[771-8bit]

Summary

Restores behavior of the C# version (v0.0.8) that the Tauri/Rust rewrite had lost, found by checking the blog post and the C# source against the current app. Based on dev, so after this is merged, #8 carries everything and beta.2 is released once. One commit per item:

• A lone CR ends a line (CRLF = one break, LF CR = two), also across chunk boundaries
• Port names no longer read USB Serial Port (COM5) (COM5)
• Hex send accepts the C# separators and one-digit bytes (0A-0B, 1,2,3, 0x41). Before, 12 3 4 was silently sent as 12 34. Invalid bytes are named under the input, not in a blocking dialog
• Line-break-only input is not added to the send history
• Larger font in the Send box than in the receive view
• Show CR/LF / Show NUL in the ASCII view (default off; hidden CR/LF still copy as line breaks)
• Timestamps in the Hex view, and in Hex-mode Copy (Hex-mode Save stays raw bytes)
• "Copied" / "Saved" / "Nothing to copy" toast
• Auto Reconnect → Auto Connect as in C#: connects to the selected port whenever it is available (startup, plug-in, after reset). Disconnect / Cancel turns it off. Shows why when the port is in use and backs off to 1 s. 200 ms retries. New setting key, off by default
• Defaults: DTR and RTS off, so connecting resets neither an Uno (DTR) nor an ESP32 (RTS). A ? next to DtrEnable / RtsEnable explains the Arduino cases on hover. Other defaults follow C#: no line ending, Send with Enter on, Line Wrap off, separator >
• README and CHANGELOG (folded into the beta.2 section)

Owner decisions: no "User's Note" field; parity / stop bits / flow control stay as the serialport crate supports them; DTR off by default. Designs were reviewed before implementation.

Verification

• Every commit checked on its own: tsc / eslint / prettier / vitest, cargo fmt / clippy / test. Final state: frontend 233 tests, Rust 441 tests, Node MCP smoke test.
• In the app (com0com COM15/COM16):
  • CR-only, CRLF, NUL, TAB and LF CR data, with Show CR/LF / Show NUL off and on
  • Drag-selection copy keeps the line breaks while CR/LF are hidden
  • Hex view timestamps and Hex Copy with timestamps; the Copied toast
  • Auto Connect: turning it on while idle, connecting at startup after a restart, Disconnect turning it off, and a port held by another program (message, then connects once it is released)
  • The ? hover note
• Not verified on real boards: whether an Uno / ESP32 is actually reset by the defaults, or how native-USB boards behave with DTR off. The reasoning is the boards' auto-reset circuits, not a measurement.

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