mpremote: Fix disconnect handling on Windows and Linux.

- Handle SerialException on Windows when device disconnects
- Print clean 'device disconnected' message instead of stack trace
- Fix terminal formatting issues on Linux after disconnect
- Return disconnected state after console cleanup to avoid terminal issues

This ensures proper disconnect messages on both platforms without
showing confusing error traces to users.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

tools/mpremote/mpremote/console.py

@@ -96,8 +96,19 @@ def inWaiting(self):
         return 1 if self.ctrl_c or msvcrt.kbhit() else 0
 
     def waitchar(self, pyb_serial):
-        while not (self.inWaiting() or pyb_serial.inWaiting()):
-            time.sleep(0.01)
+        import serial
+
+        while True:
+            try:
+                if self.inWaiting() or pyb_serial.inWaiting():
+                    break
+                time.sleep(0.01)
+            except serial.SerialException as e:
+                if "ClearCommError failed" in str(e):
+                    # Device disconnected on Windows
+                    raise serial.SerialException("Device disconnected")
+                else:
+                    raise
 
     def readchar(self):
         if self.ctrl_c:

tools/mpremote/mpremote/main.py

@@ -574,7 +574,11 @@ def main():
         # If no commands were "actions" then implicitly finish with the REPL
         # using default args.
         if state.run_repl_on_completion():
-            do_repl(state, argparse_repl().parse_args([]))
+            disconnected = do_repl(state, argparse_repl().parse_args([]))
+
+            # Handle disconnection message
+            if disconnected:
+                print("\ndevice disconnected")
 
         return 0
     except CommandError as e:

tools/mpremote/mpremote/repl.py

@@ -2,13 +2,23 @@
 
 from .transport import TransportError
 
+import serial
+
 
 def do_repl_main_loop(
     state, console_in, console_out_write, *, escape_non_printable, code_to_inject, file_to_inject
 ):
+    disconnected = False
     while True:
-        console_in.waitchar(state.transport.serial)
-        c = console_in.readchar()
+        try:
+            console_in.waitchar(state.transport.serial)
+            c = console_in.readchar()
+        except serial.SerialException as e:
+            if "Device disconnected" in str(e) or "ClearCommError failed" in str(e):
+                disconnected = True
+                break
+            else:
+                raise
         if c:
             if c in (b"\x1d", b"\x18"):  # ctrl-] or ctrl-x, quit
                 break
@@ -35,8 +45,15 @@ def do_repl_main_loop(
             n = state.transport.serial.inWaiting()
         except OSError as er:
             if er.args[0] == 5:  # IO error, device disappeared
-                print("device disconnected")
+                disconnected = True
                 break
+        except Exception as er:
+            # Handle Windows serial exception
+            if isinstance(er, serial.SerialException) and "ClearCommError failed" in str(er):
+                disconnected = True
+                break
+            else:
+                raise
 
         if n > 0:
             dev_data_in = state.transport.serial.read(n)
@@ -53,6 +70,8 @@ def do_repl_main_loop(
                     console_data_out = dev_data_in
                 console_out_write(console_data_out)
 
+    return disconnected
+
 
 def do_repl(state, args):
     state.ensure_friendly_repl()
@@ -85,8 +104,9 @@ def console_out_write(b):
             capture_file.write(b)
             capture_file.flush()
 
+    disconnected = False
     try:
-        do_repl_main_loop(
+        disconnected = do_repl_main_loop(
             state,
             console,
             console_out_write,
@@ -98,3 +118,5 @@ def console_out_write(b):
         console.exit()
         if capture_file is not None:
             capture_file.close()
+
+    return disconnected