fix(tmux): only enable extended-keys when outer terminal supports CSI u#418
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asheshgoplani merged 1 commit intoasheshgoplani:mainfrom Mar 26, 2026
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agent-deck unconditionally sets `extended-keys on` and appends `extkeys` to `terminal-features` on every session create/restart. This breaks Shift+key combos (Shift+R, Shift+D, etc.) in terminal emulators that don't support the CSI u / kitty keyboard protocol, because tmux encodes modified keys as CSI sequences that the terminal silently drops. Add `outerTerminalSupportsExtKeys()` that checks TERM and TERM_PROGRAM to detect terminals known to support the protocol (Ghostty, kitty, WezTerm). Notably, cmux sets TERM=xterm-ghostty but does not support CSI u, so we check TERM_PROGRAM to distinguish real Ghostty from cmux. Default to off — breaking Shift+key input is worse than missing extended key reports for the majority of users. Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
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Summary
Fixes #417
agent-deck unconditionally enables tmux
extended-keys on, which breaks Shift+key combos in terminals that don't support the CSI u / kitty keyboard protocol (cmux, Alacritty, Terminal.app, etc.).outerTerminalSupportsExtKeys()that checksTERMandTERM_PROGRAMto detect CSI u-capable terminals (Ghostty, kitty, WezTerm)TERM=xterm-ghosttywithout supporting CSI u — we checkTERM_PROGRAMto distinguish real Ghosttyextended-keys onand appendextkeystoterminal-featureswhen the outer terminal supports itStartandStartQuick)Test plan
TestOuterTerminalSupportsExtKeys— 14 cases covering Ghostty, cmux-as-ghostty, kitty, WezTerm, plain xterm, tmux, screen, unknown terminals, and TERM_PROGRAM-only detectiongo build ./...)🤖 Generated with Claude Code