Saving and Loading Fixed

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

@@ -6,17 +6,28 @@ local LANDTRAIN_DEBUG = true
 local LANDTRAIN_FALLBACK_MAX_DIST_SQ = 3.25 -- ~1.8 tiles
 local LANDTRAIN_FALLBACK_MAX_DZ = 0.9
 local LANDTRAIN_FRONT_SQL_ID_KEY = "landtrainTowbarFrontSqlId"
-local LANDTRAIN_FRONT_ID_KEY_LEGACY = "landtrainTowbarFrontVehicleId"
 local LANDTRAIN_FRONT_ATTACHMENT_A_KEY = "landtrainTowbarAttachmentA"
 local LANDTRAIN_FRONT_ATTACHMENT_B_KEY = "landtrainTowbarAttachmentB"
+local LANDTRAIN_REAR_SQL_ID_KEY = "landtrainTowbarRearSqlId"
+local LANDTRAIN_SAVED_POS_X_KEY = "landtrainSavedPosX"
+local LANDTRAIN_SAVED_POS_Y_KEY = "landtrainSavedPosY"
+local LANDTRAIN_SAVED_POS_Z_KEY = "landtrainSavedPosZ"
+local LANDTRAIN_SAVED_DIR_KEY = "landtrainSavedDir"
+
+local function emitLandtrainLog(line)
+    print(line)
+    if type(writeLog) == "function" then
+        pcall(writeLog, "Landtrain", line)
+    end
+end
 
 local function ltLog(msg)
     if not LANDTRAIN_DEBUG then return end
-    print("[Landtrain] " .. tostring(msg))
+    emitLandtrainLog("[Landtrain] " .. tostring(msg))
 end
 
 local function ltInfo(msg)
-    print("[Landtrain][Info] " .. tostring(msg))
+    emitLandtrainLog("[Landtrain][Info] " .. tostring(msg))
 end
 
 ltInfo("UnlimitedTowbarChains loaded. debug=" .. tostring(LANDTRAIN_DEBUG))
@@ -27,6 +38,115 @@ local function vehLabel(vehicle)
     return tostring(vehicle:getId()) .. ":" .. tostring(name)
 end
 
+local _landtrainPairPickPosA = Vector3f.new()
+local _landtrainPairPickPosB = Vector3f.new()
+
+local function hasAttachmentById(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 getTowbarStyleAttachmentPair(towingVehicle, towedVehicle)
+    local attachmentA = nil
+    local attachmentB = nil
+
+    if hasAttachmentById(towingVehicle, "trailer") then
+        attachmentA = "trailer"
+    elseif towingVehicle ~= nil then
+        attachmentA = towingVehicle:getTowAttachmentSelf()
+    end
+
+    if hasAttachmentById(towedVehicle, "trailerfront") then
+        attachmentB = "trailerfront"
+    elseif towedVehicle ~= nil then
+        attachmentB = towedVehicle:getTowAttachmentSelf()
+    end
+
+    if attachmentA == attachmentB then
+        if attachmentA == "trailer" and hasAttachmentById(towedVehicle, "trailerfront") then
+            attachmentB = "trailerfront"
+        elseif attachmentA == "trailerfront" and hasAttachmentById(towingVehicle, "trailer") then
+            attachmentA = "trailer"
+        end
+    end
+
+    if attachmentA == nil then attachmentA = "trailer" end
+    if attachmentB == nil then attachmentB = "trailerfront" end
+    return attachmentA, attachmentB
+end
+
+local function chooseLandtrainAttachmentPair(towingVehicle, towedVehicle, preferredA, preferredB)
+    local seen = {}
+    local candidates = {}
+    local function addCandidate(a, b)
+        if a == nil or b == nil or a == b then return end
+        local key = tostring(a) .. "|" .. tostring(b)
+        if seen[key] then return end
+        seen[key] = true
+        table.insert(candidates, { a = a, b = b })
+    end
+
+    addCandidate(preferredA, preferredB)
+    addCandidate(towingVehicle and towingVehicle:getTowAttachmentSelf() or nil, towedVehicle and towedVehicle:getTowAttachmentSelf() or nil)
+    addCandidate("trailer", "trailerfront")
+    addCandidate("trailerfront", "trailer")
+
+    local bestPair = nil
+    local bestDistSq = nil
+    local bestDz = nil
+    for _, pair in ipairs(candidates) do
+        if hasAttachmentById(towingVehicle, pair.a) and hasAttachmentById(towedVehicle, pair.b) then
+            local posA = towingVehicle:getAttachmentWorldPos(pair.a, _landtrainPairPickPosA)
+            local posB = towedVehicle:getAttachmentWorldPos(pair.b, _landtrainPairPickPosB)
+            if posA ~= nil and posB ~= nil then
+                local dx = posA:x() - posB:x()
+                local dy = posA:y() - posB:y()
+                local dz = math.abs(posA:z() - posB:z())
+                local distSq = dx * dx + dy * dy + (posA:z() - posB:z()) * (posA:z() - posB:z())
+                if bestPair == nil or distSq < bestDistSq or (distSq == bestDistSq and dz < bestDz) then
+                    bestPair = pair
+                    bestDistSq = distSq
+                    bestDz = dz
+                end
+            elseif bestPair == nil then
+                bestPair = pair
+            end
+        end
+    end
+
+    if bestPair ~= nil then
+        return bestPair.a, bestPair.b
+    end
+
+    local fallbackA = preferredA or (towingVehicle and towingVehicle:getTowAttachmentSelf()) or "trailer"
+    local fallbackB = preferredB or (towedVehicle and towedVehicle:getTowAttachmentSelf()) or "trailerfront"
+    if fallbackA == fallbackB then
+        if fallbackA == "trailerfront" then
+            fallbackA = "trailer"
+        else
+            fallbackB = "trailerfront"
+        end
+    end
+    return fallbackA, fallbackB
+end
+
+local function chooseLandtrainTowbarPair(towingVehicle, towedVehicle, preferredA, preferredB)
+    local towbarA, towbarB = getTowbarStyleAttachmentPair(towingVehicle, towedVehicle)
+    if towbarA ~= towbarB and hasAttachmentById(towingVehicle, towbarA) and hasAttachmentById(towedVehicle, towbarB) then
+        return towbarA, towbarB
+    end
+
+    if preferredA ~= nil and preferredB ~= nil and preferredA ~= preferredB
+        and hasAttachmentById(towingVehicle, preferredA)
+        and hasAttachmentById(towedVehicle, preferredB) then
+        return preferredA, preferredB
+    end
+
+    return chooseLandtrainAttachmentPair(towingVehicle, towedVehicle, preferredA, preferredB)
+end
+
 local function dumpTowState(prefix, vehicle)
     if not LANDTRAIN_DEBUG then return end
     if vehicle == nil then
@@ -131,7 +251,7 @@ local function getVehicleBySqlIdSafe(sqlId)
 
     for i = 0, vehicles:size() - 1 do
         local vehicle = vehicles:get(i)
-        if vehicle ~= nil and vehicle:getSqlId and vehicle:getSqlId() == targetSqlId then
+        if vehicle ~= nil and vehicle.getSqlId and vehicle:getSqlId() == targetSqlId then
             return vehicle
         end
     end
@@ -140,11 +260,13 @@ end
 
 local function storeLandtrainFrontLinkData(towingVehicle, towedVehicle, attachmentA, attachmentB)
     if towingVehicle == nil or towedVehicle == nil then return end
+    local towingModData = towingVehicle:getModData()
     local towedModData = towedVehicle:getModData()
-    if towedModData == nil then return end
+    if towingModData == nil or towedModData == nil then return end
     if towingVehicle == towedVehicle or towingVehicle:getId() == towedVehicle:getId() then
+        towingModData[LANDTRAIN_REAR_SQL_ID_KEY] = nil
+        towingVehicle:transmitModData()
         towedModData[LANDTRAIN_FRONT_SQL_ID_KEY] = nil
-        towedModData[LANDTRAIN_FRONT_ID_KEY_LEGACY] = nil
         towedModData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = nil
         towedModData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = nil
         towedVehicle:transmitModData()
@@ -152,15 +274,22 @@ local function storeLandtrainFrontLinkData(towingVehicle, towedVehicle, attachme
         return
     end
 
-    local towingSqlId = towingVehicle:getSqlId and towingVehicle:getSqlId() or -1
+    local towingSqlId = towingVehicle.getSqlId and towingVehicle:getSqlId() or -1
     if towingSqlId ~= nil and towingSqlId >= 0 then
         towedModData[LANDTRAIN_FRONT_SQL_ID_KEY] = towingSqlId
     else
         towedModData[LANDTRAIN_FRONT_SQL_ID_KEY] = nil
     end
-    towedModData[LANDTRAIN_FRONT_ID_KEY_LEGACY] = nil
+    local towedSqlId = towedVehicle.getSqlId and towedVehicle:getSqlId() or -1
-    towedModData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = attachmentA or towingVehicle:getTowAttachmentSelf() or "trailer"
+    if towedSqlId ~= nil and towedSqlId >= 0 then
-    towedModData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = attachmentB or towedVehicle:getTowAttachmentSelf() or "trailerfront"
+        towingModData[LANDTRAIN_REAR_SQL_ID_KEY] = towedSqlId
+    else
+        towingModData[LANDTRAIN_REAR_SQL_ID_KEY] = nil
+    end
+    towingVehicle:transmitModData()
+    local resolvedA, resolvedB = chooseLandtrainTowbarPair(towingVehicle, towedVehicle, attachmentA, attachmentB)
+    towedModData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = resolvedA
+    towedModData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = resolvedB
     towedVehicle:transmitModData()
 end
 
@@ -168,8 +297,19 @@ local function clearLandtrainFrontLinkData(vehicle)
     if vehicle == nil then return end
     local modData = vehicle:getModData()
     if modData == nil then return end
+    local frontSqlId = tonumber(modData[LANDTRAIN_FRONT_SQL_ID_KEY])
+    local vehicleSqlId = vehicle.getSqlId and vehicle:getSqlId() or nil
+    if frontSqlId ~= nil and vehicleSqlId ~= nil and vehicleSqlId >= 0 then
+        local frontVehicle = getVehicleBySqlIdSafe(frontSqlId)
+        if frontVehicle ~= nil then
+            local frontModData = frontVehicle:getModData()
+            if frontModData ~= nil and tonumber(frontModData[LANDTRAIN_REAR_SQL_ID_KEY]) == vehicleSqlId then
+                frontModData[LANDTRAIN_REAR_SQL_ID_KEY] = nil
+                frontVehicle:transmitModData()
+            end
+        end
+    end
     modData[LANDTRAIN_FRONT_SQL_ID_KEY] = nil
-    modData[LANDTRAIN_FRONT_ID_KEY_LEGACY] = nil
     modData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = nil
     modData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = nil
     vehicle:transmitModData()
@@ -187,6 +327,7 @@ local function isTowbarManagedVehicle(vehicle)
         or modData["isChangedTowedAttachment"] == true
         or modData["towBarChangedAttachmentId"] ~= nil
         or modData[LANDTRAIN_FRONT_SQL_ID_KEY] ~= nil
+        or modData[LANDTRAIN_REAR_SQL_ID_KEY] ~= nil
 end
 
 local function restoreVehicleTowbarDefaults(vehicle)
@@ -244,9 +385,9 @@ local function restoreVehicleTowbarDefaults(vehicle)
     modData.towBarOriginalMass = nil
     modData.towBarOriginalBrakingForce = nil
     modData[LANDTRAIN_FRONT_SQL_ID_KEY] = nil
-    modData[LANDTRAIN_FRONT_ID_KEY_LEGACY] = nil
     modData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = nil
     modData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = nil
+    modData[LANDTRAIN_REAR_SQL_ID_KEY] = nil
 
     if TowBarMod and TowBarMod.Hook and TowBarMod.Hook.clearReapplied then
         TowBarMod.Hook.clearReapplied(vehicle)
@@ -277,7 +418,7 @@ local function reconcileTowbarSplitVehicle(vehicle)
     end
 
     modData["towed"] = (frontVehicle ~= nil)
-    modData["isTowingByTowBar"] = (frontVehicle ~= nil) or (hasTowbarRear == true)
+    modData["isTowingByTowBar"] = (modData["towed"] == true) or (hasTowbarRear == true)
     vehicle:transmitModData()
 end
 
@@ -344,7 +485,7 @@ end
 
 local function sanitizeLoadedTowLinks()
     local vehicles = getLoadedVehicles()
-    if #vehicles == 0 then return end
+    if #vehicles == 0 then return vehicles end
 
     for _, vehicle in ipairs(vehicles) do
         local front = vehicle:getVehicleTowedBy()
@@ -357,252 +498,382 @@ local function sanitizeLoadedTowLinks()
         end
     end
 
-    for _, vehicle in ipairs(vehicles) do
+    return vehicles
-        reconcileTowbarSplitAround(vehicle)
-        refreshTowBarState(vehicle)
-        local frontVehicle = vehicle:getVehicleTowedBy()
-        if frontVehicle ~= nil and isTowbarManagedVehicle(vehicle) then
-            storeLandtrainFrontLinkData(frontVehicle, vehicle)
-        end
-    end
 end
 
-local _landtrainLoadSanityTicks = 0
+local function setModDataNumberIfChanged(modData, key, value)
-local function onLandtrainLoadSanityTick()
+    if modData == nil or key == nil or value == nil then return false end
-    if _landtrainLoadSanityTicks <= 0 then
+    local current = tonumber(modData[key])
-        Events.OnTick.Remove(onLandtrainLoadSanityTick)
+    if current ~= nil and math.abs(current - value) < 0.0001 then
-        return
-    end
-
-    _landtrainLoadSanityTicks = _landtrainLoadSanityTicks - 1
-    if (_landtrainLoadSanityTicks % 30) ~= 0 then
-        return
-    end
-    sanitizeLoadedTowLinks()
-end
-
-local function scheduleLandtrainLoadSanity()
-    _landtrainLoadSanityTicks = 300 -- run for ~5 seconds
-    Events.OnTick.Remove(onLandtrainLoadSanityTick)
-    Events.OnTick.Add(onLandtrainLoadSanityTick)
-    sanitizeLoadedTowLinks()
-end
-
-local landtrainPendingRestoreVehicleIds = {}
-local landtrainReapplyTickCounter = 0
-
-local function hasLandtrainFrontLinkData(vehicle)
-    if vehicle == nil then return false end
-    local modData = vehicle:getModData()
-    if modData == nil then return false end
-    return modData[LANDTRAIN_FRONT_SQL_ID_KEY] ~= nil
-end
-
-local function queueLandtrainTowbarRestore(vehicle)
-    if vehicle == nil then return end
-    local modData = vehicle:getModData()
-    if modData == nil then return end
-
-    -- Drop legacy runtime-id metadata; it is not stable across save/load sessions.
-    if modData[LANDTRAIN_FRONT_ID_KEY_LEGACY] ~= nil then
-        modData[LANDTRAIN_FRONT_ID_KEY_LEGACY] = nil
-        vehicle:transmitModData()
-    end
-
-    local vehicleSqlId = vehicle.getSqlId and vehicle:getSqlId() or nil
-    local frontVehicleSqlId = tonumber(modData[LANDTRAIN_FRONT_SQL_ID_KEY])
-    if frontVehicleSqlId ~= nil and vehicleSqlId ~= nil and vehicleSqlId >= 0 and frontVehicleSqlId == vehicleSqlId then
-        modData[LANDTRAIN_FRONT_SQL_ID_KEY] = nil
-        modData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] = nil
-        modData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] = nil
-        modData["towed"] = false
-        vehicle:transmitModData()
-        ltLog("queueLandtrainTowbarRestore cleared invalid self front sqlId for " .. vehLabel(vehicle))
-    end
-
-    if modData["towed"] == true
-        or modData["isTowingByTowBar"] == true
-        or modData[LANDTRAIN_FRONT_SQL_ID_KEY] ~= nil
-        or modData.towBarOriginalScriptName ~= nil
-        or modData.towBarOriginalMass ~= nil
-        or modData.towBarOriginalBrakingForce ~= nil then
-        landtrainPendingRestoreVehicleIds[vehicle:getId()] = true
-    end
-end
-
-local function tryLandtrainTowbarRestore(vehicle, playerObj)
-    if vehicle == nil then return true end
-    local modData = vehicle:getModData()
-    if modData == nil then return true end
-
-    local frontVehicle = vehicle:getVehicleTowedBy()
-    if frontVehicle == vehicle then
-        ltLog("tryLandtrainTowbarRestore cleared self front link for " .. vehLabel(vehicle))
-        clearLandtrainFrontLinkData(vehicle)
-        modData["towed"] = false
-        vehicle:transmitModData()
-        return true
-    end
-    if frontVehicle ~= nil then
-        if modData["isTowingByTowBar"] == true or modData["towed"] == true then
-            storeLandtrainFrontLinkData(frontVehicle, vehicle)
-            if TowBarMod and TowBarMod.Hook and TowBarMod.Hook.setVehiclePostAttach then
-                TowBarMod.Hook.setVehiclePostAttach(playerObj, vehicle)
-            end
-            if TowBarMod and TowBarMod.Hook and TowBarMod.Hook.markReapplied then
-                TowBarMod.Hook.markReapplied(vehicle)
-            end
-            setTowBarModelVisibleForVehicle(vehicle, true)
-            refreshTowBarState(frontVehicle)
-            refreshTowBarState(vehicle)
-        end
-        return true
-    end
-
-    if modData["towed"] ~= true and not hasLandtrainFrontLinkData(vehicle) then
-        clearLandtrainFrontLinkData(vehicle)
-        return true
-    end
-
-    local frontVehicleSqlId = tonumber(modData[LANDTRAIN_FRONT_SQL_ID_KEY])
-    if frontVehicleSqlId == nil then
-        clearLandtrainFrontLinkData(vehicle)
-        if modData["towed"] == true then
-            modData["towed"] = false
-            vehicle:transmitModData()
-        end
-        return true
-    end
-
-    local vehicleSqlId = vehicle.getSqlId and vehicle:getSqlId() or nil
-    if vehicleSqlId ~= nil and vehicleSqlId >= 0 and frontVehicleSqlId == vehicleSqlId then
-        ltLog("tryLandtrainTowbarRestore dropped self metadata sqlId for " .. vehLabel(vehicle))
-        clearLandtrainFrontLinkData(vehicle)
-        modData["towed"] = false
-        vehicle:transmitModData()
-        return true
-    end
-
-    local savedFrontVehicle = getVehicleBySqlIdSafe(frontVehicleSqlId)
-    if savedFrontVehicle == nil then
         return false
     end
-    if savedFrontVehicle == vehicle or savedFrontVehicle:getId() == vehicle:getId() then
+    modData[key] = value
-        ltLog("tryLandtrainTowbarRestore dropped self resolved front for " .. vehLabel(vehicle))
-        clearLandtrainFrontLinkData(vehicle)
-        modData["towed"] = false
-        vehicle:transmitModData()
-        return true
-    end
-
-    local currentRear = savedFrontVehicle:getVehicleTowing()
-    if currentRear ~= nil and currentRear ~= vehicle then
-        return false
-    end
-
-    local attachmentA = modData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] or savedFrontVehicle:getTowAttachmentSelf() or "trailer"
-    local attachmentB = modData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] or vehicle:getTowAttachmentSelf() or "trailerfront"
-    local scriptA = savedFrontVehicle:getScript()
-    local scriptB = vehicle:getScript()
-    if scriptA == nil or scriptB == nil then
-        return false
-    end
-    if scriptA:getAttachmentById(attachmentA) == nil then
-        attachmentA = savedFrontVehicle:getTowAttachmentSelf() or "trailer"
-    end
-    if scriptB:getAttachmentById(attachmentB) == nil then
-        attachmentB = vehicle:getTowAttachmentSelf() or "trailerfront"
-    end
-    if scriptA:getAttachmentById(attachmentA) == nil or scriptB:getAttachmentById(attachmentB) == nil then
-        return false
-    end
-
-    playerObj = playerObj or getPlayer()
-    if playerObj == nil then
-        return false
-    end
-    if TowBarMod == nil or TowBarMod.Utils == nil or TowBarMod.Utils.updateAttachmentsForRigidTow == nil then
-        return false
-    end
-
-    TowBarMod.Utils.updateAttachmentsForRigidTow(savedFrontVehicle, vehicle, attachmentA, attachmentB)
-    vehicle:setScriptName("notTowingA_Trailer")
-    local args = {
-        vehicleA = savedFrontVehicle:getId(),
-        vehicleB = vehicle:getId(),
-        attachmentA = attachmentA,
-        attachmentB = attachmentB
-    }
-    if args.vehicleA == args.vehicleB then
-        ltLog("tryLandtrainTowbarRestore blocked self attach args for " .. vehLabel(vehicle))
-        clearLandtrainFrontLinkData(vehicle)
-        modData["towed"] = false
-        vehicle:transmitModData()
-        return true
-    end
-    sendClientCommand(playerObj, "vehicle", "attachTrailer", args)
-    if TowBarScheduleAction and TowBarMod and TowBarMod.Hook and TowBarMod.Hook.setVehiclePostAttach then
-        ISTimedActionQueue.add(TowBarScheduleAction:new(playerObj, 10, TowBarMod.Hook.setVehiclePostAttach, vehicle))
-    elseif TowBarMod and TowBarMod.Hook and TowBarMod.Hook.setVehiclePostAttach then
-        TowBarMod.Hook.setVehiclePostAttach(playerObj, vehicle)
-    end
-
-    savedFrontVehicle:getModData()["isTowingByTowBar"] = true
-    modData["isTowingByTowBar"] = true
-    modData["towed"] = true
-    savedFrontVehicle:transmitModData()
-    vehicle:transmitModData()
-    storeLandtrainFrontLinkData(savedFrontVehicle, vehicle, attachmentA, attachmentB)
-    setTowBarModelVisibleForVehicle(vehicle, true)
-    refreshTowBarState(savedFrontVehicle)
-    refreshTowBarState(vehicle)
-    if TowBarMod and TowBarMod.Hook and TowBarMod.Hook.markReapplied then
-        TowBarMod.Hook.markReapplied(vehicle)
-    end
     return true
 end
 
-local function processLandtrainPendingRestores()
+local function saveLandtrainVehiclePosition(vehicle)
-    landtrainReapplyTickCounter = landtrainReapplyTickCounter + 1
+    if vehicle == nil then return false end
-    if landtrainReapplyTickCounter < 15 then
+    local modData = vehicle:getModData()
+    if modData == nil then return false end
+
+    local changed = false
+    changed = setModDataNumberIfChanged(modData, LANDTRAIN_SAVED_POS_X_KEY, vehicle:getX()) or changed
+    changed = setModDataNumberIfChanged(modData, LANDTRAIN_SAVED_POS_Y_KEY, vehicle:getY()) or changed
+    changed = setModDataNumberIfChanged(modData, LANDTRAIN_SAVED_POS_Z_KEY, vehicle:getZ()) or changed
+    if vehicle.getDirectionAngle then
+        local ok, angle = pcall(function()
+            return vehicle:getDirectionAngle()
+        end)
+        if ok and angle ~= nil then
+            changed = setModDataNumberIfChanged(modData, LANDTRAIN_SAVED_DIR_KEY, angle) or changed
+        end
+    end
+
+    if changed then
+        vehicle:transmitModData()
+    end
+    return changed
+end
+
+local function isLandtrainTowbarLink(frontVehicle, rearVehicle)
+    if frontVehicle == nil or rearVehicle == nil then return false end
+    if frontVehicle == rearVehicle or frontVehicle:getId() == rearVehicle:getId() then return false end
+    if frontVehicle:getVehicleTowing() ~= rearVehicle or rearVehicle:getVehicleTowedBy() ~= frontVehicle then
+        return false
+    end
+
+    local frontModData = frontVehicle:getModData()
+    local rearModData = rearVehicle:getModData()
+    if frontModData == nil or rearModData == nil then return false end
+    return isTowbarManagedVehicle(frontVehicle)
+        or isTowbarManagedVehicle(rearVehicle)
+        or tonumber(rearModData[LANDTRAIN_FRONT_SQL_ID_KEY]) ~= nil
+        or tonumber(frontModData[LANDTRAIN_REAR_SQL_ID_KEY]) ~= nil
+end
+
+local function saveLandtrainTowbarLink(frontVehicle, rearVehicle, attachmentA, attachmentB)
+    if not isLandtrainTowbarLink(frontVehicle, rearVehicle) then return false end
+    storeLandtrainFrontLinkData(frontVehicle, rearVehicle, attachmentA, attachmentB)
+    local changed = false
+    changed = saveLandtrainVehiclePosition(frontVehicle) or changed
+    changed = saveLandtrainVehiclePosition(rearVehicle) or changed
+    return changed
+end
+
+local function saveActiveLandtrainTowbarSnapshot(vehicles)
+    local loaded = vehicles or getLoadedVehicles()
+    local savedLinks = 0
+    for _, rearVehicle in ipairs(loaded) do
+        local frontVehicle = rearVehicle:getVehicleTowedBy()
+        if isLandtrainTowbarLink(frontVehicle, rearVehicle) then
+            local rearModData = rearVehicle:getModData()
+            local attachmentA, attachmentB = chooseLandtrainTowbarPair(
+                frontVehicle,
+                rearVehicle,
+                rearModData and rearModData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] or nil,
+                rearModData and rearModData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] or nil
+            )
+            if saveLandtrainTowbarLink(frontVehicle, rearVehicle, attachmentA, attachmentB) then
+                savedLinks = savedLinks + 1
+            end
+        end
+    end
+    return savedLinks
+end
+
+local function callVehicleMethodSafe(vehicle, methodName, ...)
+    if vehicle == nil then return false end
+    local method = vehicle[methodName]
+    if type(method) ~= "function" then return false end
+    local ok = pcall(method, vehicle, ...)
+    return ok
+end
+
+local function restoreSavedVehiclePosition(vehicle)
+    if vehicle == nil then return false end
+    local modData = vehicle:getModData()
+    if modData == nil then return false end
+
+    local x = tonumber(modData[LANDTRAIN_SAVED_POS_X_KEY])
+    local y = tonumber(modData[LANDTRAIN_SAVED_POS_Y_KEY])
+    local z = tonumber(modData[LANDTRAIN_SAVED_POS_Z_KEY])
+    if x == nil or y == nil or z == nil then
+        return false
+    end
+
+    local moved = false
+    moved = callVehicleMethodSafe(vehicle, "setX", x) or moved
+    moved = callVehicleMethodSafe(vehicle, "setY", y) or moved
+    moved = callVehicleMethodSafe(vehicle, "setZ", z) or moved
+    callVehicleMethodSafe(vehicle, "setLx", x)
+    callVehicleMethodSafe(vehicle, "setLy", y)
+    callVehicleMethodSafe(vehicle, "setLz", z)
+
+    local dir = tonumber(modData[LANDTRAIN_SAVED_DIR_KEY])
+    if dir ~= nil then
+        callVehicleMethodSafe(vehicle, "setDirectionAngle", dir)
+    end
+
+    local cell = getCell()
+    if cell ~= nil then
+        local square = cell:getGridSquare(math.floor(x), math.floor(y), math.floor(z))
+        if square ~= nil then
+            callVehicleMethodSafe(vehicle, "setCurrent", square)
+        end
+    end
+
+    callVehicleMethodSafe(vehicle, "transmitPosition")
+    return moved
+end
+
+local function collectSavedLandtrainLinks(vehicles)
+    local links = {}
+    local seenRear = {}
+    local frontSqlByRearSql = {}
+    for _, vehicle in ipairs(vehicles) do
+        local modData = vehicle and vehicle:getModData() or nil
+        local rearSqlId = vehicle and vehicle.getSqlId and vehicle:getSqlId() or nil
+        local frontSqlId = modData and tonumber(modData[LANDTRAIN_FRONT_SQL_ID_KEY]) or nil
+        if rearSqlId ~= nil and rearSqlId >= 0 and frontSqlId ~= nil and frontSqlId >= 0 and frontSqlId ~= rearSqlId then
+            frontSqlByRearSql[rearSqlId] = frontSqlId
+        end
+    end
+
+    local function getSavedDepthForRearSql(rearSqlId)
+        if rearSqlId == nil or rearSqlId < 0 then return 0 end
+        local depth = 0
+        local seen = {}
+        local cursorSqlId = rearSqlId
+        while cursorSqlId ~= nil do
+            local frontSqlId = frontSqlByRearSql[cursorSqlId]
+            if frontSqlId == nil or frontSqlId < 0 then
+                break
+            end
+            if seen[frontSqlId] then
+                break
+            end
+            seen[frontSqlId] = true
+            depth = depth + 1
+            cursorSqlId = frontSqlId
+        end
+        return depth
+    end
+
+    for _, rearVehicle in ipairs(vehicles) do
+        if rearVehicle ~= nil then
+            local rearId = rearVehicle:getId()
+            if not seenRear[rearId] then
+                local rearModData = rearVehicle:getModData()
+                local frontSqlId = rearModData and tonumber(rearModData[LANDTRAIN_FRONT_SQL_ID_KEY]) or nil
+                local frontVehicle = nil
+                if frontSqlId ~= nil and frontSqlId >= 0 then
+                    frontVehicle = getVehicleBySqlIdSafe(frontSqlId)
+                end
+                if frontVehicle == nil then
+                    frontVehicle = rearVehicle:getVehicleTowedBy()
+                end
+                if frontVehicle ~= nil and frontVehicle ~= rearVehicle and frontVehicle:getId() ~= rearVehicle:getId() then
+                    local attachmentA, attachmentB = chooseLandtrainTowbarPair(
+                        frontVehicle,
+                        rearVehicle,
+                        rearModData and rearModData[LANDTRAIN_FRONT_ATTACHMENT_A_KEY] or nil,
+                        rearModData and rearModData[LANDTRAIN_FRONT_ATTACHMENT_B_KEY] or nil
+                    )
+                    table.insert(links, {
+                        frontVehicle = frontVehicle,
+                        rearVehicle = rearVehicle,
+                        attachmentA = attachmentA,
+                        attachmentB = attachmentB,
+                        depth = getSavedDepthForRearSql(rearVehicle.getSqlId and rearVehicle:getSqlId() or nil)
+                    })
+                    seenRear[rearId] = true
+                end
+            end
+        end
+    end
+    table.sort(links, function(a, b)
+        if a.depth == b.depth then
+            return a.rearVehicle:getId() < b.rearVehicle:getId()
+        end
+        return a.depth < b.depth
+    end)
+    return links
+end
+
+local function detachSavedLandtrainLinks(links)
+    local detached = 0
+    for i = #links, 1, -1 do
+        local link = links[i]
+        local frontVehicle = link.frontVehicle
+        local rearVehicle = link.rearVehicle
+        if frontVehicle ~= nil and rearVehicle ~= nil
+            and (frontVehicle:getVehicleTowing() == rearVehicle or rearVehicle:getVehicleTowedBy() == frontVehicle) then
+            if breakConstraintSafe(frontVehicle, "load-rebuild-detach") then
+                detached = detached + 1
+            end
+        end
+    end
+    return detached
+end
+
+local function attachSavedLandtrainLink(playerObj, link, delayTicks)
+    local frontVehicle = link.frontVehicle
+    local rearVehicle = link.rearVehicle
+    if playerObj == nil or frontVehicle == nil or rearVehicle == nil then return false end
+    if TowBarMod == nil or TowBarMod.Utils == nil or TowBarMod.Utils.updateAttachmentsForRigidTow == nil then
+        return false
+    end
+    if frontVehicle == rearVehicle or frontVehicle:getId() == rearVehicle:getId() then
+        return false
+    end
+
+    local scriptA = frontVehicle:getScript()
+    local scriptB = rearVehicle:getScript()
+    if scriptA == nil or scriptB == nil then
+        return false
+    end
+    if scriptA:getAttachmentById(link.attachmentA) == nil or scriptB:getAttachmentById(link.attachmentB) == nil then
+        return false
+    end
+
+    local originalScriptName = rearVehicle:getScriptName()
+    TowBarMod.Utils.updateAttachmentsForRigidTow(frontVehicle, rearVehicle, link.attachmentA, link.attachmentB)
+    rearVehicle:setScriptName("notTowingA_Trailer")
+    local args = {
+        vehicleA = frontVehicle:getId(),
+        vehicleB = rearVehicle:getId(),
+        attachmentA = link.attachmentA,
+        attachmentB = link.attachmentB
+    }
+    if args.vehicleA == args.vehicleB then
+        return false
+    end
+    sendClientCommand(playerObj, "vehicle", "attachTrailer", args)
+
+    local frontModData = frontVehicle:getModData()
+    local rearModData = rearVehicle:getModData()
+    if frontModData == nil or rearModData == nil then return false end
+    frontModData["isTowingByTowBar"] = true
+    rearModData["isTowingByTowBar"] = true
+    rearModData["towed"] = true
+    if rearModData.towBarOriginalScriptName == nil and originalScriptName ~= "notTowingA_Trailer" then
+        rearModData.towBarOriginalScriptName = originalScriptName
+    end
+    if rearModData.towBarOriginalMass == nil then
+        rearModData.towBarOriginalMass = rearVehicle:getMass()
+    end
+    if rearModData.towBarOriginalBrakingForce == nil then
+        rearModData.towBarOriginalBrakingForce = rearVehicle:getBrakingForce()
+    end
+    frontVehicle:transmitModData()
+    rearVehicle:transmitModData()
+    storeLandtrainFrontLinkData(frontVehicle, rearVehicle, link.attachmentA, link.attachmentB)
+
+    if TowBarScheduleAction and TowBarMod and TowBarMod.Hook and TowBarMod.Hook.setVehiclePostAttach then
+        ISTimedActionQueue.add(TowBarScheduleAction:new(playerObj, delayTicks, TowBarMod.Hook.setVehiclePostAttach, rearVehicle))
+    elseif TowBarMod and TowBarMod.Hook and TowBarMod.Hook.setVehiclePostAttach then
+        TowBarMod.Hook.setVehiclePostAttach(playerObj, rearVehicle)
+    end
+    if TowBarMod and TowBarMod.Hook and TowBarMod.Hook.markReapplied then
+        TowBarMod.Hook.markReapplied(rearVehicle)
+    end
+
+    setTowBarModelVisibleForVehicle(rearVehicle, true)
+    refreshTowBarState(frontVehicle)
+    refreshTowBarState(rearVehicle)
+    return true
+end
+
+local function runLandtrainSingleLoadRestorePass()
+    local vehicles = sanitizeLoadedTowLinks()
+    if vehicles == nil or #vehicles == 0 then
+        ltInfo("Landtrain load rebuild: no loaded vehicles")
         return
     end
-    landtrainReapplyTickCounter = 0
 
-    local resolvedVehicleIds = {}
+    local links = collectSavedLandtrainLinks(vehicles)
-    local playerObj = getPlayer()
+    if #links == 0 then
-    for vehicleId, _ in pairs(landtrainPendingRestoreVehicleIds) do
+        ltInfo("Landtrain load rebuild: no saved towbar links")
-        local vehicle = getVehicleByIdSafe(vehicleId)
+        return
-        if vehicle == nil or tryLandtrainTowbarRestore(vehicle, playerObj) then
+    end
-            table.insert(resolvedVehicleIds, vehicleId)
+
+    local playerObj = getPlayer() or getSpecificPlayer(0)
+    if playerObj == nil then
+        ltInfo("Landtrain load rebuild skipped: no player")
+        return
+    end
+    if TowBarMod == nil or TowBarMod.Utils == nil or TowBarMod.Utils.updateAttachmentsForRigidTow == nil then
+        ltInfo("Landtrain load rebuild skipped: TowBar utilities unavailable")
+        return
+    end
+
+    local movedVehicles = 0
+    local movedSeen = {}
+    for _, link in ipairs(links) do
+        local frontId = link.frontVehicle:getId()
+        local rearId = link.rearVehicle:getId()
+        if not movedSeen[frontId] then
+            if restoreSavedVehiclePosition(link.frontVehicle) then
+                movedVehicles = movedVehicles + 1
+            end
+            movedSeen[frontId] = true
+        end
+        if not movedSeen[rearId] then
+            if restoreSavedVehiclePosition(link.rearVehicle) then
+                movedVehicles = movedVehicles + 1
+            end
+            movedSeen[rearId] = true
         end
     end
 
-    for _, vehicleId in ipairs(resolvedVehicleIds) do
+    local detachedCount = detachSavedLandtrainLinks(links)
-        landtrainPendingRestoreVehicleIds[vehicleId] = nil
+    local attachedCount = 0
-    end
+    for index, link in ipairs(links) do
-end
+        local delay = 10 + ((index - 1) * 5)
-
+        if attachSavedLandtrainLink(playerObj, link, delay) then
-local function queueLandtrainLoadedTowbarRestores()
+            attachedCount = attachedCount + 1
-    local vehicles = getLoadedVehicles()
-    for _, vehicle in ipairs(vehicles) do
-        local frontVehicle = vehicle:getVehicleTowedBy()
-        if frontVehicle ~= nil and isTowbarManagedVehicle(vehicle) then
-            storeLandtrainFrontLinkData(frontVehicle, vehicle)
         end
-        queueLandtrainTowbarRestore(vehicle)
     end
+
+    saveActiveLandtrainTowbarSnapshot(vehicles)
+    ltInfo("Landtrain load rebuild complete moved=" .. tostring(movedVehicles)
+        .. " detached=" .. tostring(detachedCount)
+        .. " attached=" .. tostring(attachedCount)
+        .. " links=" .. tostring(#links))
 end
 
-local function onLandtrainSpawnVehicleEnd(vehicle)
+local landtrainLoadRebuildDone = false
-    if vehicle == nil then return end
+local landtrainSaveSnapshotTickCounter = 0
-    local frontVehicle = vehicle:getVehicleTowedBy()
+local function onLandtrainSaveSnapshotTick()
-    if frontVehicle ~= nil and isTowbarManagedVehicle(vehicle) then
+    if not landtrainLoadRebuildDone then
-        storeLandtrainFrontLinkData(frontVehicle, vehicle)
+        return
     end
-    queueLandtrainTowbarRestore(vehicle)
+    landtrainSaveSnapshotTickCounter = landtrainSaveSnapshotTickCounter + 1
-    queueLandtrainTowbarRestore(vehicle:getVehicleTowedBy())
+    if landtrainSaveSnapshotTickCounter < 60 then
-    queueLandtrainTowbarRestore(vehicle:getVehicleTowing())
+        return
+    end
+    landtrainSaveSnapshotTickCounter = 0
+    saveActiveLandtrainTowbarSnapshot()
+end
+
+local landtrainLoadRestoreDelayTicks = 0
+local function onLandtrainSingleLoadRestoreTick()
+    if landtrainLoadRestoreDelayTicks > 0 then
+        landtrainLoadRestoreDelayTicks = landtrainLoadRestoreDelayTicks - 1
+        return
+    end
+    Events.OnTick.Remove(onLandtrainSingleLoadRestoreTick)
+    runLandtrainSingleLoadRestorePass()
+    landtrainLoadRebuildDone = true
+end
+
+local function scheduleLandtrainSingleLoadRestore()
+    -- Single delayed load pass: restore saved positions, detach all saved links, reattach in chain order.
+    landtrainLoadRebuildDone = false
+    landtrainSaveSnapshotTickCounter = 0
+    landtrainLoadRestoreDelayTicks = 90
+    Events.OnTick.Remove(onLandtrainSingleLoadRestoreTick)
+    Events.OnTick.Add(onLandtrainSingleLoadRestoreTick)
 end
 
 local _landtrainHookPosA = Vector3f.new()
@@ -700,11 +971,12 @@ local function captureTowbarFrontLink(towingVehicle)
         return nil
     end
 
+    local attachmentA, attachmentB = chooseLandtrainTowbarPair(frontVehicle, towingVehicle, nil, nil)
     local link = {
         frontVehicle = frontVehicle,
         towingVehicle = towingVehicle,
-        attachmentA = frontVehicle:getTowAttachmentSelf() or "trailer",
+        attachmentA = attachmentA,
-        attachmentB = towingVehicle:getTowAttachmentSelf() or "trailerfront"
+        attachmentB = attachmentB
     }
     ltLog("captureTowbarFrontLink captured front=" .. vehLabel(frontVehicle) .. " middle=" .. vehLabel(towingVehicle)
         .. " attA=" .. tostring(link.attachmentA) .. " attB=" .. tostring(link.attachmentB))
@@ -809,9 +1081,16 @@ end
 
 local function menuHasTowbarAttachSlice(menu)
     if menu == nil or menu.slices == nil then return false end
+    local attachAction = TowBarMod and TowBarMod.Hook and TowBarMod.Hook.attachByTowBarAction or nil
+    local chooseAction = TowBarMod and TowBarMod.UI and TowBarMod.UI.showChooseVehicleMenu or nil
+    if attachAction == nil and chooseAction == 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
+        if (attachAction ~= nil and command == attachAction)
+            or (chooseAction ~= nil and command == chooseAction) then
             return true
         end
     end
@@ -820,9 +1099,13 @@ end
 
 local function menuHasTowbarDetachSlice(menu)
     if menu == nil or menu.slices == nil then return false end
+    local detachAction = TowBarMod and TowBarMod.Hook and TowBarMod.Hook.deattachTowBarAction or nil
+    if detachAction == nil then
+        return false
+    end
     for _, slice in ipairs(menu.slices) do
         local command = slice.command and slice.command[1]
-        if command == TowBarMod.Hook.deattachTowBarAction then
+        if command == detachAction then
             return true
         end
     end
@@ -971,7 +1254,18 @@ end
 
 local function addLandtrainHookOptionToMenu(playerObj, vehicle)
     if playerObj == nil or vehicle == nil then return end
-    if not playerObj:getInventory():getItemFromTypeRecurse("TowBar.TowBar") then
+    local hasTowBarItem = false
+    if playerObj.getInventory and playerObj:getInventory() ~= nil then
+        hasTowBarItem = playerObj:getInventory():getItemFromTypeRecurse("TowBar.TowBar") ~= nil
+    end
+    if not hasTowBarItem and TowBarMod and TowBarMod.Hook and TowBarMod.Hook.getTowBarInventoryItem then
+        hasTowBarItem = TowBarMod.Hook.getTowBarInventoryItem(playerObj) ~= nil
+    end
+    if not hasTowBarItem and TowBarMod and TowBarMod.Utils and TowBarMod.Utils.getTowBarInventoryItem then
+        hasTowBarItem = TowBarMod.Utils.getTowBarInventoryItem(playerObj) ~= nil
+    end
+
+    if not hasTowBarItem then
         ltLog("addLandtrainHookOptionToMenu no TowBar item for " .. vehLabel(vehicle))
         return
     end
@@ -1093,7 +1387,7 @@ local function installLandtrainTowbarPatch()
             if towedVehicle then
                 refreshTowBarState(towedVehicle:getVehicleTowing())
             end
-            queueLandtrainTowbarRestore(towedVehicle)
+            saveActiveLandtrainTowbarSnapshot()
         end
 
         TowBarMod.Hook.performAttachTowBar = performAttachWrapper
@@ -1166,8 +1460,7 @@ local function installLandtrainTowbarPatch()
             refreshTowBarState(resolvedTowingVehicle:getVehicleTowing())
             refreshTowBarState(resolvedTowedVehicle:getVehicleTowedBy())
             refreshTowBarState(resolvedTowedVehicle:getVehicleTowing())
-            queueLandtrainTowbarRestore(resolvedTowingVehicle)
+            saveActiveLandtrainTowbarSnapshot()
-            queueLandtrainTowbarRestore(resolvedTowedVehicle)
 
             dumpTowState("performDeattachTowBar post-reconcile towing", resolvedTowingVehicle)
             dumpTowState("performDeattachTowBar post-reconcile towed", resolvedTowedVehicle)
@@ -1202,7 +1495,7 @@ local function installLandtrainTowbarPatch()
         ltLog("installLandtrainTowbarPatch patched ISVehicleMenu.onDetachTrailer")
     end
 
-    -- Towbar UI only adds attach when fully unlinked; add attach option for linked vehicles too.
+    -- Towbar UI only adds attach when fully unlinked; add attach for linked/chain-related interactions too.
     if ISVehicleMenu and ISVehicleMenu.showRadialMenu and ISVehicleMenu.showRadialMenu ~= TowBarMod.UI._landtrainShowRadialWrapper then
         local originalShowRadialMenu = ISVehicleMenu.showRadialMenu
         local showRadialWrapper = function(playerObj)
@@ -1228,7 +1521,15 @@ local function installLandtrainTowbarPatch()
                 return
             end
 
-            if (vehicle:getVehicleTowing() or vehicle:getVehicleTowedBy()) then
+            local vehicleLinked = vehicle:getVehicleTowing() ~= nil or vehicle:getVehicleTowedBy() ~= nil
+            local chainRelated = isTowbarChainVehicleOrNeighbor(vehicle)
+            local shouldInjectAttach = vehicleLinked or chainRelated
+            ltLog("showRadial attach check vehicle=" .. vehLabel(vehicle)
+                .. " linked=" .. tostring(vehicleLinked)
+                .. " chainRelated=" .. tostring(chainRelated)
+                .. " shouldInject=" .. tostring(shouldInjectAttach))
+
+            if shouldInjectAttach then
                 addLandtrainHookOptionToMenu(playerObj, vehicle)
             else
                 ltLog("showRadial vehicle not linked, Landtrain attach not injected for " .. vehLabel(vehicle))
@@ -1299,7 +1600,5 @@ end
 Events.OnGameBoot.Add(ensureTowAttachmentsForTrailers)
 Events.OnGameBoot.Add(startLandtrainInstallWatchdog)
 Events.OnGameStart.Add(startLandtrainInstallWatchdog)
-Events.OnGameStart.Add(scheduleLandtrainLoadSanity)
+Events.OnGameStart.Add(scheduleLandtrainSingleLoadRestore)
-Events.OnGameStart.Add(queueLandtrainLoadedTowbarRestores)
+Events.OnTick.Add(onLandtrainSaveSnapshotTick)
-Events.OnSpawnVehicleEnd.Add(onLandtrainSpawnVehicleEnd)
-Events.OnTick.Add(processLandtrainPendingRestores)