Bug

agent-deck unconditionally enables tmux extended-keys on and appends extkeys to terminal-features on every session create/restart. This breaks Shift+R, Shift+D, and other modified key combos in terminal emulators that don't support the CSI u / kitty keyboard protocol.

Impact

With extended-keys on, tmux encodes Shift+R as \e[82;2u (CSI u sequence) instead of ASCII R. Terminals that don't understand this encoding silently drop the keypress, making TUI keybindings like Restart (R), Delete (D), Close (D) completely non-functional.

Affected Terminals

• cmux — sets TERM=xterm-ghostty but does not support CSI u
• Alacritty — no CSI u support
• Terminal.app — no CSI u support
• iTerm2 — partial support
• Any terminal not implementing the kitty keyboard protocol

Working Terminals

• Ghostty — full CSI u support
• kitty — originates the protocol
• WezTerm — full support
• foot — full support

Additional Issue: terminal-features accumulation

ensureTerminalFeatures was appending *:hyperlinks:extkeys on every session start, leading to 70+ duplicate entries in terminal-features. This was addressed by #366 with a dedup check, but users who ran earlier versions still have the accumulated entries in their running tmux server.

Suggested Fix

Check whether the outer terminal supports CSI u before enabling extended-keys and extkeys. A TERM + TERM_PROGRAM check can reliably distinguish supported terminals. Default to off — breaking Shift+key input is worse than missing extended key reports.

Workaround

tmux set-option -g extended-keys off

Must be re-run after every tmux restart or session creation.

Version

v0.26.4