Copy mode was compared with the installed tmux 3.6 by differential fuzzing and 842 recorded results instead of being written from memory: the cursor stands between characters and remembers its column (lastcx/lastsx), pages are rows - 2, searches land at the match end for emacs keys and the match start for vi keys and scroll by tmux's rule, a failed search is a status message, emacs selections are half open and vi selections include the cursor character and the line end, select-word on blanks takes the previous word, copy-line and copy-end-of-line start a fresh selection. Window selection keeps a history (last, then previous with wrap when the current window dies), swap-window keeps the current window current, new-session -d -x -y sizes the window as given. Server loop logs and survives a failing iteration (50 in a row end it).
mplex.md is the specification (architecture, wire format, caps, every option, command and default key, what was checked against tmux, known differences); MplexSpecTests fails when it drifts from the code. New: MplexCopyModeVersusTmuxTests (tmux-recorded fixtures), MplexSessionTests, MplexServerLoopTests.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
