diff --git a/drivers/SmartThings/zigbee-window-treatment/capabilities/statelessWindowShadeLevelStep.yaml b/drivers/SmartThings/zigbee-window-treatment/capabilities/statelessWindowShadeLevelStep.yaml
new file mode 100644
index 0000000000..69ba89c184
--- /dev/null
+++ b/drivers/SmartThings/zigbee-window-treatment/capabilities/statelessWindowShadeLevelStep.yaml
@@ -0,0 +1,16 @@
+id: stse.statelessWindowShadeLevelStep
+version: 1
+status: proposed
+name: stateless window shade level step
+ephemeral: false
+attributes: {}
+commands:
+  stepShadeLevel:
+    name: stepShadeLevel
+    arguments:
+      - name: stepSize
+        optional: false
+        schema:
+          type: integer
+          minimum: -100
+          maximum: 100
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara-roller-shade-rotate.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara-roller-shade-rotate.yml
index c454c4d590..e7f5e8d8af 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara-roller-shade-rotate.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara-roller-shade-rotate.yml
@@ -6,6 +6,8 @@ components:
         version: 1
       - id: windowShadeLevel
         version: 1
+      - id: statelessWindowShadeLevelStep
+        version: 1
       - id: stse.initializedStateWithGuide
         version: 1
       - id: stse.shadeRotateState
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara.yml
index 6c2cc967e7..4dc959ef93 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-aqara.yml
@@ -6,6 +6,8 @@ components:
         version: 1
       - id: windowShadeLevel
         version: 1
+      - id: statelessWindowShadeLevelStep
+        version: 1
       - id: stse.deviceInitialization
         version: 1
       - id: firmwareUpdate
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-battery.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-battery.yml
index be0ae73d76..e9b6178ff8 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-battery.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-battery.yml
@@ -8,6 +8,8 @@ components:
     version: 1
   - id: windowShadeLevel
     version: 1
+  - id: statelessWindowShadeLevelStep
+    version: 1
   - id: battery
     version: 1
   - id: firmwareUpdate
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-no-preset.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-no-preset.yml
index 7a65434c46..67ba3c186d 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-no-preset.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-no-preset.yml
@@ -8,6 +8,8 @@ components:
     version: 1
   - id: windowShadeLevel
     version: 1
+  - id: statelessWindowShadeLevelStep
+    version: 1
   - id: firmwareUpdate
     version: 1
   - id: refresh
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-powerSource.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-powerSource.yml
index 7323ee0218..9dd0afeb48 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-powerSource.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-powerSource.yml
@@ -6,6 +6,8 @@ components:
         version: 1
       - id: windowShadeLevel
         version: 1
+      - id: statelessWindowShadeLevelStep
+        version: 1
       - id: windowShadePreset
         version: 1
       - id: powerSource
@@ -17,4 +19,4 @@ components:
       - id: firmwareUpdate
         version: 1
     categories:
-      - name: Blind
\ No newline at end of file
+      - name: Blind
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile-no-firmware-update.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile-no-firmware-update.yml
index 8e641e6b42..1a1e4bfeda 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile-no-firmware-update.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile-no-firmware-update.yml
@@ -8,7 +8,9 @@ components:
     version: 1
   - id: windowShadeLevel
     version: 1
+  - id: statelessWindowShadeLevelStep
+    version: 1
   - id: refresh
     version: 1
   categories:
-  - name: Blind
\ No newline at end of file
+  - name: Blind
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile.yml
index b10a5ea101..c9fce872c0 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-profile.yml
@@ -8,6 +8,8 @@ components:
     version: 1
   - id: windowShadeLevel
     version: 1
+  - id: statelessWindowShadeLevelStep
+    version: 1
   - id: firmwareUpdate
     version: 1
   - id: refresh
diff --git a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-reverse.yml b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-reverse.yml
index 0eb666a5d2..54b4312210 100644
--- a/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-reverse.yml
+++ b/drivers/SmartThings/zigbee-window-treatment/profiles/window-treatment-reverse.yml
@@ -6,6 +6,8 @@ components:
     version: 1
   - id: windowShadeLevel
     version: 1
+  - id: statelessWindowShadeLevelStep
+    version: 1
   - id: windowShadePreset
     version: 1
   - id: firmwareUpdate
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/aqara/aqara_utils.lua b/drivers/SmartThings/zigbee-window-treatment/src/aqara/aqara_utils.lua
index 9ecfc6a605..bea714e838 100644
--- a/drivers/SmartThings/zigbee-window-treatment/src/aqara/aqara_utils.lua
+++ b/drivers/SmartThings/zigbee-window-treatment/src/aqara/aqara_utils.lua
@@ -31,11 +31,14 @@ local function shade_level_cmd(driver, device, command)
   end
   level = utils.round(level)
 
-  -- update ui to the new level
+  -- Invert percentage: 100-level, so user's 100% means closed, 0% means open
+  local inverted_level = 100 - level
+
+  -- update ui to the new level 
   device:emit_event(capabilities.windowShadeLevel.shadeLevel(level))
 
-  -- send
-  device:send_to_component(command.component, WindowCovering.server.commands.GoToLiftPercentage(device, level))
+  -- send (send inverted value to device)
+  device:send_to_component(command.component, WindowCovering.server.commands.GoToLiftPercentage(device, inverted_level))
 end
 
 local function emit_shade_event_by_state(device, value)
@@ -82,8 +85,11 @@ local function emit_shade_level_event(device, value)
   end
   level = utils.round(level)
 
-  -- update level ui
-  device:emit_event(capabilities.windowShadeLevel.shadeLevel(level))
+  -- Invert percentage: 100-level, invert device-reported value for UI display
+  local inverted_level = 100 - level
+
+  -- update level ui (display inverted value)
+  device:emit_event(capabilities.windowShadeLevel.shadeLevel(inverted_level))
 end
 
 aqara_utils.PRIVATE_CLUSTER_ID = PRIVATE_CLUSTER_ID
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/hanssem/init.lua b/drivers/SmartThings/zigbee-window-treatment/src/hanssem/init.lua
index 41b4eb1cac..f422dd61ca 100644
--- a/drivers/SmartThings/zigbee-window-treatment/src/hanssem/init.lua
+++ b/drivers/SmartThings/zigbee-window-treatment/src/hanssem/init.lua
@@ -25,8 +25,6 @@ local TUYA_CLUSTER = 0xEF00
 local DP_TYPE_VALUE = "\x02"
 local DP_TYPE_ENUM = "\x04"
 
-local SeqNum = 0
-
 -------- Send Command Function for Tuya Zigbee device -------------
 -- ZigbeeMessageTx:
 --    Uint16: 0x0000
@@ -45,6 +43,14 @@ local SeqNum = 0
 --        ReadAttribute:
 --            AttributeId: 0x0000
 
+-- Get next sequence number for Tuya commands (per-device storage to avoid counter conflicts)
+local function get_next_tuya_seq_num(device)
+  local seq = device:get_field("tuya_seq_num") or 0
+  seq = (seq + 1) % 65536
+  device:set_field("tuya_seq_num", seq)
+  return seq
+end
+
 local function SendCommand(device, DpId, Type, Value)
   local addrh = Messages.AddressHeader(
     ZigbeeConstants.HUB.ADDR, 					-- Source Address
@@ -57,8 +63,7 @@ local function SendCommand(device, DpId, Type, Value)
   local zclh = ZigbeeZcl.ZclHeader({cmd = data_types.ZCLCommandId(0x00)})
   zclh.frame_ctrl:set_cluster_specific()	-- sets this frame control field to be cluster specific
   -- Make a payload body
-  SeqNum = (SeqNum + 1) % 65536
-  local strSeqNum = string.pack(">I2", SeqNum)  -- Pack the Sequence number to 2 bytes unsigned integer type with big endian.
+  local strSeqNum = string.pack(">I2", get_next_tuya_seq_num(device))  -- Pack the Sequence number to 2 bytes unsigned integer type with big endian.
   local LenOfValue = string.pack(">I2",string.len(Value))  -- Pack length of Value to 2 bytes unsigned integer type wiht big endian.
   local PayloadBody = generic_body.GenericBody(strSeqNum .. DpId .. Type .. LenOfValue .. Value)
   local MsgBody = ZigbeeZcl.ZclMessageBody({zcl_header = zclh, zcl_body = PayloadBody})
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/brand_configs.lua b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/brand_configs.lua
new file mode 100644
index 0000000000..e9e31ccd5a
--- /dev/null
+++ b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/brand_configs.lua
@@ -0,0 +1,96 @@
+-- Copyright 2026 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+-- Brand-specific configuration for window treatment devices
+-- Supports statelessWindowShadeLevelStep capability
+
+local BRAND_CONFIGS = {
+  -- invert_level = true: Device reports inverted values (0 = open, 100 = closed)
+  -- When sending command: device_target_level = 100 - ui_target_level
+  -- When receiving report: ui_reported_level = 100 - reported_level
+  {
+    name = "aqara",
+    mfr = "LUMI",
+    models = { "lumi.curtain", "lumi.curtain.v1", "lumi.curtain.aq2", "lumi.curtain.agl001", "lumi.curtain.acn002" },
+    invert_level = true,
+  },
+  {
+    name = "somfy",
+    mfr = "Somfy",
+    models = {},  -- Empty models = match any model from this manufacturer
+    invert_level = true,
+  },
+  {
+    name = "vimar",
+    mfr = "VIMAR",
+    models = {},
+    invert_level = true,
+  },
+  {
+    name = "invert-lift-percentage",
+    mfr = "IKEA of Sweden",
+    models = {},
+    invert_level = true,
+  },
+  {
+    name = "invert-lift-percentage",
+    mfr = "Smartwings",
+    models = {},
+    invert_level = true,
+  },
+  {
+    name = "invert-lift-percentage",
+    mfr = "Insta GmbH",
+    models = {},
+    invert_level = true,
+  },
+  {
+    name = "yoolax",
+    mfr = "Yookee",
+    models = { "D10110" },
+    invert_level = true,
+  },
+  {
+    name = "yoolax",
+    mfr = "yooksmart",
+    models = { "D10110" },
+    invert_level = true,
+  },
+  -- use_level_cluster = true: Use Level cluster instead of WindowCovering
+  -- Level cluster uses 0-254 range, converted from percentage: level_value = math.floor(percentage / 100.0 * 254)
+  {
+    name = "feibit",
+    mfr = "Feibit Co.Ltd",
+    models = { "FTB56-ZT218AK1.6", "FTB56-ZT218AK1.8" },
+    use_level_cluster = true,
+  },
+  {
+    name = "axis",
+    mfr = "AXIS",
+    models = {},
+    use_level_cluster = true,
+  },
+  -- Standard devices (no special handling needed)
+  -- Use WindowCovering.GoToLiftPercentage with 0-100 percentage
+  {
+    name = "hanssem",
+    mfr = "",
+    models = { "TS0601" },
+    match_by_model = true,  -- Match by model only, not manufacturer
+    use_tuya_cluster = true,  -- Use Tuya custom cluster 0xEF00
+  },
+  {
+    name = "rooms-beautiful",
+    mfr = "Rooms Beautiful",
+    models = { "C001" },
+  },
+  {
+    name = "screen-innovations",
+    mfr = "",
+    models = { "WM25/L-Z" },
+    match_by_model = true,
+  },
+  -- Note: HOPOsmart and VIVIDSTORM are NOT supported (use custom clusters)
+}
+
+return BRAND_CONFIGS
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/can_handle.lua b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/can_handle.lua
new file mode 100644
index 0000000000..209af9f887
--- /dev/null
+++ b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/can_handle.lua
@@ -0,0 +1,13 @@
+-- Copyright 2026 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+local capabilities = require "st.capabilities"
+
+return function(opts, driver, device)
+  local can_handle = device:supports_capability(capabilities.statelessWindowShadeLevelStep)
+  if can_handle then
+    local subdriver = require("stateless_handler")
+    return true, subdriver
+  end
+  return false
+end
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/init.lua b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/init.lua
new file mode 100644
index 0000000000..ae1cd19bbb
--- /dev/null
+++ b/drivers/SmartThings/zigbee-window-treatment/src/stateless_handler/init.lua
@@ -0,0 +1,156 @@
+-- Copyright 2026 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+local capabilities = require "st.capabilities"
+local clusters = require "st.zigbee.zcl.clusters"
+local utils = require "st.utils"
+local BRAND_CONFIGS = require "stateless_handler.brand_configs"
+local ZigbeeZcl = require "st.zigbee.zcl"
+local Messages = require "st.zigbee.messages"
+local data_types = require "st.zigbee.data_types"
+local ZigbeeConstants = require "st.zigbee.constants"
+local generic_body = require "st.zigbee.generic_body"
+
+-- Tuya cluster constants (for hanssem)
+local TUYA_CLUSTER = 0xEF00
+local DP_TYPE_VALUE = "\x02"
+local DP_ID_SET_POSITION = "\x02"
+
+-- Get next sequence number for Tuya commands (per-device storage to avoid counter conflicts)
+local function get_next_tuya_seq_num(device)
+  local seq = device:get_field("tuya_seq_num") or 0
+  seq = (seq + 1) % 65536
+  device:set_field("tuya_seq_num", seq)
+  return seq
+end
+
+-- Field keys for tracking target level and timeout timer
+local LATEST_TARGET_LEVEL = "__latest_target_level"
+
+-- Get brand configuration for a device
+local function get_brand_config(device)
+  local manufacturer = device:get_manufacturer() or ""
+  local model = device:get_model() or ""
+  
+  for _, config in ipairs(BRAND_CONFIGS) do
+    -- Check if this config matches by model only (match_by_model = true)
+    if config.match_by_model then
+      -- Match model only (case-insensitive)
+      for _, model_pattern in ipairs(config.models) do
+        if string.lower(model) == string.lower(model_pattern) then
+          return config
+        end
+      end
+    else
+      -- Match manufacturer (case-insensitive)
+      if string.lower(manufacturer) == string.lower(config.mfr) then
+        -- If models list is empty, match any model from this manufacturer
+        if #config.models == 0 then
+          return config
+        end
+        -- Check if model matches any in the list (case-insensitive substring match)
+        for _, model_pattern in ipairs(config.models) do
+          if string.find(string.lower(model), string.lower(model_pattern), 1, true) then
+            return config
+          end
+        end
+      end
+    end
+  end
+  return nil -- No matching brand, use default behavior
+end
+
+-- Step shade level handler for statelessWindowShadeLevelStep capability
+local function step_shade_level_handler(driver, device, command)
+  -- Get brand-specific configuration
+  local brand_config = get_brand_config(device)
+  
+  -- Support both args.stepSize (named) and args[1] (array) formats
+  local step = command.args.stepSize or command.args[1]
+
+  if not step or step == 0 then
+    return
+  end
+
+  -- Priority: use target_level if exists, otherwise use latest state
+  local latest_target_level = device:get_field(LATEST_TARGET_LEVEL)
+  local current_level = latest_target_level or
+    device:get_latest_state("main", capabilities.windowShadeLevel.ID, capabilities.windowShadeLevel.shadeLevel.NAME) or 0
+
+  -- Calculate UI target_level (user's expected percentage)
+  local ui_target_level= utils.clamp_value(current_level + step, 0, 100)
+  
+  ui_target_level = utils.round(ui_target_level)
+
+  -- Apply brand-specific inversion if needed
+  local device_target_level = ui_target_level
+  if brand_config and brand_config.invert_level then
+    device_target_level = 100 - ui_target_level
+  end
+
+  -- Set target_level for tracking (store UI value)
+  device:set_field(LATEST_TARGET_LEVEL, ui_target_level)
+
+  -- Send command based on brand configuration
+  if brand_config and brand_config.use_level_cluster then
+    -- Feibit/Axis uses Level cluster
+    local level_value = math.floor(device_target_level / 100.0 * 254)
+    device:send_to_component(command.component, clusters.Level.server.commands.MoveToLevelWithOnOff(device, level_value))
+  elseif brand_config and brand_config.use_tuya_cluster then
+    -- Hanssem uses Tuya custom cluster 0xEF00
+    local strSeqNum = string.pack(">I2", get_next_tuya_seq_num(device))
+    local value = string.pack(">I4", device_target_level)
+    local LenOfValue = string.pack(">I2", string.len(value))
+    local PayloadBody = generic_body.GenericBody(strSeqNum .. DP_ID_SET_POSITION .. DP_TYPE_VALUE .. LenOfValue .. value)
+    local zclh = ZigbeeZcl.ZclHeader({cmd = data_types.ZCLCommandId(0x00)})
+    zclh.frame_ctrl:set_cluster_specific()
+    local addrh = Messages.AddressHeader(
+      ZigbeeConstants.HUB.ADDR,
+      ZigbeeConstants.HUB.ENDPOINT,
+      device:get_short_address(),
+      device:get_endpoint(TUYA_CLUSTER),
+      ZigbeeConstants.HA_PROFILE_ID,
+      TUYA_CLUSTER
+    )
+    local MsgBody = ZigbeeZcl.ZclMessageBody({zcl_header = zclh, zcl_body = PayloadBody})
+    local TxMsg = Messages.ZigbeeMessageTx({address_header = addrh, body = MsgBody})
+    device:send(TxMsg)
+  else
+    -- Standard: use WindowCovering.GoToLiftPercentage
+    device:send_to_component(command.component, clusters.WindowCovering.server.commands.GoToLiftPercentage(device, device_target_level))
+  end
+end
+
+local function shade_level_report_handler(driver, device, value, zb_rx)
+  local latest_target_level = device:get_field(LATEST_TARGET_LEVEL)
+  if latest_target_level ~= nil then
+      -- Device reached target position, clear target marker and timeout timer
+      device:set_field(LATEST_TARGET_LEVEL, nil)
+  end
+end
+
+
+local stateless_handler = {
+  NAME = "Zigbee Window Treatment Stateless Step Handlers",
+  capability_handlers = {
+    [capabilities.statelessWindowShadeLevelStep.ID] = {
+      [capabilities.statelessWindowShadeLevelStep.commands.stepShadeLevel.NAME] = step_shade_level_handler,
+    },
+  },
+  zigbee_handlers = {
+    attr = {
+      [clusters.WindowCovering.ID] = {
+        [clusters.WindowCovering.attributes.CurrentPositionLiftPercentage.ID] = shade_level_report_handler,
+      },
+      [clusters.Level.ID] = {
+        [clusters.Level.attributes.CurrentLevel.ID] = shade_level_report_handler,
+      },
+      [clusters.AnalogOutput.ID] = {
+        [clusters.AnalogOutput.attributes.PresentValue.ID] = shade_level_report_handler,
+      },
+    },
+  },
+  can_handle = require("stateless_handler.can_handle")
+}
+
+return stateless_handler
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/sub_drivers.lua b/drivers/SmartThings/zigbee-window-treatment/src/sub_drivers.lua
index 959c8d8c22..035e076b88 100644
--- a/drivers/SmartThings/zigbee-window-treatment/src/sub_drivers.lua
+++ b/drivers/SmartThings/zigbee-window-treatment/src/sub_drivers.lua
@@ -15,5 +15,7 @@ local sub_drivers = {
    lazy_load_if_possible("screen-innovations"),
    lazy_load_if_possible("VIVIDSTORM"),
    lazy_load_if_possible("HOPOsmart"),
+   -- Generic stateless handlers (must be after vendor-specific drivers)
+   lazy_load_if_possible("stateless_handler"),
 }
 return sub_drivers
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/test/test_zigbee_window_treatment_stateless_handler.lua b/drivers/SmartThings/zigbee-window-treatment/src/test/test_zigbee_window_treatment_stateless_handler.lua
new file mode 100644
index 0000000000..8df45cdc43
--- /dev/null
+++ b/drivers/SmartThings/zigbee-window-treatment/src/test/test_zigbee_window_treatment_stateless_handler.lua
@@ -0,0 +1,398 @@
+-- Copyright 2026 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+-- Direct unit test for stateless_handler module
+-- Tests boundary conditions for stepShadeLevel command
+
+local capabilities = require "st.capabilities"
+local clusters = require "st.zigbee.zcl.clusters"
+local t_utils = require "integration_test.utils"
+local test = require "integration_test"
+local zigbee_test_utils = require "integration_test.zigbee_test_utils"
+
+local WindowCovering = clusters.WindowCovering
+local AnalogOutput = clusters.AnalogOutput
+
+-- Register the statelessWindowShadeLevelStep capability for testing
+test.add_package_capability("statelessWindowShadeLevelStep.yaml")
+
+-- Create mock Aqara curtain device
+-- Aqara has invert_level = true, meaning:
+-- - Device reports: 0 = fully open, 100 = fully closed
+-- - UI shows: 0 = fully closed, 100 = fully open (inverted)
+-- - UI value = 100 - device value
+local aqara_device = test.mock_device.build_test_zigbee_device(
+  {
+    profile = t_utils.get_profile_definition("window-treatment-aqara.yml"),
+    fingerprinted_endpoint_id = 0x01,
+    zigbee_endpoints = {
+      [1] = {
+        id = 1,
+        manufacturer = "LUMI",
+        model = "lumi.curtain",
+        server_clusters = { WindowCovering.ID, AnalogOutput.ID }
+      }
+    }
+  }
+)
+
+zigbee_test_utils.prepare_zigbee_env_info()
+
+local function test_init()
+  test.mock_device.add_test_device(aqara_device)
+end
+
+test.set_test_init_function(test_init)
+
+-- Test 1: Boundary condition - stepSize = 0 should not send command
+-- Tests stateless_handler: stepShadeLevel command with stepSize=0 should not send Zigbee command
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - stepSize 0 does not send command",
+  function()
+    -- Set initial state via device report: device=50% -> UI = 100 - 50 = 50%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 50)
+    })
+    -- Device report triggers windowShadeLevel and windowShade events (handled by zigbee_handlers, not stateless_handler)
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 50 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = 0 (tests stateless_handler)
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 0 } }
+    })
+
+    -- Should NOT send any Zigbee command (stepSize 0 is ignored by stateless_handler)
+    test.wait_for_events()
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 2: Boundary condition - value clamped to 100 (UI)
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - value clamped to 100",
+  function()
+    -- Set initial state: device=10% -> UI = 100 - 10 = 90%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 10)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 90 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = 50 (would exceed 100)
+    -- Expected: clamp(90 + 50, 0, 100) = 100 UI, device = 100 - 100 = 0
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 50 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 0 (clamped and inverted)
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 0)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 3: Boundary condition - value clamped to 0 (UI, negative step)
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - value clamped to 0",
+  function()
+    -- Set initial state: device=90% -> UI = 100 - 90 = 10%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 90)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 10 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = -20 (would go below 0)
+    -- Expected: clamp(10 + (-20), 0, 100) = 0 UI, device = 100 - 0 = 100
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { -20 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 100 (clamped and inverted)
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 100)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 4: Normal step up operation
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - normal step up",
+  function()
+    -- Set initial state: device=70% -> UI = 100 - 70 = 30%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 70)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 30 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = 10
+    -- Expected: 30 + 10 = 40 UI, device = 100 - 40 = 60
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 10 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 60
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 60)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 5: Normal step down operation
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - normal step down",
+  function()
+    -- Set initial state: device=30% -> UI = 100 - 30 = 70%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 30)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 70 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = -20
+    -- Expected: 70 + (-20) = 50 UI, device = 100 - 50 = 50
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { -20 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 50
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 50)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 6: stepSize is nil
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - nil stepSize does not send command",
+  function()
+    -- Reset Aqara device state
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 50)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 50 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with nil stepSize
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = {} }
+    })
+
+    -- Should NOT send any Zigbee command
+    test.wait_for_events()
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 7: Boundary condition - minimum stepSize (stepSize = 1)
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - minimum stepSize 1 works correctly",
+  function()
+    -- Set initial state: device=50% -> UI = 100 - 50 = 50%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 50)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 50 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = 1 (minimum positive step)
+    -- Expected: 50 + 1 = 51 UI, device = 100 - 51 = 49
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 1 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 49
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 49)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 8: Boundary condition - minimum negative stepSize (stepSize = -1)
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - minimum negative stepSize -1 works correctly",
+  function()
+    -- Set initial state: device=50% -> UI = 100 - 50 = 50%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 50)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 50 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Send stepShadeLevel command with stepSize = -1 (minimum negative step)
+    -- Expected: 50 + (-1) = 49 UI, device = 100 - 49 = 51
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { -1 } }
+    })
+
+    -- Should send GoToLiftPercentage with value 51
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 51)
+    })
+  end,
+  { min_api_version = 17 }
+)
+
+-- Test 9: Continuous step operation - multiple consecutive steps with mixed directions
+test.register_coroutine_test(
+  "stateless_handler: stepShadeLevel - continuous step operations with mixed directions",
+  function()
+    -- Set initial state: device=50% -> UI = 100 - 50 = 50%
+    test.socket.zigbee:__queue_receive({
+      aqara_device.id,
+      WindowCovering.attributes.CurrentPositionLiftPercentage:build_test_attr_report(aqara_device, 50)
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShadeLevel", component_id = "main", attribute_id = "shadeLevel", state = { value = 50 } }
+    })
+    test.socket.capability:__expect_send({
+      aqara_device.id,
+      { capability_id = "windowShade", component_id = "main", attribute_id = "windowShade", state = { value = "partially open" } }
+    })
+    test.wait_for_events()
+
+    -- Step 1: stepSize = 10 (up), Expected: 50 + 10 = 60 UI, device = 100 - 60 = 40
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 10 } }
+    })
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 40)
+    })
+    test.wait_for_events()
+
+    -- Step 2: stepSize = 10 (up), Expected: 60 + 10 = 70 UI, device = 100 - 70 = 30
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 10 } }
+    })
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 30)
+    })
+    test.wait_for_events()
+
+    -- Step 3: stepSize = -20 (down), Expected: 70 + (-20) = 50 UI, device = 100 - 50 = 50
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { -20 } }
+    })
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 50)
+    })
+    test.wait_for_events()
+
+    -- Step 4: stepSize = 15 (up), Expected: 50 + 15 = 65 UI, device = 100 - 65 = 35
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { 15 } }
+    })
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 35)
+    })
+    test.wait_for_events()
+
+    -- Step 5: stepSize = -5 (down), Expected: 65 + (-5) = 60 UI, device = 100 - 60 = 40
+    test.socket.capability:__queue_receive({
+      aqara_device.id,
+      { capability = "statelessWindowShadeLevelStep", component = "main", command = "stepShadeLevel", args = { -5 } }
+    })
+    test.socket.zigbee:__expect_send({
+      aqara_device.id,
+      WindowCovering.server.commands.GoToLiftPercentage(aqara_device, 40)
+    })
+    test.wait_for_events()
+  end,
+  { min_api_version = 17 }
+)
+
+test.run_registered_tests()
diff --git a/drivers/SmartThings/zigbee-window-treatment/src/tuya_utils/init.lua b/drivers/SmartThings/zigbee-window-treatment/src/tuya_utils/init.lua
new file mode 100644
index 0000000000..e69de29bb2