Summary

This PR adds automatic reconnection capability to the mpremote tool. When a MicroPython device disconnects, mpremote can now automatically reconnect to the same device, eliminating the need to manually
restart the tool during development.

The newreconnect command enables automatic reconnection to the exact same port, even when usingauto mode. This is particularly important in multi-device environments where you want to ensure reconnection to the same physical device.

Key features:

• Newreconnect command that works likeresume (standalone command, not a flag)
• Always reconnects to the exact same port that was previously connected when originally started inconnect auto mode
• Always reconnects to the exact same device (on any port) when started inconnect id:abc123 mode.
• Preserves resume state through reconnections
• Handles Windows COM port timing issues with retry logic

Usage:

mpremote reconnectmpremote connect id:cc8da28c04c40000 reconnect replmpremote connect /dev/ttyACM0 reconnect

This PR builds on top of#17321 which improves disconnect message handling.

Testing

Testing was performed on:

• Windows 11 with ESP32S2 devices connected via USB (COM ports)
• Linux (Ubuntu WSL) with ESP32S2 devices connected via USB (/dev/ttyACM*)

Tested scenarios:

• Basic reconnection after device unplug/replug cycles
• Using auto mode and verifying it reconnects to the same specific port (e.g., only /dev/ttyACM2)
• Windows-specific COM port timing issues requiring multiple connection attempts
• Multiple devices present to verify it only reconnects to the original device
• Connection types: auto, specific ports, and device serial numbers (id:)

All tests confirmed that the tool reliably reconnects to the same physical device.

Trade-offs and Alternatives

The implementation adds minimal code complexity and has no impact on users who don't use the reconnect feature. The reconnect command is opt-in and doesn't affect existing behavior.

Design decisions:

• Implemented as a standalone command rather than a --reconnect flag for consistency with other mpremote commands like resume
• Always reconnects to the exact same port (even in auto mode) rather than any available device, prioritizing safety in multi-device environments
• Added retry logic with delays specifically for Windows COM port timing issues

The only trade-off is a small increase in code size from the reconnect logic, which is justified by the significant improvement in developer workflow.