non-consumer leaves the item stu
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1024,7 +1045,8 @@ TEST_CASE("BuildingSystem: setRecipe clears output buffer and active production"
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1067,7 +1089,8 @@ TEST_CASE("BuildingSystem: reprocessing plant output buffer capacity equals max
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1099,7 +1122,8 @@ TEST_CASE("BuildingSystem: reprocessing plant produces one cycle output then sta
    // Seed chosen so first roll produces 2-item output (iron_ingot), filling buffer.
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1157,7 +1181,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns nullopt when tile is
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1176,7 +1201,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns the site id for a que
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1199,7 +1225,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns the building id for a
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1226,7 +1253,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns nullopt when building
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1248,7 +1276,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget never rotates a tunnel in pla
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1274,7 +1303,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns nullopt when footprin
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1298,7 +1328,8 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget works for a symmetric multi-t
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1327,7 +1358,8 @@ TEST_CASE("BuildingSystem: rotateInPlace updates the rotation field of a constru
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1350,7 +1382,8 @@ TEST_CASE("BuildingSystem: rotateInPlace preserves the construction progress of
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1374,7 +1407,8 @@ TEST_CASE("BuildingSystem: rotateInPlace updates rotation and output port direct
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
@@ -1405,7 +1439,8 @@ TEST_CASE("BuildingSystem: rotateInPlace re-registers a belt tile with BeltSyste
    int stock = 0;
    std::mt19937 rng(0);
    BuildingId nextBuildingId = 1;
-    BuildingSystem bs(cfg, belts,
+    FactoryState state_bs;
+    BuildingSystem bs(cfg, state_bs, belts,
                      [&nextBuildingId]() { return nextBuildingId++; },
                      [&stock](int n) { stock += n; },
                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
--- a/src/test/CombatSystemTest.cpp
+++ b/src/test/CombatSystemTest.cpp
@@ -5,6 +5,7 @@
 #include "BeltSystem.h"
 #include "Building.h"
 #include "BuildingSystem.h"
+#include "FactoryState.h"
 #include "BuildingType.h"
 #include "CombatSystem.h"
 #include "ConfigLoader.h"
@@ -51,6 +52,7 @@ static entt::entity findWeaponChild(EntityAdmin& admin, entt::entity ship)
 struct CombatFixture
 {
    GameConfig cfg;
+    FactoryState state;
    std::mt19937 rng;
    EntityAdmin admin;
    BuildingId nextBuildingId;
@@ -65,7 +67,7 @@ struct CombatFixture
        , nextBuildingId(1)
        , belts(cfg.world.beltSpeed_tps)
        , ships(cfg, admin)
-        , buildings(cfg, belts,
+        , buildings(cfg, state, belts,
                    [this]() { return nextBuildingId++; },
                    [](int){},
                    [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},