Index: firmware/App/Modes/ModePreTreat.c
===================================================================
diff -u -rfff7eb3560421130e0cd4788f84bce0a8ee7ff44 -rbbd48b033ef7307a30815e490eb28825c7afcc2b
--- firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision fff7eb3560421130e0cd4788f84bce0a8ee7ff44)
+++ firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision bbd48b033ef7307a30815e490eb28825c7afcc2b)
@@ -8,24 +8,28 @@
 * @file    ModePreTreat.c
 *
 * @author  (last)      Vijay Pamula
-* @date    (last)      12-Jun-2026
+* @date    (last)      14-Jul-2026
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  25-Sep-2025
 *
 ***************************************************************************/
 
+#include "AirPump.h"
+#include "AirTrap.h"
 #include "BloodFlow.h"
 #include "Buttons.h"
 #include "DDInterface.h"
 #include "HemoDiaFiltration.h"
 #include "ModePreTreat.h"
 #include "OperationModes.h"
 #include "StatePreTxRecirculate.h"
+#include "SyringePump.h"
 #include "Timers.h"
 #include "TubeSetInstall.h"
 #include "TxParams.h"
 #include "Valves.h"
+#include "Valve3Way.h"
 
 /**
  *  @addtogroup TDPreTreatmentMode
@@ -40,15 +44,13 @@
 
 // ********** private function prototypes **********
 
-static TD_PRE_TREATMENT_MODE_STATE_T handleWaterSampleState( void );        ///< Handle Water Sample state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestConsumableState( void ); ///< Handle Self Test Consumable state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestNoCartState( void );     ///< Handle Self Test No Cart state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleInstallState( void );            ///< Handle Install state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestDryState( void );        ///< Handle Self Test Dry state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handlePrimeState( void );              ///< Handle Prime state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleRecirculateState( void );        ///< Handle Recirculate state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handleRxState( void );                 ///< Handle Confirm Rx state during Pre-Treatment
-static TD_PRE_TREATMENT_MODE_STATE_T handlePatientConnectionState( void );  ///< Handle Patient Connection state during Pre-Treatment
+static void setPreTreatStateTransition( void );                                 ///< Configure actuators and variables for Pre-Treatment state transitions.
+static TD_PRE_TREATMENT_MODE_STATE_T handleInstallState( void );                ///< Handle Install state during Pre-Treatment
+static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestDryState( void );            ///< Handle Self Test Dry state during Pre-Treatment
+static TD_PRE_TREATMENT_MODE_STATE_T handlePrimeState( void );                  ///< Handle Prime state during Pre-Treatment
+static TD_PRE_TREATMENT_MODE_STATE_T handleRecirculateState( void );            ///< Handle Recirculate state during Pre-Treatment
+static TD_PRE_TREATMENT_MODE_STATE_T handleRxState( void );                     ///< Handle Confirm Rx state during Pre-Treatment
+static TD_PRE_TREATMENT_MODE_STATE_T handlePatientConnectionState( void );      ///< Handle Patient Connection state during Pre-Treatment
 
 /*********************************************************************//**
 * @brief
@@ -103,6 +105,7 @@
 U32 execPreTreatmentMode( void )
 {
     BOOL stop = isStopButtonPressed();
+    TD_PRE_TREATMENT_MODE_STATE_T prevPreTreatmentState = currentPreTreatmentState;
 
     if ( TRUE == stop )
     {
@@ -112,18 +115,6 @@
     // Execute mode state machine
     switch ( currentPreTreatmentState )
     {
-        case TD_PRE_TREATMENT_WATER_SAMPLE_STATE:
-            // currentPreTreatmentState = handleWaterSampleState();
-            break;
-
-        case TD_PRE_TREATMENT_SELF_TEST_CONSUMABLE_STATE:
-            // currentPreTreatmentState = handleSelfTestConsumableState();
-            break;
-
-        case TD_PRE_TREATMENT_SELF_TEST_NO_CART_STATE:
-            // currentPreTreatmentState = handleSelfTestNoCartState();
-            break;
-
         case TD_PRE_TREATMENT_TUBING_SET_INSTALL_STATE:
             currentPreTreatmentState = handleInstallState();
             break;
@@ -154,61 +145,60 @@
             break;
     }
 
+    if ( prevPreTreatmentState != currentPreTreatmentState )
+    {
+        setPreTreatStateTransition();
+    }
+
     return (U32)currentPreTreatmentState;
 }
 
 /*********************************************************************//**
- * @brief
- * The handleWaterSampleState function executes the Water Sample state of
- * pre-treatment mode.
- * @details \b Inputs: TODO fill up if any
- * @details \b Outputs: TODO fill up if any
- * @return next Pre-Treatment mode state.
- *************************************************************************/
-static TD_PRE_TREATMENT_MODE_STATE_T handleWaterSampleState( void )
+* @brief
+* The setPreTreatStateTransition function sets the actuators and variables
+* for the state transition in Pre-Treatment mode.
+* @details \b Inputs: currentPreTreatmentState
+* @details \b Outputs: Actuate valves, pumps as desired
+* @return none
+**************************************************************************/
+static void setPreTreatStateTransition( void )
 {
-    TD_PRE_TREATMENT_MODE_STATE_T state = TD_PRE_TREATMENT_WATER_SAMPLE_STATE;
+    switch ( currentPreTreatmentState )
+    {
+        case TD_PRE_TREATMENT_TUBING_SET_INSTALL_STATE:
+            // H4 and H5 are controlled by the Tube Set Install Service.
+            setValvePosition( H1_VALV, VALVE_POSITION_A_INSERT_EJECT );
+            setValvePosition( H19_VALV, VALVE_POSITION_A_INSERT_EJECT );
+            setAirPumpState( AIR_PUMP_STATE_OFF, AIR_PUMP_MOTOR_OFF );
+            set3WayValveState( H13_VALV, VALVE_3WAY_COMMON_TO_CLOSED_STATE );
+            set3WayValveState( H20_VALV, VALVE_3WAY_COMMON_TO_CLOSED_STATE );
+            stopSyringePump();
+            break;
 
-    // TODO: Transition to Self test consumable state on completion when implemented
-    // state = TD_PRE_TREATMENT_SELF_TEST_CONSUMABLE_STATE;
+        case TD_PRE_TREATMENT_SELF_TEST_DRY_STATE:
+            // TODO: actuator configuration
+            break;
 
-    return state;
-}
+        case TD_PRE_TREATMENT_PRIME_STATE:
+            // TODO: actuator configuration
+            break;
 
-/*********************************************************************//**
- * @brief
- * The handleSelfTestConsumableState function executes the Self Test
- * Consumable state of pre-treatment mode.
- * @details \b Inputs: TODO fill up if any
- * @details \b Outputs: TODO fill up if any
- * @return next Pre-Treatment mode state.
- *************************************************************************/
-static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestConsumableState( void )
-{
-    TD_PRE_TREATMENT_MODE_STATE_T state = TD_PRE_TREATMENT_SELF_TEST_CONSUMABLE_STATE;
+        case TD_PRE_TREATMENT_CONFIRM_RX_STATE:
+            // No action required.
+            break;
 
-    // TODO: Transition to Self test no cart state on completion when implemented
-    // state = TD_PRE_TREATMENT_SELF_TEST_NO_CART_STATE;
+        case TD_PRE_TREATMENT_RECIRCULATE_STATE:
+            // No action required.
+            break;
 
-    return state;
-}
+        case TD_PRE_TREATMENT_PATIENT_CONNECTION_STATE:
+            // TODO: actuator configuration
+            break;
 
-/*********************************************************************//**
- * @brief
- * The handleSelfTestNoCartState function executes the Self Test No Cart
- * state of pre-treatment mode.
- * @details \b Inputs: TODO fill up if any
- * @details \b Outputs: TODO fill up if any
- * @return next Pre-Treatment mode state.
- *************************************************************************/
-static TD_PRE_TREATMENT_MODE_STATE_T handleSelfTestNoCartState( void )
-{
-    TD_PRE_TREATMENT_MODE_STATE_T state = TD_PRE_TREATMENT_SELF_TEST_NO_CART_STATE;
-
-    // TODO: Transition to Tubing set install state on completion when implemented
-    // state = TD_PRE_TREATMENT_TUBING_SET_INSTALL_STATE;
-
-    return state;
+        default:
+            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_TD_SOFTWARE_FAULT, SW_FAULT_ID_MODE_PRE_TREATMENT_INVALID_STATE, (U32)currentPreTreatmentState );
+            break;
+    }
 }
 
 /*********************************************************************//**