The terminal's only ingestion API was write(String), so both byte
consumers decoded per chunk — a multi-byte rune split across PTY
reads (or a tail window starting mid-character, which FileTailFollower
does by construction) rendered as U+FFFD garbage. writeBytes feeds a
per-instance chunked Utf8Decoder that carries partial-rune state
across calls; the terminal pane and the Bash live-tail follower now
use it, and write(String) stays for tests and programmatic writes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>