xterm diffs the helper textarea with newValue.replace(oldValue, ''), which only works when the keyboard appended. SwiftKey/Gboard autocorrect on space deletes a word and inserts the corrected one, so xterm sent the whole value and then the inserted text again (testing the peompt + space became 'testing the peompttesting the prompt rompt '), and a multi-character delete was one DEL. The keyCode-229 controller now swaps in an edit-based diff against what was already sent.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JrzFKEdBLwVfu6ev2ZscJS
