Fix plan: use atomically dupTChan, not nonexistent dupTChanIO

docs/superpowers/plans/2026-08-20-concurrent-runtime.md

@@ -61,7 +61,7 @@ module BusSpec (spec) where
 
 import Control.Concurrent.STM
   ( atomically
-  , dupTChanIO
+  , dupTChan
   , readTChan
   , writeTChan
   )
@@ -74,8 +74,8 @@ spec :: Spec
 spec = describe "Bus" $ do
   it "broadcasts inbound messages to every dup'd channel in order" $ do
     bus <- newBus 0
-    p1 <- dupTChanIO (busInbound bus)
-    p2 <- dupTChanIO (busInbound bus)
+    p1 <- atomically (dupTChan (busInbound bus))
+    p2 <- atomically (dupTChan (busInbound bus))
     atomically $ writeTChan (busInbound bus) (Number 1)
     atomically $ writeTChan (busInbound bus) (Number 2)
     r1 <- atomically $ (,) <$> readTChan p1 <*> readTChan p1
@@ -165,7 +165,7 @@ import HomeAssistant.Controller (HASSEff (..), Service)
 import Network.WebSockets (Connection)
 
 -- | Shared runtime state: inbound is a broadcast channel (controllers
--- read from 'dupTChanIO' copies), outbound queues service calls for the
+-- read from 'dupTChan' copies), outbound queues service calls for the
 -- writer, conn holds the current websocket (Nothing before first connect).
 data Bus = Bus
   { busInbound  :: TChan Value
@@ -492,7 +492,7 @@ module HomeAssistant.Runtime
 
 import AFRP (Event (..), Mealy (..))
 import Control.Concurrent.Async (mapConcurrently_)
-import Control.Concurrent.STM (atomically, dupTChanIO, readTChan)
+import Control.Concurrent.STM (atomically, dupTChan, readTChan)
 import Data.Aeson (Value)
 import qualified Data.Text as T
 import Data.Time (getCurrentTime)
@@ -518,7 +518,7 @@ controllers = [Controller "light" lightController]
 -- initial state; messages broadcast during the restart window are lost.
 runController :: Bus -> Controller -> IO Void
 runController bus (Controller _name machine) = do
-  inbound <- dupTChanIO (busInbound bus)
+  inbound <- atomically (dupTChan (busInbound bus))
   go inbound machine
   where
     go inbound f = do