diff --git a/inventoryManager.lua b/inventoryManager.lua
index c5c7509..668b4de 100644
--- a/inventoryManager.lua
+++ b/inventoryManager.lua
@@ -2835,6 +2835,12 @@ local function main()
             while true do
                 local event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
                 if channel == ORDER_CHANNEL and type(message) == "table" then
+                    -- Idempotency: skip duplicate commands
+                    if isCommandDuplicate(message.commandId) then
+                        log.debug("NET", "Duplicate command skipped: %s", tostring(message.commandId))
+                    else
+                    recordCommandId(message.commandId)
+                    cleanupCommandIds()
                     local handlerOk, handlerErr = pcall(function()
                     if message.type == "order" and message.itemName and message.amount then
                         log.info("NET", "Order: %s x%d", message.itemName, message.amount)
@@ -2848,10 +2854,11 @@ local function main()
                         end
                         pcall(function()
                             networkModem.transmit(replyChannel, ORDER_CHANNEL, {
-                                type    = "order_result",
-                                success = success,
-                                message = statusMessage,
-                                color   = statusColor,
+                                type      = "order_result",
+                                commandId = message.commandId,
+                                success   = success,
+                                message   = statusMessage,
+                                color     = statusColor,
                             })
                         end)
                         pcall(broadcastState)
@@ -2941,9 +2948,10 @@ local function main()
                         end
                         pcall(function()
                             networkModem.transmit(replyChannel, ORDER_CHANNEL, {
-                                type    = "craft_result",
-                                success = ok,
-                                error   = err,
+                                type      = "craft_result",
+                                commandId = message.commandId,
+                                success   = ok,
+                                error     = err,
                             })
                         end)
                         smelterNeedsRedraw = true
@@ -2954,6 +2962,7 @@ local function main()
                     if not handlerOk then
                         log.error("NET", "Handler error: %s", tostring(handlerErr))
                     end
+                    end -- end idempotency else
                 end
             end
         end