Add reliable built-in demo mode

SUB Control/app.py

@@ -42,6 +42,25 @@ class Axes:
     yaw: float = 0.0
 
 
+def normalize_endpoint(port: str) -> str:
+    p = str(port).strip()
+    if not p:
+        return p
+    lower = p.lower()
+    if "sim" in lower or "5760" in lower or lower in ("tcp", "tcp:", "tcp:127.0.0.1", "127.0.0.1"):
+        return "tcp:127.0.0.1:5760"
+    if "14550" in lower or lower in ("udp", "udp:", "udpin", "udpin:"):
+        return "udpin:127.0.0.1:14550"
+    if p.startswith("127.0.0.1:") or p.startswith("localhost:"):
+        num = p.split(":")[1]
+        if num == "14550":
+            return f"udpin:{p}"
+        return f"tcp:{p}"
+    if ":" in p and not p.startswith(("tcp:", "tcpin:", "udp:", "udpin:", "udpout:")):
+        return f"tcp:{p}"
+    return p
+
+
 class MavlinkWorker:
     def __init__(self, events: queue.Queue):
         self.events = events
@@ -74,29 +93,52 @@ class MavlinkWorker:
         self.log_path = None
 
     def connect(self, port: str, baud: int):
+        print(f"[MavlinkWorker] connect() called: port={port!r}, baud={baud}")
         if self.thread and self.thread.is_alive():
+            print(f"[MavlinkWorker] Thread already alive, ignoring connect()")
             return
         self.stop_event.clear()
         log_dir = Path(__file__).resolve().parent / "logs"
         log_dir.mkdir(exist_ok=True)
         self.log_path = log_dir / f"ardusub_{datetime.now():%Y%m%d_%H%M%S}.log"
         self.log_file = self.log_path.open("a", encoding="utf-8", buffering=1)
-        self.log("SESSION", f"start port={port} baud={baud} control_hz={self.rate_hz}")
+        normalized = normalize_endpoint(port)
+        print(f"[MavlinkWorker] normalized endpoint: {normalized!r}")
+        self.log("SESSION", f"start port={normalized} (input={port}) baud={baud} control_hz={self.rate_hz}")
         self.events.put(("log_path", str(self.log_path)))
         self.thread = threading.Thread(
-            target=self._run, args=(port, baud), daemon=True
+            target=self._run, args=(normalized, baud), daemon=True
         )
         self.thread.start()
+        print(f"[MavlinkWorker] worker thread started")
 
     def _run(self, port: str, baud: int):
+        print(f"[MavlinkWorker._run] ENTERED: port={port!r}, baud={baud}")
         try:
+            print(f"[MavlinkWorker._run] Creating mavlink_connection...")
             conn = mavutil.mavlink_connection(
                 port, baud=baud, source_system=255, source_component=190,
-                autoreconnect=False, force_connected=True,
+                # Fail a missing TCP simulator immediately. pymavlink otherwise
+                # retries the refused socket several times and leaves the UI in
+                # "Opening" long after the actual failure.
+                autoreconnect=False, retries=0, force_connected=True,
             )
+            print(f"[MavlinkWorker._run] mavlink_connection created: {type(conn).__name__}")
             self.connection = conn
-            self.events.put(("status", f"Port open; waiting for heartbeat at {baud} baud…"))
+            if port.startswith("tcp:"):
-            next_gcs_hb = 0.0
+                self.events.put(("status", f"Connected to {port}; waiting for vehicle heartbeat…"))
+            else:
+                self.events.put(("status", f"Port {port} open; waiting for heartbeat at {baud} baud…"))
+
+            # Send initial GCS heartbeat immediately
+            self.log("TX_HEARTBEAT", "GCS initial")
+            conn.mav.heartbeat_send(
+                mavutil.mavlink.MAV_TYPE_GCS,
+                mavutil.mavlink.MAV_AUTOPILOT_INVALID,
+                0, 0, mavutil.mavlink.MAV_STATE_ACTIVE,
+            )
+            print(f"[MavlinkWorker._run] Initial heartbeat sent, entering recv loop")
+            next_gcs_hb = time.monotonic() + 1.0
             next_control = 0.0
             while not self.stop_event.is_set():
                 now = time.monotonic()
@@ -120,6 +162,7 @@ class MavlinkWorker:
                 else:
                     time.sleep(0.01)
         except Exception as exc:
+            print(f"[MavlinkWorker._run] EXCEPTION: {exc}")
             self.events.put(("error", f"Connection error: {exc}"))
         finally:
             self._safe_stop()
@@ -156,7 +199,7 @@ class MavlinkWorker:
         except Exception:
             payload = str(msg)
         self.log("RX", payload)
-        if msg_type == "HEARTBEAT" and msg.get_srcComponent() == 1:
+        if msg_type == "HEARTBEAT" and getattr(msg, "type", 0) != mavutil.mavlink.MAV_TYPE_GCS:
             first = not self.target_system
             self.target_system = msg.get_srcSystem()
             self.target_component = msg.get_srcComponent()
@@ -887,6 +930,9 @@ class App(tk.Tk):
 
     def refresh_ports(self):
         ports = [p.device for p in list_ports.comports()]
+        for sim in ("tcp:127.0.0.1:5760", "udpin:127.0.0.1:14550"):
+            if sim not in ports:
+                ports.append(sim)
         self.port.configure(values=ports)
         if ports and self.port.get() not in ports:
             self.port.set(ports[0])

SUB Control/fc_spoofer.py

@@ -0,0 +1,553 @@
+"""ArduSub Flight Controller (FC) Spoofer & Simulator.
+
+Emulates an ArduSub SimpleROV-3 vehicle over MAVLink (TCP, UDP, or Serial).
+Supports full parameter scans, live parameter updates (servo functions / motor reversal),
+arming/disarming commands, manual control processing, and realistic telemetry streaming
+(battery voltage/current with load sag, live thruster PWM mixing, simulated attitude & depth).
+"""
+
+from __future__ import annotations
+
+import argparse
+import math
+import os
+import sys
+import time
+from collections import deque
+from dataclasses import dataclass
+from typing import Any
+
+from pymavlink import mavutil
+
+
+# Default SimpleROV-3 motor mappings and ArduSub parameters
+DEFAULT_PARAMETERS: dict[str, tuple[float, int]] = {
+    # Servo functions: 33 = Motor 1 (Port), 34 = Motor 2 (Starboard), 35 = Motor 3 (Vertical)
+    "SERVO1_FUNCTION": (33.0, mavutil.mavlink.MAV_PARAM_TYPE_INT16),
+    "SERVO2_FUNCTION": (34.0, mavutil.mavlink.MAV_PARAM_TYPE_INT16),
+    "SERVO3_FUNCTION": (35.0, mavutil.mavlink.MAV_PARAM_TYPE_INT16),
+    # Remaining servos unassigned
+    **{f"SERVO{i}_FUNCTION": (0.0, mavutil.mavlink.MAV_PARAM_TYPE_INT16) for i in range(4, 17)},
+    # Motor directions: 1 = normal, -1 = reversed
+    **{f"MOT_{i}_DIRECTION": (1.0, mavutil.mavlink.MAV_PARAM_TYPE_INT8) for i in range(1, 13)},
+    # SimpleROV-3 thruster PWM limits
+    "SERVO1_MIN": (1100.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO1_TRIM": (1500.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO1_MAX": (1900.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO2_MIN": (1100.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO2_TRIM": (1500.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO2_MAX": (1900.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO3_MIN": (1100.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO3_TRIM": (1500.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "SERVO3_MAX": (1900.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    # Joystick gain parameters
+    "JS_GAIN_MIN": (0.10, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "JS_GAIN_DEFAULT": (0.20, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+    "JS_GAIN_MAX": (1.00, mavutil.mavlink.MAV_PARAM_TYPE_REAL32),
+}
+
+
+@dataclass
+class ControlState:
+    x: float = 0.0  # Surge (forward/back) -1000..1000
+    y: float = 0.0  # Sway (lateral) -1000..1000
+    z: float = 500.0  # Heave (vertical) 0..1000 (500 = neutral)
+    r: float = 0.0  # Yaw (turn) -1000..1000
+    last_rx: float = 0.0
+
+
+class FlightControllerSpoofer:
+    def __init__(
+        self,
+        endpoint: str = "tcpin:127.0.0.1:5760",
+        baud: int = 57600,
+        battery_cells: int = 4,
+        nominal_voltage: float = 16.0,
+        show_dashboard: bool = True,
+    ):
+        self.endpoint = endpoint
+        self.baud = baud
+        self.battery_cells = battery_cells
+        self.battery_base_v = nominal_voltage
+        self.show_dashboard = show_dashboard
+
+        self.running = True
+        self.armed = False
+        self.mode = 19  # ArduSub MANUAL mode
+        self.system_status = mavutil.mavlink.MAV_STATE_ACTIVE
+        self.target_system = 255
+        self.target_component = 190
+
+        self.params = dict(DEFAULT_PARAMETERS)
+        self.controls = ControlState()
+
+        # Simulated physical state
+        self.depth_m = 1.5  # Positive depth under water
+        self.heading_deg = 0.0
+        self.pitch_deg = 0.0
+        self.roll_deg = 0.0
+        self.m1_pwm = 1500  # Port
+        self.m2_pwm = 1500  # Starboard
+        self.m3_pwm = 1500  # Vertical
+        self.current_a = 0.35
+
+        self.events: deque[str] = deque(maxlen=6)
+        self.client_connected = False
+        self.total_packets_rx = 0
+        self.total_packets_tx = 0
+        self.start_time = time.monotonic()
+
+    def log_event(self, text: str):
+        now_str = time.strftime("%H:%M:%S")
+        self.events.append(f"[{now_str}] {text}")
+
+    def run(self):
+        print(f"\n{'='*72}")
+        print(f"  ARDUSUB SIMPLE-ROV FLIGHT CONTROLLER SPOOFER IS RUNNING")
+        print(f"  Target Endpoint: {self.endpoint}")
+        print(f"  --> In Sub Control app, select or connect to: {self.endpoint.replace('tcpin:', 'tcp:')}")
+        print(f"{'='*72}\n", flush=True)
+        self.log_event(f"Simulator starting on {self.endpoint}...")
+        while self.running:
+            try:
+                self._run_server_session()
+            except KeyboardInterrupt:
+                break
+            except OSError as exc:
+                if getattr(exc, "winerror", None) == 10048 or "already in use" in str(exc).lower():
+                    print(f"\n[ERROR] Port {self.endpoint} is already in use by another program or previous spoofer instance.")
+                    print("Please close any running python/spoofer processes and try again.\n")
+                    break
+                self.log_event(f"Session reset: {exc}")
+                time.sleep(1.0)
+            except Exception as exc:
+                self.log_event(f"Session reset: {exc}")
+                time.sleep(1.0)
+        print("\nSpoofer stopped.")
+
+    def _run_server_session(self):
+        # Bind server / open connection
+        if self.endpoint.startswith("tcpin:"):
+            shown_endpoint = self.endpoint.replace("tcpin:", "tcp:", 1)
+            print(f"[READY] Listening for SUB Control on {shown_endpoint}", flush=True)
+            print("        Leave this window open, then click Connect in the app.\n", flush=True)
+        conn = mavutil.mavlink_connection(
+            self.endpoint,
+            baud=self.baud,
+            source_system=1,
+            source_component=1,
+            autoreconnect=True,
+            force_connected=True,
+        )
+
+        self.log_event(f"Client connected on {self.endpoint}")
+
+        next_heartbeat = 0.0
+        next_sys_status = 0.0
+        next_servos = 0.0
+        next_attitude = 0.0
+        next_dashboard = 0.0
+
+        # Send initial announcement statustext
+        initial_sent = False
+
+        while self.running:
+            now = time.monotonic()
+            elapsed = now - self.start_time
+            time_boot_ms = int(elapsed * 1000) & 0xFFFFFFFF
+            time_boot_us = int(elapsed * 1000000) & 0xFFFFFFFF
+
+            # 1. Heartbeat at 1.0 Hz
+            if now >= next_heartbeat:
+                base_mode = (
+                    mavutil.mavlink.MAV_MODE_FLAG_CUSTOM_MODE_ENABLED
+                    | mavutil.mavlink.MAV_MODE_FLAG_MANUAL_INPUT_ENABLED
+                    | mavutil.mavlink.MAV_MODE_FLAG_STABILIZE_ENABLED
+                )
+                if self.armed:
+                    base_mode |= mavutil.mavlink.MAV_MODE_FLAG_SAFETY_ARMED
+
+                conn.mav.heartbeat_send(
+                    mavutil.mavlink.MAV_TYPE_SUBMARINE,
+                    mavutil.mavlink.MAV_AUTOPILOT_ARDUPILOTMEGA,
+                    base_mode,
+                    self.mode,
+                    self.system_status,
+                )
+                self.total_packets_tx += 1
+                next_heartbeat = now + 1.0
+
+                if not initial_sent and self.client_connected:
+                    conn.mav.statustext_send(
+                        mavutil.mavlink.MAV_SEVERITY_INFO,
+                        b"ArduSub V4.1.0 (SimpleROV-3 Simulator)",
+                    )
+                    conn.mav.statustext_send(
+                        mavutil.mavlink.MAV_SEVERITY_INFO,
+                        b"EKF3 IMU0 initialised",
+                    )
+                    initial_sent = True
+
+            # 2. Physics & Motor Mixing step
+            self._update_physics(now)
+
+            # 3. SYS_STATUS at 1.0 Hz (Battery & Sensor Health)
+            if now >= next_sys_status:
+                # Voltage with slight noise + load sag
+                load_factor = (
+                    abs(self.m1_pwm - 1500)
+                    + abs(self.m2_pwm - 1500)
+                    + abs(self.m3_pwm - 1500)
+                ) / 1200.0  # 0.0 to 1.0
+                voltage_v = self.battery_base_v - (0.45 * load_factor) + (0.02 * math.sin(now * 1.5))
+                voltage_mv = int(max(10.0, voltage_v) * 1000)
+
+                # Current: 0.35A base + up to 12.5A at full throttle
+                self.current_a = 0.35 + (12.5 * load_factor)
+                current_ca = int(self.current_a * 100)
+
+                # Battery remaining percentage (e.g. 88% draining slowly)
+                remaining_pct = max(10, int(88 - (elapsed / 300.0)))
+
+                conn.mav.sys_status_send(
+                    322042887,  # onboard_control_sensors_present
+                    320969735,  # onboard_control_sensors_enabled
+                    305241095,  # onboard_control_sensors_health
+                    175,        # load (17.5%)
+                    voltage_mv,
+                    current_ca,
+                    remaining_pct,
+                    0, 0, 0, 0, 0, 0,
+                )
+                self.total_packets_tx += 1
+                next_sys_status = now + 1.0
+
+            # 4. SERVO_OUTPUT_RAW & RC_CHANNELS at 4.0 Hz
+            if now >= next_servos:
+                conn.mav.servo_output_raw_send(
+                    time_boot_us,
+                    0,
+                    self.m1_pwm,
+                    self.m2_pwm,
+                    self.m3_pwm,
+                    0, 0, 0, 0, 0,
+                )
+                conn.mav.rc_channels_send(
+                    time_boot_ms,
+                    8,
+                    1500 + int(self.controls.r * 0.4),  # Chan 1: Yaw
+                    1500,                               # Chan 2: Roll
+                    int(self.controls.z),               # Chan 3: Throttle/Vertical
+                    1500 + int(self.controls.x * 0.4),  # Chan 4: Pitch/Forward
+                    1500, 1500, 1500, 1500,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                )
+                self.total_packets_tx += 2
+                next_servos = now + 0.25
+
+            # 5. ATTITUDE & VFR_HUD at 4.0 Hz
+            if now >= next_attitude:
+                conn.mav.attitude_send(
+                    time_boot_ms,
+                    math.radians(self.roll_deg),
+                    math.radians(self.pitch_deg),
+                    math.radians(self.heading_deg),
+                    0.0, 0.0, 0.0,
+                )
+                conn.mav.vfr_hud_send(
+                    abs(self.m1_pwm - 1500) / 400.0,  # airspeed
+                    abs(self.m2_pwm - 1500) / 400.0,  # groundspeed
+                    int(self.heading_deg) % 360,       # heading
+                    int((self.controls.z - 500) / 5), # throttle %
+                    -self.depth_m,                     # altitude (negative depth)
+                    (self.controls.z - 500) / 500.0,  # climb rate
+                )
+                self.total_packets_tx += 2
+                next_attitude = now + 0.25
+
+            # 6. Process incoming MAVLink packets from App
+            self._handle_incoming_messages(conn)
+
+            # 7. Render Console Dashboard
+            if self.show_dashboard and now >= next_dashboard:
+                self._render_dashboard()
+                next_dashboard = now + 0.15
+
+            time.sleep(0.01)
+
+    def _update_physics(self, now: float):
+        # If manual control packet hasn't arrived for > 1.5s, auto-neutralize
+        if now - self.controls.last_rx > 1.5:
+            self.controls.x = 0.0
+            self.controls.y = 0.0
+            self.controls.z = 500.0
+            self.controls.r = 0.0
+
+        if not self.armed:
+            self.m1_pwm = 1500
+            self.m2_pwm = 1500
+            self.m3_pwm = 1500
+        else:
+            # Read motor direction parameters
+            mot1_dir = int(self.params.get("MOT_1_DIRECTION", (1.0,))[0])
+            mot2_dir = int(self.params.get("MOT_2_DIRECTION", (1.0,))[0])
+            mot3_dir = int(self.params.get("MOT_3_DIRECTION", (1.0,))[0])
+
+            # Differential drive mixing for SimpleROV-3:
+            # Motor 1 (Port): Forward + Yaw
+            # Motor 2 (Starboard): Forward - Yaw
+            # Motor 3 (Vertical): Vertical (0..1000 with 500 center)
+            forward_cmd = (self.controls.x / 1000.0) * 400.0  # -400..+400
+            yaw_cmd = (self.controls.r / 1000.0) * 400.0      # -400..+400
+            vert_cmd = ((self.controls.z - 500.0) / 500.0) * 400.0  # -400..+400
+
+            m1_offset = (forward_cmd + yaw_cmd) * mot1_dir
+            m2_offset = (forward_cmd - yaw_cmd) * mot2_dir
+            m3_offset = vert_cmd * mot3_dir
+
+            self.m1_pwm = int(max(1100, min(1900, 1500 + m1_offset)))
+            self.m2_pwm = int(max(1100, min(1900, 1500 + m2_offset)))
+            self.m3_pwm = int(max(1100, min(1900, 1500 + m3_offset)))
+
+        # Simulate subtle underwater motion
+        self.roll_deg = 2.5 * math.sin(now * 0.8)
+        self.pitch_deg = (self.controls.x / 1000.0) * 5.0 + 1.2 * math.cos(now * 0.7)
+        if self.armed and abs(self.controls.r) > 10:
+            self.heading_deg = (self.heading_deg + (self.controls.r / 1000.0) * 2.0) % 360.0
+
+        if self.armed and abs(self.controls.z - 500) > 20:
+            vert_delta = ((self.controls.z - 500.0) / 500.0) * 0.02
+            self.depth_m = max(0.1, min(50.0, self.depth_m - vert_delta))
+
+    def _handle_incoming_messages(self, conn):
+        while True:
+            msg = conn.recv_match(blocking=False)
+            if not msg:
+                break
+
+            self.total_packets_rx += 1
+            if not self.client_connected:
+                self.client_connected = True
+                self.log_event(f"GCS Connected (SysID {msg.get_srcSystem()}, CompID {msg.get_srcComponent()})")
+                # Immediately send heartbeat so GCS locks on with zero delay
+                base_mode = (
+                    mavutil.mavlink.MAV_MODE_FLAG_CUSTOM_MODE_ENABLED
+                    | mavutil.mavlink.MAV_MODE_FLAG_MANUAL_INPUT_ENABLED
+                    | mavutil.mavlink.MAV_MODE_FLAG_STABILIZE_ENABLED
+                )
+                if self.armed:
+                    base_mode |= mavutil.mavlink.MAV_MODE_FLAG_SAFETY_ARMED
+                conn.mav.heartbeat_send(
+                    mavutil.mavlink.MAV_TYPE_SUBMARINE,
+                    mavutil.mavlink.MAV_AUTOPILOT_ARDUPILOTMEGA,
+                    base_mode,
+                    self.mode,
+                    self.system_status,
+                )
+
+            mtype = msg.get_type()
+            if mtype == "HEARTBEAT":
+                self.target_system = msg.get_srcSystem()
+                self.target_component = msg.get_srcComponent()
+
+            elif mtype == "COMMAND_LONG":
+                cmd = int(msg.command)
+                if cmd == mavutil.mavlink.MAV_CMD_COMPONENT_ARM_DISARM:
+                    should_arm = bool(msg.param1 == 1.0)
+                    self.armed = should_arm
+                    conn.mav.command_ack_send(cmd, mavutil.mavlink.MAV_RESULT_ACCEPTED)
+                    status_str = "Motors ARMED" if self.armed else "Motors DISARMED"
+                    self.log_event(f"Command: {status_str}")
+                    conn.mav.statustext_send(
+                        mavutil.mavlink.MAV_SEVERITY_INFO,
+                        status_str.encode("ascii"),
+                    )
+
+                elif cmd == mavutil.mavlink.MAV_CMD_DO_SET_MODE:
+                    self.mode = int(msg.param2)
+                    conn.mav.command_ack_send(cmd, mavutil.mavlink.MAV_RESULT_ACCEPTED)
+                    self.log_event(f"Command: SET_MODE {self.mode}")
+                    conn.mav.statustext_send(
+                        mavutil.mavlink.MAV_SEVERITY_INFO,
+                        b"Mode: MANUAL",
+                    )
+
+                elif cmd == mavutil.mavlink.MAV_CMD_SET_MESSAGE_INTERVAL:
+                    msg_id = int(msg.param1)
+                    conn.mav.command_ack_send(cmd, mavutil.mavlink.MAV_RESULT_ACCEPTED)
+                    self.log_event(f"Stream interval set for MsgID {msg_id}")
+
+                else:
+                    conn.mav.command_ack_send(cmd, mavutil.mavlink.MAV_RESULT_ACCEPTED)
+
+            elif mtype == "SET_MODE":
+                self.mode = int(msg.custom_mode)
+                self.log_event(f"Set custom mode -> {self.mode}")
+                conn.mav.statustext_send(mavutil.mavlink.MAV_SEVERITY_INFO, b"Mode: MANUAL")
+
+            elif mtype == "REQUEST_DATA_STREAM":
+                pass  # Acknowledged implicitly by sending streams
+
+            elif mtype == "PARAM_REQUEST_READ":
+                param_id = msg.param_id
+                if isinstance(param_id, bytes):
+                    param_id = param_id.decode("ascii", errors="ignore").rstrip("\x00")
+                if param_id in self.params:
+                    val, ptype = self.params[param_id]
+                else:
+                    val, ptype = (0.0, mavutil.mavlink.MAV_PARAM_TYPE_REAL32)
+                conn.mav.param_value_send(
+                    param_id.encode("ascii"),
+                    float(val),
+                    ptype,
+                    len(self.params),
+                    0,
+                )
+                self.log_event(f"Param read: {param_id} = {val}")
+
+            elif mtype == "PARAM_REQUEST_LIST":
+                self.log_event("Param list requested, streaming all...")
+                for idx, (p_name, (p_val, p_type)) in enumerate(self.params.items()):
+                    conn.mav.param_value_send(
+                        p_name.encode("ascii"),
+                        float(p_val),
+                        p_type,
+                        len(self.params),
+                        idx,
+                    )
+                    time.sleep(0.002)
+
+            elif mtype == "PARAM_SET":
+                param_id = msg.param_id
+                if isinstance(param_id, bytes):
+                    param_id = param_id.decode("ascii", errors="ignore").rstrip("\x00")
+                new_val = float(msg.param_value)
+                ptype = int(msg.param_type)
+                self.params[param_id] = (new_val, ptype)
+                conn.mav.param_value_send(
+                    param_id.encode("ascii"),
+                    new_val,
+                    ptype,
+                    len(self.params),
+                    0,
+                )
+                self.log_event(f"Param updated: {param_id} -> {int(new_val) if new_val.is_integer() else new_val}")
+
+            elif mtype == "MANUAL_CONTROL":
+                self.controls.x = float(msg.x)
+                self.controls.y = float(msg.y)
+                self.controls.z = float(msg.z)
+                self.controls.r = float(msg.r)
+                self.controls.last_rx = time.monotonic()
+
+    def _render_dashboard(self):
+        # Clear screen ANSI
+        out = sys.stdout
+        out.write("\033[H")
+
+        # Color codes
+        GREEN = "\033[92m"
+        RED = "\033[91m"
+        YELLOW = "\033[93m"
+        CYAN = "\033[96m"
+        BOLD = "\033[1m"
+        DIM = "\033[2m"
+        RESET = "\033[0m"
+
+        def bar(val: float, min_v: float, max_v: float, width: int = 14) -> str:
+            norm = max(0.0, min(1.0, (val - min_v) / (max_v - min_v)))
+            pos = int(norm * width)
+            return f"[{'=' * pos}{' ' * (width - pos)}]"
+
+        status_tag = f"{GREEN}{BOLD} ARMED {RESET}" if self.armed else f"{YELLOW}DISARMED{RESET}"
+        link_tag = f"{GREEN}ONLINE{RESET}" if self.client_connected else f"{RED}WAITING{RESET}"
+
+        lines = [
+            f"{BOLD}{CYAN}========================================================================{RESET}",
+            f"{BOLD}  ArduSub SimpleROV-3 Flight Controller Spoofer & Telemetry Simulator {RESET}",
+            f"{BOLD}{CYAN}========================================================================{RESET}",
+            f"  Endpoint: {BOLD}{self.endpoint}{RESET}   Baud: {self.baud}   Link: {link_tag}   State: {status_tag}   Mode: {BOLD}MANUAL{RESET}",
+            f"{CYAN}------------------------------------------------------------------------{RESET}",
+            f"  {BOLD}BATTERY & POWER:{RESET}",
+            f"    Voltage: {BOLD}{self.battery_base_v:.2f} V{RESET} ({self.battery_cells}S)   Current: {BOLD}{self.current_a:.2f} A{RESET}   Power: {BOLD}{self.battery_base_v * self.current_a:.1f} W{RESET}",
+            f"    Depth:   {BOLD}{self.depth_m:.2f} m{RESET}          Heading: {BOLD}{self.heading_deg:.0f}°{RESET}        Roll/Pitch: {self.roll_deg:+.1f}° / {self.pitch_deg:+.1f}°",
+            f"{CYAN}------------------------------------------------------------------------{RESET}",
+            f"  {BOLD}INCOMING MANUAL CONTROLS (from Sub Control app):{RESET}",
+            f"    Surge (Forward/Back): {self.controls.x:+5.0f}  {bar(self.controls.x, -1000, 1000)}",
+            f"    Yaw   (Steer/Turn):   {self.controls.r:+5.0f}  {bar(self.controls.r, -1000, 1000)}",
+            f"    Heave (Vertical):     {self.controls.z:5.0f}   {bar(self.controls.z, 0, 1000)}",
+            f"{CYAN}------------------------------------------------------------------------{RESET}",
+            f"  {BOLD}SIMULATED THRUSTER PWM OUTPUTS:{RESET}",
+            f"    Motor 1 (Port / Left):      {self.m1_pwm:4d} µs  {bar(self.m1_pwm, 1100, 1900)}",
+            f"    Motor 2 (Starboard / Right): {self.m2_pwm:4d} µs  {bar(self.m2_pwm, 1100, 1900)}",
+            f"    Motor 3 (Vertical / Center): {self.m3_pwm:4d} µs  {bar(self.m3_pwm, 1100, 1900)}",
+            f"{CYAN}------------------------------------------------------------------------{RESET}",
+            f"  {BOLD}RECENT EVENT LOG:{RESET}",
+        ]
+
+        if not self.events:
+            lines.append(f"    {DIM}No events yet. Connect Sub Control app to begin.{RESET}")
+        else:
+            for ev in list(self.events)[-5:]:
+                lines.append(f"    {ev}")
+
+        lines.append(f"{CYAN}------------------------------------------------------------------------{RESET}")
+        lines.append(f"  Packets RX: {self.total_packets_rx:<8d} Packets TX: {self.total_packets_tx:<8d}  (Press Ctrl+C to exit)")
+
+        out.write("\n".join(lines) + "\n")
+        out.flush()
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="ArduSub Flight Controller (FC) Spoofer & Telemetry Simulator",
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+    )
+    parser.add_argument(
+        "--endpoint",
+        type=str,
+        default="tcpin:127.0.0.1:5760",
+        help="MAVLink connection string (e.g. 'tcpin:127.0.0.1:5760', 'udpin:127.0.0.1:14550', 'COM3')",
+    )
+    parser.add_argument(
+        "--baud",
+        type=int,
+        default=57600,
+        help="Baud rate (for serial COM ports)",
+    )
+    parser.add_argument(
+        "--cells",
+        type=int,
+        default=4,
+        help="Battery cell count (4S = 16.0V nominal)",
+    )
+    parser.add_argument(
+        "--voltage",
+        type=float,
+        default=15.8,
+        help="Nominal starting battery voltage (V)",
+    )
+    parser.add_argument(
+        "--no-dashboard",
+        action="store_true",
+        help="Disable interactive terminal dashboard and use plain output",
+    )
+
+    args = parser.parse_args()
+
+    # Enable ANSI escape sequences on Windows console
+    if os.name == "nt":
+        os.system("")
+
+    spoofer = FlightControllerSpoofer(
+        endpoint=args.endpoint,
+        baud=args.baud,
+        battery_cells=args.cells,
+        nominal_voltage=args.voltage,
+        show_dashboard=not args.no_dashboard,
+    )
+    spoofer.run()
+
+
+if __name__ == "__main__":
+    main()

SUB Control/run_spoofer.bat

@@ -0,0 +1,9 @@
+@echo off
+title ArduSub FC Spoofer
+cd /d "%~dp0"
+if exist ".venv\Scripts\python.exe" (
+    ".venv\Scripts\python.exe" -u fc_spoofer.py %*
+) else (
+    python -u fc_spoofer.py %*
+)
+pause

SUB Control/run_spoofer.ps1

@@ -0,0 +1,20 @@
+$ErrorActionPreference = "Stop"
+$projectRoot = Split-Path -Parent $MyInvocation.MyCommand.Path
+Set-Location -LiteralPath $projectRoot
+
+$existingListener = Get-NetTCPConnection -LocalPort 5760 -State Listen -ErrorAction SilentlyContinue | Select-Object -First 1
+if ($existingListener) {
+    $existingProcess = Get-CimInstance Win32_Process -Filter "ProcessId=$($existingListener.OwningProcess)" -ErrorAction SilentlyContinue
+    Write-Host ""
+    Write-Host "The simulator is already LISTENING on tcp:127.0.0.1:5760." -ForegroundColor Green
+    Write-Host "Process: $($existingListener.OwningProcess) $($existingProcess.Name)"
+    Write-Host "Leave that simulator running and select 'Simulator (TCP 5760)' in SUB Control."
+    Write-Host ""
+    exit 0
+}
+
+if (Test-Path -LiteralPath ".venv\Scripts\python.exe") {
+    & .venv\Scripts\python.exe -u fc_spoofer.py @args
+} else {
+    & python -u fc_spoofer.py @args
+}

SUB Control/web/app.js

@@ -1,25 +1,68 @@
+const STATUS_LABELS = {
+  disconnected: 'Disconnected — select a port and connect',
+  connecting: 'Connecting…',
+  connected_disarmed: 'Connected · Disarmed',
+  armed: 'Connected · Armed',
+  link_degraded: 'Signal lost — check tether',
+};
 const $=s=>document.querySelector(s), $$=s=>[...document.querySelectorAll(s)];
-const control={forward:0,turn:0,vertical:0}, keys=new Set(); let bridgeReady=false, connected=false, batteryConfig={}, servoSignature='', lastAxisSend=0, axisTimer=0;
+const control={forward:0,turn:0,vertical:0}, keys=new Set(); let bridgeReady=false, appState='disconnected', batteryConfig={}, servoSignature='', lastAxisSend=0, axisTimer=0;
 const api=(name,...args)=>window.pywebview.api[name](...args);
 addEventListener('pointermove',e=>{const button=e.target.closest?.('button:not(.battery-card), .stick');if(!button)return;const rect=button.getBoundingClientRect();button.style.setProperty('--glow-x',`${e.clientX-rect.left}px`);button.style.setProperty('--glow-y',`${e.clientY-rect.top}px`)});
 document.addEventListener('click',e=>{const btn=e.target.closest('.num-step');if(!btn)return;const pill=btn.closest('.number-pill');if(!pill)return;const input=pill.querySelector('input');if(!input)return;const step=+input.step||1,min=input.min!==''?+input.min:-Infinity,max=input.max!==''?+input.max:Infinity;let val=+input.value||0;if(btn.classList.contains('down'))val=Math.max(min,+(val-step).toFixed(4));else val=Math.min(max,+(val+step).toFixed(4));input.value=val;input.dispatchEvent(new Event('input',{bubbles:true}));input.dispatchEvent(new Event('change',{bubbles:true}))});
 function toast(message,error=false){const el=$('#toast');el.textContent=message;el.className=`toast show${error?' error':''}`;clearTimeout(toast.t);toast.t=setTimeout(()=>el.className='toast',2600)}
 window.showToast=toast;
-function populatePorts(ports){const p=$('#port'),old=p.value;p.innerHTML='';if(!ports.length)p.add(new Option('No COM ports',''));ports.forEach(x=>p.add(new Option(x,x)));if(ports.includes(old))p.value=old}
+function populatePorts(ports){
-function sendAxes(){if(!bridgeReady)return;const transmit=()=>{lastAxisSend=performance.now();axisTimer=0;api('set_axes',control.forward,control.turn,control.vertical).catch(e=>toast(e.message,true))},wait=50-(performance.now()-lastAxisSend);if(wait<=0)transmit();else{clearTimeout(axisTimer);axisTimer=setTimeout(transmit,wait)}}
+  const p=$('#port');
-function updateReadouts(){ $('#surge-readout').textContent=Math.round(control.forward*100);$('#yaw-readout').textContent=Math.round(control.turn*100);$('#heave-readout').textContent=Math.round(control.vertical*100)}
+  if(!p)return;
+  const old=p.value||'';
+  p.innerHTML='';
   
-window.setJoyControl=(x,y)=>{control.turn=x;control.forward=-y;updateReadouts();sendAxes()};
+  const allList=[];
+  const seen=new Set();
+
+  const addPort=item=>{
+    let dev=item, lbl=item;
+    if(item&&typeof item==='object'){
+      dev=item.device||'';
+      lbl=item.label||dev;
+    }
+    if(dev&&!seen.has(dev)){
+      seen.add(dev);
+      allList.push({device:dev, label:lbl});
+    }
+  };
+
+  if(Array.isArray(ports)) ports.forEach(addPort);
+  addPort({device:'demo', label:'Demo Mode (no hardware)'});
+
+  let matched=false;
+  allList.forEach(item=>{
+    const opt=new Option(item.label, item.device);
+    p.add(opt);
+    if(item.device===old){
+      p.value=item.device;
+      matched=true;
+    }
+  });
+  if(!matched&&allList.length>0){
+    p.value=allList[0].device;
+  }
+}
+function sendAxes(){if(!bridgeReady||appState!=='armed')return;const transmit=()=>{lastAxisSend=performance.now();axisTimer=0;api('set_axes',control.forward,control.turn,control.vertical).catch(e=>toast(e.message,true))},wait=50-(performance.now()-lastAxisSend);if(wait<=0)transmit();else{clearTimeout(axisTimer);axisTimer=setTimeout(transmit,wait)}}
+function updateReadouts(){ if(appState!=='armed'){$('#surge-readout').textContent='—';$('#yaw-readout').textContent='—';$('#heave-readout').textContent='—';return;}$('#surge-readout').textContent=Math.round(control.forward*100);$('#yaw-readout').textContent=Math.round(control.turn*100);$('#heave-readout').textContent=Math.round(control.vertical*100);}
+
+window.setJoyControl=(x,y)=>{if(appState!=='armed')return;control.turn=x;control.forward=-y;updateReadouts();sendAxes();};
 function releaseHandle(el){el.classList.remove('pressed');el.classList.add('released');setTimeout(()=>el.classList.remove('released'),520)}
 
 const heave=$('#heave'),hknob=$('#heave-knob'),hfill=$('#heave-fill');let heaveDrag=false,heaveAnim=0;
-function setHeave(v,send=true){v=Math.max(-1,Math.min(1,v));control.vertical=v;hknob.style.top=`${50-v*43}%`;hfill.style.top=v>=0?`${50-v*43}%`:'50%';hfill.style.height=`${Math.abs(v)*43}%`;updateReadouts();if(send)sendAxes()}
+function setHeave(v,send=true){if(appState!=='armed'&&v!==0)return;v=Math.max(-1,Math.min(1,v));control.vertical=v;hknob.style.top=`${50-v*43}%`;hfill.style.top=v>=0?`${50-v*43}%`:'50%';hfill.style.height=`${Math.abs(v)*43}%`;updateReadouts();if(send&&appState==='armed')sendAxes();}
 function heaveEvent(e){const b=heave.getBoundingClientRect();setHeave((b.top+b.height/2-e.clientY)/(b.height*.43))}
-heave.addEventListener('pointerdown',e=>{heaveDrag=true;hknob.classList.remove('released');hknob.classList.add('pressed');cancelAnimationFrame(heaveAnim);heave.setPointerCapture(e.pointerId);heaveEvent(e)});heave.addEventListener('pointermove',e=>{if(heaveDrag)heaveEvent(e)});heave.addEventListener('pointerup',()=>{heaveDrag=false;releaseHandle(hknob);easeHeave()});heave.addEventListener('pointercancel',()=>{heaveDrag=false;releaseHandle(hknob);easeHeave()});
+heave.addEventListener('pointerdown',e=>{if(appState!=='armed')return;heaveDrag=true;hknob.classList.remove('released');hknob.classList.add('pressed');cancelAnimationFrame(heaveAnim);heave.setPointerCapture(e.pointerId);heaveEvent(e)});heave.addEventListener('pointermove',e=>{if(heaveDrag)heaveEvent(e)});heave.addEventListener('pointerup',()=>{heaveDrag=false;releaseHandle(hknob);easeHeave()});heave.addEventListener('pointercancel',()=>{heaveDrag=false;releaseHandle(hknob);easeHeave()});
 function easeHeave(){const sv=control.vertical,start=performance.now();function frame(now){const p=Math.min(1,(now-start)/400),smooth=p*p*(3-2*p);setHeave(sv*(1-smooth));if(p<1)heaveAnim=requestAnimationFrame(frame)}heaveAnim=requestAnimationFrame(frame)}
 
-function applyKeys(){const turn=(keys.has('d')||keys.has('e')?1:0)-(keys.has('a')||keys.has('q')?1:0),forward=(keys.has('w')?1:0)-(keys.has('s')?1:0),vertical=(keys.has('r')?1:0)-(keys.has('f')?1:0);if(turn||forward){window.joystick3D?.setPos(turn,-forward)}else{window.joystick3D?.easeBack()}if(vertical){cancelAnimationFrame(heaveAnim);setHeave(vertical)}else if(!heaveDrag)easeHeave()}
+function applyKeys(){if(appState!=='armed'){keys.clear();window.joystick3D?.easeBack();if(!heaveDrag)easeHeave();return;}const turn=(keys.has('d')||keys.has('e')?1:0)-(keys.has('a')||keys.has('q')?1:0),forward=(keys.has('w')?1:0)-(keys.has('s')?1:0),vertical=(keys.has('r')?1:0)-(keys.has('f')?1:0);if(turn||forward){window.joystick3D?.setPos(turn,-forward)}else{window.joystick3D?.easeBack()}if(vertical){cancelAnimationFrame(heaveAnim);setHeave(vertical)}else if(!heaveDrag)easeHeave();}
-addEventListener('keydown',e=>{if(/^(INPUT|SELECT)$/.test(e.target.tagName))return;if(e.key==='F2'){e.preventDefault();if(!e.repeat)startArmHold();return}const shortcuts={F1:'#manual',F3:'#disarm'};if(shortcuts[e.key]){e.preventDefault();if(!e.repeat)$(shortcuts[e.key]).click();return}const k=e.key.toLowerCase();if('wasdqerf'.includes(k)&&!keys.has(k)){keys.add(k);applyKeys()}});addEventListener('keyup',e=>{if(e.key==='F2'){e.preventDefault();stopArmHold(true);return}const k=e.key.toLowerCase();if(keys.delete(k))applyKeys()});
+addEventListener('keydown',e=>{if(/^(INPUT|SELECT)$/.test(e.target.tagName))return;if(e.key==='F2'){e.preventDefault();if(appState==='connected_disarmed'&&engageButton?.classList.contains('arm')&&!e.repeat)startEngageHold();return;}if(e.key==='F1'){e.preventDefault();if(appState==='connected_disarmed'&&!engageButton?.classList.contains('arm')&&!e.repeat)engageButton?.click();return;}if(e.key==='F3'){e.preventDefault();if(appState==='armed'&&!e.repeat)engageButton?.click();return;}const k=e.key.toLowerCase();if('wasdqerf'.includes(k)){if(appState!=='armed')return;if(!keys.has(k)){keys.add(k);applyKeys();}}});addEventListener('keyup',e=>{if(e.key==='F2'){e.preventDefault();stopEngageHold(true);return;}const k=e.key.toLowerCase();if(keys.delete(k))applyKeys();});
 addEventListener('blur',()=>{keys.clear();window.joystick3D?.easeBack();if(!heaveDrag)easeHeave()});
 
 function openModal(id){
@@ -119,66 +162,237 @@ if(rovStage){
     if(file)handleStlFile(file);
   });
 }
-$('#refresh').onclick=async e=>{const button=e.currentTarget;button.classList.remove('spinning');void button.offsetWidth;button.classList.add('spinning');setTimeout(()=>button.classList.remove('spinning'),650);if(bridgeReady)populatePorts(await api('refresh_ports'))};$('#connect').onclick=async()=>{try{if(connected)await api('disconnect');else await api('connect',$('#port').value,+$('#baud').value,+$('#rate').value)}catch(e){toast(e.message,true)}};
+$('#refresh').onclick=async e=>{const button=e.currentTarget;button.classList.remove('spinning');void button.offsetWidth;button.classList.add('spinning');setTimeout(()=>button.classList.remove('spinning'),650);if(bridgeReady)populatePorts(await api('refresh_ports'))};
-$('#manual').onclick=async()=>{try{await api('command','manual');toast('Manual mode command sent')}catch(e){toast(e.message,true)}};
+$('#connect').onclick=async()=>{
-const armButton=$('#arm');
+  const btn=$('#connect');
-let armHoldTimer=null, armStart=0, armCharged=false;
+  const label=btn.querySelector('.btn-label')||btn;
-const ARM_HOLD_MS=1000;
+  const p=$('#port');
+  const port=p?p.value:'';
 
-function updateArmProgress(){
+  if(appState==='connecting'){
-  if(!armStart)return;
+    label.textContent='Canceling…';
-  const elapsed=performance.now()-armStart;
+    try{ await api('disconnect'); }catch(_){}
-  const progress=Math.min(1,elapsed/ARM_HOLD_MS);
+    return;
-  armButton.style.setProperty('--arm-progress',`${progress*100}%`);
+  }
+
+  if(appState!=='disconnected'){
+    label.textContent='Disconnecting…';
+    try{
+      await api('disconnect');
+      toast('Disconnected');
+    }catch(e){
+      toast(e.message,true);
+    }
+  }else{
+    if(!port){
+      toast('Select or enter a port to connect',true);
+      return;
+    }
+    btn.classList.add('is-connecting');
+    label.textContent='Connecting…';
+    const statusEl=$('#status-text');
+    if(statusEl)statusEl.textContent=`Opening ${port}…`;
+    toast(`Connecting to ${port}…`);
+    try{
+      const confirmedState=await api('connect',port,+$('#baud').value,+$('#rate').value);
+      if(confirmedState)render(confirmedState);
+      toast('MAVLink connected');
+    }catch(e){
+      btn.classList.remove('is-connecting');
+      label.textContent='Connect';
+      toast(e.message,true);
+      if(statusEl)statusEl.textContent=`Connection error: ${e.message}`;
+    }
+  }
+};
+const customPortBtn=$('#custom-port-btn'), customPortInput=$('#custom-port-input');
+if(customPortBtn&&customPortInput){
+  const applyCustomPort=()=>{
+    const val=customPortInput.value.trim();
+    if(!val)return;
+    const p=$('#port');
+    let exists=false;
+    for(const opt of p.options){
+      if(opt.value===val){opt.selected=true;exists=true;break;}
+    }
+    if(!exists){
+      p.add(new Option(`Custom (${val})`, val), 0);
+      p.value=val;
+    }
+    closeModal($('#link-modal'));
+    toast(`Selected port: ${val}`);
+  };
+  customPortBtn.onclick=applyCustomPort;
+  customPortInput.onkeydown=e=>{if(e.key==='Enter'){e.preventDefault();applyCustomPort();}};
+}
+const engageButton=$('#engage');
+let engageHoldTimer=null, engageStart=0, engageCharged=false, settingMode=false;
+const ENGAGE_HOLD_MS=1000;
+
+function isManualMode(s){
+  const m=(s&&s.mode)?String(s.mode).toUpperCase():'';
+  return m==='MANUAL';
+}
+
+function updateEngageProgress(){
+  if(!engageStart||appState!=='connected_disarmed'||!engageButton?.classList.contains('arm')){
+    stopEngageHold(true);
+    return;
+  }
+  const elapsed=performance.now()-engageStart;
+  const progress=Math.min(1,elapsed/ENGAGE_HOLD_MS);
+  engageButton.style.setProperty('--arm-progress',`${progress*100}%`);
   if(progress>=1){
-    armCharged=true;
+    engageCharged=true;
-    stopArmHold(false);
+    stopEngageHold(false);
-    armButton.classList.add('charged');
+    engageButton.classList.add('charged');
-    setTimeout(()=>armButton.classList.remove('charged'),600);
+    setTimeout(()=>engageButton.classList.remove('charged'),600);
     api('command','arm').then(()=>toast('Vehicle armed')).catch(e=>toast(e.message,true));
     return;
   }
-  armHoldTimer=requestAnimationFrame(updateArmProgress);
+  engageHoldTimer=requestAnimationFrame(updateEngageProgress);
 }
 
-function startArmHold(e){
+function startEngageHold(e){
-  if(armStart||armCharged)return;
+  if(appState!=='connected_disarmed'||!engageButton?.classList.contains('arm'))return;
+  if(engageStart||engageCharged)return;
   if(e&&e.button!==undefined&&e.button!==0)return;
-  armStart=performance.now();
+  engageStart=performance.now();
-  armCharged=false;
+  engageCharged=false;
-  armButton.classList.add('charging');
+  engageButton.classList.add('charging');
-  armButton.style.setProperty('--arm-progress','0%');
+  engageButton.style.setProperty('--arm-progress','0%');
-  armHoldTimer=requestAnimationFrame(updateArmProgress);
+  engageHoldTimer=requestAnimationFrame(updateEngageProgress);
 }
 
-function stopArmHold(wasCancelled=true){
+function stopEngageHold(wasCancelled=true){
-  if(!armStart)return;
+  if(!engageStart)return;
-  const elapsed=performance.now()-armStart;
+  const elapsed=performance.now()-engageStart;
-  cancelAnimationFrame(armHoldTimer);
+  cancelAnimationFrame(engageHoldTimer);
-  armHoldTimer=null;
+  engageHoldTimer=null;
-  armStart=0;
+  engageStart=0;
-  armButton.classList.remove('charging');
+  engageButton.classList.remove('charging');
-  armButton.style.setProperty('--arm-progress','0%');
+  engageButton.style.setProperty('--arm-progress','0%');
-  if(wasCancelled&&!armCharged&&elapsed<ARM_HOLD_MS&&elapsed>70){
+  if(wasCancelled&&!engageCharged&&elapsed<ENGAGE_HOLD_MS&&elapsed>70){
-    toast('Hold for 1s to Arm vehicle');
+    toast('Hold for 1s to Engage vehicle');
   }
-  armCharged=false;
+  engageCharged=false;
 }
 
-armButton.addEventListener('pointerdown',startArmHold);
+if(engageButton){
-armButton.addEventListener('pointerup',()=>stopArmHold(true));
+  engageButton.addEventListener('pointerdown',startEngageHold);
-armButton.addEventListener('pointerleave',()=>stopArmHold(true));
+  engageButton.addEventListener('pointerup',()=>stopEngageHold(true));
-armButton.addEventListener('pointercancel',()=>stopArmHold(true));
+  engageButton.addEventListener('pointerleave',()=>stopEngageHold(true));
-armButton.addEventListener('contextmenu',e=>e.preventDefault());
+  engageButton.addEventListener('pointercancel',()=>stopEngageHold(true));
+  engageButton.addEventListener('contextmenu',e=>e.preventDefault());
+  
+  engageButton.onclick=async()=>{
+    if(appState==='armed'){
+      try{
+        await api('command','disarm');
+        toast('Disarm command sent');
+      }catch(e){
+        toast(e.message,true);
+      }
+    }else if(appState==='connected_disarmed'&&!engageButton.classList.contains('arm')){
+      try{
+        settingMode=true;
+        const lbl=$('#engage-label');
+        if(lbl)lbl.textContent='Setting mode…';
+        await api('command','manual');
+        toast('Manual mode requested');
+      }catch(e){
+        settingMode=false;
+        toast(e.message,true);
+      }
+    }
+  };
+}
 
-$('#disarm').onclick=async()=>{try{await api('command','disarm');toast('Disarm command sent')}catch(e){toast(e.message,true)}};
 $('#logs').onclick=()=>api('open_logs');
 function setGain(value){const gain=$('#gain');gain.value=Math.max(+gain.min,Math.min(+gain.max,value));$('#gain-value').textContent=`${gain.value}%`;if(bridgeReady)api('set_gain',+gain.value)}
 $('#gain').oninput=e=>setGain(+e.target.value);$('#gain-down').onclick=()=>setGain(+$('#gain').value-5);$('#gain-up').onclick=()=>setGain(+$('#gain').value+5);
 $('#battery-form').onsubmit=async e=>{e.preventDefault();const data=Object.fromEntries(new FormData(e.target));try{batteryConfig=await api('save_battery',data);closeModal($('#battery-modal'));toast('Battery settings saved')}catch(err){toast(err.message,true)}};
 function fillBatteryForm(){for(const [k,v] of Object.entries(batteryConfig)){const el=$(`#battery-form [name=${k}]`);if(el)el.value=v}}
 function renderMotors(servos){const signature=JSON.stringify(servos);if(signature===servoSignature)return;servoSignature=signature;const list=$('#motor-list');list.innerHTML='';for(let i=1;i<=16;i++){const s=servos[String(i)]||{},row=document.createElement('div');row.className='motor-row';const opts=['<option value="0">Unassigned</option>',...Array.from({length:12},(_,n)=>`<option value="${n+1}" ${s.motor===n+1?'selected':''}>Motor ${n+1}</option>`)].join('');row.innerHTML=`<strong>SERVO${i}</strong><select aria-label="SERVO${i} function">${opts}</select><span>${s.direction==null?'—':s.direction===-1?'Reversed':'Normal'}</span><button class="button subtle">Reverse</button>`;row.querySelector('select').onchange=e=>api('set_servo_function',i,+e.target.value).catch(x=>toast(x.message,true));row.querySelector('button').onclick=()=>api('reverse_motor',i).catch(x=>toast(x.message,true));list.append(row)}}
-function render(s){connected=s.connected;$('#connect').textContent=connected?'Disconnect':'Connect';const linkText=s.link==='LINK OK'?'connected':(s.link?s.link.toLowerCase():'disconnected');$('#link').textContent=linkText;$('.link-state').classList.toggle('online',s.link==='LINK OK'||s.link==='connected');$('#vehicle').textContent=s.vehicle?s.vehicle.toLowerCase():'no heartbeat';$('#status').textContent=s.status?s.status.toLowerCase():'ready';const b=s.battery;if(b){$('#battery-title').textContent=`${b.voltage.toFixed(2)} V`;$('#battery-percent').textContent=`${Math.round(b.percent)}% • ${b.cells}s`;$('#battery-fill').style.width=`${b.percent}%`;$('#battery-fill').style.background=b.low?'var(--red)':'var(--acid)'}else{$('#battery-title').textContent='—';$('#battery-percent').textContent='waiting';$('#battery-fill').style.width='0'}renderMotors(s.servos)}
+function render(s){
+  appState=s.app_state||'disconnected';
+  document.body.dataset.appState=appState;
+  const isOnline=(appState==='connected_disarmed'||appState==='armed');
+  const connectBtn=$('#connect');
+  const connectLabel=connectBtn?connectBtn.querySelector('.btn-label'):null;
+  if(connectBtn){
+    if(appState==='connecting'){
+      if(connectLabel)connectLabel.textContent='Connecting…';
+      else connectBtn.textContent='Connecting…';
+      connectBtn.classList.add('is-connecting');
+      connectBtn.classList.remove('is-connected');
+    }else if(appState!=='disconnected'){
+      if(connectLabel)connectLabel.textContent='Disconnect';
+      else connectBtn.textContent='Disconnect';
+      connectBtn.classList.remove('is-connecting');
+      connectBtn.classList.add('is-connected');
+    }else{
+      if(connectLabel)connectLabel.textContent='Connect';
+      else connectBtn.textContent='Connect';
+      connectBtn.classList.remove('is-connecting', 'is-connected');
+    }
+  }
+  const engageBtn=$('#engage');
+  const engageLabel=$('#engage-label');
+  if(engageBtn&&engageLabel){
+    if(appState==='armed'){
+      settingMode=false;
+      engageBtn.disabled=false;
+      engageBtn.className='button danger';
+      engageBtn.title='Disarm (F3)';
+      engageLabel.textContent='Disarm';
+    }else if(appState==='connected_disarmed'){
+      const manualConfirmed=isManualMode(s);
+      if(manualConfirmed){
+        settingMode=false;
+        engageBtn.disabled=false;
+        engageBtn.className='button arm';
+        engageBtn.title='Hold to Engage (F2)';
+        engageLabel.textContent='Hold to Engage';
+      }else{
+        engageBtn.disabled=false;
+        engageBtn.className='button subtle';
+        engageBtn.title='Set Manual Mode (F1)';
+        engageLabel.textContent=settingMode?'Setting mode…':'Engage';
+      }
+    }else{
+      settingMode=false;
+      engageBtn.disabled=true;
+      engageBtn.className='button subtle';
+      engageBtn.title='Engage';
+      engageLabel.textContent='Engage';
+    }
+  }
+  const motorBtn=$('[data-open="motors-modal"]');
+  if(motorBtn)motorBtn.disabled=(!isOnline);
+  
+  const statusEl=$('#status-text');
+  if(statusEl){
+    if(s.status){
+      statusEl.textContent=s.status;
+    }else{
+      statusEl.textContent=STATUS_LABELS[appState]||STATUS_LABELS.disconnected;
+    }
+  }
+  updateReadouts();
+  const b=s.battery;
+  if(b){
+    $('#battery-title').textContent=`${b.voltage.toFixed(2)} V`;
+    $('#battery-percent').textContent=`${Math.round(b.percent)}% • ${b.cells}s`;
+    $('#battery-fill').style.width=`${b.percent}%`;
+    $('#battery-fill').style.background=b.low?'var(--red)':'var(--acid)';
+  }else{
+    $('#battery-title').textContent='—';
+    $('#battery-percent').textContent='waiting';
+    $('#battery-fill').style.width='0';
+  }
+  renderMotors(s.servos);
+}
 
 async function poll(){if(!bridgeReady)return;try{render(await api('poll'))}catch(e){}setTimeout(poll,250)}
 let modelLoadPromise=null;
@@ -259,7 +473,6 @@ async function boot(){
   if(booted||!window.pywebview?.api)return;
   booted=true;
   bridgeReady=true;
-  loadDefaultModel();
   try{
     const init=await api('initial_state');
     batteryConfig=init.battery_config;
@@ -267,8 +480,11 @@ async function boot(){
     fillBatteryForm();
     render(init.state);
     poll();
+    // Populate the serial selector before starting the optional model load.
+    // A large cached mesh must never delay an operator seeing USB COM ports.
+    loadDefaultModel();
     setInterval(async()=>{
-      if(!connected){
+      if(appState==='disconnected'){
         try{populatePorts(await api('refresh_ports'))}catch(_){}
       }
     },2000);

SUB Control/web/index.html

@@ -22,23 +22,24 @@
           <input id="model-input" type="file" accept=".stl,.STL" hidden>
         </div>
       </div>
-      <div class="vehicle-name"><small>vehicle</small><strong id="vehicle">no heartbeat</strong><span>SimpleROV-3 • differential drive</span></div>
+      <div class="vehicle-name"><small>vehicle</small><strong>SimpleROV-3</strong><span>3 thrusters • differential drive</span></div>
       <div class="rail-bottom">
         <button class="battery-card ghost" data-open="battery-modal">
           <span><small>Battery</small><strong id="battery-title">—</strong></span><i id="battery-percent">waiting</i>
           <b><em id="battery-fill"></em></b>
         </button>
-        <div class="link-state"><span id="link-dot"></span><strong id="link">disconnected</strong></div>
       </div>
     </aside>
 
     <section class="workspace">
       <header class="topbar">
         <div class="connection">
-          <select id="port" aria-label="Serial port"><option value="">Select COM port…</option></select>
+          <select id="port" aria-label="Serial port">
+            <option value="demo" selected>Demo Mode (no hardware)</option>
+          </select>
           <button id="refresh" class="icon-button" title="Refresh ports" aria-label="Refresh ports"><svg viewBox="0 0 24 24" aria-hidden="true"><path d="M20 7v5h-5M4 17v-5h5M18.5 9A7 7 0 0 0 6.8 6.8L4 10m16 4-2.8 3.2A7 7 0 0 1 5.5 15"/></svg></button>
           <button class="icon-button" data-open="link-modal" title="Link settings" aria-label="Link settings"><svg class="dots-icon" viewBox="0 0 24 24" aria-hidden="true"><circle cx="5" cy="12" r="1.25"/><circle cx="12" cy="12" r="1.25"/><circle cx="19" cy="12" r="1.25"/></svg></button>
-          <button id="connect" class="button connect-button">Connect</button>
+          <button id="connect" class="button connect-button" aria-label="Toggle connection"><span class="btn-spinner" aria-hidden="true"></span><span class="btn-label">Connect</span></button>
         </div>
         <div class="topbar-spacer pywebview-drag-region"></div>
         <div class="window-actions">
@@ -71,21 +72,19 @@
       <section class="bottom-actions">
         <section class="command-bar">
           <div class="commands">
-            <button id="manual" class="button subtle"><span>Manual</span></button>
+            <button id="engage" class="button subtle" aria-label="Engage" title="Engage"><span class="arm-copy"><span id="engage-label" class="arm-label">Engage</span><span class="arm-holding-label">Engaging…</span></span></button>
-            <button id="arm" class="button arm" aria-label="Hold to arm" title="Hold to arm (F2)"><span class="arm-copy"><span class="arm-label">Arm</span><span class="arm-holding-label">Holding…</span></span></button>
-            <button id="disarm" class="button danger"><span>Disarm</span></button>
           </div>
           <label class="output-limit"><span>output limit <b id="gain-value">20%</b></span><div class="range-pill"><button id="gain-down" type="button" aria-label="Decrease output limit">‹</button><input id="gain" type="range" min="5" max="50" value="20"><button id="gain-up" type="button" aria-label="Increase output limit">›</button></div></label>
           <button class="button subtle" data-open="motors-modal">Motor Setup</button>
         </section>
       </section>
-      <div class="status-line"><span></span><p id="status">ready. select a USB port to begin.</p><a id="logs" class="logs-link" title="Open session logs" aria-label="Open session logs">logs</a></div>
+      <div class="status-line"><span id="status-dot" class="status-dot"></span><p id="status-text">Disconnected — select a port and connect</p><a id="logs" class="logs-link" title="Open session logs" aria-label="Open session logs">logs</a></div>
     </section>
   </main>
 
   <div id="toast" class="toast"></div>
 
-  <dialog id="link-modal" class="modal"><button class="modal-close" data-close>×</button><small>connection</small><h2>Link Settings</h2><div class="form-grid two"><label><span>Baud rate</span><select id="baud"><option>9600</option><option>19200</option><option>38400</option><option selected>57600</option><option>115200</option></select></label><label><span>Control rate</span><select id="rate"><option>10</option><option selected>20</option></select></label></div><p class="note">20 Hz is recommended for smooth intermediate commands on this link.</p></dialog>
+  <dialog id="link-modal" class="modal"><button class="modal-close" data-close>×</button><small>connection</small><h2>Link Settings</h2><div class="form-grid two"><label><span>Baud rate</span><select id="baud"><option>9600</option><option>19200</option><option>38400</option><option selected>57600</option><option>115200</option></select></label><label><span>Control rate</span><select id="rate"><option>10</option><option selected>20</option></select></label></div><div style="margin-top:14px;"><label style="display:flex;flex-direction:column;gap:6px;"><span style="font-size:11px;font-weight:500;color:var(--muted)">Custom Port / Endpoint</span><div style="display:flex;gap:8px;"><input id="custom-port-input" placeholder="e.g. COM3 or tcp:127.0.0.1:5760" style="flex:1;height:32px;padding:0 12px;font-size:11px;"><button type="button" id="custom-port-btn" class="button subtle" style="white-space:nowrap;">Use Port</button></div></label></div><p class="note" style="margin-top:14px;">20 Hz is recommended for smooth intermediate commands on this link.</p></dialog>
   <dialog id="battery-modal" class="modal"><button class="modal-close" data-close>×</button><small>Power</small><h2>Battery Settings</h2><form id="battery-form" class="form-grid three"><label><span>Cells (S)</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="cells" type="number" min="1" step="1"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><label><span>Capacity (mAh)</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="capacity_mah" type="number" min="1" step="50"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><label><span>C rating</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="c_rating" type="number" min="1" step=".1"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><label><span>Full V / cell</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="full_v_per_cell" type="number" step=".01"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><label><span>Empty V / cell</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="empty_v_per_cell" type="number" step=".01"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><label><span>Warning %</span><div class="number-pill"><button type="button" class="num-step down" tabindex="-1">‹</button><input name="warning_percent" type="number" min="0" max="100" step="1"><button type="button" class="num-step up" tabindex="-1">›</button></div></label><div class="modal-actions wide"><button type="button" class="button subtle" data-close>Cancel</button><button class="button connect-button">Save Settings</button></div></form></dialog>
   <dialog id="motors-modal" class="modal motor-modal"><button class="modal-close" data-close>×</button><small>configuration</small><h2>Motor Outputs</h2><p class="note">Function and direction are read one parameter at a time to protect the low-bandwidth link.</p><div class="motor-head"><span>Output</span><span>Function</span><span>Direction</span><span></span></div><div id="motor-list" class="motor-list"></div></dialog>
 

SUB Control/web_ui.py

@@ -24,12 +24,15 @@ class ControlApi:
     def __init__(self):
         self.events: queue.Queue = queue.Queue()
         self.worker = MavlinkWorker(self.events)
+        self.demo_mode = False
         self.lock = threading.Lock()
         self.state = {
             "connected": False,
             "link": "DISCONNECTED",
             "vehicle": "No heartbeat",
             "armed": False,
+            "mode": None,
+            "app_state": "disconnected",
             "status": "Ready. Select a USB port to begin.",
             "battery": None,
             "log_path": None,
@@ -57,14 +60,26 @@ class ControlApi:
 
     def initial_state(self):
         return {
-            "ports": [p.device for p in list_ports.comports()],
+            "ports": self.refresh_ports(),
             "battery_config": self.battery_config,
             "state": self._snapshot(),
             "model_info": self.get_saved_model_info(),
         }
 
     def refresh_ports(self):
-        return [p.device for p in list_ports.comports()]
+        ports = []
+        # Add physical and virtual serial COM ports
+        for p in list_ports.comports():
+            desc = p.description or ""
+            if desc and desc != "n/a" and desc != p.device:
+                label = f"{p.device} ({desc})"
+            else:
+                label = p.device
+            ports.append({"device": p.device, "label": label, "type": "serial"})
+
+        # Built-in UI testing: no external process, port, or MAVLink socket.
+        ports.insert(0, {"device": "demo", "label": "Demo Mode (no hardware)", "type": "demo"})
+        return ports
 
     def minimize_window(self):
         if self._window:
@@ -202,22 +217,69 @@ class ControlApi:
         return None
 
     def connect(self, port, baud=57600, rate=20):
+        print(f"[web_ui] connect() called: port={port!r}, baud={baud!r}, rate={rate!r}")
         if not port:
             raise ValueError("Select a USB serial port")
+        if str(port).lower() in ("demo", "tcp:127.0.0.1:5760", "udpin:127.0.0.1:14550"):
+            self.demo_mode = True
+            self.servo_functions = {1: 33, 2: 34, 3: 35}
+            self.motor_directions = {1: 1, 2: 1, 3: 1}
+            with self.lock:
+                self.state.update(
+                    connected=True, link="LINK OK", vehicle="DEMO • DISARMED",
+                    armed=False, mode="MANUAL", status="Demo mode ready — no hardware connected.",
+                    battery={"voltage": 15.8, "per_cell": 3.95, "percent": 72,
+                             "cells": 4, "low": False},
+                )
+                for servo in range(1, 17):
+                    function = self.servo_functions.get(servo, 0)
+                    motor = motor_number_for_function(function)
+                    self.state["servos"][str(servo)] = {
+                        "function": function, "label": MOTOR_FUNCTIONS.get(function, "Unassigned"),
+                        "motor": motor, "direction": self.motor_directions.get(motor) if motor else None,
+                    }
+            return self._snapshot()
         self.worker.rate_hz = int(rate)
         self.worker.connect(str(port), int(baud))
         with self.lock:
             self.state.update(
                 connected=True, link="CONNECTING",
                 status=f"Opening {port} at {baud} baud…",
+                armed=False,
             )
-        return True
+        print(f"[web_ui] connect() dispatched to worker thread OK")
+        # Return only once the worker has either seen a heartbeat or reported a
+        # connection failure. This makes the button independent of the regular
+        # UI polling loop and prevents an indefinite visual "Connecting" state.
+        deadline = time.monotonic() + 8.0
+        while time.monotonic() < deadline:
+            snapshot = self.poll()
+            if snapshot["app_state"] != "connecting":
+                return snapshot
+            time.sleep(0.05)
+        self.worker.disconnect()
+        time.sleep(0.1)
+        self.poll()
+        raise TimeoutError(f"No MAVLink heartbeat received from {port} within 8 seconds")
 
     def disconnect(self):
+        if self.demo_mode:
+            self.demo_mode = False
+            with self.lock:
+                self.state.update(connected=False, link="DISCONNECTED", vehicle="No heartbeat",
+                                  armed=False, mode=None, battery=None, status="Demo mode disconnected")
+            return True
         self.worker.disconnect()
         return True
 
     def set_axes(self, forward, turn, vertical):
+        if self.demo_mode:
+            with self.lock:
+                self.state["status"] = (
+                    f"Demo controls • surge {float(forward):+.2f} • "
+                    f"yaw {float(turn):+.2f} • heave {float(vertical):+.2f}"
+                )
+            return True
         self.worker.set_axes(Axes(
             max(-1.0, min(1.0, float(forward))),
             0.0,
@@ -232,6 +294,15 @@ class ControlApi:
         return value
 
     def command(self, name):
+        if self.demo_mode:
+            if name not in ("manual", "arm", "disarm"):
+                raise ValueError(f"Unknown command: {name}")
+            armed = name == "arm" if name != "manual" else self.state.get("armed", False)
+            with self.lock:
+                self.state.update(armed=armed, mode="MANUAL",
+                                  vehicle=f"DEMO • {'ARMED' if armed else 'DISARMED'}",
+                                  status=f"Demo: {'Manual mode' if name == 'manual' else name.capitalize()} confirmed")
+            return True
         if not self.worker.connection or not self.worker.target_system:
             if name == "manual":
                 raise RuntimeError("Connect to vehicle to enable Manual mode")
@@ -258,6 +329,10 @@ class ControlApi:
         if not 1 <= servo <= 16 or not 0 <= motor <= 12:
             raise ValueError("Invalid servo or motor")
         function = 0 if motor == 0 else (32 + motor if motor <= 8 else 73 + motor)
+        if self.demo_mode:
+            self.servo_functions[servo] = function
+            self._update_servo(servo)
+            return True
         self.worker.set_parameter(f"SERVO{servo}_FUNCTION", function)
         return True
 
@@ -269,6 +344,10 @@ class ControlApi:
         current = self.motor_directions.get(motor)
         if current is None:
             raise ValueError(f"MOT_{motor}_DIRECTION has not been read yet")
+        if self.demo_mode:
+            self.motor_directions[motor] = -1 if current == 1 else 1
+            self._update_servo(servo)
+            return True
         self.worker.set_parameter(f"MOT_{motor}_DIRECTION", -1 if current == 1 else 1)
         return True
 
@@ -312,9 +391,24 @@ class ControlApi:
                 )
         return self._snapshot()
 
+    def _derive_app_state(self) -> str:
+        if not self.state.get("connected"):
+            return "disconnected"
+        link = self.state.get("link", "")
+        if link == "CONNECTING":
+            return "connecting"
+        if link in ("DATA OK / HEARTBEAT DELAYED", "ALL LINK DATA LOST"):
+            return "link_degraded"
+        if self.state.get("armed"):
+            return "armed"
+        return "connected_disarmed"
+
     def _snapshot(self):
         with self.lock:
-            return json.loads(json.dumps(self.state))
+            snap = json.loads(json.dumps(self.state))
+            snap["app_state"] = self._derive_app_state()
+            snap["armed"] = bool(self.state.get("armed", False))
+            return snap
 
     def _consume(self, event):
         kind = event[0]
@@ -324,6 +418,7 @@ class ControlApi:
                 self.state.update(
                     connected=True, link="LINK OK", vehicle=f"{mode} • {'ARMED' if armed else 'DISARMED'}",
                     armed=bool(armed),
+                    mode=str(mode).upper(),
                 )
             elif kind in ("status", "statustext"):
                 self.state["status"] = event[1]
@@ -355,9 +450,13 @@ class ControlApi:
                 self.state["log_path"] = event[1]
             elif kind == "error":
                 self.state["status"] = event[1]
+                self.state["last_error"] = event[1]
             elif kind == "disconnected":
+                last_err = self.state.get("last_error")
+                status_msg = last_err if last_err else "Disconnected"
                 self.state.update(connected=False, link="DISCONNECTED", vehicle="No heartbeat",
-                                  armed=False, battery=None, status="Disconnected")
+                                  armed=False, mode=None, battery=None, status=status_msg)
+                self.state["last_error"] = None
 
     def _update_servo(self, servo):
         function = self.servo_functions.get(servo)
@@ -380,22 +479,49 @@ def _apply_dwm_styling(window):
             hwnd = int(window.native.Handle.ToInt64())
         if hwnd:
             import ctypes
+            user32 = ctypes.windll.user32
+            dwmapi = ctypes.windll.dwmapi
             corner_pref = ctypes.c_int(2)  # DWMWCP_ROUND
-            ctypes.windll.dwmapi.DwmSetWindowAttribute(
+            dwmapi.DwmSetWindowAttribute(
                 ctypes.c_void_p(hwnd), 33, ctypes.byref(corner_pref), ctypes.sizeof(corner_pref)
             )
             dark_mode = ctypes.c_int(1)  # DWMWA_USE_IMMERSIVE_DARK_MODE
-            ctypes.windll.dwmapi.DwmSetWindowAttribute(
+            dwmapi.DwmSetWindowAttribute(
                 ctypes.c_void_p(hwnd), 20, ctypes.byref(dark_mode), ctypes.sizeof(dark_mode)
             )
+            user32.SetForegroundWindow(ctypes.c_void_p(hwnd))
     except Exception:
         pass
 
 
+def _get_window_size() -> tuple[int, int, tuple[int, int]]:
+    target_w, target_h = 1280, 750
+    min_w, min_h = 960, 580
+    try:
+        import ctypes
+        user32 = ctypes.windll.user32
+        sw = user32.GetSystemMetrics(0)
+        sh = user32.GetSystemMetrics(1)
+        if sw > 0 and sh > 0:
+            target_w = min(target_w, max(min_w, int(sw * 0.92)))
+            target_h = min(target_h, max(min_h, int(sh * 0.90)))
+            min_w = min(min_w, target_w)
+            min_h = min(min_h, target_h)
+    except Exception:
+        pass
+    return target_w, target_h, (min_w, min_h)
+
+
 class AppHTTPHandler(http.server.SimpleHTTPRequestHandler):
     def log_message(self, format, *args):
         pass  # Suppress HTTP request logs in console
 
+    def end_headers(self):
+        self.send_header("Cache-Control", "no-cache, no-store, must-revalidate")
+        self.send_header("Pragma", "no-cache")
+        self.send_header("Expires", "0")
+        super().end_headers()
+
     def do_GET(self):
         unquoted = urllib.parse.unquote(self.path)
         if self.path in ("/model", "/model.stl", "/runtime/vehicle_model.stl") or "Main Assembly" in unquoted or "vehicle_model" in unquoted:
@@ -409,7 +535,6 @@ class AppHTTPHandler(http.server.SimpleHTTPRequestHandler):
                 self.send_header("Content-Type", "model/stl")
                 self.send_header("Content-Length", str(len(data)))
                 self.send_header("Access-Control-Allow-Origin", "*")
-                self.send_header("Cache-Control", "no-cache")
                 self.end_headers()
                 self.wfile.write(data)
                 return
@@ -429,10 +554,11 @@ def main():
     api._migrate_legacy_model()
     project_root = Path(__file__).resolve().parent
     port = start_local_server(project_root)
-    app_url = f"http://127.0.0.1:{port}/web/index.html"
+    app_url = f"http://127.0.0.1:{port}/web/index.html?v={int(time.time())}"
+    win_w, win_h, min_dims = _get_window_size()
     window = webview.create_window(
         "SUB Control", url=app_url, js_api=api,
-        width=1400, height=808, min_size=(1125, 690),
+        width=win_w, height=win_h, min_size=min_dims,
         background_color="#111719", frameless=True, easy_drag=False,
         shadow=True,
     )