tmux Setup

Source: https://pi.dev/docs/latest/tmux

tmux strips modifier information from some keys by default, so without configuration Shift+Enter and Ctrl+Enter are indistinguishable from plain Enter.

Recommended Configuration

Add to ~/.tmux.conf:

set -g extended-keys on
set -g extended-keys-format csi-u

Then restart tmux fully:

tmux kill-server
tmux

Pi requests extended key reporting automatically when the Kitty keyboard protocol is unavailable. extended-keys-format csi-u requires tmux 3.5 or later (check with tmux -V). With tmux 3.2–3.4, omit that line; Pi still supports tmux's default xterm modifyOtherKeys format.

Why csi-u

With only set -g extended-keys on, tmux defaults to extended-keys-format xterm and forwards modified keys as modifyOtherKeys sequences — Ctrl+C as ESC [27;5;99~, Ctrl+Enter as ESC [27;5;13~. With csi-u the same keys arrive as ESC [99;5u and ESC [13;5u. Pi supports both formats; csi-u is the recommended setup.

What It Fixes

ESC below is the escape byte (0x1b).

This affects the default bindings (Enter to submit, Shift+Enter for newline) and any custom keybindings using modified Enter.

Requirements

tmux 3.5+ for extended-keys-format csi-u, plus a terminal emulator that supports extended keys: Ghostty, Kitty, iTerm2, WezTerm, or Windows Terminal.