42.20 and Towtrucks

2026-08-13 18:59:54 -04:00
parent a6ba4877d0
commit e403323017
33 changed files with 2333 additions and 142 deletions
@@ -6,5 +6,3 @@ TowBarMod.Config.rigidTowbarDistance = 1.0
 TowBarMod.Config.towAttachmentExteriorPadding = 0.25
 TowBarMod.Config.towedVehicleRollingMass = 75
 TowBarMod.Config.devMode = false
-TowBarMod.Config.vanillaTowbarModelScaleMin = 1.5
-TowBarMod.Config.vanillaTowbarModelScaleMax = 2.0
@@ -4,6 +4,23 @@ if not TowBarMod then TowBarMod = {} end
 TowBarMod.Sync = TowBarMod.Sync or {}
 if TowBarMod.Sync._towSyncClientLoaded then return end
 TowBarMod.Sync._towSyncClientLoaded = true
+TowBarMod.Sync.appliedPairs = TowBarMod.Sync.appliedPairs or {}
+
+local function pairKeyContainsVehicle(key, vehicleId)
+    local id = tostring(vehicleId)
+    return string.sub(key, 1, #id + 1) == id .. ":"
+        or string.sub(key, -(#id + 1)) == ":" .. id
+end
+
+local function clearAppliedPairForVehicle(vehicle)
+    if not vehicle then return end
+    local vehicleId = vehicle:getId()
+    for key in pairs(TowBarMod.Sync.appliedPairs) do
+        if pairKeyContainsVehicle(key, vehicleId) then
+            TowBarMod.Sync.appliedPairs[key] = nil
+        end
+    end
+end

 local function resolveVehicle(id)
    if not id then return nil end
@@ -89,6 +106,8 @@ local function reconcilePairState(vehicleA, vehicleB, attachmentA, attachmentB)
    end
 end

+local breakTowBarPair
+
 local function applyAttachSync(args)
    if not args then return end

@@ -102,8 +121,25 @@ local function applyAttachSync(args)
        return
    end

-    if not isLinked(vehicleA, vehicleB) then
-        vehicleA:addPointConstraint(nil, vehicleB, attachmentA, attachmentB)
+    local key = tostring(vehicleA:getId()) .. ":" .. tostring(vehicleB:getId())
+    if TowBarMod.Sync.appliedPairs[key] and not isLinked(vehicleA, vehicleB) then
+        -- Vehicle streaming can remove the native constraint while the Lua
+        -- module remains loaded. Allow the authoritative recovery sync to
+        -- rebuild local physics for the returning pair.
+        TowBarMod.Sync.appliedPairs[key] = nil
+    end
+    if not TowBarMod.Sync.appliedPairs[key] then
+        -- The server initially creates a normal Build 42 tow relation. It may
+        -- also restore one from the save. Replace that native rope exactly
+        -- once with this mod's rigid fake-trailer constraint.
+        breakTowBarPair(vehicleA, vehicleB)
+        if TowBarMod.Hook and TowBarMod.Hook.setVehicleScriptWithTowBarHidden then
+            TowBarMod.Hook.setVehicleScriptWithTowBarHidden(vehicleB, "notTowingA_Trailer")
+        end
+        -- The final true keeps this a local physics rebuild. The server owns
+        -- the persisted logical relation and must not receive a detach/attach race.
+        vehicleA:addPointConstraint(nil, vehicleB, attachmentA, attachmentB, true)
+        TowBarMod.Sync.appliedPairs[key] = true
    end

    reconcilePairState(vehicleA, vehicleB, attachmentA, attachmentB)
@@ -130,18 +166,17 @@ local function hasConflictingTowLink(vehicle, expectedOther)
            and modData["towBarTowingVehicleId"] ~= expectedOtherId)
 end

-local function breakTowBarPair(vehicleA, vehicleB)
+breakTowBarPair = function(vehicleA, vehicleB)
    if not vehicleA or not vehicleB then return end

    local vehicleAReferencesB = vehicleA:getVehicleTowing() == vehicleB
        or vehicleA:getVehicleTowedBy() == vehicleB
    local vehicleBReferencesA = vehicleB:getVehicleTowing() == vehicleA
        or vehicleB:getVehicleTowedBy() == vehicleA
-    if vehicleBReferencesA then
-        vehicleB:breakConstraint(true, true)
-    end
    if vehicleAReferencesB then
        vehicleA:breakConstraint(true, true)
+    elseif vehicleBReferencesA then
+        vehicleB:breakConstraint(true, true)
    end
 end

@@ -154,6 +189,7 @@ local function applyDetachSync(args)
        return
    end
    breakTowBarPair(vehicleA, vehicleB)
+    TowBarMod.Sync.appliedPairs[tostring(vehicleA:getId()) .. ":" .. tostring(vehicleB:getId())] = nil

    if TowBarMod.Hook and TowBarMod.Hook.cleanupDetachedTowBar then
        pcall(TowBarMod.Hook.cleanupDetachedTowBar, vehicleA, vehicleB)
@@ -170,4 +206,10 @@ local function onServerCommand(module, command, args)
    end
 end

+TowBarMod.Sync.applyAttachSync = applyAttachSync
+TowBarMod.Sync.applyDetachSync = applyDetachSync
+
 Events.OnServerCommand.Add(onServerCommand)
+if Events.OnSpawnVehicleEnd then
+    Events.OnSpawnVehicleEnd.Add(clearAppliedPairForVehicle)
+end
@@ -128,61 +128,54 @@ local function sendTowAttachCommand(playerObj, args)
 end

 local TowbarVariantSize = 24
-local TowbarNormalStart = 0
-local TowbarLargeStart = 24
 local TowbarMaxIndex = TowbarVariantSize - 1
-local VanillaScaleMin = 1.5
-local VanillaScaleMax = 2.0
+local TowbarFirstZ = 1.0
+local TowbarSlotStep = 0.1
+-- Measured from Towbar.fbx at its original 0.01 script scale. The visual is
+-- enlarged uniformly, so its center must move outward by the scaled half-length
+-- to keep the inner end on the same vehicle-hitbox contact point.
+local TowbarVisualScale = 2.5
+local TowbarModelLength = 0.9714089036
+local TowbarScaledModelLength = TowbarModelLength * TowbarVisualScale
+local TowbarModelHalfLength = TowbarScaledModelLength / 2

-local function getVehicleModelScale(script)
+local function getTowbarFrontEdgeZ(script)
    if not script then return nil end

-    local ok, result = pcall(function()
-        return script:getModelScale()
+    local ok, shape = pcall(function()
+        return script:getPhysicsChassisShape()
    end)
-    if ok and type(result) == "number" then
-        return result
-    end
+    if not ok or not shape then return nil end

-    ok, result = pcall(function()
-        local model = script:getModel()
-        if model then
-            return model:getScale()
-        end
-        return nil
+    local shapeOk, shapeZ = pcall(function()
+        return shape:z()
    end)
-    if ok and type(result) == "number" then
-        return result
-    end
-
+    if not shapeOk or type(shapeZ) ~= "number" or shapeZ <= 0 then
        return nil
    end

-local function isVanillaScale(script)
-    local modelScale = getVehicleModelScale(script)
-    if modelScale == nil then
-        return true
-    end
+    local centerOk, center = pcall(function()
+        return script:getCenterOfMassOffset()
+    end)
+    if not centerOk or not center then return nil end

-    local configuredMin = TowBarMod.Config and tonumber(TowBarMod.Config.vanillaTowbarModelScaleMin)
-    local configuredMax = TowBarMod.Config and tonumber(TowBarMod.Config.vanillaTowbarModelScaleMax)
-    local minScale = configuredMin or VanillaScaleMin
-    local maxScale = configuredMax or VanillaScaleMax
-    return modelScale >= minScale and modelScale <= maxScale
-end
+    local zOk, centerZ = pcall(function()
+        return center:z()
+    end)
+    if not zOk or type(centerZ) ~= "number" then return nil end

-local function getTowbarIndexVanilla(script)
-    local z = script:getPhysicsChassisShape():z() / 2 - 0.1
-    local index = math.floor((z * 2 / 3 - 1) * 10)
-    return math.max(0, math.min(TowbarMaxIndex, index))
+    return centerZ + shapeZ / 2
 end

 local function getTowbarModelSlot(script)
-    if not isVanillaScale(script) then
-        -- KI5/small-scale vehicles use the normal towbar0 mesh at Z=1.
-        return 0
-    end
-    return getTowbarIndexVanilla(script)
+    local frontEdgeZ = getTowbarFrontEdgeZ(script)
+    if frontEdgeZ == nil then return nil end
+
+    -- Model offsets position the mesh origin. Move its center outward so the
+    -- towbar's inner end, rather than its center, meets the vehicle hitbox.
+    local modelCenterZ = frontEdgeZ + TowbarModelHalfLength
+    local index = math.floor(((modelCenterZ - TowbarFirstZ) / TowbarSlotStep) + 0.5)
+    return math.max(0, math.min(TowbarMaxIndex, index))
 end

 local function setTowBarModelVisible(vehicle, isVisible)
@@ -210,7 +203,7 @@ local function setTowBarModelVisible(vehicle, isVisible)

    local index = getTowbarModelSlot(script)
    local part = normalPart
-    if part then
+    if part and index ~= nil then
        part:setModelVisible("towbar" .. index, true)
    end

@@ -409,15 +402,11 @@ local function recoverTowBarVehicleAfterLoad(playerObj, vehicle, retriesLeft)

    if towingVehicle then
        -- Apply rigid spacing as soon as the tow link exists to avoid a visible
-        -- bumper-to-bumper snap while waiting for reattach recovery.
+        -- bumper-to-bumper snap. Server/SP reconciliation owns recovery and
+        -- never refunds or consumes an item while loading a save.
        TowBarMod.Hook.setVehiclePostAttach(nil, vehicle)
-    end
-
-    if localPlayer and towingVehicle then
-        if reattachTowBarPairAfterCleanDetach(localPlayer, towingVehicle, vehicle, false) then
        return
    end
-    end

    if localPlayer and retries > 0 then
        -- During world load, tow links can become available a few ticks later.
@@ -425,9 +414,8 @@ local function recoverTowBarVehicleAfterLoad(playerObj, vehicle, retriesLeft)
        return
    end

-    -- Fallback: keep original post-attach restoration behavior.
-    setTowBarModelVisible(vehicle, true)
-    TowBarMod.Hook.setVehiclePostAttach(nil, vehicle)
+    -- Leave reciprocal saved state untouched. The authoritative audit will
+    -- reconnect it when both vehicle chunks are loaded.
 end

 function TowBarMod.Hook.setVehiclePostAttach(playerObj, towedVehicle, retriesLeft)
@@ -514,8 +502,6 @@ end
 function TowBarMod.Hook.cleanupDetachedTowBar(towingVehicle, towedVehicle)
    if towingVehicle == nil or towedVehicle == nil then return end

-    TowBarMod.Utils.updateAttachmentsOnDefaultValues(towingVehicle, towedVehicle)
-
    local towingModData = towingVehicle:getModData()
    local towedModData = towedVehicle:getModData()
    if not towingModData or not towedModData then return end
@@ -523,17 +509,25 @@ function TowBarMod.Hook.cleanupDetachedTowBar(towingVehicle, towedVehicle)
    if towedModData.towBarOriginalScriptName then
        TowBarMod.Hook.setVehicleScriptWithTowBarHidden(towedVehicle, towedModData.towBarOriginalScriptName)
    end
+    -- A very fast break can happen while the temporary fake-trailer script is
+    -- still active. Restore the real script first so the saved offsets are
+    -- written back to the actual vehicle attachments, not the temporary script.
+    TowBarMod.Utils.updateAttachmentsOnDefaultValues(towingVehicle, towedVehicle)
    restoreFreeRollingTowState(towedVehicle, towedModData)

    towingModData["isTowingByTowBar"] = false
    towingModData["towed"] = false
    towingModData["towBarTowedVehicleId"] = nil
+    towingModData["towBarTowedVehicleSqlId"] = nil
    towingModData["towBarTowingVehicleId"] = nil
+    towingModData["towBarTowingVehicleSqlId"] = nil
    towingModData["towBarExpectedAttachment"] = nil
    towedModData["isTowingByTowBar"] = false
    towedModData["towed"] = false
    towedModData["towBarTowedVehicleId"] = nil
+    towedModData["towBarTowedVehicleSqlId"] = nil
    towedModData["towBarTowingVehicleId"] = nil
+    towedModData["towBarTowingVehicleSqlId"] = nil
    towedModData["towBarExpectedAttachment"] = nil
    towedModData.towBarOriginalScriptName = nil
    towedModData.towBarOriginalMass = nil
@@ -762,7 +756,6 @@ function TowBarMod.Hook.devShowAllTowbarModels(playerObj, vehicle)
    local script = vehicle:getScript()
    local chassisZ = script and script:getPhysicsChassisShape():z() or 0
    local halfZ = chassisZ / 2
-    local modelScale = script and getVehicleModelScale(script) or nil
    local index = 0
    if script then
        index = getTowbarModelSlot(script)
@@ -770,7 +763,7 @@ function TowBarMod.Hook.devShowAllTowbarModels(playerObj, vehicle)
    local selectedPart = "towbar"
    print("[TowBar DEV] Vehicle: " .. tostring(vehicle:getScriptName()))
    print("[TowBar DEV] chassisShape.z = " .. tostring(chassisZ) .. ", half = " .. tostring(halfZ))
-    print("[TowBar DEV] modelScale = " .. tostring(modelScale) .. ", part = " .. selectedPart)
+    print("[TowBar DEV] frontEdgeZ = " .. tostring(script and getTowbarFrontEdgeZ(script) or nil) .. ", part = " .. selectedPart)
    print("[TowBar DEV] Formula picks index = " .. tostring(index) .. " (towbar" .. tostring(index) .. " at Z offset " .. tostring(1.0 + index * 0.1) .. ")")
    print("[TowBar DEV] Showing towbar0..towbar23 on both parts")
    for j = 0, TowbarVariantSize - 1 do
@@ -215,7 +215,13 @@ end
 function ISVehicleMenu.showRadialMenu(playerObj)
   TowBarMod.UI.defaultShowRadialMenu(playerObj)

-   if playerObj:getVehicle() then return end
+   local currentVehicle = playerObj:getVehicle()
+   if currentVehicle then
+      if TowBarMod.WreckerUI then
+         TowBarMod.WreckerUI.addOptionsToMenu(playerObj, currentVehicle)
+      end
+      return
+   end

   local vehicle = ISVehicleMenu.getVehicleToInteractWith(playerObj)
   if vehicle == nil then return end
@@ -0,0 +1,216 @@
+if isServer() then return end
+if not TowBarMod then TowBarMod = {} end
+TowBarMod.WreckerSync = TowBarMod.WreckerSync or {}
+
+local Sync = TowBarMod.WreckerSync
+Sync.appliedLevels = Sync.appliedLevels or {}
+
+local function pairKeyContainsVehicle(key, vehicleId)
+    local id = tostring(vehicleId)
+    return string.sub(key, 1, #id + 1) == id .. ":"
+        or string.sub(key, -(#id + 1)) == ":" .. id
+end
+
+local function clearAppliedLevelForVehicle(vehicle)
+    if not vehicle then return end
+    local vehicleId = vehicle:getId()
+    for key in pairs(Sync.appliedLevels) do
+        if pairKeyContainsVehicle(key, vehicleId) then
+            Sync.appliedLevels[key] = nil
+        end
+    end
+end
+
+local function pairKey(wrecker, target)
+    return tostring(wrecker:getId()) .. ":" .. tostring(target:getId())
+end
+
+local function callVehicle(vehicle, methodName, value)
+    local method = vehicle and vehicle[methodName] or nil
+    if not method then return false, nil end
+    return pcall(function()
+        if value ~= nil then return method(vehicle, value) end
+        return method(vehicle)
+    end)
+end
+
+local function applyFreeRollingState(vehicle)
+    local md = vehicle and vehicle:getModData() or nil
+    if not md then return end
+    local capturedOriginal = false
+    if md.wreckerOriginalMass == nil then
+        md.wreckerOriginalMass = vehicle:getMass()
+        capturedOriginal = true
+    end
+    if md.wreckerOriginalBrakingForce == nil then
+        md.wreckerOriginalBrakingForce = vehicle:getBrakingForce()
+        capturedOriginal = true
+    end
+    if md.wreckerOriginalParkingBrakeOn == nil then
+        local ok, value = callVehicle(vehicle, "isParkingBrakeOn")
+        if ok then
+            md.wreckerOriginalParkingBrakeOn = value
+            capturedOriginal = true
+        end
+    end
+    if md.wreckerOriginalParkingBrake == nil then
+        local ok, value = callVehicle(vehicle, "getParkingBrake")
+        if ok then
+            md.wreckerOriginalParkingBrake = value
+            capturedOriginal = true
+        end
+    end
+    if md.wreckerOriginalHandbrake == nil then
+        local ok, value = callVehicle(vehicle, "isHandbrake")
+        if ok then
+            md.wreckerOriginalHandbrake = value
+            capturedOriginal = true
+        end
+    end
+    vehicle:setMass(200)
+    vehicle:setBrakingForce(0)
+    if md.wreckerOriginalParkingBrakeOn ~= nil then callVehicle(vehicle, "setParkingBrakeOn", false) end
+    if md.wreckerOriginalParkingBrake ~= nil then callVehicle(vehicle, "setParkingBrake", false) end
+    if md.wreckerOriginalHandbrake ~= nil then callVehicle(vehicle, "setHandbrake", false) end
+    if capturedOriginal then vehicle:transmitModData() end
+end
+
+local function restoreFreeRollingState(vehicle)
+    local md = vehicle and vehicle:getModData() or nil
+    if not md then return end
+    if md.wreckerOriginalMass ~= nil then vehicle:setMass(md.wreckerOriginalMass) end
+    if md.wreckerOriginalBrakingForce ~= nil then vehicle:setBrakingForce(md.wreckerOriginalBrakingForce) end
+    if md.wreckerOriginalParkingBrakeOn ~= nil then
+        callVehicle(vehicle, "setParkingBrakeOn", md.wreckerOriginalParkingBrakeOn)
+    end
+    if md.wreckerOriginalParkingBrake ~= nil then
+        callVehicle(vehicle, "setParkingBrake", md.wreckerOriginalParkingBrake)
+    end
+    if md.wreckerOriginalHandbrake ~= nil then
+        callVehicle(vehicle, "setHandbrake", md.wreckerOriginalHandbrake)
+    end
+    md.wreckerOriginalMass = nil
+    md.wreckerOriginalBrakingForce = nil
+    md.wreckerOriginalParkingBrakeOn = nil
+    md.wreckerOriginalParkingBrake = nil
+    md.wreckerOriginalHandbrake = nil
+    vehicle:transmitModData()
+end
+
+local function isPairLinked(wrecker, target)
+    return wrecker and target
+        and wrecker:getVehicleTowing() == target
+        and target:getVehicleTowedBy() == wrecker
+end
+
+local function hasConflictingLink(vehicle, other)
+    return vehicle and ((vehicle:getVehicleTowing() and vehicle:getVehicleTowing() ~= other)
+        or (vehicle:getVehicleTowedBy() and vehicle:getVehicleTowedBy() ~= other))
+end
+
+local function breakWreckerPair(wrecker, target)
+    if not wrecker or not target then return end
+    if isPairLinked(wrecker, target) then
+        wrecker:breakConstraint(true, true)
+    end
+end
+
+local function setScriptSafely(vehicle, scriptName)
+    if TowBarMod.Hook and TowBarMod.Hook.setVehicleScriptWithTowBarHidden then
+        return TowBarMod.Hook.setVehicleScriptWithTowBarHidden(vehicle, scriptName)
+    end
+    vehicle:setScriptName(scriptName)
+    return true
+end
+
+local function applyAttachSync(args)
+    if not args then return end
+    local wrecker = getVehicleById(args.wrecker)
+    local target = getVehicleById(args.target)
+    if not wrecker or not target then return end
+    if hasConflictingLink(wrecker, target) or hasConflictingLink(target, wrecker) then return end
+
+    local hookAttachment = TowBarMod.Wrecker.getHeightAttachmentId(args.heightLevel)
+    local targetAttachment = args.targetAttachment
+    if not hookAttachment or (targetAttachment ~= "trailer" and targetAttachment ~= "trailerfront") then return end
+    if not wrecker:attachmentExist(hookAttachment) or not target:attachmentExist(targetAttachment) then return end
+
+    local key = pairKey(wrecker, target)
+    local canonicalLevel = tonumber(args.heightLevel) or 0
+    local appliedLevel = Sync.appliedLevels[key]
+    if isPairLinked(wrecker, target) and appliedLevel == canonicalLevel then
+        Sync.appliedLevels[key] = canonicalLevel
+        applyFreeRollingState(target)
+        return
+    end
+
+    breakWreckerPair(wrecker, target)
+    local targetMd = target:getModData()
+    local originalScript = targetMd.wreckerOriginalScriptName or target:getScriptName()
+    targetMd.wreckerOriginalScriptName = originalScript
+    applyFreeRollingState(target)
+
+    setScriptSafely(target, "notTowingA_Trailer")
+    wrecker:addPointConstraint(nil, target, hookAttachment, targetAttachment, true)
+    setScriptSafely(target, originalScript)
+
+    local wreckerMd = wrecker:getModData()
+    wreckerMd.wreckerTowActive = true
+    wreckerMd.wreckerTowedVehicleId = target:getId()
+    wreckerMd.wreckerTowedVehicleSqlId = tonumber(args.targetSqlId)
+    wreckerMd.wreckerTargetAttachment = targetAttachment
+    wreckerMd.wreckerHeightLevel = canonicalLevel
+    targetMd.wreckerTowingVehicleId = wrecker:getId()
+    targetMd.wreckerTowingVehicleSqlId = tonumber(args.wreckerSqlId)
+    Sync.appliedLevels[key] = canonicalLevel
+end
+
+local function applyDetachSync(args)
+    if not args then return end
+    local wrecker = getVehicleById(args.wrecker)
+    local target = getVehicleById(args.target)
+    if not target then return end
+    local targetMd = target:getModData()
+    local expectedWreckerId = tonumber(targetMd.wreckerTowingVehicleId)
+    local expectedWreckerSqlId = tonumber(targetMd.wreckerTowingVehicleSqlId)
+    local commandWreckerSqlId = tonumber(args.wreckerSqlId)
+    if expectedWreckerSqlId and commandWreckerSqlId then
+        if expectedWreckerSqlId ~= commandWreckerSqlId then return end
+    elseif expectedWreckerId and expectedWreckerId ~= tonumber(args.wrecker) then
+        return
+    end
+    if wrecker and (hasConflictingLink(wrecker, target) or hasConflictingLink(target, wrecker)) then return end
+    if wrecker then breakWreckerPair(wrecker, target) end
+    if targetMd.wreckerOriginalScriptName and target:getScriptName() ~= targetMd.wreckerOriginalScriptName then
+        setScriptSafely(target, targetMd.wreckerOriginalScriptName)
+    end
+    restoreFreeRollingState(target)
+    if wrecker then Sync.appliedLevels[pairKey(wrecker, target)] = nil end
+
+    if wrecker then
+        local wreckerMd = wrecker:getModData()
+        wreckerMd.wreckerTowActive = nil
+        wreckerMd.wreckerTowedVehicleId = nil
+        wreckerMd.wreckerTowedVehicleSqlId = nil
+        wreckerMd.wreckerTargetAttachment = nil
+        wreckerMd.wreckerHeightLevel = nil
+    end
+    targetMd.wreckerTowingVehicleId = nil
+    targetMd.wreckerTowingVehicleSqlId = nil
+    targetMd.wreckerOriginalScriptName = nil
+end
+
+Sync.applyAttachSync = applyAttachSync
+Sync.applyDetachSync = applyDetachSync
+
+Events.OnServerCommand.Add(function(module, command, args)
+    if module ~= "towbar" then return end
+    if command == "wreckerAttachSync" then
+        applyAttachSync(args)
+    elseif command == "wreckerDetachSync" then
+        applyDetachSync(args)
+    end
+end)
+if Events.OnSpawnVehicleEnd then
+    Events.OnSpawnVehicleEnd.Add(clearAppliedLevelForVehicle)
+end
@@ -0,0 +1,35 @@
+require("TimedActions/ISBaseTimedAction")
+
+WreckerTimedAction = ISBaseTimedAction:derive("WreckerTimedAction")
+
+function WreckerTimedAction:isValid()
+    return self.isValidFunc ~= nil
+        and self.isValidFunc(self.character, self.arg1, self.arg2) == true
+end
+
+function WreckerTimedAction:start()
+end
+
+function WreckerTimedAction:perform()
+    if self:isValid() and self.performFunc then
+        self.performFunc(self.character, self.arg1, self.arg2)
+    end
+    ISBaseTimedAction.perform(self)
+end
+
+function WreckerTimedAction:stop()
+    ISBaseTimedAction.stop(self)
+end
+
+function WreckerTimedAction:new(character, time, isValidFunc, performFunc, arg1, arg2)
+    local action = ISBaseTimedAction.new(self, character)
+    action.maxTime = time
+    action.stopOnWalk = false
+    action.stopOnRun = false
+    action.useProgressBar = true
+    action.isValidFunc = isValidFunc
+    action.performFunc = performFunc
+    action.arg1 = arg1
+    action.arg2 = arg2
+    return action
+end
@@ -0,0 +1,109 @@
+if isServer() then return end
+require("TowBar/WreckerTimedAction")
+if not TowBarMod then TowBarMod = {} end
+TowBarMod.WreckerUI = TowBarMod.WreckerUI or {}
+
+local UI = TowBarMod.WreckerUI
+local Wrecker = TowBarMod.Wrecker
+local AttachDuration = 300
+local DetachDuration = 200
+
+local function sendAttachCommand(playerObj, wrecker, target)
+    if not playerObj or not wrecker or not target then return end
+    sendClientCommand(playerObj, "towbar", "attachWrecker", {
+        wrecker = wrecker:getId(),
+        target = target:getId()
+    })
+end
+
+local function sendDetachCommand(playerObj, wrecker, target)
+    if not playerObj or not wrecker or not target then return end
+    sendClientCommand(playerObj, "towbar", "detachWrecker", {
+        wrecker = wrecker:getId(),
+        target = target:getId()
+    })
+end
+
+local function isAttachStillValid(playerObj, wrecker, target)
+    if not playerObj or not wrecker or not target then return false end
+    if not wrecker:isDriver(playerObj) or not Wrecker.isSupportedWrecker(wrecker) then return false end
+    if wrecker:getVehicleTowing() or wrecker:getVehicleTowedBy()
+            or target:getVehicleTowing() or target:getVehicleTowedBy() then return false end
+    local nearest = Wrecker.resolveNearestTarget(wrecker, Wrecker.getWorldVehicles())
+    return nearest ~= nil and nearest.vehicle == target
+end
+
+local function isDetachStillValid(playerObj, wrecker, target)
+    if not playerObj or not wrecker or not target or not wrecker:isDriver(playerObj) then return false end
+    local md = wrecker:getModData()
+    return wrecker:getVehicleTowing() == target
+        or (md and tonumber(md.wreckerTowedVehicleId) == target:getId())
+end
+
+local function requestAttach(playerObj, wrecker, target)
+    if not isAttachStillValid(playerObj, wrecker, target) then return end
+    ISTimedActionQueue.add(WreckerTimedAction:new(
+        playerObj, AttachDuration, isAttachStillValid, sendAttachCommand, wrecker, target
+    ))
+end
+
+local function requestDetach(playerObj, wrecker, target)
+    if not isDetachStillValid(playerObj, wrecker, target) then return end
+    ISTimedActionQueue.add(WreckerTimedAction:new(
+        playerObj, DetachDuration, isDetachStillValid, sendDetachCommand, wrecker, target
+    ))
+end
+
+local function requestHeight(playerObj, wrecker, direction)
+    if not playerObj or not wrecker then return end
+    sendClientCommand(playerObj, "towbar", "adjustWreckerHeight", {
+        wrecker = wrecker:getId(),
+        direction = direction
+    })
+end
+
+function UI.addOptionsToMenu(playerObj, wrecker)
+    if not playerObj or not wrecker or not Wrecker.isSupportedWrecker(wrecker) then return false end
+    if not wrecker:isDriver(playerObj) then return false end
+
+    local menu = getPlayerRadialMenu(playerObj:getPlayerNum())
+    if not menu then return false end
+
+    local md = wrecker:getModData()
+    local targetId = md and tonumber(md.wreckerTowedVehicleId) or nil
+    local target = targetId and getVehicleById(targetId) or wrecker:getVehicleTowing()
+    if target and (target == wrecker:getVehicleTowing() or targetId == target:getId()) then
+        TowBarMod.UI.removeDefaultDetachOption(playerObj)
+        local level = tonumber(md.wreckerHeightLevel) or 0
+        if level < Wrecker.MaxHeightLevel then
+            menu:addSlice(
+                getText("UI_Text_Towing_heightUp"),
+                getTexture("media/textures/arrow_up.png"),
+                requestHeight, playerObj, wrecker, 1
+            )
+        end
+        if level > Wrecker.MinHeightLevel then
+            menu:addSlice(
+                getText("UI_Text_Towing_heightDown"),
+                getTexture("media/textures/arrow_down.png"),
+                requestHeight, playerObj, wrecker, -1
+            )
+        end
+        menu:addSlice(
+            getText("UI_Text_Towing_detachHook", ISVehicleMenu.getVehicleDisplayName(target)),
+            getTexture("media/textures/untow_car_icon.png"),
+            requestDetach, playerObj, wrecker, target
+        )
+        return true
+    end
+
+    if wrecker:getVehicleTowing() or wrecker:getVehicleTowedBy() then return false end
+    local nearest = Wrecker.resolveNearestTarget(wrecker, Wrecker.getWorldVehicles())
+    if not nearest then return false end
+    menu:addSlice(
+        getText("UI_Text_Towing_attachHook", ISVehicleMenu.getVehicleDisplayName(nearest.vehicle)),
+        getTexture("media/textures/tow_car_icon.png"),
+        requestAttach, playerObj, wrecker, nearest.vehicle
+    )
+    return true
+end
@@ -3,61 +3,54 @@ BTtow.Create = {}
 BTtow.Init = {}

 local TowbarVariantSize = 24
-local TowbarNormalStart = 0
-local TowbarLargeStart = 24
 local TowbarMaxIndex = TowbarVariantSize - 1
-local VanillaScaleMin = 1.5
-local VanillaScaleMax = 2.0
+local TowbarFirstZ = 1.0
+local TowbarSlotStep = 0.1
+-- Measured from Towbar.fbx at its original 0.01 script scale. Keep this in
+-- lockstep with the client selector so the enlarged mesh's inner end remains
+-- on the same vehicle-hitbox contact point.
+local TowbarVisualScale = 2.5
+local TowbarModelLength = 0.9714089036
+local TowbarScaledModelLength = TowbarModelLength * TowbarVisualScale
+local TowbarModelHalfLength = TowbarScaledModelLength / 2

-local function getVehicleModelScale(script)
+local function getTowbarFrontEdgeZ(script)
    if not script then return nil end

-    local ok, result = pcall(function()
-        return script:getModelScale()
+    local ok, shape = pcall(function()
+        return script:getPhysicsChassisShape()
    end)
-    if ok and type(result) == "number" then
-        return result
-    end
+    if not ok or not shape then return nil end

-    ok, result = pcall(function()
-        local model = script:getModel()
-        if model then
-            return model:getScale()
-        end
-        return nil
+    local shapeOk, shapeZ = pcall(function()
+        return shape:z()
    end)
-    if ok and type(result) == "number" then
-        return result
-    end
-
+    if not shapeOk or type(shapeZ) ~= "number" or shapeZ <= 0 then
        return nil
    end

-local function isVanillaScale(script)
-    local modelScale = getVehicleModelScale(script)
-    if modelScale == nil then
-        return true
-    end
+    local centerOk, center = pcall(function()
+        return script:getCenterOfMassOffset()
+    end)
+    if not centerOk or not center then return nil end

-    local configuredMin = TowBarMod and TowBarMod.Config and tonumber(TowBarMod.Config.vanillaTowbarModelScaleMin)
-    local configuredMax = TowBarMod and TowBarMod.Config and tonumber(TowBarMod.Config.vanillaTowbarModelScaleMax)
-    local minScale = configuredMin or VanillaScaleMin
-    local maxScale = configuredMax or VanillaScaleMax
-    return modelScale >= minScale and modelScale <= maxScale
-end
+    local zOk, centerZ = pcall(function()
+        return center:z()
+    end)
+    if not zOk or type(centerZ) ~= "number" then return nil end

-local function getTowbarIndexVanilla(script)
-    local z = script:getPhysicsChassisShape():z() / 2 - 0.1
-    local index = math.floor((z * 2 / 3 - 1) * 10)
-    return math.max(0, math.min(TowbarMaxIndex, index))
+    return centerZ + shapeZ / 2
 end

 local function getTowbarModelSlot(script)
-    if not isVanillaScale(script) then
-        -- KI5/small-scale vehicles use the normal towbar0 mesh at Z=1.
-        return 0
-    end
-    return getTowbarIndexVanilla(script)
+    local frontEdgeZ = getTowbarFrontEdgeZ(script)
+    if frontEdgeZ == nil then return nil end
+
+    -- Model offsets position the mesh origin. Move its center outward so the
+    -- towbar's inner end, rather than its center, meets the vehicle hitbox.
+    local modelCenterZ = frontEdgeZ + TowbarModelHalfLength
+    local index = math.floor(((modelCenterZ - TowbarFirstZ) / TowbarSlotStep) + 0.5)
+    return math.max(0, math.min(TowbarMaxIndex, index))
 end

 function BTtow.Create.towbar(vehicle, part)  
@@ -81,7 +74,7 @@ function BTtow.Init.towbar(vehicle, part)
        if script then
            local index = getTowbarModelSlot(script)
            local shouldShowOnThisPart = part:getId() == "towbar"
-            if shouldShowOnThisPart then
+            if shouldShowOnThisPart and index ~= nil then
                part:setModelVisible("towbar" .. index, true)
            end
        end
@@ -1,4 +1,5 @@
 if isClient() then return end
+require("TowBar/Persistence")

 local TowingCommands = {}
 local Commands = {}
@@ -10,6 +11,9 @@ local pendingSync = {}
 local snapshotTickCounter = 0
 local brokenPairAuditTickCounter = 0
 local confirmedTowPairs = {}
+local towPairRuntime = {}
+local RestoreRetryMs = 2000
+local SustainedBreakMs = 5000
 local giveTowBar

 TowingCommands.wantNoise = getDebug() or false
@@ -88,6 +92,22 @@ local function isLinked(vehicleA, vehicleB)
    return vehicleA:getVehicleTowing() == vehicleB and vehicleB:getVehicleTowedBy() == vehicleA
 end

+local function getPersistentVehicleId(vehicle)
+    if not vehicle or not vehicle.getSqlId then return nil end
+    local ok, sqlId = pcall(function() return vehicle:getSqlId() end)
+    if ok and type(sqlId) == "number" and sqlId >= 0 then return sqlId end
+    return nil
+end
+
+local function matchesSavedVehicle(runtimeId, sqlId, vehicle)
+    if not vehicle then return false end
+    local stableId = tonumber(sqlId)
+    if stableId and stableId >= 0 then
+        return getPersistentVehicleId(vehicle) == stableId
+    end
+    return tonumber(runtimeId) == vehicle:getId()
+end
+
 local function hasAnyTowLink(vehicle)
    if not vehicle then return false end
    return vehicle:getVehicleTowing() ~= nil or vehicle:getVehicleTowedBy() ~= nil
@@ -95,12 +115,17 @@ end

 local function getTowBarPairKey(vehicleA, vehicleB)
    if not vehicleA or not vehicleB then return nil end
-    return tostring(vehicleA:getId()) .. ":" .. tostring(vehicleB:getId())
+    local vehicleAId = getPersistentVehicleId(vehicleA) or vehicleA:getId()
+    local vehicleBId = getPersistentVehicleId(vehicleB) or vehicleB:getId()
+    return tostring(vehicleAId) .. ":" .. tostring(vehicleBId)
 end

 local function markTowBarPairConfirmed(vehicleA, vehicleB)
    local key = getTowBarPairKey(vehicleA, vehicleB)
-    if key then confirmedTowPairs[key] = true end
+    if key then
+        confirmedTowPairs[key] = true
+        towPairRuntime[key] = { confirmed = true }
+    end
 end

 local function isTowBarPairConfirmed(vehicleA, vehicleB)
@@ -110,7 +135,10 @@ end

 local function forgetTowBarPair(vehicleA, vehicleB)
    local key = getTowBarPairKey(vehicleA, vehicleB)
-    if key then confirmedTowPairs[key] = nil end
+    if key then
+        confirmedTowPairs[key] = nil
+        towPairRuntime[key] = nil
+    end
 end

 local function hasTowBarState(vehicle)
@@ -130,25 +158,35 @@ local function markExpectedTowBarPair(vehicleA, vehicleB, attachmentA, attachmen
    towingModData["isTowingByTowBar"] = true
    towingModData["towed"] = false
    towingModData["towBarTowedVehicleId"] = vehicleB:getId()
+    towingModData["towBarTowedVehicleSqlId"] = getPersistentVehicleId(vehicleB)
    towingModData["towBarTowingVehicleId"] = nil
+    towingModData["towBarTowingVehicleSqlId"] = nil
    towingModData["towBarExpectedAttachment"] = attachmentA
    towedModData["isTowingByTowBar"] = true
    towedModData["towed"] = true
    towedModData["towBarTowedVehicleId"] = nil
+    towedModData["towBarTowedVehicleSqlId"] = nil
    towedModData["towBarTowingVehicleId"] = vehicleA:getId()
+    towedModData["towBarTowingVehicleSqlId"] = getPersistentVehicleId(vehicleA)
    towedModData["towBarExpectedAttachment"] = attachmentB
    vehicleA:transmitModData()
    vehicleB:transmitModData()
+    TowBarMod.Persistence.savePair("towbar", vehicleA, vehicleB, attachmentA, attachmentB)
 end

 local function clearExpectedTowBarPair(vehicleA, vehicleB)
+    if vehicleA and vehicleB then
+        TowBarMod.Persistence.removePair("towbar", vehicleA, vehicleB)
+    end
    if vehicleA then
        local towingModData = vehicleA:getModData()
        if towingModData then
            towingModData["isTowingByTowBar"] = false
            towingModData["towed"] = false
            towingModData["towBarTowedVehicleId"] = nil
+            towingModData["towBarTowedVehicleSqlId"] = nil
            towingModData["towBarTowingVehicleId"] = nil
+            towingModData["towBarTowingVehicleSqlId"] = nil
            towingModData["towBarExpectedAttachment"] = nil
            vehicleA:transmitModData()
        end
@@ -160,7 +198,9 @@ local function clearExpectedTowBarPair(vehicleA, vehicleB)
            towedModData["isTowingByTowBar"] = false
            towedModData["towed"] = false
            towedModData["towBarTowedVehicleId"] = nil
+            towedModData["towBarTowedVehicleSqlId"] = nil
            towedModData["towBarTowingVehicleId"] = nil
+            towedModData["towBarTowingVehicleSqlId"] = nil
            towedModData["towBarExpectedAttachment"] = nil
            vehicleB:transmitModData()
        end
@@ -174,8 +214,11 @@ local function isExpectedTowBarPair(vehicleA, vehicleB)
    local towedModData = vehicleB:getModData()
    if not towingModData or not towedModData then return false end

-    return towingModData["towBarTowedVehicleId"] == vehicleB:getId()
-        and towedModData["towBarTowingVehicleId"] == vehicleA:getId()
+    return matchesSavedVehicle(
+            towingModData["towBarTowedVehicleId"], towingModData["towBarTowedVehicleSqlId"], vehicleB
+        ) and matchesSavedVehicle(
+            towedModData["towBarTowingVehicleId"], towedModData["towBarTowingVehicleSqlId"], vehicleA
+        )
 end

 local function isLegacyTowBarPair(vehicleA, vehicleB)
@@ -295,14 +338,34 @@ local function forEachCollectionItem(collection, callback)
    end
 end

+local function findLoadedVehicle(runtimeId, sqlId)
+    local stableId = tonumber(sqlId)
+    if stableId and stableId >= 0 then
+        local cell = getCell()
+        local vehicles = cell and cell:getVehicles() or nil
+        local match
+        forEachCollectionItem(vehicles, function(vehicle)
+            if not match and getPersistentVehicleId(vehicle) == stableId then match = vehicle end
+        end)
+        return match
+    end
+    return runtimeId and getVehicleById(tonumber(runtimeId)) or nil
+end
+
 local function broadcastAttach(vehicleA, vehicleB, attachmentA, attachmentB)
    if not vehicleA or not vehicleB then return end
-    sendServerCommand("towbar", "forceAttachSync", {
+    local args = {
        vehicleA = vehicleA:getId(),
        vehicleB = vehicleB:getId(),
        attachmentA = attachmentA,
        attachmentB = attachmentB
-    })
+    }
+    if isServer() then
+        sendServerCommand("towbar", "forceAttachSync", args)
+    elseif not isClient() and TowBarMod and TowBarMod.Sync
+            and TowBarMod.Sync.applyAttachSync then
+        TowBarMod.Sync.applyAttachSync(args)
+    end
 end

 local function broadcastDetach(vehicleAId, vehicleBId)
@@ -320,6 +383,33 @@ local function broadcastSpontaneousDetach(vehicleA, vehicleB)
    })
 end

+local function restorePersistedTowBarPair(towingVehicle, towedVehicle)
+    if not isExpectedTowBarPair(towingVehicle, towedVehicle)
+            or hasAnyTowLink(towingVehicle) or hasAnyTowLink(towedVehicle) then
+        return false
+    end
+
+    local towingModData = towingVehicle:getModData()
+    local towedModData = towedVehicle:getModData()
+    local attachmentA = towingModData["towBarExpectedAttachment"] or "trailer"
+    local attachmentB = towedModData["towBarExpectedAttachment"] or "trailerfront"
+    if not towingVehicle:attachmentExist(attachmentA)
+            or not towedVehicle:attachmentExist(attachmentB) then
+        return false
+    end
+
+    markExpectedTowBarPair(towingVehicle, towedVehicle, attachmentA, attachmentB)
+    if isServer() then
+        towingVehicle:addPointConstraint(nil, towedVehicle, attachmentA, attachmentB)
+    end
+    broadcastAttach(towingVehicle, towedVehicle, attachmentA, attachmentB)
+    if isLinked(towingVehicle, towedVehicle) then
+        markTowBarPairConfirmed(towingVehicle, towedVehicle)
+        return true
+    end
+    return false
+end
+
 local function breakTowBarConstraint(towingVehicle, towedVehicle)
    if not towingVehicle or not towedVehicle then return end

@@ -400,19 +490,80 @@ local function reconcileBrokenTowBarPairsServer()
    local vehicles = cell:getVehicles()
    if not vehicles then return end

+    local loadedBySqlId = {}
+    forEachCollectionItem(vehicles, function(vehicle)
+        local sqlId = getPersistentVehicleId(vehicle)
+        if sqlId then loadedBySqlId[sqlId] = vehicle end
+    end)
+
+    local processed = {}
+    local function reconcilePair(towingVehicle, towedVehicle, attachmentA, attachmentB)
+        if not towingVehicle or not towedVehicle then return end
+        local key = getTowBarPairKey(towingVehicle, towedVehicle)
+        if not key or processed[key] then return end
+        processed[key] = true
+
+        if not isExpectedTowBarPair(towingVehicle, towedVehicle) then
+            markExpectedTowBarPair(
+                towingVehicle, towedVehicle,
+                attachmentA or "trailer", attachmentB or "trailerfront"
+            )
+        end
+        if not isExpectedTowBarPair(towingVehicle, towedVehicle) then return end
+
+        local now = getTimestampMs()
+        local state = towPairRuntime[key] or {}
+        local linked = isLinked(towingVehicle, towedVehicle)
+        local occupied = hasAnyTowLink(towingVehicle) or hasAnyTowLink(towedVehicle)
+        local action
+        state, action = TowBarMod.Persistence.advanceRecoveryState(
+            state, now, linked, occupied, RestoreRetryMs, SustainedBreakMs
+        )
+        towPairRuntime[key] = state
+        if action == "adopt" then
+            local towingMd = towingVehicle:getModData()
+            local towedMd = towedVehicle:getModData()
+            local savedAttachmentA = towingMd["towBarExpectedAttachment"] or attachmentA or "trailer"
+            local savedAttachmentB = towedMd["towBarExpectedAttachment"] or attachmentB or "trailerfront"
+            if tonumber(towingMd["towBarTowedVehicleId"]) ~= towedVehicle:getId()
+                    or tonumber(towedMd["towBarTowingVehicleId"]) ~= towingVehicle:getId() then
+                markExpectedTowBarPair(
+                    towingVehicle, towedVehicle,
+                    savedAttachmentA, savedAttachmentB
+                )
+            end
+            TowBarMod.Persistence.savePair(
+                "towbar", towingVehicle, towedVehicle, savedAttachmentA, savedAttachmentB
+            )
+            confirmedTowPairs[key] = true
+        elseif action == "break" then
+            finalizeBrokenTowBarPair(towingVehicle, towedVehicle, "sustained-physical-link-audit")
+        elseif action == "restore" then
+            restorePersistedTowBarPair(towingVehicle, towedVehicle)
+        end
+    end
+
+    TowBarMod.Persistence.forEachPair("towbar", function(record)
+        local towingVehicle = loadedBySqlId[tonumber(record.towingSqlId)]
+        local towedVehicle = loadedBySqlId[tonumber(record.towedSqlId)]
+        local key = tostring(record.towingSqlId) .. ":" .. tostring(record.towedSqlId)
+        towPairRuntime[key] = TowBarMod.Persistence.notePeerAvailability(
+            towPairRuntime[key], towingVehicle ~= nil and towedVehicle ~= nil
+        )
+        reconcilePair(
+            towingVehicle,
+            towedVehicle,
+            record.attachmentA,
+            record.attachmentB
+        )
+    end)
+
    forEachCollectionItem(vehicles, function(towingVehicle)
        local towingModData = towingVehicle and towingVehicle:getModData() or nil
        local towedVehicleId = towingModData and towingModData["towBarTowedVehicleId"] or nil
-        local towedVehicle = towedVehicleId and getVehicleById(towedVehicleId) or nil
-        if towingVehicle and towedVehicle and isExpectedTowBarPair(towingVehicle, towedVehicle) then
-            if isLinked(towingVehicle, towedVehicle) then
-                markTowBarPairConfirmed(towingVehicle, towedVehicle)
-            elseif isTowBarPairConfirmed(towingVehicle, towedVehicle)
-                    and not hasAnyTowLink(towingVehicle)
-                    and not hasAnyTowLink(towedVehicle) then
-                finalizeBrokenTowBarPair(towingVehicle, towedVehicle, "physical-link-audit")
-            end
-        end
+        local towedVehicleSqlId = towingModData and towingModData["towBarTowedVehicleSqlId"] or nil
+        local towedVehicle = findLoadedVehicle(towedVehicleId, towedVehicleSqlId)
+        if towingVehicle and towedVehicle then reconcilePair(towingVehicle, towedVehicle) end
    end)
 end

@@ -0,0 +1,397 @@
+if isClient() then return end
+require("TowBar/Persistence")
+if not TowBarMod or not TowBarMod.Wrecker then return end
+
+local Wrecker = TowBarMod.Wrecker
+local Commands = {}
+local AuditInterval = 30
+local SnapshotInterval = 120
+local CommandCooldownMs = 150
+local auditTicks = 0
+local snapshotTicks = 0
+local commandTimes = {}
+local confirmedWreckerPairs = {}
+local wreckerPairRuntime = {}
+local RestoreRetryMs = 2000
+local SustainedBreakMs = 5000
+
+local function isInteger(value)
+    return type(value) == "number" and value == math.floor(value)
+end
+
+local function resolveVehicleId(value)
+    if not isInteger(value) or value < 0 then return nil end
+    return getVehicleById(value)
+end
+
+local function isLinked(wrecker, target)
+    return wrecker and target
+        and wrecker:getVehicleTowing() == target
+        and target:getVehicleTowedBy() == wrecker
+end
+
+local function getPersistentVehicleId(vehicle)
+    if not vehicle or not vehicle.getSqlId then return nil end
+    local ok, sqlId = pcall(function() return vehicle:getSqlId() end)
+    if ok and type(sqlId) == "number" and sqlId >= 0 then return sqlId end
+    return nil
+end
+
+local function findLoadedVehicle(runtimeId, sqlId)
+    local stableId = tonumber(sqlId)
+    if stableId and stableId >= 0 then
+        local vehicles = Wrecker.getWorldVehicles()
+        local iterator = vehicles and vehicles:iterator() or nil
+        while iterator and iterator:hasNext() do
+            local vehicle = iterator:next()
+            if getPersistentVehicleId(vehicle) == stableId then return vehicle end
+        end
+        return nil
+    end
+    return runtimeId and getVehicleById(tonumber(runtimeId)) or nil
+end
+
+local function matchesSavedVehicle(runtimeId, sqlId, vehicle)
+    if not vehicle then return false end
+    local stableId = tonumber(sqlId)
+    if stableId and stableId >= 0 then
+        return getPersistentVehicleId(vehicle) == stableId
+    end
+    return tonumber(runtimeId) == vehicle:getId()
+end
+
+local function pairKey(wrecker, target)
+    local wreckerId = getPersistentVehicleId(wrecker) or wrecker:getId()
+    local targetId = getPersistentVehicleId(target) or target:getId()
+    return tostring(wreckerId) .. ":" .. tostring(targetId)
+end
+
+
+local function markWreckerPairConfirmed(wrecker, target)
+    local key = pairKey(wrecker, target)
+    confirmedWreckerPairs[key] = true
+    wreckerPairRuntime[key] = { confirmed = true }
+end
+
+local function isWreckerPairConfirmed(wrecker, target)
+    return confirmedWreckerPairs[pairKey(wrecker, target)] == true
+end
+
+local function forgetWreckerPair(wrecker, target)
+    local key = pairKey(wrecker, target)
+    confirmedWreckerPairs[key] = nil
+    wreckerPairRuntime[key] = nil
+end
+
+local function isExpectedPair(wrecker, target)
+    if not wrecker or not target then return false end
+    local wreckerMd = wrecker:getModData()
+    local targetMd = target:getModData()
+    return matchesSavedVehicle(
+            wreckerMd.wreckerTowedVehicleId, wreckerMd.wreckerTowedVehicleSqlId, target
+        ) and matchesSavedVehicle(
+            targetMd.wreckerTowingVehicleId, targetMd.wreckerTowingVehicleSqlId, wrecker
+        )
+end
+
+local function setPairState(wrecker, target, targetAttachment, heightLevel)
+    local wreckerMd = wrecker:getModData()
+    local targetMd = target:getModData()
+    wreckerMd.wreckerTowActive = true
+    wreckerMd.wreckerTowedVehicleId = target:getId()
+    wreckerMd.wreckerTowedVehicleSqlId = getPersistentVehicleId(target)
+    wreckerMd.wreckerTowingVehicleId = nil
+    wreckerMd.wreckerTowingVehicleSqlId = nil
+    wreckerMd.wreckerTargetAttachment = targetAttachment
+    wreckerMd.wreckerHeightLevel = Wrecker.normalizeHeightLevel(heightLevel)
+    targetMd.wreckerTowingVehicleId = wrecker:getId()
+    targetMd.wreckerTowingVehicleSqlId = getPersistentVehicleId(wrecker)
+    targetMd.wreckerTowedVehicleId = nil
+    targetMd.wreckerTowedVehicleSqlId = nil
+    wrecker:transmitModData()
+    target:transmitModData()
+    TowBarMod.Persistence.savePair(
+        "wrecker", wrecker, target,
+        Wrecker.getHeightAttachmentId(wreckerMd.wreckerHeightLevel),
+        targetAttachment,
+        wreckerMd.wreckerHeightLevel
+    )
+end
+
+local function clearPairState(wrecker, target)
+    if not wrecker or not target then return end
+    local wreckerMd = wrecker:getModData()
+    local targetMd = target:getModData()
+    TowBarMod.Persistence.removePair("wrecker", wrecker, target)
+    wreckerMd.wreckerTowActive = nil
+    wreckerMd.wreckerTowedVehicleId = nil
+    wreckerMd.wreckerTowedVehicleSqlId = nil
+    wreckerMd.wreckerTowingVehicleId = nil
+    wreckerMd.wreckerTowingVehicleSqlId = nil
+    wreckerMd.wreckerTargetAttachment = nil
+    wreckerMd.wreckerHeightLevel = nil
+    targetMd.wreckerTowingVehicleId = nil
+    targetMd.wreckerTowingVehicleSqlId = nil
+    targetMd.wreckerTowedVehicleId = nil
+    targetMd.wreckerTowedVehicleSqlId = nil
+    wrecker:transmitModData()
+    target:transmitModData()
+end
+
+local function broadcastWreckerSync(command, args)
+    if isServer() then
+        sendServerCommand("towbar", command, args)
+    elseif TowBarMod.WreckerSync then
+        if command == "wreckerAttachSync" then
+            TowBarMod.WreckerSync.applyAttachSync(args)
+        else
+            TowBarMod.WreckerSync.applyDetachSync(args)
+        end
+    end
+end
+
+local function syncPairState(wrecker, target, hookAttachment, targetAttachment, heightLevel, player)
+    if isServer() then
+        -- Dedicated servers own the logical relation; clients replace their
+        -- local rope with the rigid height-indexed constraint on sync.
+        wrecker:addPointConstraint(player, target, hookAttachment, targetAttachment)
+    end
+    broadcastWreckerSync("wreckerAttachSync", {
+        wrecker = wrecker:getId(), target = target:getId(),
+        wreckerSqlId = getPersistentVehicleId(wrecker),
+        targetSqlId = getPersistentVehicleId(target),
+        targetAttachment = targetAttachment, heightLevel = heightLevel
+    })
+    if isLinked(wrecker, target) then markWreckerPairConfirmed(wrecker, target) end
+end
+
+local function breakPair(wrecker, target)
+    if isLinked(wrecker, target) then
+        wrecker:breakConstraint(true, false)
+    end
+end
+
+local function detachPair(wrecker, target)
+    if not isExpectedPair(wrecker, target) then return false end
+    breakPair(wrecker, target)
+    forgetWreckerPair(wrecker, target)
+    clearPairState(wrecker, target)
+    broadcastWreckerSync("wreckerDetachSync", {
+        wrecker = wrecker:getId(), target = target:getId(),
+        wreckerSqlId = getPersistentVehicleId(wrecker)
+    })
+    return true
+end
+
+function Commands.attachWrecker(player, args)
+    if type(args) ~= "table" then return end
+    local wrecker = resolveVehicleId(args.wrecker)
+    local target = resolveVehicleId(args.target)
+    if not wrecker or not target or wrecker == target then return end
+    if not wrecker:isDriver(player) or not Wrecker.isSupportedWrecker(wrecker) then return end
+    if wrecker:getVehicleTowing() or wrecker:getVehicleTowedBy()
+            or target:getVehicleTowing() or target:getVehicleTowedBy() then return end
+
+    local nearest = Wrecker.resolveNearestTarget(wrecker, Wrecker.getWorldVehicles())
+    if not nearest or nearest.vehicle ~= target then return end
+    local targetAttachment = nearest.attachment
+    local heightLevel = 0
+    local hookAttachment = Wrecker.getHeightAttachmentId(heightLevel)
+    if not hookAttachment or not wrecker:attachmentExist(hookAttachment) then return end
+
+    setPairState(wrecker, target, targetAttachment, heightLevel)
+    syncPairState(wrecker, target, hookAttachment, targetAttachment, heightLevel, player)
+end
+
+function Commands.detachWrecker(player, args)
+    if type(args) ~= "table" then return end
+    local wrecker = resolveVehicleId(args.wrecker)
+    local target = resolveVehicleId(args.target)
+    if not wrecker or not target or not wrecker:isDriver(player) then return end
+    detachPair(wrecker, target)
+end
+
+function Commands.adjustWreckerHeight(player, args)
+    if type(args) ~= "table" then return end
+    local wrecker = resolveVehicleId(args.wrecker)
+    local direction = args.direction
+    if not wrecker or not wrecker:isDriver(player) or not Wrecker.isSupportedWrecker(wrecker) then return end
+    if direction ~= -1 and direction ~= 1 then return end
+
+    local md = wrecker:getModData()
+    local target = findLoadedVehicle(md.wreckerTowedVehicleId, md.wreckerTowedVehicleSqlId)
+    if not target or not isExpectedPair(wrecker, target) or not isLinked(wrecker, target) then return end
+    local currentLevel = tonumber(md.wreckerHeightLevel) or 0
+    local nextLevel = Wrecker.nextHeightLevel(currentLevel, direction)
+    if not nextLevel or nextLevel == currentLevel then return end
+    local hookAttachment = Wrecker.getHeightAttachmentId(nextLevel)
+    local targetAttachment = md.wreckerTargetAttachment
+    if not hookAttachment or not wrecker:attachmentExist(hookAttachment)
+            or (targetAttachment ~= "trailer" and targetAttachment ~= "trailerfront") then return end
+
+    breakPair(wrecker, target)
+    setPairState(wrecker, target, targetAttachment, nextLevel)
+    syncPairState(wrecker, target, hookAttachment, targetAttachment, nextLevel, player)
+end
+
+local function onClientCommand(module, command, player, args)
+    if module == "towbar" and Commands[command] then
+        if not player then return end
+        local playerTimes = commandTimes[player]
+        if not playerTimes then
+            playerTimes = {}
+            commandTimes[player] = playerTimes
+        end
+        local now = getTimestampMs()
+        local previous = playerTimes[command]
+        if previous and now - previous < CommandCooldownMs then return end
+        playerTimes[command] = now
+        Commands[command](player, args)
+        return
+    end
+    if module == "vehicle" and command == "detachTrailerSpontaneous" then
+        local vehicle = args and resolveVehicleId(args.vehicle) or nil
+        if not vehicle then return end
+        local md = vehicle:getModData()
+        local wrecker = (md.wreckerTowedVehicleId or md.wreckerTowedVehicleSqlId) and vehicle or nil
+        local target = wrecker and findLoadedVehicle(
+            md.wreckerTowedVehicleId, md.wreckerTowedVehicleSqlId
+        ) or nil
+        if not wrecker and (md.wreckerTowingVehicleId or md.wreckerTowingVehicleSqlId) then
+            wrecker = findLoadedVehicle(md.wreckerTowingVehicleId, md.wreckerTowingVehicleSqlId)
+            target = vehicle
+        end
+        if wrecker and target then detachPair(wrecker, target) end
+    end
+end
+
+local function auditWreckerPairs()
+    auditTicks = auditTicks + 1
+    if auditTicks < AuditInterval then return end
+    auditTicks = 0
+    snapshotTicks = snapshotTicks + AuditInterval
+    local shouldSnapshot = snapshotTicks >= SnapshotInterval
+    if shouldSnapshot then snapshotTicks = 0 end
+    local vehicles = Wrecker.getWorldVehicles()
+    if not vehicles then return end
+
+    local loadedBySqlId = {}
+    local scan = vehicles:iterator()
+    while scan:hasNext() do
+        local vehicle = scan:next()
+        local sqlId = getPersistentVehicleId(vehicle)
+        if sqlId then loadedBySqlId[sqlId] = vehicle end
+    end
+
+    local processed = {}
+    local function reconcilePair(wrecker, target, targetAttachment, heightLevel)
+        if not wrecker or not target or not Wrecker.isSupportedWrecker(wrecker) then return end
+        local key = pairKey(wrecker, target)
+        if processed[key] then return end
+        processed[key] = true
+
+        local canonicalLevel = Wrecker.normalizeHeightLevel(heightLevel)
+        local canonicalTargetAttachment = targetAttachment
+        if canonicalTargetAttachment ~= "trailer" and canonicalTargetAttachment ~= "trailerfront" then return end
+        local hookAttachment = Wrecker.getHeightAttachmentId(canonicalLevel)
+        if not hookAttachment or not wrecker:attachmentExist(hookAttachment)
+                or not target:attachmentExist(canonicalTargetAttachment) then return end
+
+        if not isExpectedPair(wrecker, target) then
+            setPairState(wrecker, target, canonicalTargetAttachment, canonicalLevel)
+        end
+        if not isExpectedPair(wrecker, target) then return end
+
+        local now = getTimestampMs()
+        local state = wreckerPairRuntime[key] or {}
+        local linked = isLinked(wrecker, target)
+        local occupied = wrecker:getVehicleTowing() or wrecker:getVehicleTowedBy()
+            or target:getVehicleTowing() or target:getVehicleTowedBy()
+        local action
+        state, action = TowBarMod.Persistence.advanceRecoveryState(
+            state, now, linked, occupied ~= nil, RestoreRetryMs, SustainedBreakMs
+        )
+        wreckerPairRuntime[key] = state
+        if action == "adopt" then
+            local wreckerMd = wrecker:getModData()
+            local targetMd = target:getModData()
+            if tonumber(wreckerMd.wreckerTowedVehicleId) ~= target:getId()
+                    or tonumber(targetMd.wreckerTowingVehicleId) ~= wrecker:getId()
+                    or tonumber(wreckerMd.wreckerTowedVehicleSqlId) ~= getPersistentVehicleId(target)
+                    or tonumber(targetMd.wreckerTowingVehicleSqlId) ~= getPersistentVehicleId(wrecker) then
+                setPairState(wrecker, target, canonicalTargetAttachment, canonicalLevel)
+            end
+            TowBarMod.Persistence.savePair(
+                "wrecker", wrecker, target, hookAttachment, canonicalTargetAttachment, canonicalLevel
+            )
+            confirmedWreckerPairs[key] = true
+            if shouldSnapshot then
+                broadcastWreckerSync("wreckerAttachSync", {
+                    wrecker = wrecker:getId(), target = target:getId(),
+                    wreckerSqlId = getPersistentVehicleId(wrecker),
+                    targetSqlId = getPersistentVehicleId(target),
+                    targetAttachment = canonicalTargetAttachment,
+                    heightLevel = canonicalLevel
+                })
+            end
+        elseif action == "break" then
+            detachPair(wrecker, target)
+        elseif action == "restore" then
+            setPairState(wrecker, target, canonicalTargetAttachment, canonicalLevel)
+            syncPairState(wrecker, target, hookAttachment, canonicalTargetAttachment, canonicalLevel, nil)
+        end
+    end
+
+    TowBarMod.Persistence.forEachPair("wrecker", function(record)
+        local wrecker = loadedBySqlId[tonumber(record.towingSqlId)]
+        local target = loadedBySqlId[tonumber(record.towedSqlId)]
+        local key = tostring(record.towingSqlId) .. ":" .. tostring(record.towedSqlId)
+        wreckerPairRuntime[key] = TowBarMod.Persistence.notePeerAvailability(
+            wreckerPairRuntime[key], wrecker ~= nil and target ~= nil
+        )
+        reconcilePair(
+            wrecker,
+            target,
+            record.attachmentB,
+            record.heightLevel
+        )
+    end)
+
+    local iterator = vehicles:iterator()
+    while iterator:hasNext() do
+        local vehicle = iterator:next()
+        local vehicleMd = vehicle:getModData()
+        local targetId = tonumber(vehicleMd.wreckerTowedVehicleId)
+        local targetSqlId = tonumber(vehicleMd.wreckerTowedVehicleSqlId)
+        if targetId or targetSqlId then
+            local wrecker = vehicle
+            local target = findLoadedVehicle(targetId, targetSqlId)
+            if target then
+                reconcilePair(
+                    wrecker, target,
+                    vehicleMd.wreckerTargetAttachment,
+                    vehicleMd.wreckerHeightLevel
+                )
+            end
+        end
+
+        local towingVehicleId = tonumber(vehicleMd.wreckerTowingVehicleId)
+        local towingVehicleSqlId = tonumber(vehicleMd.wreckerTowingVehicleSqlId)
+        if towingVehicleId or towingVehicleSqlId then
+            local towingVehicle = findLoadedVehicle(towingVehicleId, towingVehicleSqlId)
+            if towingVehicle and not isExpectedPair(towingVehicle, vehicle) then
+                vehicleMd.wreckerTowingVehicleId = nil
+                vehicleMd.wreckerTowingVehicleSqlId = nil
+                vehicle:transmitModData()
+                broadcastWreckerSync("wreckerDetachSync", {
+                    wrecker = towingVehicleId,
+                    wreckerSqlId = towingVehicleSqlId,
+                    target = vehicle:getId()
+                })
+            end
+        end
+    end
+end
+
+Events.OnClientCommand.Add(onClientCommand)
+Events.OnTick.Add(auditWreckerPairs)
@@ -0,0 +1,122 @@
+if not TowBarMod then TowBarMod = {} end
+TowBarMod.Persistence = TowBarMod.Persistence or {}
+
+local Persistence = TowBarMod.Persistence
+local RegistryName = "TowBar.PersistentPairsV2"
+
+local function getRegistry()
+    if not ModData or not ModData.getOrCreate then return nil end
+    local registry = ModData.getOrCreate(RegistryName)
+    registry.pairs = registry.pairs or {}
+    return registry
+end
+
+local function getSqlId(vehicle)
+    if not vehicle or not vehicle.getSqlId then return nil end
+    local ok, sqlId = pcall(function() return vehicle:getSqlId() end)
+    if ok and type(sqlId) == "number" and sqlId >= 0 then return sqlId end
+    return nil
+end
+
+local function makeKey(kind, towingSqlId, towedSqlId)
+    if type(kind) ~= "string" or type(towingSqlId) ~= "number" or type(towedSqlId) ~= "number" then
+        return nil
+    end
+    return kind .. ":" .. tostring(towingSqlId) .. ":" .. tostring(towedSqlId)
+end
+
+local function transmit()
+    if isServer and isServer() and ModData.transmit then
+        ModData.transmit(RegistryName)
+    end
+end
+
+function Persistence.savePair(kind, towingVehicle, towedVehicle, attachmentA, attachmentB, heightLevel)
+    local towingSqlId = getSqlId(towingVehicle)
+    local towedSqlId = getSqlId(towedVehicle)
+    local key = makeKey(kind, towingSqlId, towedSqlId)
+    local registry = getRegistry()
+    if not key or not registry then return false end
+    local previous = registry.pairs[key]
+    if previous and previous.attachmentA == attachmentA and previous.attachmentB == attachmentB
+            and previous.heightLevel == heightLevel then
+        return true
+    end
+    registry.pairs[key] = {
+        kind = kind,
+        towingSqlId = towingSqlId,
+        towedSqlId = towedSqlId,
+        attachmentA = attachmentA,
+        attachmentB = attachmentB,
+        heightLevel = heightLevel
+    }
+    transmit()
+    return true
+end
+
+function Persistence.getPair(kind, towingVehicle, towedVehicle)
+    local key = makeKey(kind, getSqlId(towingVehicle), getSqlId(towedVehicle))
+    local registry = getRegistry()
+    return key and registry and registry.pairs[key] or nil
+end
+
+function Persistence.removePair(kind, towingVehicle, towedVehicle)
+    local key = makeKey(kind, getSqlId(towingVehicle), getSqlId(towedVehicle))
+    local registry = getRegistry()
+    if not key or not registry or registry.pairs[key] == nil then return false end
+    registry.pairs[key] = nil
+    transmit()
+    return true
+end
+
+function Persistence.forEachPair(kind, callback)
+    local registry = getRegistry()
+    if not registry or not callback then return end
+    for _, record in pairs(registry.pairs) do
+        if type(record) == "table" and record.kind == kind then callback(record) end
+    end
+end
+
+function Persistence.notePeerAvailability(state, available)
+    state = state or {}
+    if not available then
+        state.peerMissing = true
+        return state
+    end
+    if state.peerMissing then
+        -- A missing vehicle means its cell was not loaded. When both members
+        -- return, treat the absent native constraint as load recovery rather
+        -- than a runtime break of a previously confirmed pair.
+        state.peerMissing = nil
+        state.confirmed = false
+        state.pendingUntil = nil
+        state.unlinkedSince = nil
+    end
+    return state
+end
+
+function Persistence.advanceRecoveryState(state, now, linked, occupied, retryMs, breakMs)
+    state = state or {}
+    if linked then
+        state.confirmed = true
+        state.pendingUntil = nil
+        state.unlinkedSince = nil
+        return state, "adopt"
+    end
+    if occupied then
+        state.unlinkedSince = nil
+        return state, "wait"
+    end
+    if state.confirmed then
+        state.unlinkedSince = state.unlinkedSince or now
+        if now - state.unlinkedSince >= breakMs then return state, "break" end
+        return state, "wait"
+    end
+    if not state.pendingUntil or now >= state.pendingUntil then
+        state.pendingUntil = now + retryMs
+        return state, "restore"
+    end
+    return state, "wait"
+end
+
+Persistence.getSqlId = getSqlId
@@ -0,0 +1,163 @@
+if not TowBarMod then TowBarMod = {} end
+TowBarMod.Wrecker = TowBarMod.Wrecker or {}
+
+local Wrecker = TowBarMod.Wrecker
+
+Wrecker.MaxAttachDistance = 0.6
+Wrecker.HeightStep = 0.30
+Wrecker.MinHeightLevel = 0
+Wrecker.MaxHeightLevel = 2
+Wrecker.ScanRadius = 8
+
+local SupportedWreckers = {
+    -- KI5 '76 Chevrolet K Series (Workshop 3161951724)
+    ["Base.76chevyC30CCwrecker"] = true,
+    ["Base.76chevyC30SCwrecker"] = true,
+    ["Base.76chevyK30CCwrecker"] = true,
+    ["Base.76chevyK30SCwrecker"] = true,
+
+    -- KI5 '93 Chevrolet Suburban / Silverado (Workshop 3152529790).
+    -- The mechanic variant inherits the K3500 wrecker template.
+    ["Base.93chevySilveradoK3500wrecker"] = true,
+    ["Base.93chevySilveradoK3500mechanic"] = true,
+
+    -- KI5 '78 AM General M35 Series Trucks (Workshop 2799152995).
+    ["Base.78amgeneralM62"] = true
+}
+
+local HeightAttachmentIds = {
+    [0] = "towbarWreckerHookLow",
+    [1] = "towbarWreckerHookMid",
+    [2] = "towbarWreckerHookHigh"
+}
+
+local function getScriptFullName(script)
+    if not script then return nil end
+    local ok, fullName = pcall(function() return script:getFullName() end)
+    if ok and fullName then return tostring(fullName) end
+    local name = script:getName()
+    return name and ("Base." .. tostring(name)) or nil
+end
+
+function Wrecker.isSupportedWrecker(vehicle)
+    if not vehicle then return false end
+    local script = vehicle:getScript()
+    local fullName = getScriptFullName(script)
+    return SupportedWreckers[fullName] == true
+        and vehicle:attachmentExist("hook")
+end
+
+function Wrecker.getHeightAttachmentId(level)
+    return HeightAttachmentIds[Wrecker.normalizeHeightLevel(level)]
+end
+
+function Wrecker.normalizeHeightLevel(level)
+    local numeric = tonumber(level) or Wrecker.MinHeightLevel
+    numeric = math.floor(numeric + 0.5)
+    return math.max(Wrecker.MinHeightLevel, math.min(Wrecker.MaxHeightLevel, numeric))
+end
+
+function Wrecker.nextHeightLevel(currentLevel, direction)
+    local current = Wrecker.normalizeHeightLevel(currentLevel)
+    local delta = tonumber(direction)
+    if delta ~= -1 and delta ~= 1 then return nil end
+    return math.max(Wrecker.MinHeightLevel, math.min(Wrecker.MaxHeightLevel, current + delta))
+end
+
+local function distanceSquared(pointA, pointB)
+    if not pointA or not pointB then return nil end
+    local dx = pointA:x() - pointB:x()
+    local dy = pointA:y() - pointB:y()
+    return dx * dx + dy * dy
+end
+
+local function forEachVehicle(collection, callback)
+    if not collection then return end
+    if type(collection) == "table" then
+        for _, vehicle in ipairs(collection) do callback(vehicle) end
+        return
+    end
+
+    local ok, iterator = pcall(function() return collection:iterator() end)
+    if ok and iterator then
+        while iterator:hasNext() do callback(iterator:next()) end
+        return
+    end
+
+    local sizeOk, size = pcall(function() return collection:size() end)
+    if not sizeOk then return end
+    for index = 0, size - 1 do callback(collection:get(index)) end
+end
+
+local function isTargetEligible(wrecker, vehicle)
+    if not vehicle or vehicle == wrecker then return false end
+    if vehicle:getVehicleTowing() or vehicle:getVehicleTowedBy() then return false end
+    if wrecker:getVehicleTowing() or wrecker:getVehicleTowedBy() then return false end
+    local script = vehicle:getScript()
+    if not script then return false end
+    local name = string.lower(tostring(script:getName() or ""))
+    return not string.find(name, "trailer", 1, true)
+end
+
+function Wrecker.resolveNearestTarget(wrecker, candidates)
+    if not Wrecker.isSupportedWrecker(wrecker) then return nil end
+    local hookPoint = wrecker:getAttachmentWorldPos("hook", Vector3f.new())
+    if not hookPoint then return nil end
+
+    local best
+    local maxDistanceSquared = Wrecker.MaxAttachDistance * Wrecker.MaxAttachDistance
+    forEachVehicle(candidates, function(vehicle)
+        if not isTargetEligible(wrecker, vehicle) then return end
+        for _, attachmentId in ipairs({ "trailerfront", "trailer" }) do
+            if vehicle:attachmentExist(attachmentId) then
+                local targetPoint = vehicle:getAttachmentWorldPos(attachmentId, Vector3f.new())
+                local score = distanceSquared(hookPoint, targetPoint)
+                if score and score <= maxDistanceSquared then
+                    local vehicleId = vehicle:getId()
+                    if not best or score < best.distanceSquared
+                            or (score == best.distanceSquared and vehicleId < best.vehicle:getId()) then
+                        best = {
+                            vehicle = vehicle,
+                            attachment = attachmentId,
+                            distanceSquared = score
+                        }
+                    end
+                end
+            end
+        end
+    end)
+    return best
+end
+
+function Wrecker.getWorldVehicles()
+    local cell = getCell()
+    return cell and cell:getVehicles() or nil
+end
+
+local function registerHookAttachments()
+    local manager = getScriptManager()
+    if not manager then return end
+    for fullName in pairs(SupportedWreckers) do
+        local script = manager:getVehicle(fullName)
+        local baseAttachment = script and script:getAttachmentById("hook") or nil
+        local baseOffset = baseAttachment and baseAttachment:getOffset() or nil
+        if baseOffset then
+            for level = Wrecker.MinHeightLevel, Wrecker.MaxHeightLevel do
+                local attachmentId = HeightAttachmentIds[level]
+                if script:getAttachmentById(attachmentId) == nil then
+                    local attachment = ModelAttachment.new(attachmentId)
+                    attachment:getOffset():set(
+                        baseOffset:x(),
+                        baseOffset:y() + level * Wrecker.HeightStep,
+                        baseOffset:z()
+                    )
+                    attachment:setUpdateConstraint(false)
+                    script:addAttachment(attachment)
+                end
+            end
+        end
+    end
+end
+
+Wrecker.registerHookAttachments = registerHookAttachments
+Events.OnGameBoot.Add(registerHookAttachments)
@@ -1,3 +1,3 @@
 {
-    "ItemName_TowBar.TowBar": "Tow Bar"
+    "TowBar.TowBar": "Tow Bar"
 }
@@ -7,6 +7,10 @@
    "UI_Text_Towing_byRope": "by rope",
    "UI_Text_Towing_byTowBar": "by tow bar",
    "UI_Text_Towing_byHook": "by hook",
+    "UI_Text_Towing_attachHook": "Tow %1 by hook",
+    "UI_Text_Towing_detachHook": "Detach %1 from hook",
+    "UI_Text_Towing_heightUp": "Raise tow hook",
+    "UI_Text_Towing_heightDown": "Lower tow hook",
    "UI_Text_Towing_flipUpright": "Flip upright",
    "UI_Text_Towing_cannotDriveWhileTowed": "Cannot drive while being towed",
    "UI_Text_PushByHands": "Push vehicle",
@@ -4,7 +4,7 @@ module Base
    {
        mesh = vehicles/Towbar,
        texture = Vehicles/Towbar_Texture,
-        scale = 0.01,
+        scale = 0.025,
    }

    model towbarModelLarge
@@ -1,10 +1,11 @@
 name=Towbars
-id=hrsys_towbars
+id=hrsys_towbars_testing
 poster=../common/media/textures/preview.png
 description=Tow bars for vehicle-to-vehicle towing.
 author=Riggs0
 category=vehicle
 icon=../common/media/textures/tow_bar_icon.png
 url=https://hudsonriggs.systems
-modversion=1.0.5
+modversion=1.0.12
 versionMin=42.20.0
+incompatible=\STowTruck_B42
@@ -1,3 +1,31 @@
 # Towbar

-Do you want to build a towbar
+Vehicle-to-vehicle tow bars and server-authoritative wrecker controls for
+Project Zomboid Build 42.20.
+
+Portable towbar and wrecker connections persist through solo save/exit,
+dedicated-server restarts, and vehicle-cell streaming. Saved pairs are matched
+with stable vehicle database IDs and reconnected without consuming, refunding,
+or dropping another tow bar during load recovery.
+
+## Supported wrecker mods
+
+Only the listed vehicle scripts receive the seated-driver hook controls. Each
+vehicle must still expose its expected `hook`, `trailer`, and `trailerfront`
+attachments at runtime.
+
+| KI5 mod | Workshop ID | Mod ID | Supported vehicles |
+| --- | --- | --- | --- |
+| '76 Chevrolet K Series | [3161951724](https://steamcommunity.com/sharedfiles/filedetails/?id=3161951724) | `76chevyKseries` | `Base.76chevyC30CCwrecker`, `Base.76chevyC30SCwrecker`, `Base.76chevyK30CCwrecker`, `Base.76chevyK30SCwrecker` |
+| '93 Chevrolet Suburban / Silverado | [3152529790](https://steamcommunity.com/sharedfiles/filedetails/?id=3152529790) | `93chevySuburban`, `93chevySuburbanExpanded` | `Base.93chevySilveradoK3500wrecker`, `Base.93chevySilveradoK3500mechanic` |
+| '78 AM General M35 Series Trucks | [2799152995](https://steamcommunity.com/sharedfiles/filedetails/?id=2799152995) | `78amgeneralM35A2`, optional spawn module `78amgeneralM62` | `Base.78amgeneralM62` |
+
+The ordinary AM General M35A2 and non-wrecker Chevrolet variants are not
+included because their vehicle scripts do not define a tow hook.
+
+## Incompatible mods
+
+`Tow Truck[B42]` (Workshop `3446203945`, Mod ID `STowTruck_B42`) is marked
+incompatible. It owns a competing radial menu, towing state, and vehicle
+constraint implementation, so loading both systems could attach or detach the
+same pair twice.
@@ -1,10 +1,11 @@
 name=Towbars
-id=hrsys_towbars
+id=hrsys_towbars_testing
 poster=common/media/textures/preview.png
 description=Tow bars for vehicle-to-vehicle towing.
 author=Riggs0
 category=vehicle
 versionMin=42.13.0
 url=https://hudsonriggs.systems
-modversion=1.0.5
+modversion=1.0.12
 icon=common/media/textures/tow_bar_icon.png
+incompatible=\STowTruck_B42
@@ -0,0 +1,280 @@
+local failures = 0
+
+local function expect(condition, message)
+    if not condition then
+        failures = failures + 1
+        io.stderr:write("FAIL: " .. message .. "\n")
+    end
+end
+
+package.path = "42.20/media/lua/shared/?.lua;" .. package.path
+
+local globalData = {}
+ModData = {
+    getOrCreate = function(name)
+        globalData[name] = globalData[name] or {}
+        return globalData[name]
+    end,
+    transmit = function() end
+}
+
+TowBarMod = {}
+require("TowBar/Persistence")
+
+local function collection(items)
+    return {
+        iterator = function()
+            local index = 0
+            return {
+                hasNext = function() return index < #items end,
+                next = function()
+                    index = index + 1
+                    return items[index]
+                end
+            }
+        end
+    }
+end
+
+local function newMetrics()
+    return {
+        addConstraint = 0,
+        breakConstraint = 0,
+        attachSync = 0,
+        detachSync = 0,
+        worldDrops = 0
+    }
+end
+
+local function newVehicle(id, sqlId, metrics)
+    local vehicle = {
+        id = id,
+        sqlId = sqlId,
+        modData = {},
+        towing = nil,
+        towedBy = nil
+    }
+
+    function vehicle:getId() return self.id end
+    function vehicle:getSqlId() return self.sqlId end
+    function vehicle:getModData() return self.modData end
+    function vehicle:transmitModData() end
+    function vehicle:getVehicleTowing() return self.towing end
+    function vehicle:getVehicleTowedBy() return self.towedBy end
+    function vehicle:attachmentExist() return true end
+    function vehicle:addPointConstraint()
+        -- Deliberately do not establish the link. Build 42 may acknowledge a
+        -- new native constraint on a later tick.
+        metrics.addConstraint = metrics.addConstraint + 1
+    end
+    function vehicle:breakConstraint()
+        metrics.breakConstraint = metrics.breakConstraint + 1
+        self.towing = nil
+        self.towedBy = nil
+    end
+    function vehicle:getSquare()
+        return {
+            AddWorldInventoryItem = function()
+                metrics.worldDrops = metrics.worldDrops + 1
+                return {}
+            end
+        }
+    end
+
+    return vehicle
+end
+
+local function linkPair(towing, towed)
+    towing.towing = towed
+    towing.towedBy = nil
+    towed.towing = nil
+    towed.towedBy = towing
+end
+
+local function unlinkPair(towing, towed)
+    towing.towing = nil
+    towing.towedBy = nil
+    towed.towing = nil
+    towed.towedBy = nil
+end
+
+local function installEvents()
+    local callbacks = {}
+    Events = {
+        OnClientCommand = {
+            Add = function(callback) callbacks.clientCommand = callback end
+        },
+        OnTick = {
+            Add = function(callback) callbacks.tick = callback end
+        }
+    }
+    return callbacks
+end
+
+local function fireTicks(callback, count)
+    for _ = 1, count do callback() end
+end
+
+local function resetRegistry()
+    globalData["TowBar.PersistentPairsV2"] = { pairs = {} }
+end
+
+local function runPortableHandlerSpec()
+    resetRegistry()
+    local metrics = newMetrics()
+    local callbacks = installEvents()
+    local now = 1000
+    local towing = newVehicle(101, 1001, metrics)
+    local towed = newVehicle(202, 2002, metrics)
+    local loaded = { towing, towed }
+    local byId = { [101] = towing, [202] = towed }
+
+    isClient = function() return false end
+    isServer = function() return true end
+    getDebug = function() return false end
+    getTimestampMs = function() return now end
+    getCell = function()
+        return { getVehicles = function() return collection(loaded) end }
+    end
+    getVehicleById = function(id) return byId[id] end
+    sendServerCommand = function(_, command)
+        if command == "forceAttachSync" then
+            metrics.attachSync = metrics.attachSync + 1
+        elseif command == "forceDetachSync" or command == "spontaneousDetachSync" then
+            metrics.detachSync = metrics.detachSync + 1
+        end
+    end
+
+    expect(
+        TowBarMod.Persistence.savePair(
+            "towbar", towing, towed, "trailer", "trailerfront"
+        ),
+        "portable setup must persist a stable pair"
+    )
+    dofile("42.20/media/lua/server/TowingCommands.lua")
+    expect(type(callbacks.tick) == "function", "portable server must register its audit tick")
+
+    fireTicks(callbacks.tick, 5)
+    expect(metrics.addConstraint == 1, "portable restart must request one native restore")
+    expect(metrics.attachSync == 1, "portable restart must broadcast one restore")
+
+    now = 1500
+    fireTicks(callbacks.tick, 5)
+    expect(metrics.addConstraint == 1, "portable pending restore must not duplicate its constraint")
+    expect(metrics.attachSync == 1, "portable pending restore must not duplicate its sync")
+
+    linkPair(towing, towed)
+    now = 2000
+    fireTicks(callbacks.tick, 5)
+    expect(metrics.addConstraint == 1, "portable delayed acknowledgement must be adopted without re-adding")
+    expect(towing.modData.towBarTowedVehicleId == towed:getId(), "portable adoption must refresh the towing live ID")
+    expect(towed.modData.towBarTowingVehicleId == towing:getId(), "portable adoption must refresh the towed live ID")
+
+    unlinkPair(towing, towed)
+    loaded = { towing }
+    byId[202] = nil
+    now = 10000
+    fireTicks(callbacks.tick, 5)
+    now = 16000
+    fireTicks(callbacks.tick, 5)
+    expect(metrics.worldDrops == 0, "an unloaded portable peer must not drop a towbar")
+    expect(metrics.detachSync == 0, "an unloaded portable peer must not broadcast destructive cleanup")
+    expect(towing.modData.isTowingByTowBar == true, "an unloaded portable peer must keep active metadata")
+    expect(towing.modData.towBarTowedVehicleSqlId == towed:getSqlId(), "an unloaded portable peer must keep stable identity")
+
+    loaded = { towing, towed }
+    byId[202] = towed
+    now = 17000
+    fireTicks(callbacks.tick, 5)
+    expect(metrics.addConstraint == 2, "a reloaded portable peer must re-enter recovery")
+    expect(metrics.attachSync == 2, "a reloaded portable peer must receive one fresh restore sync")
+    expect(metrics.worldDrops == 0, "portable peer reload must not be mistaken for a break")
+    expect(metrics.breakConstraint == 0, "portable peer reload must not break an unrelated constraint")
+end
+
+local function runWreckerHandlerSpec()
+    resetRegistry()
+    local metrics = newMetrics()
+    local callbacks = installEvents()
+    local now = 1000
+    local wrecker = newVehicle(303, 3003, metrics)
+    local target = newVehicle(404, 4004, metrics)
+    local loaded = { wrecker, target }
+    local byId = { [303] = wrecker, [404] = target }
+
+    TowBarMod.Wrecker = {
+        getWorldVehicles = function() return collection(loaded) end,
+        isSupportedWrecker = function(vehicle) return vehicle == wrecker end,
+        normalizeHeightLevel = function(level)
+            return math.max(0, math.min(2, tonumber(level) or 0))
+        end,
+        getHeightAttachmentId = function(level)
+            return ({ [0] = "towbarWreckerHookLow", [1] = "towbarWreckerHookMid", [2] = "towbarWreckerHookHigh" })[level]
+        end
+    }
+
+    isClient = function() return false end
+    isServer = function() return true end
+    getTimestampMs = function() return now end
+    getVehicleById = function(id) return byId[id] end
+    sendServerCommand = function(_, command)
+        if command == "wreckerAttachSync" then
+            metrics.attachSync = metrics.attachSync + 1
+        elseif command == "wreckerDetachSync" then
+            metrics.detachSync = metrics.detachSync + 1
+        end
+    end
+
+    expect(
+        TowBarMod.Persistence.savePair(
+            "wrecker", wrecker, target,
+            "towbarWreckerHookHigh", "trailerfront", 2
+        ),
+        "wrecker setup must persist a stable pair"
+    )
+    dofile("42.20/media/lua/server/WreckerCommands.lua")
+    expect(type(callbacks.tick) == "function", "wrecker server must register its audit tick")
+
+    fireTicks(callbacks.tick, 30)
+    expect(metrics.addConstraint == 1, "wrecker restart must request one native restore")
+    expect(metrics.attachSync == 1, "wrecker restart must broadcast one restore")
+
+    now = 1500
+    fireTicks(callbacks.tick, 30)
+    expect(metrics.addConstraint == 1, "wrecker pending restore must not duplicate its constraint")
+    expect(metrics.attachSync == 1, "wrecker pending restore must not duplicate its sync")
+
+    linkPair(wrecker, target)
+    now = 2000
+    fireTicks(callbacks.tick, 30)
+    expect(metrics.addConstraint == 1, "wrecker delayed acknowledgement must be adopted without re-adding")
+    expect(wrecker.modData.wreckerHeightLevel == 2, "wrecker adoption must preserve the saved hook height")
+    expect(wrecker.modData.wreckerTargetAttachment == "trailerfront", "wrecker adoption must preserve the target endpoint")
+
+    unlinkPair(wrecker, target)
+    loaded = { wrecker }
+    byId[404] = nil
+    now = 10000
+    fireTicks(callbacks.tick, 30)
+    now = 16000
+    fireTicks(callbacks.tick, 30)
+    expect(metrics.detachSync == 0, "an unloaded wrecker peer must not broadcast destructive cleanup")
+    expect(wrecker.modData.wreckerTowActive == true, "an unloaded wrecker peer must keep active metadata")
+    expect(wrecker.modData.wreckerTowedVehicleSqlId == target:getSqlId(), "an unloaded wrecker peer must keep stable identity")
+
+    loaded = { wrecker, target }
+    byId[404] = target
+    now = 17000
+    fireTicks(callbacks.tick, 30)
+    expect(metrics.addConstraint == 2, "a reloaded wrecker peer must re-enter recovery")
+    expect(metrics.attachSync == 2, "a reloaded wrecker peer must receive one fresh restore sync")
+    expect(metrics.detachSync == 0, "wrecker peer reload must not be mistaken for a break")
+    expect(metrics.worldDrops == 0, "wrecker recovery must never create a portable towbar item")
+    expect(metrics.breakConstraint == 0, "wrecker peer reload must not break an unrelated constraint")
+end
+
+runPortableHandlerSpec()
+runWreckerHandlerSpec()
+
+if failures > 0 then os.exit(1) end
+print("PASS: production persistence handlers debounce recovery and survive peer unload")
@@ -0,0 +1,69 @@
+local failures = 0
+local function expect(condition, message)
+    if not condition then
+        failures = failures + 1
+        io.stderr:write("FAIL: " .. message .. "\n")
+    end
+end
+
+local globalData = {}
+local transmitted = 0
+ModData = {
+    getOrCreate = function(name)
+        globalData[name] = globalData[name] or {}
+        return globalData[name]
+    end,
+    transmit = function() transmitted = transmitted + 1 end
+}
+function isServer() return true end
+TowBarMod = {}
+
+dofile("42.20/media/lua/shared/TowBar/Persistence.lua")
+
+local function vehicle(sqlId)
+    return { getSqlId = function() return sqlId end }
+end
+
+local towing, towed = vehicle(101), vehicle(202)
+expect(TowBarMod.Persistence.savePair("towbar", towing, towed, "trailer", "trailerfront"), "valid SQL pair must save")
+local pair = TowBarMod.Persistence.getPair("towbar", towing, towed)
+expect(pair and pair.towingSqlId == 101 and pair.towedSqlId == 202, "saved pair must use stable SQL IDs")
+expect(pair and pair.attachmentA == "trailer" and pair.attachmentB == "trailerfront", "saved pair must retain attachments")
+
+expect(TowBarMod.Persistence.savePair("wrecker", towing, towed, "towbarWreckerHookHigh", "trailer", 2), "wrecker pair must save")
+local wreckerPair = TowBarMod.Persistence.getPair("wrecker", towing, towed)
+expect(wreckerPair and wreckerPair.heightLevel == 2, "wrecker pair must retain hook height")
+
+local seen = 0
+TowBarMod.Persistence.forEachPair("towbar", function(record)
+    if record.towingSqlId == 101 and record.towedSqlId == 202 then seen = seen + 1 end
+end)
+expect(seen == 1, "registry iteration must return the saved pair exactly once")
+expect(TowBarMod.Persistence.removePair("towbar", towing, towed), "saved pair must be removable")
+expect(TowBarMod.Persistence.getPair("towbar", towing, towed) == nil, "removed pair must stay absent")
+expect(transmitted >= 3, "server registry changes must transmit")
+expect(not TowBarMod.Persistence.savePair("towbar", vehicle(-1), towed, "trailer", "trailerfront"), "unsaved vehicles must not create unstable records")
+
+local state, action = TowBarMod.Persistence.advanceRecoveryState(nil, 1000, false, false, 2000, 5000)
+expect(action == "restore", "first missing-link observation must start one restore")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 1500, false, false, 2000, 5000)
+expect(action == "wait", "an in-flight restore must not be duplicated")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 3000, true, false, 2000, 5000)
+expect(action == "adopt" and state.confirmed, "a restored link must be adopted")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 3100, false, false, 2000, 5000)
+expect(action == "wait", "one missing sample must not destroy an adopted link")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 8099, false, false, 2000, 5000)
+expect(action == "wait", "cleanup must wait for the complete break grace period")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 8100, false, false, 2000, 5000)
+expect(action == "break", "a continuously missing confirmed link must eventually break")
+
+state = TowBarMod.Persistence.notePeerAvailability({ confirmed = true }, false)
+expect(state.peerMissing, "an unloaded peer must be remembered")
+state = TowBarMod.Persistence.notePeerAvailability(state, true)
+expect(state.confirmed == false, "a reloaded pair must re-enter recovery instead of break cleanup")
+expect(state.peerMissing == nil, "the peer-missing marker must clear after both vehicles load")
+state, action = TowBarMod.Persistence.advanceRecoveryState(state, 9000, false, false, 2000, 5000)
+expect(action == "restore", "a reloaded pair must rebuild its constraint")
+
+if failures > 0 then os.exit(1) end
+print("PASS: persistent pair registry behavior")
@@ -0,0 +1,183 @@
+local failures = 0
+
+local function expect(condition, message)
+    if not condition then
+        failures = failures + 1
+        io.stderr:write("FAIL: " .. message .. "\n")
+    end
+end
+
+local serverCommand
+local vehicleSpawned
+Events = {
+    OnServerCommand = {
+        Add = function(callback) serverCommand = callback end
+    },
+    OnSpawnVehicleEnd = {
+        Add = function(callback) vehicleSpawned = callback end
+    }
+}
+
+isServer = function() return false end
+
+local trace = {}
+local function record(value) trace[#trace + 1] = value end
+
+local function script()
+    return {
+        getAttachmentById = function(_, id)
+            if id == "trailer" or id == "trailerfront" then return {} end
+            return nil
+        end,
+        getWheelCount = function() return 0 end,
+        getPhysicsChassisShape = function()
+            return { z = function() return 4 end }
+        end,
+        addAttachment = function() end
+    }
+end
+
+local rigidAdds = 0
+local breaks = 0
+local towing
+local towed
+
+local function vehicle(id)
+    local value = {
+        id = id,
+        modData = {},
+        script = script(),
+        towing = nil,
+        towedBy = nil
+    }
+
+    function value:getId() return self.id end
+    function value:getScript() return self.script end
+    function value:getScriptName() return "Base.TestVehicle" end
+    function value:getModData() return self.modData end
+    function value:transmitModData() end
+    function value:getMass() return 1200 end
+    function value:getBrakingForce() return 25 end
+    function value:getVehicleTowing() return self.towing end
+    function value:getVehicleTowedBy() return self.towedBy end
+    function value:addPointConstraint(_, other, attachmentA, attachmentB, localOnly)
+        rigidAdds = rigidAdds + 1
+        record("rigid-add")
+        expect(self == towing and other == towed, "rigid rebuild must use the original pair")
+        expect(attachmentA == "trailer" and attachmentB == "trailerfront", "rigid rebuild must preserve endpoints")
+        expect(localOnly == true, "rigid rebuild must be local-only to avoid an attach/detach command race")
+        self.towing = other
+        other.towedBy = self
+    end
+    function value:breakConstraint()
+        breaks = breaks + 1
+        record("break-native")
+        if self == towing or self == towed then
+            towing.towing = nil
+            towing.towedBy = nil
+            towed.towing = nil
+            towed.towedBy = nil
+        end
+    end
+
+    return value
+end
+
+towing = vehicle(101)
+towed = vehicle(202)
+local vehicles = { [101] = towing, [202] = towed }
+getVehicleById = function(id) return vehicles[id] end
+
+TowBarMod = {
+    Utils = {
+        updateAttachmentsForRigidTow = function()
+            record("rigid-offsets")
+        end
+    },
+    Hook = {
+        cleanupDetachedTowBar = function()
+            record("cleanup")
+            towing.modData = {}
+            towed.modData = {}
+        end,
+        setVehicleScriptWithTowBarHidden = function(_, scriptName)
+            record("script:" .. tostring(scriptName))
+            return true
+        end,
+        setVehiclePostAttach = function()
+            record("post-attach")
+        end
+    }
+}
+
+dofile("42.20/media/lua/client/TowBar/TowSyncClient.lua")
+expect(type(serverCommand) == "function", "client sync must register its server-command handler")
+
+-- Begin with the old physical pair so spontaneous cleanup exercises the same
+-- path as a real Build 42 break notification.
+towing.towing = towed
+towed.towedBy = towing
+towing.modData.towBarTowedVehicleId = towed:getId()
+towed.modData.towBarTowingVehicleId = towing:getId()
+serverCommand("towbar", "spontaneousDetachSync", {
+    vehicleA = towing:getId(),
+    vehicleB = towed:getId()
+})
+expect(breaks > 0, "spontaneous cleanup must remove the old native relation")
+expect(towing:getVehicleTowing() == nil and towed:getVehicleTowedBy() == nil, "spontaneous cleanup must leave the pair unlinked")
+
+-- A direct reattach can arrive from the server as a native B42 relationship
+-- before forceAttachSync reaches the client. That native relationship is the
+-- rope-like constraint; forceAttachSync must replace it with the rigid path.
+towing.towing = towed
+towed.towedBy = towing
+local breaksBeforeReattach = breaks
+serverCommand("towbar", "forceAttachSync", {
+    vehicleA = towing:getId(),
+    vehicleB = towed:getId(),
+    attachmentA = "trailer",
+    attachmentB = "trailerfront"
+})
+
+expect(breaks == breaksBeforeReattach + 1, "direct reattach must replace the native B42 rope relation")
+expect(rigidAdds == 1, "direct reattach must create exactly one rigid local constraint")
+
+local fakeScriptIndex
+local rigidAddIndex
+for index, value in ipairs(trace) do
+    if value == "script:notTowingA_Trailer" and not fakeScriptIndex then fakeScriptIndex = index end
+    if value == "rigid-add" and not rigidAddIndex then rigidAddIndex = index end
+end
+expect(fakeScriptIndex ~= nil, "rigid reattach must select the fake-trailer script")
+expect(rigidAddIndex ~= nil and fakeScriptIndex < rigidAddIndex, "fake-trailer selection must precede rigid constraint creation")
+expect(towing:getVehicleTowing() == towed and towed:getVehicleTowedBy() == towing, "rigid rebuild must finish with a reciprocal tow relation")
+
+local rigidAddsAfterFirstSync = rigidAdds
+local breaksAfterFirstSync = breaks
+serverCommand("towbar", "forceAttachSync", {
+    vehicleA = towing:getId(),
+    vehicleB = towed:getId(),
+    attachmentA = "trailer",
+    attachmentB = "trailerfront"
+})
+expect(rigidAdds == rigidAddsAfterFirstSync, "a repeated attach snapshot must not layer a second rigid constraint")
+expect(breaks == breaksAfterFirstSync, "a repeated attach snapshot must adopt the already-rigid pair")
+
+-- Streaming can recreate a native relationship with the same runtime IDs
+-- while the Lua module and its applied cache survive. The spawn notification
+-- must invalidate that stale cache so the next snapshot replaces the rope.
+expect(type(vehicleSpawned) == "function", "client sync must observe vehicle streaming")
+vehicleSpawned(towed)
+local rigidAddsBeforeStreamRestore = rigidAdds
+local breaksBeforeStreamRestore = breaks
+serverCommand("towbar", "forceAttachSync", {
+    vehicleA = towing:getId(),
+    vehicleB = towed:getId(),
+    attachmentA = "trailer",
+    attachmentB = "trailerfront"
+})
+expect(rigidAdds == rigidAddsBeforeStreamRestore + 1, "stream-restored native rope must be rebuilt rigid")
+expect(breaks == breaksBeforeStreamRestore + 1, "stream-restored native rope must be removed exactly once")
+
+if failures > 0 then os.exit(1) end
+print("PASS: spontaneous break followed by direct attach rebuilds a rigid towbar")
@@ -29,14 +29,23 @@ Assert-True (Test-Path -LiteralPath $releaseRoot) "Missing 42.20 release folder.

 $releaseInfo = Get-Content -LiteralPath (Join-Path $releaseRoot "mod.info")
 $rootInfo = Get-Content -LiteralPath (Join-Path $repositoryRoot "mod.info")
-Assert-True ($releaseInfo -contains "id=hrsys_towbars") "42.20 must use the stable mod id."
+Assert-True ($releaseInfo -contains "id=hrsys_towbars_testing") "42.20 must retain the current testing mod id."
 Assert-True ($releaseInfo -contains "versionMin=42.20.0") "42.20 must require Build 42.20."
-Assert-True ($releaseInfo -contains "modversion=1.0.5") "42.20 must declare mod version 1.0.5."
-Assert-True ($rootInfo -contains "modversion=1.0.5") "Root and release mod versions must match."
+Assert-True ($releaseInfo -contains "modversion=1.0.12") "42.20 must declare mod version 1.0.12."
+Assert-True ($rootInfo -contains "modversion=1.0.12") "Root and release mod versions must match."

 $baselineFiles = Get-RelativeFileNames $baselineRoot
 $releaseFiles = Get-RelativeFileNames $releaseRoot
-Assert-True (-not (Compare-Object $baselineFiles $releaseFiles)) "42.20 file layout must match the latest baseline."
+$allowedAdditions = @(
+    "media/lua/client/TowBar/WreckerSyncClient.lua",
+    "media/lua/client/TowBar/WreckerTimedAction.lua",
+    "media/lua/client/TowBar/WreckerUI.lua",
+    "media/lua/server/WreckerCommands.lua",
+    "media/lua/shared/TowBar/Persistence.lua",
+    "media/lua/shared/TowBar/WreckerUtils.lua"
+)
+$expectedReleaseFiles = @($baselineFiles) + $allowedAdditions | Sort-Object
+Assert-True (-not (Compare-Object $expectedReleaseFiles $releaseFiles)) "42.20 file layout must match baseline plus declared wrecker compatibility files."

 foreach ($jsonFile in Get-ChildItem -LiteralPath $releaseRoot -Recurse -Filter "*.json") {
    try {
@@ -52,18 +61,42 @@ $btTowPath = Join-Path $releaseRoot "media/lua/server/BTTow.lua"
 $clientSyncPath = Join-Path $releaseRoot "media/lua/client/TowBar/TowSyncClient.lua"
 $hookingPath = Join-Path $releaseRoot "media/lua/client/TowBar/TowingHooking.lua"
 $towbarTemplatePath = Join-Path $releaseRoot "media/scripts/vehicles/template_towbar.txt"
+$itemNamePath = Join-Path $releaseRoot "media/lua/shared/Translate/EN/ItemName.json"
+$persistencePath = Join-Path $releaseRoot "media/lua/shared/TowBar/Persistence.lua"
+$legacyItemNamePath = Join-Path $repositoryRoot "common/media/lua/shared/Translate/EN/ItemName_EN.txt"
 $serverCommands = Get-Content -LiteralPath $serverCommandsPath -Raw
 $btTow = Get-Content -LiteralPath $btTowPath -Raw
 $clientSync = Get-Content -LiteralPath $clientSyncPath -Raw
 $hooking = Get-Content -LiteralPath $hookingPath -Raw
 $towbarTemplate = Get-Content -LiteralPath $towbarTemplatePath -Raw
+$itemNames = Get-Content -LiteralPath $itemNamePath -Raw | ConvertFrom-Json
+$persistence = Get-Content -LiteralPath $persistencePath -Raw
+$legacyItemNames = Get-Content -LiteralPath $legacyItemNamePath -Raw
+
+$towbarVisualScale = 2.5
+$towbarBaseScriptScale = 0.01
+$towbarScaledScriptScale = $towbarBaseScriptScale * $towbarVisualScale
+$towbarMeasuredLengthAtBaseScale = 0.9714089036
+$towbarScaledHalfLength = ($towbarMeasuredLengthAtBaseScale * $towbarVisualScale) / 2
+
+Assert-True ($towbarTemplate -match ('(?s)model towbarModel\s*\{{.*?scale = {0},' -f [regex]::Escape($towbarScaledScriptScale.ToString('0.000', [Globalization.CultureInfo]::InvariantCulture)))) "The normal towbar visual must render at 2.5x its measured 0.01 script scale."
+Assert-True ($hooking -match 'local TowbarVisualScale = 2\.5') "Client placement must declare the 2.5x visual scale."
+Assert-True ($btTow -match 'local TowbarVisualScale = 2\.5') "Part initialization must declare the 2.5x visual scale."
+Assert-True ($hooking -match '(?s)local TowbarScaledModelLength = TowbarModelLength \* TowbarVisualScale.*?local TowbarModelHalfLength = TowbarScaledModelLength / 2') "Client placement must compensate offsets using the scaled mesh length."
+Assert-True ($btTow -match '(?s)local TowbarScaledModelLength = TowbarModelLength \* TowbarVisualScale.*?local TowbarModelHalfLength = TowbarScaledModelLength / 2') "Part initialization must compensate offsets using the scaled mesh length."
+Assert-True ([Math]::Abs((0.9714089036 / 2) - ($towbarScaledHalfLength / $towbarVisualScale)) -lt 0.000000001) "Scaling and offset compensation must retain the original mesh-relative half-length contact point."
+
+$towBarDisplayName = $itemNames.PSObject.Properties["TowBar.TowBar"]
+Assert-True ($null -ne $towBarDisplayName -and $towBarDisplayName.Value -ceq "Tow Bar") "B42.20 must display TowBar.TowBar as Tow Bar."
+Assert-True ($null -eq $itemNames.PSObject.Properties["ItemName_TowBar.TowBar"]) "B42 JSON must not use the legacy ItemName_ prefix."
+Assert-True ($legacyItemNames -match 'ItemName_TowBar\.TowBar\s*=\s*"Tow Bar"') "Legacy translations must retain their prefixed item-name key."

 Assert-True ($serverCommands -match 'detachTrailerSpontaneous') "Server must handle Build 42.20 spontaneous towing detach."
 Assert-True ($serverCommands -match 'towBarTowedVehicleId') "Server must persist the expected towbar pair."
 Assert-True ($serverCommands -match '(?s)local function markExpectedTowBarPair.*?towingModData\["towBarTowingVehicleId"\] = nil.*?towedModData\["towBarTowedVehicleId"\] = nil') "Pair marking must clear stale opposite-role IDs."
 Assert-True ($serverCommands -match '(?s)local function clearExpectedTowBarPair.*?towingModData\["towBarTowedVehicleId"\] = nil.*?towingModData\["towBarTowingVehicleId"\] = nil.*?towedModData\["towBarTowedVehicleId"\] = nil.*?towedModData\["towBarTowingVehicleId"\] = nil') "Pair cleanup must clear both role IDs from both vehicles."
 Assert-True ($serverCommands -match 'local function isExpectedTowBarPair') "Server must validate reciprocal expected towbar IDs."
-Assert-True ($serverCommands -match '(?s)isExpectedTowBarPair.*?towBarTowedVehicleId.*?vehicleB:getId\(\).*?towBarTowingVehicleId.*?vehicleA:getId\(\)') "Expected towbar pair validation must be reciprocal."
+Assert-True ($serverCommands -match '(?s)isExpectedTowBarPair.*?matchesSavedVehicle\(.*?towBarTowedVehicleId.*?towBarTowedVehicleSqlId.*?vehicleB.*?matchesSavedVehicle\(.*?towBarTowingVehicleId.*?towBarTowingVehicleSqlId.*?vehicleA') "Expected towbar pair validation must use reciprocal stable vehicle identities."
 Assert-True ($serverCommands -match 'local function isLegacyTowBarPair') "Server must isolate legacy pair recovery from stale modern pair IDs."
 Assert-True ($serverCommands -match '(?s)isLegacyTowBarPair.*?hasTowBarState\(vehicleA\) and hasTowBarState\(vehicleB\).*?towed.*?== true.*?towingModData\["towBarTowedVehicleId"\].*?== nil.*?towingModData\["towBarTowingVehicleId"\].*?== nil.*?towedModData\["towBarTowedVehicleId"\].*?== nil.*?towedModData\["towBarTowingVehicleId"\].*?== nil') "Legacy recovery must require both role markers and no modern pair IDs on either vehicle."
 Assert-True ($serverCommands -match '(?s)local function resolveExpectedTowBarPair.*?towingVehicle and towedVehicle.*?isExpectedTowBarPair\(towingVehicle, towedVehicle\)') "Current-link spontaneous resolution must still require reciprocal towbar identity."
@@ -83,13 +116,30 @@ Assert-True ($serverCommands -match 'if item\.reservedTowBar then') "Failed mult
 Assert-True ($serverCommands -match 'Constraint creation may complete on a later server tick') "Multiplayer attach must preserve delayed constraint confirmation."
 Assert-True ($serverCommands -match 'local function finalizeBrokenTowBarPair') "Broken towbar cleanup must use one idempotent finalizer."
 Assert-True ($serverCommands -match 'local function reconcileBrokenTowBarPairsServer') "Server and single-player must audit confirmed towbar constraints for silent breaks."
-Assert-True ($serverCommands -match '(?s)local function reconcileBrokenTowBarPairsServer.*?towBarTowedVehicleId.*?getVehicleById.*?isExpectedTowBarPair.*?isLinked.*?markTowBarPairConfirmed.*?isTowBarPairConfirmed.*?finalizeBrokenTowBarPair') "The physical-link audit must confirm reciprocal pairs and finalize a missing constraint."
+Assert-True ($serverCommands -match '(?s)local function reconcileBrokenTowBarPairsServer.*?Persistence\.advanceRecoveryState.*?RestoreRetryMs, SustainedBreakMs.*?action == "break".*?finalizeBrokenTowBarPair.*?action == "restore".*?restorePersistedTowBarPair') "The physical-link audit must use the shared bounded recovery state machine."
+Assert-True ($persistence -match '(?s)function Persistence\.advanceRecoveryState.*?state\.unlinkedSince = state\.unlinkedSince or now.*?now - state\.unlinkedSince >= breakMs.*?return state, "break"' -and $persistence -match '(?s)if not state\.pendingUntil or now >= state\.pendingUntil then.*?state\.pendingUntil = now \+ retryMs.*?return state, "restore"') "Persistent-pair recovery must debounce restores and require a sustained break before cleanup."
+Assert-True ($serverCommands -match '(?s)local function restorePersistedTowBarPair.*?towBarExpectedAttachment.*?addPointConstraint.*?broadcastAttach') "A saved towbar pair must rebuild its physical constraint without consuming another item."
+Assert-True ($persistence -match '(?s)if not state\.pendingUntil or now >= state\.pendingUntil then.*?return state, "restore"') "An unconfirmed saved pair must schedule a bounded restoration attempt."
+Assert-True ($clientSync -match 'TowBarMod\.Sync\.applyAttachSync = applyAttachSync') "Single-player must expose the existing attach synchronizer for saved-pair recovery."
+Assert-True ($clientSync -match '(?s)local key = tostring\(vehicleA:getId\(\)\).*?if TowBarMod\.Sync\.appliedPairs\[key\] and not isLinked\(vehicleA, vehicleB\) then.*?TowBarMod\.Sync\.appliedPairs\[key\] = nil.*?if not TowBarMod\.Sync\.appliedPairs\[key\] then.*?breakTowBarPair\(vehicleA, vehicleB\).*?setVehicleScriptWithTowBarHidden\(vehicleB, "notTowingA_Trailer"\).*?addPointConstraint\(nil, vehicleB, attachmentA, attachmentB, true\)') "Every fresh or recovered towbar pair must replace the native rope with one local rigid constraint."
+Assert-True ($clientSync -notmatch '(?s)if linked then\s*--.*?appliedPairs\[key\] = true') "A newly observed native tow link must not be accepted as rigid without rebuilding it."
+Assert-True ($clientSync -match '(?s)local function clearAppliedPairForVehicle.*?TowBarMod\.Sync\.appliedPairs\[key\] = nil.*?Events\.OnSpawnVehicleEnd\.Add\(clearAppliedPairForVehicle\)') "Vehicle streaming must invalidate cached rigid towbar constraints."
+Assert-True ($serverCommands -match '(?s)local function broadcastAttach.*?if isServer\(\).*?sendServerCommand.*?elseif not isClient\(\).*?TowBarMod\.Sync\.applyAttachSync') "Saved towbar recovery must synchronize both dedicated-server and single-player sessions."
+Assert-True ($serverCommands -match 'towBarTowedVehicleSqlId' -and $serverCommands -match 'towBarTowingVehicleSqlId' -and $serverCommands -match 'getSqlId') "Towbar persistence must use stable save IDs in addition to live network IDs."
+Assert-True ($serverCommands -match 'Persistence\.savePair\("towbar"' -and $serverCommands -match 'Persistence\.forEachPair\("towbar"') "Towbar persistence must use the server-owned saved-pair registry."
+Assert-True ($hooking -match '(?s)local function recoverTowBarVehicleAfterLoad.*?authoritative audit will.*?reconnect') "Client load recovery must defer missing constraints to the authoritative saved-pair audit."
+$loadRecoveryStart = $hooking.IndexOf('local function recoverTowBarVehicleAfterLoad')
+$loadRecoveryEnd = $hooking.IndexOf('function TowBarMod.Hook.setVehiclePostAttach', $loadRecoveryStart)
+if ($loadRecoveryStart -ge 0 -and $loadRecoveryEnd -gt $loadRecoveryStart) {
+    $loadRecovery = $hooking.Substring($loadRecoveryStart, $loadRecoveryEnd - $loadRecoveryStart)
+    Assert-True ($loadRecovery -notmatch 'detachTowBar|attachTowBar|reattachTowBarPairAfterCleanDetach') "Loading a saved towbar pair must not refund or consume the item."
+}
 Assert-True ($serverCommands -match '(?s)local function processPendingSync.*?reconcileBrokenTowBarPairsServer\(\)') "The physical-link audit must run from the server/SP tick handler."
 Assert-True ($serverCommands -match '(?s)local function finalizeBrokenTowBarPair.*?dropTowBarOnGround.*?cancelPendingAttach.*?breakTowBarConstraint.*?clearExpectedTowBarPair.*?broadcastSpontaneousDetach') "Broken-pair finalization must drop, disconnect, clear state, and synchronize cleanup."
 Assert-True ($serverCommands -match '(?s)local function finalizeBrokenTowBarPair.*?if isServer\(\) then.*?elseif not isClient\(\).*?TowBarMod\.Hook\.cleanupDetachedTowBar') "Single-player breaks must directly restore the vehicle without relying on a server command." 
 Assert-True ($clientSync -match 'spontaneousDetachSync') "Client sync must receive spontaneous towbar cleanup."
 Assert-True ($clientSync -match 'local function hasConflictingTowLink') "Client detach sync must detect links to unrelated vehicles."
-Assert-True ($clientSync -match 'local function breakTowBarPair') "Client detach sync must break only the requested pair."
+Assert-True ($clientSync -match 'local breakTowBarPair' -and $clientSync -match 'breakTowBarPair = function') "Client detach sync must break only the requested pair."
 Assert-True ($clientSync -notmatch 'local function safeBreak') "Client detach sync must not use an unrestricted per-vehicle constraint break."
 Assert-True ($clientSync -match '(?s)local function applyDetachSync.*?hasConflictingTowLink\(vehicleA, vehicleB\).*?return.*?breakTowBarPair\(vehicleA, vehicleB\).*?cleanupDetachedTowBar') "Client detach sync must reject conflicting links before cleanup."
 Assert-True ($hooking -match 'function TowBarMod\.Hook\.cleanupDetachedTowBar') "Client must expose idempotent towbar cleanup."
@@ -97,13 +147,63 @@ Assert-True ($hooking -match '(?s)if modData\.towBarOriginalParkingBrakeOn ~= ni
 Assert-True ($hooking -notmatch 'tryVehicleCall\(vehicle, "setBrake"') "Free-rolling state must not change an unrestorable brake control."
 Assert-True ($hooking -notmatch 'tryVehicleCall\(vehicle, "setBraking"') "Free-rolling state must not change an unrestorable braking control."

-Assert-True ($hooking -match '(?s)local function getTowbarModelSlot\(script\).*?if not isVanillaScale\(script\) then.*?return 0\s+end') "KI5 client rendering must select towbar slot 0."
-Assert-True ($btTow -match '(?s)local function getTowbarModelSlot\(script\).*?if not isVanillaScale\(script\) then.*?return 0\s+end') "KI5 part initialization must select towbar slot 0."
+Assert-True ($hooking -match 'local TowbarFirstZ = 1\.0') "Client hitbox placement must use the first model's Z position."
+Assert-True ($hooking -match 'local TowbarSlotStep = 0\.1') "Client hitbox placement must use the model bank's Z spacing."
+Assert-True ($hooking -match 'local TowbarVisualScale = 2\.5') "Client placement must account for the enlarged visual."
+Assert-True ($hooking -match 'local TowbarScaledModelLength = TowbarModelLength \* TowbarVisualScale') "Client placement must derive the enlarged mesh length."
+Assert-True ($hooking -match 'local TowbarModelHalfLength = TowbarScaledModelLength / 2') "Client placement must offset the mesh center by half its enlarged length."
+Assert-True ($btTow -match 'local TowbarVisualScale = 2\.5') "Part initialization must account for the enlarged visual."
+Assert-True ($btTow -match 'local TowbarScaledModelLength = TowbarModelLength \* TowbarVisualScale') "Part initialization must derive the enlarged mesh length."
+Assert-True ($btTow -match 'local TowbarModelHalfLength = TowbarScaledModelLength / 2') "Part initialization must offset the mesh center by half its enlarged length."
+Assert-True ($hooking -match '(?s)local function getTowbarFrontEdgeZ\(script\).*?getPhysicsChassisShape\(\).*?getCenterOfMassOffset\(\).*?centerZ.*?shapeZ / 2') "Client visual position must derive from the hitbox front edge."
+Assert-True ($btTow -match '(?s)local function getTowbarFrontEdgeZ\(script\).*?getPhysicsChassisShape\(\).*?getCenterOfMassOffset\(\).*?centerZ.*?shapeZ / 2') "Part initialization must derive visual position from the hitbox front edge."
+Assert-True ($hooking -match '(?s)local centerOk, center = pcall.*?if not centerOk or not center then return nil end.*?if not zOk or type\(centerZ\) ~= "number" then return nil end') "Client must not show a dynamically placed towbar when center-of-mass geometry is invalid."
+Assert-True ($btTow -match '(?s)local centerOk, center = pcall.*?if not centerOk or not center then return nil end.*?if not zOk or type\(centerZ\) ~= "number" then return nil end') "Part initialization must not show a towbar when center-of-mass geometry is invalid."
+Assert-True ($hooking -match '(?s)local function getTowbarModelSlot\(script\).*?local frontEdgeZ = getTowbarFrontEdgeZ\(script\).*?local modelCenterZ = frontEdgeZ \+ TowbarModelHalfLength.*?math\.floor\(\(\(modelCenterZ - TowbarFirstZ\) / TowbarSlotStep\) \+ 0\.5\).*?math\.max\(0, math\.min\(TowbarMaxIndex, index\)\)') "Client must place the towbar's inner end at the hitbox edge."
+Assert-True ($btTow -match '(?s)local function getTowbarModelSlot\(script\).*?local frontEdgeZ = getTowbarFrontEdgeZ\(script\).*?local modelCenterZ = frontEdgeZ \+ TowbarModelHalfLength.*?math\.floor\(\(\(modelCenterZ - TowbarFirstZ\) / TowbarSlotStep\) \+ 0\.5\).*?math\.max\(0, math\.min\(TowbarMaxIndex, index\)\)') "Part initialization must place the towbar's inner end at the hitbox edge."
+Assert-True ($hooking -notmatch 'isVanillaScale|modelScale') "Dynamic hitbox placement must not apply a second model-scale correction."
+Assert-True ($btTow -notmatch 'isVanillaScale|modelScale') "Part initialization must not apply a second model-scale correction."
 Assert-True ($hooking -match '(?s)local function setTowBarModelVisible.*?local part = normalPart.*?part:setModelVisible\("towbar" \.\. index, true\)') "Automatic rendering must use the normal towbar part."
 Assert-True ($btTow -match '(?s)function BTtow\.Init\.towbar.*?local shouldShowOnThisPart = part:getId\(\) == "towbar"') "Automatic part initialization must only show the normal towbar part."
 Assert-True ($hooking -notmatch 'local part = isVanilla and normalPart or largePart') "KI5 automatic rendering must not select the large towbar part."
 $normalTowbarPart = $towbarTemplate.Substring($towbarTemplate.IndexOf('part towbar'), $towbarTemplate.IndexOf('part towbarLarge') - $towbarTemplate.IndexOf('part towbar'))
+Assert-True ($towbarTemplate -match '(?s)model towbarModel\s*\{.*?scale = 0\.025,') "The rendered towbar mesh must be exactly 2.5 times its original 0.01 scale."
 Assert-True ($normalTowbarPart -match '(?s)model towbar0\s*\{\s*file = towbarModel,\s*offset = 0 -0\.3 1\.0,') "Normal towbar0 must retain the radial-menu Z=1.0 geometry."
+$normalTowbarModels = [regex]::Matches($normalTowbarPart, '(?s)model towbar(\d+)\s*\{\s*file = towbarModel,\s*offset = ([\d.-]+) ([\d.-]+) ([\d.-]+),')
+Assert-True ($normalTowbarModels.Count -eq 24) "Normal towbar part must provide all 24 dynamic Z slots."
+for ($slot = 0; $slot -lt $normalTowbarModels.Count; $slot++) {
+    $match = $normalTowbarModels[$slot]
+    Assert-True ([int]$match.Groups[1].Value -eq $slot) "Normal towbar slots must be sequential."
+    Assert-True ([double]$match.Groups[2].Value -eq 0) "Dynamic placement must not alter lateral X."
+    Assert-True ([double]$match.Groups[3].Value -eq -0.3) "Dynamic placement must not alter vertical Y."
+    $expectedZ = 1.0 + ($slot * 0.1)
+    Assert-True ([Math]::Abs(([double]$match.Groups[4].Value) - $expectedZ) -lt 0.000001) "Towbar slot $slot must map to Z=$expectedZ."
+}
+
+function Get-ExpectedTowbarSlot {
+    param([double]$ShapeZ, [double]$CenterZ)
+    $towbarModelHalfLength = (0.9714089036 * 2.5) / 2
+    $targetCenterZ = $CenterZ + $ShapeZ / 2 + $towbarModelHalfLength
+    $raw = [Math]::Floor((($targetCenterZ - 1.0) / 0.1) + 0.5)
+    return [Math]::Max(0, [Math]::Min(23, [int]$raw))
+}
+
+$geometryCases = @(
+    @{ Name = "B42 Ranger"; ShapeZ = 2.6044; CenterZ = 0.0; Slot = 15 },
+    @{ Name = "KI5 Corolla"; ShapeZ = 4.3111; CenterZ = -0.0444; Slot = 23 },
+    @{ Name = "KI5 Range"; ShapeZ = 4.4444; CenterZ = -0.2556; Slot = 22 },
+    @{ Name = "short vehicle"; ShapeZ = 1.2; CenterZ = 0.0; Slot = 8 },
+    @{ Name = "long clamp"; ShapeZ = 7.2; CenterZ = 0.0; Slot = 23 }
+)
+foreach ($case in $geometryCases) {
+    Assert-True ((Get-ExpectedTowbarSlot $case.ShapeZ $case.CenterZ) -eq $case.Slot) "$($case.Name) hitbox must map to towbar slot $($case.Slot)."
+    $frontEdgeZ = $case.CenterZ + ($case.ShapeZ / 2)
+    $chosenCenterZ = 1.0 + ($case.Slot * 0.1)
+    $chosenInnerEndZ = $chosenCenterZ - $towbarScaledHalfLength
+    if ($case.Slot -gt 0 -and $case.Slot -lt 23) {
+        Assert-True ([Math]::Abs($chosenInnerEndZ - $frontEdgeZ) -le 0.0500001) "$($case.Name) enlarged visual must retain contact with the hitbox edge within half a model slot."
+    }
+}
 Assert-True ($hooking -match 'function TowBarMod\.Hook\.setVehicleScriptWithTowBarHidden') "Vehicle script swaps must use the anti-flicker helper."
 Assert-True ($hooking -match '(?s)setVehicleScriptWithTowBarHidden.*?setTowBarModelVisible\(vehicle, false\).*?towBarModelSwapInProgress.*?vehicle:setScriptName\(scriptName\).*?setTowBarModelVisible\(vehicle, false\)') "The anti-flicker helper must hide towbar models for the full script swap."
 Assert-True ($btTow -match '(?s)function BTtow\.Init\.towbar.*?setModelVisible\("towbar" \.\. j, false\).*?towBarModelSwapInProgress.*?return') "Part initialization must not show a towbar during a script swap."
@@ -130,6 +230,7 @@ if ($cleanupStart -ge 0 -and $cleanupEnd -gt $cleanupStart) {
    $cleanupBranch = $hooking.Substring($cleanupStart, $cleanupEnd - $cleanupStart)
    Assert-True ($cleanupBranch -match 'updateAttachmentsOnDefaultValues') "Break cleanup must restore attachment offsets."
    Assert-True ($cleanupBranch -match 'setVehicleScriptWithTowBarHidden.*?towBarOriginalScriptName') "Break cleanup must restore the original vehicle script."
+    Assert-True ($cleanupBranch -match '(?s)setVehicleScriptWithTowBarHidden.*?towBarOriginalScriptName.*?updateAttachmentsOnDefaultValues') "Break cleanup must restore the real vehicle script before restoring its attachment offsets."
    Assert-True ($cleanupBranch -match 'restoreFreeRollingTowState') "Break cleanup must restore mass, brakes, and parking-brake state."
    Assert-True ($cleanupBranch -match 'setTowBarModelVisible\(towedVehicle, false\)') "Break cleanup must hide the towbar model."
    Assert-True ($cleanupBranch -match '(?s)towingModData\["towBarTowedVehicleId"\] = nil.*?towingModData\["towBarTowingVehicleId"\] = nil.*?towedModData\["towBarTowedVehicleId"\] = nil.*?towedModData\["towBarTowingVehicleId"\] = nil') "Client cleanup must remove stale IDs for either tow role."
@@ -0,0 +1,156 @@
+$ErrorActionPreference = "Stop"
+
+$repositoryRoot = Split-Path -Parent $PSScriptRoot
+$releaseRoot = Join-Path $repositoryRoot "42.20"
+$failures = [Collections.Generic.List[string]]::new()
+
+function Assert-True {
+    param([bool]$Condition, [string]$Message)
+    if (-not $Condition) { $script:failures.Add($Message) }
+}
+
+$expectedFiles = @(
+    "media/lua/shared/TowBar/WreckerUtils.lua",
+    "media/lua/client/TowBar/WreckerTimedAction.lua",
+    "media/lua/client/TowBar/WreckerUI.lua",
+    "media/lua/client/TowBar/WreckerSyncClient.lua",
+    "media/lua/server/WreckerCommands.lua"
+)
+foreach ($relativePath in $expectedFiles) {
+    Assert-True (Test-Path -LiteralPath (Join-Path $releaseRoot $relativePath)) "Missing wrecker runtime file: $relativePath"
+}
+
+$sharedPath = Join-Path $releaseRoot "media/lua/shared/TowBar/WreckerUtils.lua"
+$timedActionPath = Join-Path $releaseRoot "media/lua/client/TowBar/WreckerTimedAction.lua"
+$uiPath = Join-Path $releaseRoot "media/lua/client/TowBar/WreckerUI.lua"
+$syncPath = Join-Path $releaseRoot "media/lua/client/TowBar/WreckerSyncClient.lua"
+$serverPath = Join-Path $releaseRoot "media/lua/server/WreckerCommands.lua"
+$persistencePath = Join-Path $releaseRoot "media/lua/shared/TowBar/Persistence.lua"
+$menuPath = Join-Path $releaseRoot "media/lua/client/TowBar/TowingUI.lua"
+
+$shared = if (Test-Path $sharedPath) { Get-Content $sharedPath -Raw } else { "" }
+$timedAction = if (Test-Path $timedActionPath) { Get-Content $timedActionPath -Raw } else { "" }
+$ui = if (Test-Path $uiPath) { Get-Content $uiPath -Raw } else { "" }
+$sync = if (Test-Path $syncPath) { Get-Content $syncPath -Raw } else { "" }
+$server = if (Test-Path $serverPath) { Get-Content $serverPath -Raw } else { "" }
+$persistence = if (Test-Path $persistencePath) { Get-Content $persistencePath -Raw } else { "" }
+$menu = Get-Content $menuPath -Raw
+
+$supportedWreckers = @(
+    "Base.76chevyC30CCwrecker",
+    "Base.76chevyC30SCwrecker",
+    "Base.76chevyK30CCwrecker",
+    "Base.76chevyK30SCwrecker",
+    "Base.93chevySilveradoK3500wrecker",
+    "Base.93chevySilveradoK3500mechanic",
+    "Base.78amgeneralM62"
+)
+foreach ($fullName in $supportedWreckers) {
+    Assert-True ($shared.Contains($fullName)) "Supported wrecker missing from exact allowlist: $fullName"
+}
+$allowlistStart = $shared.IndexOf("local SupportedWreckers = {")
+$allowlistEnd = $shared.IndexOf("local HeightAttachmentIds", $allowlistStart)
+Assert-True ($allowlistStart -ge 0 -and $allowlistEnd -gt $allowlistStart) "Could not isolate the supported wrecker allowlist."
+if ($allowlistStart -ge 0 -and $allowlistEnd -gt $allowlistStart) {
+    $allowlistBody = $shared.Substring($allowlistStart, $allowlistEnd - $allowlistStart)
+    $actualWreckers = [regex]::Matches($allowlistBody, '\["(Base\.[^"]+)"\]\s*=\s*true') |
+        ForEach-Object { $_.Groups[1].Value } | Sort-Object
+    Assert-True (-not (Compare-Object ($supportedWreckers | Sort-Object) $actualWreckers)) "Supported wrecker allowlist must contain exactly the seven verified KI5 vehicle scripts."
+}
+Assert-True ($shared -match '(?s)function Wrecker\.isSupportedWrecker.*?SupportedWreckers\[fullName\].*?attachmentExist\("hook"\)') "Wrecker detection must require an exact script name and a hook attachment."
+Assert-True ($shared -notmatch 'Chevalier_Rhino_TowTruck') "The competing Rhino tow-truck implementation must not be supported by this wrecker system."
+Assert-True ($shared -match 'Wrecker\.MaxAttachDistance = 0\.6') "Wrecker target selection must use the discovered 0.6-unit hook range."
+Assert-True ($shared -match 'Wrecker\.HeightStep = 0\.30') "Hook height must move in 0.30-unit steps."
+Assert-True ($shared -match 'Wrecker\.MinHeightLevel = 0' -and $shared -match 'Wrecker\.MaxHeightLevel = 2') "Hook height must begin at bottom and allow exactly two upward steps."
+Assert-True ($shared -match 'towbarWreckerHookLow' -and $shared -match 'towbarWreckerHookMid' -and $shared -match 'towbarWreckerHookHigh') "Wreckers must use immutable low/mid/high hook attachment IDs."
+Assert-True ($shared -match '(?s)registerHookAttachments.*?ModelAttachment\.new.*?baseOffset:y\(\) \+ level \* Wrecker\.HeightStep') "Hook banks must copy each wrecker's own hook geometry and vary only height."
+Assert-True ($shared -match '(?s)resolveNearestTarget.*?MaxAttachDistance.*?trailerfront.*?trailer.*?distanceSquared') "Target selection must server-recompute the nearest front/rear tow point."
+
+Assert-True ($menu -match '(?s)playerObj:getVehicle\(\).*?TowBarMod\.WreckerUI\.addOptionsToMenu.*?return') "The seated driver radial path must run before the existing early return."
+Assert-True ($ui -match 'media/textures/tow_car_icon\.png') "Attach radial action must use the supplied tow-car icon."
+Assert-True ($ui -match 'media/textures/untow_car_icon\.png') "Detach radial action must use the supplied untow-car icon."
+Assert-True ($ui -match 'media/textures/arrow_up\.png' -and $ui -match 'media/textures/arrow_down\.png') "Height controls must use the supplied arrow icons."
+Assert-True ($ui -match 'sendClientCommand\(playerObj, "towbar", "attachWrecker"' -and $ui -match 'sendClientCommand\(playerObj, "towbar", "adjustWreckerHeight"') "Wrecker radial actions must request server-authoritative commands."
+Assert-True ($ui -match 'local AttachDuration = 300' -and $ui -match 'local DetachDuration = 200') "Wrecker attach and detach must take about three and two seconds respectively."
+Assert-True ($ui -match '(?s)requestAttach.*?WreckerTimedAction:new.*?AttachDuration') "Attach must complete through the three-second timed action."
+Assert-True ($ui -match '(?s)requestDetach.*?WreckerTimedAction:new.*?DetachDuration') "Detach must complete through the two-second timed action."
+Assert-True ($timedAction -match 'ISBaseTimedAction:derive\("WreckerTimedAction"\)' -and $timedAction -match 'self\.isValidFunc') "Wrecker timed actions must revalidate while waiting."
+
+Assert-True ($server -match 'function Commands\.attachWrecker') "Missing server-authoritative wrecker attach command."
+Assert-True ($server -match 'function Commands\.detachWrecker') "Missing server-authoritative wrecker detach command."
+Assert-True ($server -match 'function Commands\.adjustWreckerHeight') "Missing server-authoritative hook-height command."
+Assert-True ($server -match '(?s)attachWrecker.*?isDriver\(player\).*?isSupportedWrecker.*?resolveNearestTarget.*?syncPairState\(wrecker, target, hookAttachment, targetAttachment, heightLevel, player\)') "Attach must validate driver, wrecker, geometry, and canonical target before synchronizing a constraint."
+Assert-True ($server -match '(?s)local function syncPairState.*?if isServer\(\) then.*?addPointConstraint\(player, target, hookAttachment, targetAttachment\).*?broadcastWreckerSync') "Dedicated servers must own the logical towing relation while SP uses the client rigid sync path."
+Assert-True ($server -match '(?s)auditWreckerPairs.*?shouldSnapshot.*?wreckerAttachSync') "The server must periodically reconcile active wrecker pairs for joining clients."
+Assert-True ($server -match 'local confirmedWreckerPairs = \{\}') "Wrecker persistence must distinguish restored pairs from live constraint breaks."
+Assert-True ($server -match 'wreckerTowedVehicleSqlId' -and $server -match 'wreckerTowingVehicleSqlId' -and $server -match 'getSqlId') "Wrecker persistence must use stable save IDs in addition to live network IDs."
+Assert-True ($server -match 'Persistence\.savePair\(\s*"wrecker"' -and $server -match 'Persistence\.forEachPair\("wrecker"') "Wrecker persistence must use the server-owned saved-pair registry."
+Assert-True ($server -match '(?s)auditWreckerPairs.*?isLinked\(wrecker, target\).*?wreckerTowedVehicleId.*?setPairState') "Adopting an engine-restored pair must refresh stale live IDs immediately."
+Assert-True ($server -match '(?s)auditWreckerPairs.*?Persistence\.advanceRecoveryState.*?RestoreRetryMs, SustainedBreakMs.*?action == "break".*?detachPair.*?action == "restore".*?syncPairState') "Missing wrecker constraints must use the shared bounded recovery state machine."
+Assert-True ($persistence -match '(?s)function Persistence\.advanceRecoveryState.*?state\.unlinkedSince = state\.unlinkedSince or now.*?now - state\.unlinkedSince >= breakMs.*?return state, "break"' -and $persistence -match '(?s)if not state\.pendingUntil or now >= state\.pendingUntil then.*?state\.pendingUntil = now \+ retryMs.*?return state, "restore"') "Wrecker recovery must debounce restores and require a sustained break before cleanup."
+Assert-True ($server -notmatch '(?s)elseif not target then.*?wreckerTowActive = nil') "Temporarily unloaded targets must not erase saved wrecker state."
+Assert-True ($server -match '(?s)auditWreckerPairs.*?wreckerTowingVehicleId.*?if towingVehicle and not isExpectedPair.*?wreckerDetachSync') "Loaded reciprocal mismatches must receive orphan cleanup."
+Assert-True ($server -notmatch '(?s)wreckerTowingVehicleId.*?if not towingVehicle.*?wreckerTowingVehicleId = nil') "Temporarily unloaded wreckers must not erase saved target state."
+Assert-True ($server -match '(?s)adjustWreckerHeight.*?direction ~= -1 and direction ~= 1.*?nextHeightLevel.*?syncPairState') "Height changes must validate direction, clamp on the server, and broadcast canonical state."
+Assert-True ($server -notmatch 'TowBar\.TowBar|consumeTowBar|giveTowBar|dropTowBarOnGround|inventory:AddItem') "Wrecker commands must not mutate the separate towbar item lifecycle."
+Assert-True ($server -match '(?s)onClientCommand.*?getTimestampMs.*?CommandCooldownMs') "Wrecker commands must be rate-limited at the server boundary."
+
+Assert-True ($sync -match 'notTowingA_Trailer') "Client sync must use the existing fake-trailer path to select vanilla rigid constraints."
+Assert-True ($sync -match '(?s)applyAttachSync.*?breakWreckerPair.*?setScriptSafely\(target, "notTowingA_Trailer"\).*?addPointConstraint.*?setScriptSafely\(target, originalScript\)') "Client sync must rebuild the constraint while the target uses the fake trailer script, then restore it."
+Assert-True ($sync -match 'addPointConstraint\(nil, target, hookAttachment, targetAttachment, true\)') "Wrecker local physics rebuilds must suppress server detach/attach traffic."
+Assert-True ($sync -match '(?s)local appliedLevel = Sync\.appliedLevels\[key\].*?if isPairLinked\(wrecker, target\).*?and appliedLevel == canonicalLevel then.*?return') "Only a locally applied wrecker constraint at the requested height may be reused."
+Assert-True ($sync -match '(?s)local appliedLevel = Sync\.appliedLevels\[key\].*?appliedLevel == canonicalLevel.*?return\s+end.*?breakWreckerPair\(wrecker, target\).*?addPointConstraint') "A native-restored wrecker rope without a locally applied height must be rebuilt through the rigid local constraint path."
+Assert-True ($sync -match '(?s)local function clearAppliedLevelForVehicle.*?Sync\.appliedLevels\[key\] = nil.*?Events\.OnSpawnVehicleEnd\.Add\(clearAppliedLevelForVehicle\)') "Vehicle streaming must invalidate cached local wrecker constraints."
+Assert-True ($sync -match '(?s)if isPairLinked\(wrecker, target\).*?appliedLevel.*?canonicalLevel.*?breakWreckerPair\(wrecker, target\).*?addPointConstraint') "A requested wrecker height change must rebuild the local constraint at the new hook attachment."
+Assert-True ($sync -match '(?s)local function applyFreeRollingState.*?wreckerOriginalMass.*?wreckerOriginalBrakingForce.*?setMass\(200\).*?setBrakingForce\(0\)') "Attached vehicles must be made free-rolling like trailers."
+Assert-True ($sync -match '(?s)local function restoreFreeRollingState.*?setMass.*?setBrakingForce.*?wreckerOriginalMass = nil') "Detach must restore the target vehicle's pre-tow mass and braking state."
+Assert-True ($sync -match '(?s)local function applyDetachSync.*?if not target then return end.*?if wrecker then breakWreckerPair.*?restoreFreeRollingState\(target\)') "Detach sync must restore a reloaded target even when the former wrecker is unavailable."
+Assert-True ($sync -match '(?s)applyDetachSync.*?wreckerTowingVehicleSqlId.*?args\.wreckerSqlId.*?expectedWreckerSqlId ~= commandWreckerSqlId') "Detach sync must validate stable IDs when live IDs changed across restart."
+
+foreach ($name in @("tow_car_icon.png", "untow_car_icon.png", "arrow_up.png", "arrow_down.png")) {
+    $iconPath = Join-Path $repositoryRoot "common/media/textures/$name"
+    Assert-True (Test-Path -LiteralPath $iconPath) "Missing runtime icon: $name"
+    if (Test-Path -LiteralPath $iconPath) {
+        $bytes = [IO.File]::ReadAllBytes($iconPath)
+        Assert-True ($bytes.Length -gt 24) "$name is not a valid PNG payload."
+        if ($bytes.Length -gt 24) {
+            Assert-True ($bytes[0] -eq 0x89 -and $bytes[1] -eq 0x50 -and $bytes[2] -eq 0x4E -and $bytes[3] -eq 0x47) "$name lacks a PNG signature."
+            $width = [Net.IPAddress]::NetworkToHostOrder([BitConverter]::ToInt32($bytes, 16))
+            $height = [Net.IPAddress]::NetworkToHostOrder([BitConverter]::ToInt32($bytes, 20))
+            Assert-True ($width -eq 64 -and $height -eq 64) "$name must be 64x64."
+        }
+    }
+}
+
+$luaFiles = @($sharedPath, $timedActionPath, $uiPath, $syncPath, $serverPath) | Where-Object { Test-Path $_ }
+if ($luaFiles.Count -gt 0) {
+    & npx --yes luaparse --quiet @luaFiles
+    Assert-True ($LASTEXITCODE -eq 0) "One or more wrecker Lua files failed to parse."
+}
+
+$releaseInfo = Get-Content -LiteralPath (Join-Path $releaseRoot "mod.info")
+$rootInfo = Get-Content -LiteralPath (Join-Path $repositoryRoot "mod.info")
+Assert-True ($releaseInfo -contains "incompatible=\STowTruck_B42") "42.20 must mark the competing Tow Truck [B42] implementation incompatible."
+Assert-True ($rootInfo -contains "incompatible=\STowTruck_B42") "Root metadata must mark the competing Tow Truck [B42] implementation incompatible."
+Assert-True (@($releaseInfo | Where-Object { $_ -like "incompatible=*" }).Count -eq 1) "42.20 must contain exactly one incompatibility declaration."
+Assert-True (@($rootInfo | Where-Object { $_ -like "incompatible=*" }).Count -eq 1) "Root metadata must contain exactly one incompatibility declaration."
+
+$readme = Get-Content -LiteralPath (Join-Path $repositoryRoot "README.md") -Raw
+Assert-True ($readme -match '## Supported wrecker mods') "README must publish the supported-wrecker mod list."
+foreach ($workshopId in @("3161951724", "3152529790", "2799152995")) {
+    Assert-True ($readme.Contains($workshopId)) "README supported list must include Workshop ID $workshopId."
+}
+foreach ($modId in @("76chevyKseries", "93chevySuburban", "93chevySuburbanExpanded", "78amgeneralM35A2")) {
+    Assert-True ($readme.Contains($modId)) "README supported list must include Mod ID $modId."
+}
+foreach ($fullName in $supportedWreckers) {
+    Assert-True ($readme.Contains($fullName)) "README supported list must include vehicle $fullName."
+}
+Assert-True ($readme.Contains("3446203945") -and $readme.Contains("STowTruck_B42") -and $readme -match 'incompatible') "README must identify and explain the competing Tow Truck mod incompatibility."
+
+if ($failures.Count -gt 0) {
+    $failures | ForEach-Object { Write-Error $_ }
+    exit 1
+}
+
+Write-Output "PASS: Build 42.20 wrecker compatibility contracts."
@@ -0,0 +1,89 @@
+local failures = 0
+
+local function expect(condition, message)
+    if not condition then
+        failures = failures + 1
+        io.stderr:write("FAIL: " .. message .. "\n")
+    end
+end
+
+Events = { OnGameBoot = { Add = function() end } }
+Vector3f = { new = function() return {} end }
+
+local function point(x, y, z)
+    return {
+        x = function() return x end,
+        y = function() return y end,
+        z = function() return z or 0 end
+    }
+end
+
+local function vehicle(id, fullName, attachments)
+    local linkedTowing
+    local linkedTowedBy
+    local script = {
+        getFullName = function() return fullName end,
+        getName = function() return string.gsub(fullName, "^Base%.", "") end
+    }
+    return {
+        getId = function() return id end,
+        getScript = function() return script end,
+        attachmentExist = function(_, name) return attachments[name] ~= nil end,
+        getAttachmentWorldPos = function(_, name) return attachments[name] end,
+        getVehicleTowing = function() return linkedTowing end,
+        getVehicleTowedBy = function() return linkedTowedBy end,
+        setLinks = function(_, towing, towedBy) linkedTowing, linkedTowedBy = towing, towedBy end
+    }
+end
+
+dofile("42.20/media/lua/shared/TowBar/WreckerUtils.lua")
+
+local supported = {
+    "Base.76chevyC30CCwrecker",
+    "Base.76chevyC30SCwrecker",
+    "Base.76chevyK30CCwrecker",
+    "Base.76chevyK30SCwrecker",
+    "Base.93chevySilveradoK3500wrecker",
+    "Base.93chevySilveradoK3500mechanic",
+    "Base.78amgeneralM62"
+}
+for index, fullName in ipairs(supported) do
+    expect(TowBarMod.Wrecker.isSupportedWrecker(vehicle(index, fullName, { hook = point(0, 0) })), fullName .. " should be supported")
+    expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(index + 100, fullName, {})), fullName .. " without a hook must be rejected")
+end
+expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(10, supported[1], {})), "exact variant without hook must be rejected")
+expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(11, "Base.76chevyK30CC", { hook = point(0, 0) })), "regular pickup must be rejected")
+expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(12, supported[1] .. "Burnt", { hook = point(0, 0) })), "suffixed lookalike must be rejected")
+expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(13, "Base.78amgeneralM35A2", { hook = point(0, 0) })), "ordinary M35A2 must be rejected")
+expect(not TowBarMod.Wrecker.isSupportedWrecker(vehicle(14, "Base.Chevalier_Rhino_TowTruck", { hook = point(0, 0) })), "competing Rhino tow truck must be rejected")
+
+expect(TowBarMod.Wrecker.nextHeightLevel(0, 1) == 1, "height should raise once from bottom")
+expect(TowBarMod.Wrecker.nextHeightLevel(1, 1) == 2, "height should raise twice from bottom")
+expect(TowBarMod.Wrecker.nextHeightLevel(2, 1) == 2, "height must clamp at the second upward step")
+expect(TowBarMod.Wrecker.nextHeightLevel(0, -1) == 0, "height must not move below the initial hook position")
+expect(TowBarMod.Wrecker.nextHeightLevel(2, -1) == 1, "height should lower one step")
+expect(TowBarMod.Wrecker.nextHeightLevel(0, 0) == nil, "invalid height direction must be rejected")
+expect(TowBarMod.Wrecker.getHeightAttachmentId(0) == "towbarWreckerHookLow", "level 0 must use the bottom hook")
+expect(TowBarMod.Wrecker.getHeightAttachmentId(1) == "towbarWreckerHookMid", "level 1 must use the first upward step")
+expect(TowBarMod.Wrecker.getHeightAttachmentId(2) == "towbarWreckerHookHigh", "level 2 must use the second upward step")
+expect(TowBarMod.Wrecker.normalizeHeightLevel(-1) == 0, "old below-bottom state must migrate to bottom")
+
+local wrecker = vehicle(20, supported[1], { hook = point(0, 0, 9) })
+local nearRear = vehicle(21, "Base.CarA", {
+    trailer = point(0.599, 0, -50), trailerfront = point(4, 0, 50)
+})
+local nearFront = vehicle(22, "Base.CarB", {
+    trailer = point(5, 0), trailerfront = point(0.4, 0.1)
+})
+local result = TowBarMod.Wrecker.resolveNearestTarget(wrecker, { nearRear, nearFront })
+expect(result and result.vehicle == nearFront and result.attachment == "trailerfront", "nearest endpoint across all vehicles must win")
+
+result = TowBarMod.Wrecker.resolveNearestTarget(wrecker, { nearRear })
+expect(result and result.attachment == "trailer", "0.599 endpoint must be accepted and world Z ignored")
+local tooFar = vehicle(23, "Base.CarC", { trailer = point(0.601, 0) })
+expect(TowBarMod.Wrecker.resolveNearestTarget(wrecker, { tooFar }) == nil, "0.601 endpoint must be rejected")
+local trailer = vehicle(24, "Base.UtilityTrailer", { trailerfront = point(0.1, 0) })
+expect(TowBarMod.Wrecker.resolveNearestTarget(wrecker, { trailer }) == nil, "trailers must be excluded from wrecker vehicle towing")
+
+if failures > 0 then os.exit(1) end
+print("PASS: wrecker helper behavior")
@@ -0,0 +1,54 @@
+local failures = 0
+
+local function expect(condition, message)
+    if not condition then
+        failures = failures + 1
+        io.stderr:write("FAIL: " .. message .. "\n")
+    end
+end
+
+package.preload["TimedActions/ISBaseTimedAction"] = function() return true end
+ISBaseTimedAction = {}
+function ISBaseTimedAction:derive()
+    local derived = {}
+    setmetatable(derived, { __index = self })
+    return derived
+end
+function ISBaseTimedAction.new(class, character)
+    local action = { character = character }
+    setmetatable(action, { __index = class })
+    return action
+end
+function ISBaseTimedAction.perform(action)
+    action.completed = true
+end
+function ISBaseTimedAction.stop(action)
+    action.stopped = true
+end
+
+dofile("42.20/media/lua/client/TowBar/WreckerTimedAction.lua")
+
+local sent = 0
+local valid = true
+local function validate() return valid end
+local function perform() sent = sent + 1 end
+
+local attach = WreckerTimedAction:new({}, 300, validate, perform, {}, {})
+expect(attach.maxTime == 300, "attach duration must be 300 action units")
+expect(sent == 0, "constructing an action must not send a command")
+attach:perform()
+expect(sent == 1 and attach.completed, "valid attach must send once after its timer completes")
+
+local detach = WreckerTimedAction:new({}, 200, validate, perform, {}, {})
+expect(detach.maxTime == 200, "detach duration must be 200 action units")
+valid = false
+detach:perform()
+expect(sent == 1, "an invalidated timed action must not send its command")
+
+valid = true
+local cancelled = WreckerTimedAction:new({}, 300, validate, perform, {}, {})
+cancelled:stop()
+expect(cancelled.stopped and sent == 1, "cancelling an action must not send its command")
+
+if failures > 0 then os.exit(1) end
+print("PASS: wrecker timed action behavior")