sys.stdin.read(1) on the buffered TextIOWrapper pulls the whole escape
sequence into its Python-level buffer, so the follow-up select() sees an
empty fd and every arrow/Home/End press degrades to bare Esc; the unread
'[B' tail then leaks into the next keypress. Read raw bytes via os.read()
and select() on the file descriptor instead, keeping the same key tokens
and classifications. Add pty-driven regression tests over a real cbreak
terminal covering CSI sequences, single-byte keys, bare Esc, and tail-leak.
kosmos
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