diff --git a/scripts/launch_onroad_desktop.sh b/scripts/launch_onroad_desktop.sh
index f9ee4bb77..fe1978c03 100755
--- a/scripts/launch_onroad_desktop.sh
+++ b/scripts/launch_onroad_desktop.sh
@@ -48,6 +48,7 @@ Notes:
   - --galaxy starts a local Galaxy web session with the same preview params and prints the localhost URL. It blocks replay's logged customReserved9 stream so Galaxy can own the live Testing Grounds publisher.
   - -nav injects a fake navigation demo stream and blocks replay from publishing navInstruction/navRoute.
   - --cem publishes fake CEM statuses for desktop visual review in the raylib UIs.
+  - --csc publishes a fake starpilotPlan stream that forces the CSC glow to render on desktop UI.
   - -alert blocks replay from publishing selfdriveState and fires a fake critical full-screen red alert (alertSize=full, alertStatus=critical) 20 seconds after the demo publisher starts (10s for replay route + UI to come up, plus 10s for the user to open Settings). Default alert text mimics a real controlsMismatch event; run tools/replay/fake_alert_demo.py directly to override --text1/--text2/--delay.
 EOF
 }
@@ -67,11 +68,13 @@ REPLAY_ONLY=0
 NAV_DEMO=0
 CEM_DEMO=0
 ALERT_DEMO=0
+CSC_DEMO=0
 GALAXY=0
 REPLAY_PID=""
 NAV_PID=""
 CEM_PID=""
 ALERT_PID=""
+CSC_PID=""
 GALAXY_PID=""
 GALAXY_PORT=""
 GALAXY_URL=""
@@ -117,6 +120,10 @@ parse_args() {
         CEM_DEMO=1
         shift
         ;;
+      --csc|--csc-demo)
+        CSC_DEMO=1
+        shift
+        ;;
       --galaxy)
         GALAXY=1
         shift
@@ -247,6 +254,9 @@ cleanup() {
   if [[ -n "${ALERT_PID}" ]]; then
     kill "${ALERT_PID}" >/dev/null 2>&1 || true
   fi
+  if [[ -n "${CSC_PID}" ]]; then
+    kill "${CSC_PID}" >/dev/null 2>&1 || true
+  fi
   if [[ -n "${GALAXY_PID}" ]]; then
     kill "${GALAXY_PID}" >/dev/null 2>&1 || true
   fi
@@ -268,6 +278,9 @@ cleanup() {
   if [[ -n "${ALERT_PID}" ]]; then
     wait "${ALERT_PID}" >/dev/null 2>&1 || true
   fi
+  if [[ -n "${CSC_PID}" ]]; then
+    wait "${CSC_PID}" >/dev/null 2>&1 || true
+  fi
   if [[ -n "${GALAXY_PID}" ]]; then
     wait "${GALAXY_PID}" >/dev/null 2>&1 || true
   fi
@@ -352,6 +365,10 @@ ensure_alert_demo_replay_blocklist() {
   ensure_replay_blocklist "selfdriveState"
 }
 
+ensure_csc_demo_replay_blocklist() {
+  ensure_replay_blocklist "starpilotPlan"
+}
+
 ensure_galaxy_replay_blocklist() {
   ensure_replay_blocklist "customReserved9"
 }
@@ -383,6 +400,7 @@ prepare_env() {
   export SP_ONROAD_NAV_DEMO="${NAV_DEMO}"
   export SP_CEM_DEMO="${CEM_DEMO}"
   export SP_ONROAD_ALERT_DEMO="${ALERT_DEMO}"
+  export SP_ONROAD_CSC_DEMO="${CSC_DEMO}"
 
   local generated_prefix="${PREFIX_ARG:-${OPENPILOT_PREFIX:-desktop-onroad-$$}}"
   ONROAD_TEMP_PREFIX="${generated_prefix}"
@@ -484,6 +502,18 @@ launch_alert_demo() {
   fi
 }
 
+launch_csc_demo() {
+  echo "Starting fake CSC demo publisher..."
+  "${ROOT_DIR}/.venv/bin/python3" "${ROOT_DIR}/tools/replay/fake_csc_demo.py" &
+  CSC_PID=$!
+
+  sleep 0.5
+  if ! kill -0 "${CSC_PID}" >/dev/null 2>&1; then
+    wait "${CSC_PID}"
+    return 1
+  fi
+}
+
 pick_free_local_port() {
   "${ROOT_DIR}/.venv/bin/python3" - <<'PY'
 import socket
@@ -605,6 +635,10 @@ if [[ "${ALERT_DEMO}" == "1" ]]; then
   ensure_alert_demo_replay_blocklist
 fi
 
+if [[ "${CSC_DEMO}" == "1" ]]; then
+  ensure_csc_demo_replay_blocklist
+fi
+
 if [[ "${GALAXY}" == "1" ]]; then
   ensure_galaxy_replay_blocklist
 fi
@@ -672,6 +706,10 @@ if [[ "${ALERT_DEMO}" == "1" ]]; then
   launch_alert_demo
 fi
 
+if [[ "${CSC_DEMO}" == "1" ]]; then
+  launch_csc_demo
+fi
+
 if [[ ${#UI_TARGETS[@]} -eq 0 ]]; then
   echo "Replay is running without UI windows. Press Ctrl-C to stop."
   wait "${REPLAY_PID}"
diff --git a/tools/replay/fake_csc_demo.py b/tools/replay/fake_csc_demo.py
new file mode 100644
index 000000000..07e406699
--- /dev/null
+++ b/tools/replay/fake_csc_demo.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+import time
+import math
+import cereal.messaging as messaging
+
+def main():
+  print("Starting fake CSC demo publisher (Curve Speed Controller)...")
+  
+  # Create a PubMaster for the required services
+  pm = messaging.PubMaster(['starpilotPlan'])
+  
+  # Publish at 20Hz
+  rate = 0.05 
+  
+  while True:
+    now = time.time()
+    
+    # Fake StarPilot Plan
+    sp = messaging.new_message('starpilotPlan')
+    
+    # 8-second cycle stepping through all 4 color spectrums:
+    # 0s - 2s: Green  (Low curvature, t = 0.0)
+    # 2s - 4s: Amber  (Medium curvature, t = 0.38)
+    # 4s - 6s: Orange (High curvature, t = 0.56)
+    # 6s - 8s: Red    (Max curvature, t = 1.0)
+    t = now % 8.0
+    
+    sp.starpilotPlan.cscControllingSpeed = True
+    sp.starpilotPlan.cscTraining = False
+    
+    if t < 2.0:
+      # Green phase
+      sp.starpilotPlan.roadCurvature = 0.0000
+    elif t < 4.0:
+      # Amber/Yellow phase
+      sp.starpilotPlan.roadCurvature = 0.0080
+    elif t < 6.0:
+      # Orange phase
+      sp.starpilotPlan.roadCurvature = 0.0115
+    else:
+      # Red phase
+      sp.starpilotPlan.roadCurvature = 0.0200
+      
+    pm.send('starpilotPlan', sp)
+    
+    time.sleep(rate)
+
+if __name__ == "__main__":
+  main()