Reported by: LionyxML (Reddit)

The package does not work inside tmux, even with the passthrough option enabled (set -g allow-passthrough on). Kitty graphics protocol escape sequences need to be wrapped in tmux's passthrough DCS sequence (\ePtmux;...\e\\) to reach the outer terminal.

Investigation needed:

• Detect tmux via $TMUX environment variable
• Wrap APC sequences in tmux DCS passthrough: \ePtmux;\e_G...\e\\\e\\
• Terminal detection (kitty-gfx--supported-p) needs to check the outer terminal, not tmux's $TERM
• May also need to handle screen/tmux $TERM values

References:

• Kitty docs on tmux: https://sw.kovidgoyal.net/kitty/graphics-protocol/#interaction-with-other-terminal-functionality
• tmux passthrough: allow-passthrough option