Landtrain!!!!

.gitignore

@@ -0,0 +1,18 @@
+.tools/
+
+# Logs and local patch leftovers
+*.log
+*.tmp
+*.bak
+*.orig
+*.rej
+
+# Editor/IDE
+.vscode/
+.idea/
+*.iml
+
+# OS metadata
+.DS_Store
+Thumbs.db
+desktop.ini

42.13/media/lua/client/Landtrain/UnlimitedTowbarChains.lua

@@ -0,0 +1,483 @@
+if not TowBarMod then TowBarMod = {} end
+if not TowBarMod.Utils then TowBarMod.Utils = {} end
+if not TowBarMod.UI then TowBarMod.UI = {} end
+
+local LANDTRAIN_DEBUG = false
+local LANDTRAIN_ATTACH_LABEL = "Landtrain attach"
+local LANDTRAIN_FALLBACK_MAX_DIST_SQ = 3.25 -- ~1.8 tiles
+local LANDTRAIN_FALLBACK_MAX_DZ = 0.9
+
+local function ltLog(msg)
+    if not LANDTRAIN_DEBUG then return end
+    print("[Landtrain] " .. tostring(msg))
+end
+
+local function vehLabel(vehicle)
+    if vehicle == nil then return "nil" end
+    local name = vehicle:getScriptName() or "unknown"
+    return tostring(vehicle:getId()) .. ":" .. tostring(name)
+end
+
+local function dumpTowState(prefix, vehicle)
+    if not LANDTRAIN_DEBUG then return end
+    if vehicle == nil then
+        ltLog(prefix .. " vehicle=nil")
+        return
+    end
+    local modData = vehicle:getModData() or {}
+    local front = vehicle:getVehicleTowedBy()
+    local rear = vehicle:getVehicleTowing()
+    ltLog(prefix
+        .. " v=" .. vehLabel(vehicle)
+        .. " front=" .. vehLabel(front)
+        .. " rear=" .. vehLabel(rear)
+        .. " md.isTowingByTowBar=" .. tostring(modData["isTowingByTowBar"])
+        .. " md.towed=" .. tostring(modData["towed"]))
+end
+
+local function refreshTowBarState(vehicle)
+    if vehicle == nil then return end
+
+    local modData = vehicle:getModData()
+    if modData == nil then return end
+
+    local frontVehicle = vehicle:getVehicleTowedBy()
+    local rearVehicle = vehicle:getVehicleTowing()
+
+    local isTowedByTowBar = false
+    if frontVehicle ~= nil then
+        local frontModData = frontVehicle:getModData()
+        if modData["towed"] == true or (frontModData and frontModData["isTowingByTowBar"] == true) then
+            isTowedByTowBar = true
+        end
+    end
+
+    local isTowingByTowBar = false
+    if rearVehicle ~= nil then
+        local rearModData = rearVehicle:getModData()
+        if rearModData and rearModData["towed"] == true and rearModData["isTowingByTowBar"] == true then
+            isTowingByTowBar = true
+        end
+    end
+
+    modData["towed"] = isTowedByTowBar
+    modData["isTowingByTowBar"] = (isTowedByTowBar or isTowingByTowBar)
+    vehicle:transmitModData()
+end
+
+local function setTowBarModelVisibleForVehicle(vehicle, visible)
+    if vehicle == nil then return end
+    local part = vehicle:getPartById("towbar")
+    if part == nil then return end
+
+    for j = 0, 23 do
+        part:setModelVisible("towbar" .. j, false)
+    end
+
+    if visible then
+        local z = vehicle:getScript():getPhysicsChassisShape():z() / 2 - 0.1
+        local index = math.floor((z * 2 / 3 - 1) * 10)
+        if index < 0 then index = 0 end
+        if index > 23 then index = 23 end
+        part:setModelVisible("towbar" .. index, true)
+    end
+
+    vehicle:doDamageOverlay()
+end
+
+local _landtrainHookPosA = Vector3f.new()
+local _landtrainHookPosB = Vector3f.new()
+
+local function hasTowAttachment(vehicle, attachmentId)
+    if vehicle == nil or attachmentId == nil then return false end
+    local script = vehicle:getScript()
+    if script == nil then return false end
+    return script:getAttachmentById(attachmentId) ~= nil
+end
+
+local function isAttachmentSideFree(vehicle, attachmentId)
+    if vehicle == nil then return false end
+    if attachmentId == "trailer" then
+        return vehicle:getVehicleTowing() == nil
+    end
+    if attachmentId == "trailerfront" then
+        return vehicle:getVehicleTowedBy() == nil
+    end
+    return true
+end
+
+local function canTowByLandtrain(vehicleA, vehicleB, attachmentA, attachmentB)
+    if vehicleA == nil or vehicleB == nil then return false end
+    if vehicleA == vehicleB then return false end
+    if not hasTowAttachment(vehicleA, attachmentA) then return false end
+    if not hasTowAttachment(vehicleB, attachmentB) then return false end
+    if not isAttachmentSideFree(vehicleA, attachmentA) then return false end
+    if not isAttachmentSideFree(vehicleB, attachmentB) then return false end
+    if vehicleA:getVehicleTowing() == vehicleB or vehicleA:getVehicleTowedBy() == vehicleB then
+        return false
+    end
+
+    -- Keep vanilla behavior when possible.
+    if vehicleA:canAttachTrailer(vehicleB, attachmentA, attachmentB) then
+        ltLog("canTowByLandtrain vanilla=true A=" .. vehLabel(vehicleA) .. " B=" .. vehLabel(vehicleB) .. " attA=" .. tostring(attachmentA) .. " attB=" .. tostring(attachmentB))
+        return true
+    end
+
+    -- Vanilla blocks chained towing here; allow only near-identical close-range hookups.
+    local posA = vehicleA:getAttachmentWorldPos(attachmentA, _landtrainHookPosA)
+    local posB = vehicleB:getAttachmentWorldPos(attachmentB, _landtrainHookPosB)
+    if posA == nil or posB == nil then return false end
+
+    local dx = posA:x() - posB:x()
+    local dy = posA:y() - posB:y()
+    local dz = posA:z() - posB:z()
+    local distSq = dx * dx + dy * dy + dz * dz
+    local allow = distSq <= LANDTRAIN_FALLBACK_MAX_DIST_SQ and math.abs(dz) <= LANDTRAIN_FALLBACK_MAX_DZ
+    ltLog("canTowByLandtrain fallback=" .. tostring(allow)
+        .. " A=" .. vehLabel(vehicleA)
+        .. " B=" .. vehLabel(vehicleB)
+        .. " attA=" .. tostring(attachmentA)
+        .. " attB=" .. tostring(attachmentB)
+        .. " distSq=" .. string.format("%.3f", distSq)
+        .. " dz=" .. string.format("%.3f", dz))
+    return allow
+end
+
+local function getAttachLabel(vehicleA, vehicleB)
+    local isLandtrainLink = (vehicleA and (vehicleA:getVehicleTowing() or vehicleA:getVehicleTowedBy()))
+        or (vehicleB and (vehicleB:getVehicleTowing() or vehicleB:getVehicleTowedBy()))
+    if isLandtrainLink then
+        return LANDTRAIN_ATTACH_LABEL
+    end
+    return getText("UI_Text_Towing_byTowBar")
+end
+
+local function captureTowbarFrontLink(towingVehicle)
+    if towingVehicle == nil then
+        ltLog("captureTowbarFrontLink towingVehicle=nil")
+        return nil
+    end
+
+    local frontVehicle = towingVehicle:getVehicleTowedBy()
+    if frontVehicle == nil then
+        ltLog("captureTowbarFrontLink no front link for " .. vehLabel(towingVehicle))
+        return nil
+    end
+
+    local link = {
+        frontVehicle = frontVehicle,
+        towingVehicle = towingVehicle,
+        attachmentA = frontVehicle:getTowAttachmentSelf() or "trailer",
+        attachmentB = towingVehicle:getTowAttachmentSelf() or "trailerfront"
+    }
+    ltLog("captureTowbarFrontLink captured front=" .. vehLabel(frontVehicle) .. " middle=" .. vehLabel(towingVehicle)
+        .. " attA=" .. tostring(link.attachmentA) .. " attB=" .. tostring(link.attachmentB))
+    return link
+end
+
+local function restoreTowbarFrontLink(playerObj, link)
+    if link == nil then
+        ltLog("restoreTowbarFrontLink skipped (no captured link)")
+        return
+    end
+    local frontVehicle = link.frontVehicle
+    local towingVehicle = link.towingVehicle
+    if frontVehicle == nil or towingVehicle == nil then
+        ltLog("restoreTowbarFrontLink invalid captured refs")
+        return
+    end
+    if towingVehicle:getVehicleTowedBy() ~= nil then
+        ltLog("restoreTowbarFrontLink not needed; front still connected for middle=" .. vehLabel(towingVehicle))
+        return
+    end
+
+    ltLog("restoreTowbarFrontLink restoring front=" .. vehLabel(frontVehicle) .. " middle=" .. vehLabel(towingVehicle))
+    TowBarMod.Utils.updateAttachmentsForRigidTow(frontVehicle, towingVehicle, link.attachmentA, link.attachmentB)
+    towingVehicle:setScriptName("notTowingA_Trailer")
+
+    local args = {
+        vehicleA = frontVehicle:getId(),
+        vehicleB = towingVehicle:getId(),
+        attachmentA = link.attachmentA,
+        attachmentB = link.attachmentB
+    }
+    sendClientCommand(playerObj, "vehicle", "attachTrailer", args)
+    ISTimedActionQueue.add(TowBarScheduleAction:new(playerObj, 10, TowBarMod.Hook.setVehiclePostAttach, towingVehicle))
+
+    local frontModData = frontVehicle:getModData()
+    local towingModData = towingVehicle:getModData()
+    frontModData["isTowingByTowBar"] = true
+    towingModData["isTowingByTowBar"] = true
+    towingModData["towed"] = true
+    frontVehicle:transmitModData()
+    towingVehicle:transmitModData()
+    dumpTowState("restoreTowbarFrontLink after front", frontVehicle)
+    dumpTowState("restoreTowbarFrontLink after middle", towingVehicle)
+end
+
+local function queueTowbarFrontLinkRestore(playerObj, link, delayTicks)
+    if link == nil or playerObj == nil then return end
+    local delay = delayTicks or 15
+    ISTimedActionQueue.add(TowBarScheduleAction:new(playerObj, delay, function(character, linkArg)
+        ltLog("queueTowbarFrontLinkRestore fire delay=" .. tostring(delay) .. " middle=" .. vehLabel(linkArg and linkArg.towingVehicle or nil))
+        restoreTowbarFrontLink(character, linkArg)
+    end, link))
+end
+
+local function ensureTowAttachmentsForTrailers()
+    local scriptManager = getScriptManager()
+    if scriptManager == nil then return end
+
+    local vehicleScripts = scriptManager:getAllVehicleScripts()
+    if vehicleScripts == nil then return end
+
+    for i = 0, vehicleScripts:size() - 1 do
+        local script = vehicleScripts:get(i)
+        local scriptName = script and script:getName() or nil
+        if script and scriptName and string.match(string.lower(scriptName), "trailer") then
+            local wheelCount = script:getWheelCount()
+            local attachHeightOffset = -0.5
+            if wheelCount > 0 then
+                attachHeightOffset = script:getWheel(0):getOffset():y() + 0.1
+            end
+
+            local rearTow = script:getAttachmentById("trailer")
+            if rearTow == nil then
+                local attach = ModelAttachment.new("trailer")
+                attach:getOffset():set(0, attachHeightOffset, -script:getPhysicsChassisShape():z() / 2 - 0.1)
+                attach:setZOffset(-1)
+                script:addAttachment(attach)
+            end
+
+            local frontTow = script:getAttachmentById("trailerfront")
+            if frontTow == nil then
+                local attach = ModelAttachment.new("trailerfront")
+                attach:getOffset():set(0, attachHeightOffset, script:getPhysicsChassisShape():z() / 2 + 0.1)
+                attach:setZOffset(1)
+                script:addAttachment(attach)
+            end
+        end
+    end
+end
+
+local function menuHasTowbarAttachSlice(menu)
+    if menu == nil or menu.slices == nil then return false end
+    for _, slice in ipairs(menu.slices) do
+        local command = slice.command and slice.command[1]
+        if command == TowBarMod.Hook.attachByTowBarAction or command == TowBarMod.UI.showChooseVehicleMenu then
+            return true
+        end
+    end
+    return false
+end
+
+local function getLandtrainHookTypeVariants(vehicleA, vehicleB)
+    local hookTypeVariants = {}
+    if vehicleA == nil or vehicleB == nil or vehicleA == vehicleB then
+        return hookTypeVariants
+    end
+
+    if canTowByLandtrain(vehicleA, vehicleB, "trailerfront", "trailer") then
+        local hookType = {}
+        hookType.name = getText("UI_Text_Towing_attach") .. "\n" .. ISVehicleMenu.getVehicleDisplayName(vehicleB) .. "\n" .. LANDTRAIN_ATTACH_LABEL
+        hookType.func = TowBarMod.Hook.attachByTowBarAction
+        hookType.towingVehicle = vehicleB
+        hookType.towedVehicle = vehicleA
+        hookType.textureName = "tow_bar_icon"
+        table.insert(hookTypeVariants, hookType)
+    elseif canTowByLandtrain(vehicleA, vehicleB, "trailer", "trailerfront") then
+        local hookType = {}
+        hookType.name = getText("UI_Text_Towing_attach") .. "\n" .. ISVehicleMenu.getVehicleDisplayName(vehicleB) .. "\n" .. LANDTRAIN_ATTACH_LABEL
+        hookType.func = TowBarMod.Hook.attachByTowBarAction
+        hookType.towingVehicle = vehicleA
+        hookType.towedVehicle = vehicleB
+        hookType.textureName = "tow_bar_icon"
+        table.insert(hookTypeVariants, hookType)
+    end
+
+    return hookTypeVariants
+end
+
+local function getNearbyLandtrainTargets(mainVehicle)
+    local vehicles = {}
+    local square = mainVehicle and mainVehicle:getSquare() or nil
+    if square == nil then return vehicles end
+
+    for y = square:getY() - 6, square:getY() + 6 do
+        for x = square:getX() - 6, square:getX() + 6 do
+            local square2 = getCell():getGridSquare(x, y, square:getZ())
+            if square2 then
+                for i = 1, square2:getMovingObjects():size() do
+                    local obj = square2:getMovingObjects():get(i - 1)
+                    if obj ~= nil and instanceof(obj, "BaseVehicle") and obj ~= mainVehicle then
+                        local variants = getLandtrainHookTypeVariants(mainVehicle, obj)
+                        if #variants > 0 then
+                            table.insert(vehicles, { vehicle = obj, variants = variants })
+                        end
+                    end
+                end
+            end
+        end
+    end
+    return vehicles
+end
+
+local function addLandtrainHookOptionToMenu(playerObj, vehicle)
+    if playerObj == nil or vehicle == nil then return end
+    if not playerObj:getInventory():getItemFromTypeRecurse("TowBar.TowBar") then return end
+
+    local menu = getPlayerRadialMenu(playerObj:getPlayerNum())
+    if menu == nil then return end
+
+    local targets = getNearbyLandtrainTargets(vehicle)
+    if #targets == 0 then
+        ltLog("addLandtrainHookOptionToMenu no nearby valid targets for " .. vehLabel(vehicle))
+        return
+    end
+
+    if #targets == 1 then
+        local hookType = targets[1].variants[1]
+        menu:addSlice(
+            hookType.name,
+            getTexture("media/textures/tow_bar_attach.png"),
+            hookType.func,
+            playerObj,
+            hookType.towingVehicle,
+            hookType.towedVehicle,
+            hookType.towingPoint,
+            hookType.towedPoint
+        )
+        return
+    end
+
+    -- Reuse Towbar's chooser UI by passing only the candidate vehicles.
+    local vehicleList = {}
+    for _, entry in ipairs(targets) do
+        table.insert(vehicleList, entry.vehicle)
+    end
+    menu:addSlice(
+        LANDTRAIN_ATTACH_LABEL .. "...",
+        getTexture("media/textures/tow_bar_attach.png"),
+        TowBarMod.UI.showChooseVehicleMenu,
+        playerObj,
+        vehicle,
+        vehicleList,
+        true
+    )
+end
+
+local function installLandtrainTowbarPatch()
+    if not TowBarMod or not TowBarMod.Utils then
+        return
+    end
+
+    if TowBarMod.Utils._landtrainUnlimitedChainsInstalled then
+        return
+    end
+
+    -- Override Towbar's single-link limitation so a vehicle can be part of a chain.
+    function TowBarMod.Utils.getHookTypeVariants(vehicleA, vehicleB, hasTowBar)
+        local hookTypeVariants = {}
+        if not hasTowBar then return hookTypeVariants end
+        if vehicleA == nil or vehicleB == nil then return hookTypeVariants end
+        if vehicleA == vehicleB then return hookTypeVariants end
+
+        -- Allow trailer <-> vehicle and trailer <-> trailer links for landtrains.
+        if canTowByLandtrain(vehicleA, vehicleB, "trailerfront", "trailer") then
+            local hookType = {}
+            hookType.name = getText("UI_Text_Towing_attach") .. "\n" .. ISVehicleMenu.getVehicleDisplayName(vehicleB) .. "\n" .. getAttachLabel(vehicleA, vehicleB)
+            hookType.func = TowBarMod.Hook.attachByTowBarAction
+            hookType.towingVehicle = vehicleB
+            hookType.towedVehicle = vehicleA
+            hookType.textureName = "tow_bar_icon"
+            table.insert(hookTypeVariants, hookType)
+        elseif canTowByLandtrain(vehicleA, vehicleB, "trailer", "trailerfront") then
+            local hookType = {}
+            hookType.name = getText("UI_Text_Towing_attach") .. "\n" .. ISVehicleMenu.getVehicleDisplayName(vehicleB) .. "\n" .. getAttachLabel(vehicleA, vehicleB)
+            hookType.func = TowBarMod.Hook.attachByTowBarAction
+            hookType.towingVehicle = vehicleA
+            hookType.towedVehicle = vehicleB
+            hookType.textureName = "tow_bar_icon"
+            table.insert(hookTypeVariants, hookType)
+        end
+
+        return hookTypeVariants
+    end
+
+    -- Keep towbar state valid for middle links in a chain after detach/attach.
+    local originalPerformAttach = TowBarMod.Hook and TowBarMod.Hook.performAttachTowBar
+    if originalPerformAttach then
+        TowBarMod.Hook.performAttachTowBar = function(playerObj, towingVehicle, towedVehicle, attachmentA, attachmentB)
+            ltLog("performAttachTowBar begin towing=" .. vehLabel(towingVehicle) .. " towed=" .. vehLabel(towedVehicle)
+                .. " attA=" .. tostring(attachmentA) .. " attB=" .. tostring(attachmentB))
+            dumpTowState("performAttachTowBar pre towing", towingVehicle)
+            dumpTowState("performAttachTowBar pre towed", towedVehicle)
+            local frontLink = captureTowbarFrontLink(towingVehicle)
+            originalPerformAttach(playerObj, towingVehicle, towedVehicle, attachmentA, attachmentB)
+            dumpTowState("performAttachTowBar post-original towing", towingVehicle)
+            dumpTowState("performAttachTowBar post-original towed", towedVehicle)
+            restoreTowbarFrontLink(playerObj, frontLink)
+            queueTowbarFrontLinkRestore(playerObj, frontLink, 12)
+            queueTowbarFrontLinkRestore(playerObj, frontLink, 30)
+            dumpTowState("performAttachTowBar post-restore towing", towingVehicle)
+            dumpTowState("performAttachTowBar post-restore towed", towedVehicle)
+
+            setTowBarModelVisibleForVehicle(towedVehicle, true)
+            refreshTowBarState(towingVehicle)
+            refreshTowBarState(towedVehicle)
+            if towingVehicle then
+                refreshTowBarState(towingVehicle:getVehicleTowedBy())
+            end
+            if towedVehicle then
+                refreshTowBarState(towedVehicle:getVehicleTowing())
+            end
+        end
+    end
+
+    local originalPerformDetach = TowBarMod.Hook and TowBarMod.Hook.performDeattachTowBar
+    if originalPerformDetach then
+        TowBarMod.Hook.performDeattachTowBar = function(playerObj, towingVehicle, towedVehicle)
+            originalPerformDetach(playerObj, towingVehicle, towedVehicle)
+
+            setTowBarModelVisibleForVehicle(towedVehicle, false)
+            refreshTowBarState(towingVehicle)
+            refreshTowBarState(towedVehicle)
+            if towingVehicle then
+                refreshTowBarState(towingVehicle:getVehicleTowedBy())
+                refreshTowBarState(towingVehicle:getVehicleTowing())
+            end
+            if towedVehicle then
+                refreshTowBarState(towedVehicle:getVehicleTowedBy())
+                refreshTowBarState(towedVehicle:getVehicleTowing())
+            end
+        end
+    end
+
+    -- Towbar UI only adds attach when fully unlinked; add attach option for linked vehicles too.
+    if ISVehicleMenu and ISVehicleMenu.showRadialMenu and not TowBarMod.UI._landtrainShowRadialPatched then
+        local originalShowRadialMenu = ISVehicleMenu.showRadialMenu
+        ISVehicleMenu.showRadialMenu = function(playerObj)
+            originalShowRadialMenu(playerObj)
+
+            if playerObj == nil or playerObj:getVehicle() then return end
+            local vehicle = ISVehicleMenu.getVehicleToInteractWith(playerObj)
+            if vehicle == nil then return end
+
+            local menu = getPlayerRadialMenu(playerObj:getPlayerNum())
+            if menuHasTowbarAttachSlice(menu) then
+                return
+            end
+
+            if (vehicle:getVehicleTowing() or vehicle:getVehicleTowedBy()) then
+                addLandtrainHookOptionToMenu(playerObj, vehicle)
+            end
+        end
+        TowBarMod.UI._landtrainShowRadialPatched = true
+    end
+
+    TowBarMod.Utils._landtrainUnlimitedChainsInstalled = true
+end
+
+Events.OnGameBoot.Add(ensureTowAttachmentsForTrailers)
+Events.OnGameBoot.Add(installLandtrainTowbarPatch)
+Events.OnGameStart.Add(installLandtrainTowbarPatch)

42.13/mod.info

@@ -0,0 +1,9 @@
+name=Landtrain
+id=hrsys_landtrain
+require=\hrsys_towbars
+description=Extends Towbars to allow chained vehicle towing.
+author=Riggs0
+category=vehicle
+versionMin=42.13.0
+url=https://hudsonriggs.systems
+modversion=1.0.0

README.md

@@ -1,3 +1,30 @@
 # Landtrain
 
-Yargh I be a land pirate, or g'day chap wanna vb with that land train
+Landtrain extends Towbars to support chained towing.
+
+## Important
+
+Project Zomboid base `BaseVehicle.addPointConstraint()` force-breaks existing constraints.
+To keep `1 -> 2` while attaching `2 -> 3`, Landtrain includes a Java class override:
+
+- `zombie/vehicles/BaseVehicle.class`
+
+This is the same override pattern used by mods like Realistic Car Physics (manual `zombie` folder copy).
+
+## Apply patch to game
+
+1. Run:
+
+```powershell
+.\tools\patch-game-basevehicle.ps1
+```
+
+2. Ensure both mods are enabled:
+   - `hrsys_towbars`
+   - `hrsys_landtrain`
+
+## Restore vanilla class
+
+```powershell
+.\tools\restore-game-basevehicle.ps1
+```

mod.info

@@ -0,0 +1,9 @@
+name=Landtrain
+id=hrsys_landtrain
+require=\hrsys_towbars
+description=Extends Towbars to allow chained vehicle towing.
+author=Riggs0
+category=vehicle
+versionMin=42.13.0
+url=https://hudsonriggs.systems
+modversion=1.0.0

tools/java/BaseVehicleConstraintPatch.java

@@ -0,0 +1,105 @@
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.InsnNode;
+import org.objectweb.asm.tree.InsnList;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.objectweb.asm.Opcodes;
+
+/**
+ * Patches zombie.vehicles.BaseVehicle so addPointConstraint() no longer force-breaks
+ * both vehicles before creating a new constraint.
+ */
+public final class BaseVehicleConstraintPatch {
+    private static final String TARGET_NAME = "addPointConstraint";
+    private static final String BREAK_DESC_OBJECT_BOOL = "(ZLjava/lang/Boolean;)V";
+    private static final String BREAK_DESC_PRIMITIVE_BOOL = "(ZZ)V";
+    private static final String BASE_VEHICLE_OWNER = "zombie/vehicles/BaseVehicle";
+
+    private BaseVehicleConstraintPatch() {
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (args.length != 2) {
+            System.err.println("Usage: BaseVehicleConstraintPatch <input BaseVehicle.class> <output BaseVehicle.class>");
+            System.exit(2);
+        }
+
+        Path input = Paths.get(args[0]);
+        Path output = Paths.get(args[1]);
+        byte[] original = Files.readAllBytes(input);
+
+        ClassNode classNode = new ClassNode();
+        new ClassReader(original).accept(classNode, 0);
+
+        int removedCalls = 0;
+        int inspectedAddPointMethods = 0;
+        for (MethodNode method : classNode.methods) {
+            if (!TARGET_NAME.equals(method.name) || !isTargetAddPointConstraint(method.desc)) {
+                continue;
+            }
+            inspectedAddPointMethods++;
+            removedCalls += patchAddPointConstraint(method);
+        }
+
+        if (removedCalls < 2) {
+            throw new IllegalStateException(
+                    "Expected to remove 2 breakConstraint calls, removed "
+                            + removedCalls
+                            + " (inspected addPoint methods: "
+                            + inspectedAddPointMethods
+                            + ")");
+        }
+
+        ClassWriter writer = new ClassWriter(0);
+        classNode.accept(writer);
+
+        Files.createDirectories(output.getParent());
+        Files.write(output, writer.toByteArray());
+        System.out.println("Patched BaseVehicle.class; removed breakConstraint calls: " + removedCalls);
+    }
+
+    private static boolean isTargetAddPointConstraint(String methodDesc) {
+        // We only want the 5-arg overload:
+        // (IsoPlayer, BaseVehicle, String, String, boolean|Boolean) -> void
+        return "(Lzombie/characters/IsoPlayer;Lzombie/vehicles/BaseVehicle;Ljava/lang/String;Ljava/lang/String;Z)V"
+                        .equals(methodDesc)
+                || "(Lzombie/characters/IsoPlayer;Lzombie/vehicles/BaseVehicle;Ljava/lang/String;Ljava/lang/String;Ljava/lang/Boolean;)V"
+                        .equals(methodDesc);
+    }
+
+    private static int patchAddPointConstraint(MethodNode method) {
+        int patched = 0;
+        InsnList insns = method.instructions;
+
+        for (AbstractInsnNode node = insns.getFirst(); node != null; ) {
+            AbstractInsnNode next = node.getNext();
+            if (node instanceof MethodInsnNode call
+                    && BASE_VEHICLE_OWNER.equals(call.owner)
+                    && "breakConstraint".equals(call.name)) {
+                if (!(BREAK_DESC_OBJECT_BOOL.equals(call.desc)
+                        || BREAK_DESC_PRIMITIVE_BOOL.equals(call.desc))) {
+                    node = next;
+                    continue;
+                }
+                // Keep stack-map frames valid by preserving stack effect:
+                // breakConstraint(...) consumes objectref + 2 args and returns void.
+                // Replace invoke with POP2 + POP (consume 3 category-1 stack slots).
+                InsnList replacement = new InsnList();
+                replacement.add(new InsnNode(Opcodes.POP2));
+                replacement.add(new InsnNode(Opcodes.POP));
+                insns.insert(node, replacement);
+                insns.remove(node);
+                patched++;
+            }
+            node = next;
+        }
+
+        return patched;
+    }
+}

tools/patch-game-basevehicle.ps1

@@ -0,0 +1,80 @@
+param(
+    [string]$GameRoot = "D:\SteamLibrary\steamapps\common\ProjectZomboid"
+)
+
+$ErrorActionPreference = "Stop"
+
+$repoRoot = Split-Path -Parent $PSScriptRoot
+$toolsDir = Join-Path $repoRoot ".tools"
+$classPatchDir = Join-Path $toolsDir "classpatch"
+$buildDir = Join-Path $toolsDir "patcher-build"
+
+New-Item -ItemType Directory -Force -Path $toolsDir | Out-Null
+New-Item -ItemType Directory -Force -Path $classPatchDir | Out-Null
+New-Item -ItemType Directory -Force -Path $buildDir | Out-Null
+
+$javaExe = Join-Path $GameRoot "jre64\bin\java.exe"
+$gameJar = Join-Path $GameRoot "projectzomboid.jar"
+if (-not (Test-Path $javaExe)) { throw "java.exe not found at $javaExe" }
+if (-not (Test-Path $gameJar)) { throw "projectzomboid.jar not found at $gameJar" }
+
+$ecjJar = Join-Path $toolsDir "ecj.jar"
+$asmJar = Join-Path $toolsDir "asm.jar"
+$asmTreeJar = Join-Path $toolsDir "asm-tree.jar"
+
+if (-not (Test-Path $ecjJar)) {
+    Invoke-WebRequest -Uri "https://repo1.maven.org/maven2/org/eclipse/jdt/ecj/3.38.0/ecj-3.38.0.jar" -OutFile $ecjJar
+}
+if (-not (Test-Path $asmJar)) {
+    Invoke-WebRequest -Uri "https://repo1.maven.org/maven2/org/ow2/asm/asm/9.9/asm-9.9.jar" -OutFile $asmJar
+}
+if (-not (Test-Path $asmTreeJar)) {
+    Invoke-WebRequest -Uri "https://repo1.maven.org/maven2/org/ow2/asm/asm-tree/9.9/asm-tree-9.9.jar" -OutFile $asmTreeJar
+}
+
+$patcherSource = Join-Path $PSScriptRoot "java\BaseVehicleConstraintPatch.java"
+if (-not (Test-Path $patcherSource)) { throw "Missing patcher source: $patcherSource" }
+
+& $javaExe -jar $ecjJar -17 -cp "$asmJar;$asmTreeJar" -d $buildDir $patcherSource
+if ($LASTEXITCODE -ne 0) { throw "Failed to compile BaseVehicleConstraintPatch.java" }
+
+$inputClass = Join-Path $classPatchDir "BaseVehicle.original.class"
+$patchedClass = Join-Path $classPatchDir "BaseVehicle.patched.class"
+
+Add-Type -AssemblyName System.IO.Compression.FileSystem
+$zip = [System.IO.Compression.ZipFile]::OpenRead($gameJar)
+try {
+    $entry = $zip.GetEntry("zombie/vehicles/BaseVehicle.class")
+    if ($null -eq $entry) { throw "zombie/vehicles/BaseVehicle.class not found in $gameJar" }
+
+    $entryStream = $entry.Open()
+    $fileStream = [System.IO.File]::Create($inputClass)
+    try {
+        $entryStream.CopyTo($fileStream)
+    } finally {
+        $fileStream.Close()
+        $entryStream.Close()
+    }
+} finally {
+    $zip.Dispose()
+}
+
+& $javaExe -cp "$buildDir;$asmJar;$asmTreeJar" BaseVehicleConstraintPatch $inputClass $patchedClass
+if ($LASTEXITCODE -ne 0) { throw "BaseVehicle class patch failed" }
+
+$targetDir = Join-Path $GameRoot "zombie\vehicles"
+$targetClass = Join-Path $targetDir "BaseVehicle.class"
+$backupClass = "$targetClass.landtrain.original"
+
+New-Item -ItemType Directory -Force -Path $targetDir | Out-Null
+if (-not (Test-Path $backupClass)) {
+    if (Test-Path $targetClass) {
+        Copy-Item $targetClass $backupClass -Force
+    } else {
+        Copy-Item $inputClass $backupClass -Force
+    }
+}
+
+Copy-Item $patchedClass $targetClass -Force
+Write-Output "Patched BaseVehicle.class deployed to $targetClass"
+Write-Output "Backup stored at $backupClass"

tools/restore-game-basevehicle.ps1

@@ -0,0 +1,18 @@
+param(
+    [string]$GameRoot = "D:\SteamLibrary\steamapps\common\ProjectZomboid"
+)
+
+$ErrorActionPreference = "Stop"
+
+$targetClass = Join-Path $GameRoot "zombie\vehicles\BaseVehicle.class"
+$backupClass = "$targetClass.landtrain.original"
+
+if (Test-Path $backupClass) {
+    Copy-Item $backupClass $targetClass -Force
+    Write-Output "Restored BaseVehicle.class from $backupClass"
+} elseif (Test-Path $targetClass) {
+    Remove-Item $targetClass -Force
+    Write-Output "Removed override class at $targetClass (game will use class from projectzomboid.jar)"
+} else {
+    Write-Output "No override or backup found. Nothing to restore."
+}