diff --git a/sunnypilot/selfdrive/controls/lib/dec/constants.py b/sunnypilot/selfdrive/controls/lib/dec/constants.py
index 4586afbc9f..765bb23757 100644
--- a/sunnypilot/selfdrive/controls/lib/dec/constants.py
+++ b/sunnypilot/selfdrive/controls/lib/dec/constants.py
@@ -1,17 +1,46 @@
+from openpilot.common.realtime import DT_MDL
+
+
 class WMACConstants:
-  # Lead detection parameters
-  LEAD_WINDOW_SIZE = 6  # Stable detection window
-  LEAD_PROB = 0.45  # Balanced threshold for lead detection
+  TRAJECTORY_SIZE = 33
+  PARAM_READ_FRAMES = max(1, int(round(1.0 / DT_MDL)))
 
-  # Slow down detection parameters
-  SLOW_DOWN_WINDOW_SIZE = 5  # Responsive but stable
-  SLOW_DOWN_PROB = 0.3  # Balanced threshold for slow down scenarios
+  EMERGENCY_HOLD_FRAMES = max(1, int(round(0.75 / DT_MDL)))
+  MIN_MODE_DURATION = {'acc': max(1, int(round(0.6 / DT_MDL))), 'blended': max(1, int(round(0.5 / DT_MDL)))}
+  ENTER_BLENDED_FRAMES = max(1, int(round(0.4 / DT_MDL)))
+  EXIT_BLENDED_FRAMES = max(1, int(round(0.35 / DT_MDL)))
+  STANDSTILL_FRAMES = max(1, int(round(0.2 / DT_MDL)))
 
-  # Optimized slow down distance curve - smooth and progressive
+  LEAD_PROB = 0.45
+  LEAD_EXIT_PROB = 0.25
+  LEAD_RISE_RATE = 1.0
+  LEAD_FALL_RATE = 0.35
+  RADAR_LEAD_ACC_PROB = 0.5
+  RADAR_LEAD_ACC_EXIT_PROB = 0.4
+  RADAR_LEAD_ACC_RISE_RATE = 1.0
+  RADAR_LEAD_ACC_FALL_RATE = 0.25
+  RADAR_LEAD_ACC_MAX_DREL = 80.0
+  RADAR_LEAD_ACC_MAX_TTC = 6.0
+  RADAR_LEAD_ACC_MIN_CLOSING_SPEED = -0.5
+
+  SLOW_DOWN_PROB = 0.5
+  SLOW_DOWN_EXIT_PROB = 0.4
+  SLOW_DOWN_RISE_RATE = 0.65
+  SLOW_DOWN_FALL_RATE = 0.15
   SLOW_DOWN_BP = [0., 10., 20., 30., 40., 50., 55., 60.]
   SLOW_DOWN_DIST = [32., 46., 64., 86., 108., 130., 145., 165.]
+  URGENT_SLOW_DOWN_PROB = 0.85
 
-  # Slowness detection parameters
-  SLOWNESS_WINDOW_SIZE = 10  # Stable slowness detection
-  SLOWNESS_PROB = 0.55  # Clear threshold for slowness
-  SLOWNESS_CRUISE_OFFSET = 1.025  # Conservative cruise speed offset
+  MODEL_DECEL_START = -0.5
+  MODEL_DECEL_RANGE = 2.0
+  ENDPOINT_URGENCY_GAIN = 1.3
+  CRITICAL_ENDPOINT_FACTOR = 0.3
+  CRITICAL_URGENCY_GAIN = 1.5
+  SPEED_URGENCY_MIN = 25.0
+  SPEED_URGENCY_RANGE = 80.0
+
+  SLOWNESS_PROB = 0.55
+  SLOWNESS_EXIT_PROB = 0.45
+  SLOWNESS_RISE_RATE = 0.35
+  SLOWNESS_FALL_RATE = 0.5
+  SLOWNESS_CRUISE_OFFSET = 1.025
diff --git a/sunnypilot/selfdrive/controls/lib/dec/dec.py b/sunnypilot/selfdrive/controls/lib/dec/dec.py
index 46cad1b048..a10a8fc916 100644
--- a/sunnypilot/selfdrive/controls/lib/dec/dec.py
+++ b/sunnypilot/selfdrive/controls/lib/dec/dec.py
@@ -6,129 +6,116 @@ See the LICENSE.md file in the root directory for more details.
 """
 # Version = 2025-6-30
 
-from cereal import messaging
-from opendbc.car import structs
-from numpy import interp
-from openpilot.common.params import Params
-from openpilot.common.realtime import DT_MDL
-from openpilot.sunnypilot.selfdrive.controls.lib.dec.constants import WMACConstants
 from typing import Literal
 
-# d-e2e, from modeldata.h
-TRAJECTORY_SIZE = 33
-SET_MODE_TIMEOUT = 15
+from cereal import messaging
+from numpy import interp
+from opendbc.car import structs
+from openpilot.common.params import Params
+from openpilot.sunnypilot.selfdrive.controls.lib.dec.constants import WMACConstants
 
-# Define the valid mode types
 ModeType = Literal['acc', 'blended']
 
 
-class SmoothKalmanFilter:
-  """Enhanced Kalman filter with smoothing for stable decision making."""
+def clip01(value: float) -> float:
+  return max(0.0, min(1.0, float(value)))
 
-  def __init__(self, initial_value=0, measurement_noise=0.1, process_noise=0.01,
-               alpha=1.0, smoothing_factor=0.85):
-    self.x = initial_value
-    self.P = 1.0
-    self.R = measurement_noise
-    self.Q = process_noise
-    self.alpha = alpha
-    self.smoothing_factor = smoothing_factor
-    self.initialized = False
-    self.history = []
-    self.max_history = 10
-    self.confidence = 0.0
 
-  def add_data(self, measurement):
-    if len(self.history) >= self.max_history:
-      self.history.pop(0)
-    self.history.append(measurement)
+class SmoothedSignal:
+  def __init__(self, rise_rate: float, fall_rate: float, initial_value: float = 0.0):
+    self.rise_rate = clip01(rise_rate)
+    self.fall_rate = clip01(fall_rate)
+    self.value = clip01(initial_value)
 
-    if not self.initialized:
-      self.x = measurement
-      self.initialized = True
-      self.confidence = 0.1
-      return
+  def update(self, measurement: float) -> float:
+    measurement = clip01(measurement)
+    rate = self.rise_rate if measurement > self.value else self.fall_rate
+    self.value += (measurement - self.value) * rate
+    return self.value
 
-    self.P = self.alpha * self.P + self.Q
+  def reset(self, value: float = 0.0) -> None:
+    self.value = clip01(value)
 
-    K = self.P / (self.P + self.R)
-    effective_K = K * (1.0 - self.smoothing_factor) + self.smoothing_factor * 0.1
 
-    innovation = measurement - self.x
-    self.x = self.x + effective_K * innovation
-    self.P = (1 - effective_K) * self.P
+class HysteresisSignal:
+  def __init__(self, enter_threshold: float, exit_threshold: float, rise_rate: float, fall_rate: float):
+    self.enter_threshold = clip01(enter_threshold)
+    self.exit_threshold = clip01(exit_threshold)
+    self.filter = SmoothedSignal(rise_rate, fall_rate)
+    self.active = False
 
-    if abs(innovation) < 0.1:
-      self.confidence = min(1.0, self.confidence + 0.05)
-    else:
-      self.confidence = max(0.1, self.confidence - 0.02)
+  def update(self, measurement: float) -> bool:
+    value = self.filter.update(measurement)
+    threshold = self.exit_threshold if self.active else self.enter_threshold
+    self.active = value > threshold
+    return self.active
 
-  def get_value(self):
-    return self.x if self.initialized else None
+  def reset(self) -> None:
+    self.filter.reset()
+    self.active = False
 
-  def get_confidence(self):
-    return self.confidence
-
-  def reset_data(self):
-    self.initialized = False
-    self.history = []
-    self.confidence = 0.0
+  @property
+  def value(self) -> float:
+    return self.filter.value
 
 
 class ModeTransitionManager:
-  """Manages smooth transitions between driving modes with hysteresis."""
-
   def __init__(self):
     self.current_mode: ModeType = 'acc'
-    self.mode_confidence = {'acc': 1.0, 'blended': 0.0}
-    self.transition_timeout = 0
-    self.min_mode_duration = 10
     self.mode_duration = 0
-    self.emergency_override = False
+    self._pending_mode: ModeType = 'acc'
+    self._pending_count = 0
+    self._blended_hold_frames = 0
 
-  def request_mode(self, mode: ModeType, confidence: float = 1.0, emergency: bool = False):
-    # Emergency override for critical situations (stops, collisions)
-    if emergency:
-      self.emergency_override = True
-      self.current_mode = mode
-      self.transition_timeout = SET_MODE_TIMEOUT
-      self.mode_duration = 0
+  def request_mode(self, mode: ModeType, immediate: bool = False, hold_frames: int = 0, cancel_hold: bool = False) -> None:
+    if immediate:
+      self._blended_hold_frames = max(self._blended_hold_frames, hold_frames)
+      self._pending_mode = mode
+      self._pending_count = 0
+      self._switch_mode(mode)
       return
 
-    self.mode_confidence[mode] = min(1.0, self.mode_confidence[mode] + 0.1 * confidence)
-    for m in self.mode_confidence:
-      if m != mode:
-        self.mode_confidence[m] = max(0.0, self.mode_confidence[m] - 0.05)
+    if cancel_hold and mode == 'acc':
+      self._blended_hold_frames = 0
 
-    # Require minimum duration in current mode (unless emergency)
-    if self.mode_duration < self.min_mode_duration and not self.emergency_override:
+    if self._blended_hold_frames > 0:
+      mode = 'blended'
+
+    if mode == self.current_mode:
+      self._pending_mode = mode
+      self._pending_count = 0
       return
 
-    # Hysteresis: higher threshold for mode changes
-    confidence_threshold = 0.6 if mode != self.current_mode else 0.3  # Lower threshold for faster response
+    if mode != self._pending_mode:
+      self._pending_mode = mode
+      self._pending_count = 1
+    else:
+      self._pending_count += 1
 
-    if self.mode_confidence[mode] > confidence_threshold:
-      if mode != self.current_mode and self.transition_timeout == 0:
-        self.transition_timeout = SET_MODE_TIMEOUT
-        self.current_mode = mode
-        self.mode_duration = 0
+    if self.mode_duration < WMACConstants.MIN_MODE_DURATION[self.current_mode]:
+      return
 
-  def update(self):
-    if self.transition_timeout > 0:
-      self.transition_timeout -= 1
+    required_count = WMACConstants.ENTER_BLENDED_FRAMES if mode == 'blended' else WMACConstants.EXIT_BLENDED_FRAMES
+    if self._pending_count >= required_count:
+      self._switch_mode(mode)
+
+  def update(self) -> None:
+    if self._blended_hold_frames > 0:
+      self._blended_hold_frames -= 1
     self.mode_duration += 1
 
-    # Reset emergency override after some time
-    if self.emergency_override and self.mode_duration > 20:
-      self.emergency_override = False
-
-    # Gradual confidence decay
-    for mode in self.mode_confidence:
-      self.mode_confidence[mode] *= 0.98
-
   def get_mode(self) -> ModeType:
     return self.current_mode
 
+  def _switch_mode(self, mode: ModeType) -> None:
+    if mode == self.current_mode:
+      return
+
+    self.current_mode = mode
+    self.mode_duration = 0
+    self._pending_mode = mode
+    self._pending_count = 0
+
 
 class DynamicExperimentalController:
   def __init__(self, CP: structs.CarParams, mpc, params=None):
@@ -142,35 +129,33 @@ class DynamicExperimentalController:
 
     self._mode_manager = ModeTransitionManager()
 
-    # Smooth filters for stable decision making with faster response for critical scenarios
-    self._lead_filter = SmoothKalmanFilter(
-      measurement_noise=0.15,
-      process_noise=0.05,
-      alpha=1.02,
-      smoothing_factor=0.8
+    self._lead_tracker = HysteresisSignal(
+      enter_threshold=WMACConstants.LEAD_PROB,
+      exit_threshold=WMACConstants.LEAD_EXIT_PROB,
+      rise_rate=WMACConstants.LEAD_RISE_RATE,
+      fall_rate=WMACConstants.LEAD_FALL_RATE,
+    )
+    self._radar_acc_lead_tracker = HysteresisSignal(
+      enter_threshold=WMACConstants.RADAR_LEAD_ACC_PROB,
+      exit_threshold=WMACConstants.RADAR_LEAD_ACC_EXIT_PROB,
+      rise_rate=WMACConstants.RADAR_LEAD_ACC_RISE_RATE,
+      fall_rate=WMACConstants.RADAR_LEAD_ACC_FALL_RATE,
+    )
+    self._slow_down_tracker = HysteresisSignal(
+      enter_threshold=WMACConstants.SLOW_DOWN_PROB,
+      exit_threshold=WMACConstants.SLOW_DOWN_EXIT_PROB,
+      rise_rate=WMACConstants.SLOW_DOWN_RISE_RATE,
+      fall_rate=WMACConstants.SLOW_DOWN_FALL_RATE,
+    )
+    self._slowness_tracker = HysteresisSignal(
+      enter_threshold=WMACConstants.SLOWNESS_PROB,
+      exit_threshold=WMACConstants.SLOWNESS_EXIT_PROB,
+      rise_rate=WMACConstants.SLOWNESS_RISE_RATE,
+      fall_rate=WMACConstants.SLOWNESS_FALL_RATE,
     )
 
-    self._slow_down_filter = SmoothKalmanFilter(
-      measurement_noise=0.1,
-      process_noise=0.1,
-      alpha=1.05,
-      smoothing_factor=0.7
-    )
-
-    self._slowness_filter = SmoothKalmanFilter(
-      measurement_noise=0.1,
-      process_noise=0.06,
-      alpha=1.015,
-      smoothing_factor=0.92
-    )
-
-    self._mpc_fcw_filter = SmoothKalmanFilter(
-      measurement_noise=0.2,
-      process_noise=0.1,
-      alpha=1.1,
-      smoothing_factor=0.5
-    )
     self._has_lead_filtered = False
+    self._has_radar_acc_lead = False
     self._has_slow_down = False
     self._has_slowness = False
     self._has_mpc_fcw = False
@@ -179,13 +164,14 @@ class DynamicExperimentalController:
     self._has_standstill = False
     self._mpc_fcw_crash_cnt = 0
     self._standstill_count = 0
-    # debug
+
     self._endpoint_x = float('inf')
     self._expected_distance = 0.0
     self._trajectory_valid = False
+    self._raw_urgency = 0.0
 
   def _read_params(self) -> None:
-    if self._frame % int(1. / DT_MDL) == 0:
+    if self._frame % WMACConstants.PARAM_READ_FRAMES == 0:
       self._enabled = self._params.get_bool("DynamicExperimentalControl")
 
   def mode(self) -> str:
@@ -198,7 +184,6 @@ class DynamicExperimentalController:
     return self._active
 
   def set_mpc_fcw_crash_cnt(self) -> None:
-    """Set MPC FCW crash count"""
     self._mpc_fcw_crash_cnt = self._mpc.crash_cnt
 
   def _update_calculations(self, sm: messaging.SubMaster) -> None:
@@ -210,179 +195,109 @@ class DynamicExperimentalController:
     self._v_cruise_kph = car_state.vCruise
     self._has_standstill = car_state.standstill
 
-    # standstill detection
     if self._has_standstill:
-      self._standstill_count = min(20, self._standstill_count + 1)
+      self._standstill_count = min(WMACConstants.STANDSTILL_FRAMES * 3, self._standstill_count + 1)
     else:
       self._standstill_count = max(0, self._standstill_count - 1)
 
-    # Lead detection
-    self._lead_filter.add_data(float(lead_one.status))
-    lead_value = self._lead_filter.get_value() or 0.0
-    self._has_lead_filtered = lead_value > WMACConstants.LEAD_PROB
-
-    # MPC FCW detection
-    fcw_filtered_value = self._mpc_fcw_filter.get_value() or 0.0
-    self._mpc_fcw_filter.add_data(float(self._mpc_fcw_crash_cnt > 0))
-    self._has_mpc_fcw = fcw_filtered_value > 0.5
-
-    # Slow down detection
+    self._has_lead_filtered = self._lead_tracker.update(float(lead_one.status))
+    self._has_radar_acc_lead = self._radar_acc_lead_tracker.update(self._radar_acc_lead_score(lead_one))
+    self._has_mpc_fcw = self._mpc_fcw_crash_cnt > 0
     self._calculate_slow_down(md)
 
-    # Slowness detection
-    if not (self._standstill_count > 5) and not self._has_slow_down:
+    if self._standstill_count > WMACConstants.STANDSTILL_FRAMES or self._has_slow_down:
+      self._slowness_tracker.reset()
+      self._has_slowness = False
+    else:
       current_slowness = float(self._v_ego_kph <= (self._v_cruise_kph * WMACConstants.SLOWNESS_CRUISE_OFFSET))
-      self._slowness_filter.add_data(current_slowness)
-      slowness_value = self._slowness_filter.get_value() or 0.0
+      self._has_slowness = self._slowness_tracker.update(current_slowness)
 
-      # Hysteresis for slowness
-      threshold = WMACConstants.SLOWNESS_PROB * (0.8 if self._has_slowness else 1.1)
-      self._has_slowness = slowness_value > threshold
-
-  def _calculate_slow_down(self, md):
-    """Calculate urgency based on trajectory endpoint vs expected distance."""
-
-    # Reset to safe defaults
-    urgency = 0.0
+  def _calculate_slow_down(self, md) -> None:
     self._endpoint_x = float('inf')
+    self._expected_distance = 0.0
     self._trajectory_valid = False
 
-    #Require exact trajectory size
-    position_valid = len(md.position.x) == TRAJECTORY_SIZE
-    orientation_valid = len(md.orientation.x) == TRAJECTORY_SIZE
+    urgency = self._model_action_urgency(md)
+    position_valid = len(md.position.x) == WMACConstants.TRAJECTORY_SIZE
 
-    if not (position_valid and orientation_valid):
-      # Invalid trajectory - this itself might indicate a stop scenario
-      # Apply moderate urgency for incomplete trajectories at speed
-      if self._v_ego_kph > 20.0:
-        urgency = 0.3
+    if position_valid:
+      self._trajectory_valid = True
+      self._endpoint_x = md.position.x[WMACConstants.TRAJECTORY_SIZE - 1]
+      self._expected_distance = interp(self._v_ego_kph, WMACConstants.SLOW_DOWN_BP, WMACConstants.SLOW_DOWN_DIST)
+      urgency = max(urgency, self._endpoint_urgency(self._endpoint_x, self._expected_distance))
 
-      self._slow_down_filter.add_data(urgency)
-      urgency_filtered = self._slow_down_filter.get_value() or 0.0
-      self._has_slow_down = urgency_filtered > WMACConstants.SLOW_DOWN_PROB
-      self._urgency = urgency_filtered
-      return
+    self._raw_urgency = clip01(urgency)
+    self._has_slow_down = self._slow_down_tracker.update(self._raw_urgency)
+    self._urgency = self._slow_down_tracker.value
 
-    # We have a valid full trajectory
-    self._trajectory_valid = True
+  def _radar_acc_lead_score(self, lead_one) -> float:
+    if not lead_one.status:
+      return 0.0
 
-    # Use the exact endpoint (33rd point, index 32)
-    endpoint_x = md.position.x[TRAJECTORY_SIZE - 1]
-    self._endpoint_x = endpoint_x
+    d_rel = float(getattr(lead_one, 'dRel', float('inf')))
+    v_rel = float(getattr(lead_one, 'vRel', 0.0))
+    if d_rel <= WMACConstants.RADAR_LEAD_ACC_MAX_DREL:
+      return 1.0
+    if v_rel <= WMACConstants.RADAR_LEAD_ACC_MIN_CLOSING_SPEED and d_rel / max(-v_rel, 0.1) <= WMACConstants.RADAR_LEAD_ACC_MAX_TTC:
+      return 1.0
+    return 0.0
 
-    # Get expected distance based on current speed using tuned constants
-    expected_distance = interp(self._v_ego_kph,
-                               WMACConstants.SLOW_DOWN_BP,
-                               WMACConstants.SLOW_DOWN_DIST)
-    self._expected_distance = expected_distance
+  def _model_action_urgency(self, md) -> float:
+    action = getattr(md, 'action', None)
+    if action is None:
+      return 0.0
 
-    # Calculate urgency based on trajectory shortage
-    if endpoint_x < expected_distance:
-      shortage = expected_distance - endpoint_x
-      shortage_ratio = shortage / expected_distance
+    urgency = 1.0 if getattr(action, 'shouldStop', False) else 0.0
+    desired_accel = getattr(action, 'desiredAcceleration', 0.0)
+    if desired_accel < WMACConstants.MODEL_DECEL_START:
+      urgency = max(urgency, min(1.0, (WMACConstants.MODEL_DECEL_START - desired_accel) / WMACConstants.MODEL_DECEL_RANGE))
+    return urgency
 
-      # Base urgency on shortage ratio
-      urgency = min(1.0, shortage_ratio * 2.0)
+  def _endpoint_urgency(self, endpoint_x: float, expected_distance: float) -> float:
+    if endpoint_x >= expected_distance:
+      return 0.0
 
-      # Increase urgency for very short trajectories (imminent stops)
-      critical_distance = expected_distance * 0.3
-      if endpoint_x < critical_distance:
-        urgency = min(1.0, urgency * 2.0)
+    shortage_ratio = (expected_distance - endpoint_x) / expected_distance
+    urgency = min(1.0, shortage_ratio * WMACConstants.ENDPOINT_URGENCY_GAIN)
 
-      # Speed-based urgency adjustment
-      if self._v_ego_kph > 25.0:
-        speed_factor = 1.0 + (self._v_ego_kph - 25.0) / 80.0
-        urgency = min(1.0, urgency * speed_factor)
+    if endpoint_x < expected_distance * WMACConstants.CRITICAL_ENDPOINT_FACTOR:
+      urgency = min(1.0, urgency * WMACConstants.CRITICAL_URGENCY_GAIN)
 
-    # Apply filtering but with less smoothing for stops
-    self._slow_down_filter.add_data(urgency)
-    urgency_filtered = self._slow_down_filter.get_value() or 0.0
+    if self._v_ego_kph > WMACConstants.SPEED_URGENCY_MIN:
+      speed_factor = 1.0 + (self._v_ego_kph - WMACConstants.SPEED_URGENCY_MIN) / WMACConstants.SPEED_URGENCY_RANGE
+      urgency = min(1.0, urgency * speed_factor)
 
-    # Update state with lower threshold for better stop detection
-    self._has_slow_down = urgency_filtered > (WMACConstants.SLOW_DOWN_PROB * 0.8)
-    self._urgency = urgency_filtered
+    return urgency
 
-  def _radarless_mode(self) -> None:
-    """Radarless mode decision logic with emergency handling."""
+  def _desired_mode(self) -> tuple[ModeType, bool]:
+    if not self._CP.radarUnavailable and self._has_radar_acc_lead:
+      return 'acc', False
 
-    # EMERGENCY: MPC FCW - immediate blended mode
     if self._has_mpc_fcw:
-      self._mode_manager.request_mode('blended', confidence=1.0, emergency=True)
-      return
+      return 'blended', True
 
-    # Standstill: use blended
-    if self._standstill_count > 3:
-      self._mode_manager.request_mode('blended', confidence=0.9)
-      return
+    standstill = self._standstill_count > WMACConstants.STANDSTILL_FRAMES
+    urgent_slow_down = self._has_slow_down and self._raw_urgency > WMACConstants.URGENT_SLOW_DOWN_PROB
 
-    # Slow down scenarios: emergency for high urgency, normal for lower urgency
-    if self._has_slow_down:
-      if self._urgency > 0.7:
-        # Emergency: immediate blended mode for high urgency stops
-        self._mode_manager.request_mode('blended', confidence=1.0, emergency=True)
-      else:
-        # Normal: blended with urgency-based confidence
-        confidence = min(1.0, self._urgency * 1.5)
-        self._mode_manager.request_mode('blended', confidence=confidence)
-      return
+    if self._CP.radarUnavailable:
+      if standstill or self._has_slow_down:
+        return 'blended', urgent_slow_down
+      return 'acc', False
 
-    # Driving slow: use ACC (but not if actively slowing down)
-    if self._has_slowness and not self._has_slow_down:
-      self._mode_manager.request_mode('acc', confidence=0.8)
-      return
+    if standstill or self._has_slow_down:
+      return 'blended', urgent_slow_down
 
-    # Default: ACC
-    self._mode_manager.request_mode('acc', confidence=0.7)
-
-  def _radar_mode(self) -> None:
-    """Radar mode with emergency handling."""
-
-    # EMERGENCY: MPC FCW - immediate blended mode
-    if self._has_mpc_fcw:
-      self._mode_manager.request_mode('blended', confidence=1.0, emergency=True)
-      return
-
-    # If lead detected and not in standstill: always use ACC
-    if self._has_lead_filtered and not (self._standstill_count > 3):
-      self._mode_manager.request_mode('acc', confidence=1.0)
-      return
-
-    # Slow down scenarios: emergency for high urgency, normal for lower urgency
-    if self._has_slow_down:
-      if self._urgency > 0.7:
-        # Emergency: immediate blended mode for high urgency stops
-        self._mode_manager.request_mode('blended', confidence=1.0, emergency=True)
-      else:
-        # Normal: blended with urgency-based confidence
-        confidence = min(1.0, self._urgency * 1.3)
-        self._mode_manager.request_mode('blended', confidence=confidence)
-      return
-
-    # Standstill: use blended
-    if self._standstill_count > 3:
-      self._mode_manager.request_mode('blended', confidence=0.9)
-      return
-
-    # Driving slow: use ACC (but not if actively slowing down)
-    if self._has_slowness and not self._has_slow_down:
-      self._mode_manager.request_mode('acc', confidence=0.8)
-      return
-
-    # Default: ACC
-    self._mode_manager.request_mode('acc', confidence=0.7)
+    return 'acc', False
 
   def update(self, sm: messaging.SubMaster) -> None:
     self._read_params()
-
     self.set_mpc_fcw_crash_cnt()
-
     self._update_calculations(sm)
 
-    if self._CP.radarUnavailable:
-      self._radarless_mode()
-    else:
-      self._radar_mode()
-
+    mode, immediate = self._desired_mode()
+    self._mode_manager.request_mode(mode, immediate=immediate, hold_frames=WMACConstants.EMERGENCY_HOLD_FRAMES,
+                                    cancel_hold=self._has_radar_acc_lead)
     self._mode_manager.update()
+
     self._active = sm['selfdriveState'].experimentalMode and self._enabled
     self._frame += 1
diff --git a/sunnypilot/selfdrive/controls/lib/dec/tests/pytest_dynamic_controller.py b/sunnypilot/selfdrive/controls/lib/dec/tests/pytest_dynamic_controller.py
deleted file mode 100644
index f9da39c03b..0000000000
--- a/sunnypilot/selfdrive/controls/lib/dec/tests/pytest_dynamic_controller.py
+++ /dev/null
@@ -1,94 +0,0 @@
-import pytest
-
-from openpilot.sunnypilot.selfdrive.controls.lib.dec.dec import DynamicExperimentalController
-
-class MockLeadOne:
-  def __init__(self, status=0.0):
-    self.status = status
-
-class MockRadarState:
-  def __init__(self, status=0.0):
-    self.leadOne = MockLeadOne(status=status)
-
-class MockCarState:
-  def __init__(self, vEgo=0.0, vCruise=0.0, standstill=False):
-    self.vEgo = vEgo
-    self.vCruise = vCruise
-    self.standstill = standstill
-
-class MockModelData:
-  def __init__(self, valid=True):
-    size = 33 if valid else 10  # incomplete if invalid
-    self.position = type("Pos", (), {"x": [0.0] * size})()
-    self.orientation = type("Ori", (), {"x": [0.0] * size})()
-
-class MockSelfDriveState:
-  def __init__(self, experimentalMode=False):
-    self.experimentalMode = experimentalMode
-
-class MockParams:
-  def get_bool(self, name):
-    return True
-
-@pytest.fixture
-def default_sm():
-  sm = {
-    'carState': MockCarState(vEgo=10.0, vCruise=20.0),
-    'radarState': MockRadarState(status=1.0),
-    'modelV2': MockModelData(valid=True),
-    'selfdriveState': MockSelfDriveState(experimentalMode=True),
-  }
-  return sm
-
-@pytest.fixture
-def mock_cp():
-  class CP:
-    radarUnavailable = False
-  return CP()
-
-@pytest.fixture
-def mock_mpc():
-  class MPC:
-    crash_cnt = 0
-  return MPC()
-
-# Fake Kalman Filter that always returns a given value
-class FakeKalman:
-  def __init__(self, value=1.0):
-    self.value = value
-  def add_data(self, v): pass
-  def get_value(self): return self.value
-  def get_confidence(self): return 1.0
-  def reset_data(self): pass
-
-def test_initial_mode_is_acc(mock_cp, mock_mpc):
-  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
-  assert controller.mode() == "acc"
-
-def test_standstill_triggers_blended(mock_cp, mock_mpc, default_sm):
-  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
-  default_sm['carState'].standstill = True
-  for _ in range(10):
-    controller.update(default_sm)
-  assert controller.mode() == "blended"
-
-def test_emergency_blended_on_fcw(mock_cp, mock_mpc, default_sm):
-  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
-  mock_mpc.crash_cnt = 1  # simulate FCW
-  for _ in range(2):
-    controller.update(default_sm)
-  assert controller.mode() == "blended"
-
-def test_radarless_slowdown_triggers_blended(mock_cp, mock_mpc, default_sm):
-  mock_cp.radarUnavailable = True
-  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
-
-  # Force conditions to simulate slowdown
-  controller._slow_down_filter = FakeKalman(value=1.0)  # Ensure urgency triggers slowdown
-  controller._v_ego_kph = 35.0
-  default_sm['modelV2'] = MockModelData(valid=False)  # Incomplete trajectory
-
-  for _ in range(3):
-    controller.update(default_sm)
-
-  assert controller.mode() == "blended"
diff --git a/sunnypilot/selfdrive/controls/lib/dec/tests/test_dynamic_controller.py b/sunnypilot/selfdrive/controls/lib/dec/tests/test_dynamic_controller.py
new file mode 100644
index 0000000000..d4fa748f7a
--- /dev/null
+++ b/sunnypilot/selfdrive/controls/lib/dec/tests/test_dynamic_controller.py
@@ -0,0 +1,235 @@
+import pytest
+
+from openpilot.sunnypilot.selfdrive.controls.lib.dec.dec import DynamicExperimentalController, HysteresisSignal
+
+
+class MockLeadOne:
+  def __init__(self, status=0.0, dRel=30.0, vRel=0.0):
+    self.status = status
+    self.dRel = dRel
+    self.vRel = vRel
+
+
+class MockRadarState:
+  def __init__(self, status=0.0, dRel=30.0, vRel=0.0):
+    self.leadOne = MockLeadOne(status=status, dRel=dRel, vRel=vRel)
+
+
+class MockCarState:
+  def __init__(self, vEgo=0.0, vCruise=0.0, standstill=False):
+    self.vEgo = vEgo
+    self.vCruise = vCruise
+    self.standstill = standstill
+
+
+class MockAction:
+  def __init__(self, desiredAcceleration=0.0, shouldStop=False):
+    self.desiredAcceleration = desiredAcceleration
+    self.shouldStop = shouldStop
+
+
+class MockModelData:
+  def __init__(self, valid=True, endpoint_x=200.0, orientation_valid=None, desired_acceleration=0.0, should_stop=False):
+    position_size = 33 if valid else 10
+    orientation_size = position_size if orientation_valid is None else (33 if orientation_valid else 10)
+    position_x = [0.0] * position_size
+    if position_x:
+      position_x[-1] = endpoint_x
+    self.position = type("Pos", (), {"x": position_x})()
+    self.orientation = type("Ori", (), {"x": [0.0] * orientation_size})()
+    self.acceleration = type("Accel", (), {"x": [0.0] * position_size})()
+    self.action = MockAction(desired_acceleration, should_stop)
+
+
+class MockSelfDriveState:
+  def __init__(self, experimentalMode=False):
+    self.experimentalMode = experimentalMode
+
+
+class MockParams:
+  def get_bool(self, name):
+    return True
+
+
+@pytest.fixture
+def default_sm():
+  sm = {
+    'carState': MockCarState(vEgo=10.0, vCruise=20.0),
+    'radarState': MockRadarState(status=1.0),
+    'modelV2': MockModelData(valid=True),
+    'selfdriveState': MockSelfDriveState(experimentalMode=True),
+  }
+  return sm
+
+
+@pytest.fixture
+def mock_cp():
+  class CP:
+    radarUnavailable = False
+  return CP()
+
+
+@pytest.fixture
+def mock_mpc():
+  class MPC:
+    crash_cnt = 0
+  return MPC()
+
+
+def test_initial_mode_is_acc(mock_cp, mock_mpc):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  assert controller.mode() == "acc"
+
+
+def test_standstill_triggers_blended(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['carState'].standstill = True
+  for _ in range(20):
+    controller.update(default_sm)
+  assert controller.mode() == "blended"
+
+
+def test_emergency_blended_on_fcw(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  mock_mpc.crash_cnt = 1
+  controller.update(default_sm)
+  assert controller.mode() == "blended"
+
+
+def test_radarless_slowdown_triggers_blended(mock_cp, mock_mpc, default_sm):
+  mock_cp.radarUnavailable = True
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+
+  controller.update(default_sm)
+
+  assert controller.mode() == "blended"
+
+
+def test_valid_position_with_missing_orientation_can_trigger_slowdown(mock_cp, mock_mpc, default_sm):
+  mock_cp.radarUnavailable = True
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0, orientation_valid=False)
+
+  controller.update(default_sm)
+
+  assert controller._trajectory_valid
+  assert controller.mode() == "blended"
+
+
+def test_incomplete_position_does_not_trigger_slowdown(mock_cp, mock_mpc, default_sm):
+  mock_cp.radarUnavailable = True
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['modelV2'] = MockModelData(valid=False, endpoint_x=0.0)
+
+  for _ in range(3):
+    controller.update(default_sm)
+
+  assert not controller._trajectory_valid
+  assert not controller._has_slow_down
+  assert controller.mode() == "acc"
+
+
+def test_slowdown_hysteresis_prevents_threshold_chatter():
+  signal = HysteresisSignal(enter_threshold=0.5, exit_threshold=0.4, rise_rate=1.0, fall_rate=1.0)
+
+  assert signal.update(0.55)
+  assert signal.update(0.45)
+  assert not signal.update(0.35)
+
+
+def test_model_should_stop_triggers_blended_without_valid_trajectory(mock_cp, mock_mpc, default_sm):
+  mock_cp.radarUnavailable = True
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['modelV2'] = MockModelData(valid=False, should_stop=True)
+
+  controller.update(default_sm)
+
+  assert not controller._trajectory_valid
+  assert controller.mode() == "blended"
+
+
+def test_radar_lead_keeps_acc_over_model_slowdown(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+
+  for _ in range(3):
+    controller.update(default_sm)
+
+  assert controller._has_slow_down
+  assert controller._has_radar_acc_lead
+  assert controller.mode() == "acc"
+
+
+def test_far_radar_lead_allows_blended_until_acc_relevant(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0, dRel=120.0, vRel=0.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+
+  controller.update(default_sm)
+
+  assert controller._has_lead_filtered
+  assert not controller._has_radar_acc_lead
+  assert controller.mode() == "blended"
+
+
+def test_relevant_radar_lead_smoothly_returns_to_acc(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0, dRel=120.0, vRel=0.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+  controller.update(default_sm)
+  assert controller.mode() == "blended"
+
+  default_sm['radarState'] = MockRadarState(status=1.0, dRel=45.0, vRel=0.0)
+  for _ in range(20):
+    controller.update(default_sm)
+
+  assert controller._has_radar_acc_lead
+  assert controller.mode() == "acc"
+
+
+def test_closing_far_radar_lead_returns_to_acc(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0, dRel=120.0, vRel=-25.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+
+  for _ in range(20):
+    controller.update(default_sm)
+
+  assert controller._has_radar_acc_lead
+  assert controller.mode() == "acc"
+
+
+def test_radar_lead_keeps_acc_over_fcw_and_standstill(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0)
+  default_sm['carState'].standstill = True
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0, should_stop=True)
+  mock_mpc.crash_cnt = 1
+
+  for _ in range(10):
+    controller.update(default_sm)
+
+  assert controller._has_lead_filtered
+  assert controller._has_mpc_fcw
+  assert controller.mode() == "acc"
+
+
+def test_lead_flicker_hold_prevents_one_frame_mode_flip(mock_cp, mock_mpc, default_sm):
+  controller = DynamicExperimentalController(mock_cp, mock_mpc, params=MockParams())
+  default_sm['radarState'] = MockRadarState(status=1.0)
+  controller.update(default_sm)
+
+  default_sm['radarState'] = MockRadarState(status=0.0)
+  default_sm['modelV2'] = MockModelData(valid=True, endpoint_x=0.0)
+  controller.update(default_sm)
+
+  assert controller._has_lead_filtered
+  assert controller.mode() == "acc"