tmux.conf

tmux.conf

# On macOS Sequoia 15.2, the Nix-generated default-command uses
# reattach-to-user-namespace, which causes the shell to default to
# bash even though $SHELL is set to /bin/zsh. Override these to ensure
# the correct shell is used. I don't know why or when this behaviour
# changed.
set-option -g default-shell "$SHELL"
set-option -g default-command "$SHELL"

# Unbind all key bindings in the 'copy-mode-vi' table to use Emacs key bindings throughout.
unbind-key -a -T copy-mode-vi

# Unbind the default prefix key 'C-b'.
unbind C-b

# Set a new prefix to 'C-o', which is Emacs friendly.
set -g prefix C-o

# Allow sending literal C-o to applications by pressing C-o C-o.
bind C-o send-prefix

# Set the style of the clock mode to display time in 12-hour format.
setw -g clock-mode-style 12

# Set the escape time to 0 milliseconds, reducing latency in
# recognising keybindings.
set -s escape-time 0

# Silence the bell notification.
set -g bell-action none

# Silence the visual feedback in the status bar.
set -g visual-bell off

# Make tmux more user-friendly by setting base index to 1 (default is 0) for windows and panes.
set -g base-index 1
set -g pane-base-index 1

# Enable automatic renumbering of windows when a window is closed.
set -g renumber-windows on

# Set the maximum number of commands to remember in the command history.
set -g history-limit 10000

# Enable mouse support.
set -g mouse on

# Use Emacs key bindings for copy mode and command mode.
set -g mode-keys emacs
set -g status-keys emacs

# Place the status line at the top.
set -g status-position top

# Refresh the status bar faster by setting the interval to 1 second.
set -g status-interval 1

# Monitor activity in other windows and alert when they change.
set -wg monitor-activity on

# Set the display time for tmux messages to 1s.
set -g display-time 1000

# Enable automatic renaming of windows based on the current command or
# application. This allows tmux to dynamically change the window name
# based on what's running inside the window, which can be helpful in
# quickly identifying the content of each window.
set-option -g automatic-rename on

# Allow applications inside tmux to request a window name change. This
# complements the automatic-rename setting by permitting applications
# (like certain scripts or tools) to set a custom window name if
# they're designed to do so.
set-option -g allow-rename on

# Capture the last 10000 lines of pane history, save it to a file, and
# then open it in the specified $EDITOR in a new window.
bind e capture-pane -S -10000 \; save-buffer /tmp/tmux-buffer \; \
     new-window "$EDITOR -e \"(aim/open-tmux-buffer)\""

# Bind keys for splitting windows.
bind - split-window -v    # Split window vertically
bind | split-window -h    # Split window horizontally
bind "'" split-window -h  # Split window horizontally

# Bind keys for navigating through windows.
bind -r p   previous-window   # Cycle to the previous window
bind -r n   next-window       # Cycle to the next window

bind -r C-p previous-window    # Cycle to the previous window with Ctrl-p
bind -r C-n next-window        # Cycle to the next window with Ctrl-n

# Bind a key for creating a new window at the current path.
# bind-key -n C-t new-window -c "#{pane_current_path}"
bind t new-window -c "#{pane_current_path}"

# Bind keys for selecting a window by its index.
bind -n M-1 select-window -t 1
bind -n M-2 select-window -t 2
bind -n M-3 select-window -t 3
bind -n M-4 select-window -t 4
bind -n M-5 select-window -t 5
bind -n M-6 select-window -t 6
bind -n M-7 select-window -t 7
bind -n M-8 select-window -t 8
bind -n M-9 select-window -t 9

# Bind keys for navigating through windows.
bind C-w last-window          # Go to the last active window

# Bind keys for navigating through panes.
bind o last-pane              # Go to the last active pane (C-o o)
bind h   select-pane -L       # Go to the pane to the left
bind j   select-pane -D       # Go to the pane below
bind k   select-pane -U       # Go to the pane above
bind l   select-pane -R       # Go to the pane to the right
bind z   resize-pane -Z       # Toggle pane zoom

# Bind keys for tmux command prompt, pane displaying, entering copy mode, reloading config file, listing keys, and detaching.
bind : command-prompt
bind q display-panes
bind c copy-mode
bind r source-file ~/.config/tmux/tmux.conf \; display "Reloaded!"
bind ? list-keys
bind d detach

# Update the environment variables when reattaching to tmux.
set -ag update-environment "SSH_TTY SSH_CLIENT SSH_CONNECTION DISPLAY LOCALE_ARCHIVE LANG LANGUAGE LC_ALL"

# Enable aggressive-resize to resize windows to the size of the
# current pane if all windows are shown.
setw -g aggressive-resize on

# Allow for Alt|Cmd-<N> ala gnome-terminal if the terminal is Alacritty.
if-shell -b '[[ "${TERM:-}" =~ alacritty ]]' {
  bind -n M-1 select-window -t 1
  bind -n M-2 select-window -t 2
  bind -n M-3 select-window -t 3
  bind -n M-4 select-window -t 4
  bind -n M-5 select-window -t 5
  bind -n M-6 select-window -t 6
  bind -n M-7 select-window -t 7
  bind -n M-8 select-window -t 8
  bind -n M-9 select-window -t 9
}

# Enable pane synchronisation.
bind-key = set-window-option synchronize-panes

# Bind keys for page navigation in copy mode.
bind -T copy-mode 'C-v' send-keys -X page-down
bind -T copy-mode 'M-v' send-keys -X page-up

# This bind command allows you to insert a new window at a specific
# position within the tmux window list. It opens a command prompt
# asking for the window index and then runs the shell command based on
# whether the window at that index already exists.
#
# - 'command-prompt -p "Insert window at:"' opens a prompt asking the
#   user for the window index where the new window should be inserted.
#
# - If the window exists at the given index (%1):
#     1. 'tmux select-window -t %1' tries to select the window at that
#        index.
#     2. 'tmux new-window -a' creates a new window immediately to the
#        right of the currently active window.
#     3. 'tmux swap-window -s %1 -t $((%1+1))' swaps the new window
#        into the next position, pushing the window at %1 one position
#        to the right.
#
# - If the window does not exist:
#     1. 'tmux new-window' creates a new window.
#     2. 'tmux move-window -t %1' moves this new window to the target
#        index.
#
# - Finally, it restores the user's previous window selection:
#     1. 'tmux select-window -t #{window_id}' returns to the original
#        window.
#     2. 'tmux select-window -t %1' re-selects the target window.
#
# Example 1: Inserting at position 1
#   Suppose there are windows at positions 1, 2, and 3:
#   - You insert at position 1.
#   - A new window is created to the right of the current window, and
#     the window at position 1 is pushed to position 2.
#
# Example 2: Inserting at position 5
#   Suppose there are windows at positions 1, 2, 3, and 4:
#   - You insert at position 5.
#   - The new window is created at position 5, leaving the other
#     windows unchanged.
#
# This allows users to neatly insert a window into an existing window
# list while keeping the focus on their original window before the
# operation.
bind i command-prompt -p 'Insert window at:' '      \
    run-shell "                                     \
        if tmux select-window -t %1; then           \
            tmux new-window -a;                     \
            tmux swap-window -s %1 -t \$((%1+1));   \
        else                                        \
            tmux new-window;                        \
            tmux move-window -t %1;                 \
        fi;                                         \
        tmux select-window -t #{window_id};         \
        tmux select-window -t %1;                   \
    "' 

# Set Emacs key bindings in copy mode.
setw -g mode-keys emacs

# Allow tmux to set the title of the terminal emulator.
set -g set-titles on
set -g set-titles-string "#T"

# This line sets the default terminal for tmux.
#
# See: https://github.com/tmux/tmux/wiki/FAQ:
#
#  Inside tmux TERM must be "screen", "tmux" or similar (such as
#  tmux-256color"). Don't bother reporting problems where it isn't!
set -g default-terminal "tmux-256color"

# This line sets a terminal override for various TERM types, appending
# the "Tc" capability. "Tc" tells tmux to support true color (24-bit
# color), assuming that the terminal it's running in also supports
# true color. Ditto for "RGB". "Tc" is a Tmux extension.
set -ag terminal-overrides ",alacritty*:Tc"
set -ag terminal-overrides ",alacritty*:RGB"

# OSC 52 clipboard handling for tmux over mosh.
#
# mosh ignores OSC 52 sequences with an empty selector (52;;...), so the
# target must be explicit ("c" for the system clipboard). tmux passes
# the selector and payload separately via terminfo 'Ms':
#
#   %p1 = selector (often "c")
#   %p2 = base64 payload
#
# The "%p1%.0s" construct consumes parameter 1 while printing zero
# characters. In terminfo formatting, ".0" is a precision specifier
# meaning “emit nothing”. This ensures the selector is accepted by
# tmux but never emitted, preventing it from leaking into the payload.
#
# The payload is emitted unchanged from %p2, keeping app-generated
# OSC 52 (e.g. from terminal Emacs) intact while always presenting
# mosh with a non-empty target.
set -as terminal-overrides ',*:Ms=\E]52;c%p1%.0s;%p2%s\007'

# Add XT (Extended Terminal) feature to all terminals. This feature is
# used by Tmux to identify whether a terminal supports certain
# sequences, such as the OSC 52 escape sequence for clipboard
# integration.
set -a terminal-features '*:XT'

# Set Tmux to rely on OSC 52 clipboard integration.
set -g set-clipboard on

# Allow passthrough of escape sequences unrecognised by Tmux. This
# means if Tmux receives an escape sequence that it doesn't
# understand, it will forward it to the terminal as-is. This can be
# useful in certain scenarios, for example, when certain applications
# or utilities use their own custom escape sequences.
# https://github.com/spudlyo/clipetty/issues/25#issuecomment-1327472790
set -g allow-passthrough on

# Set word boundaries for mouse text selection to match Alacritty's
# semantic_escape_chars.
set-option -g word-separators ",│`|:\"' ()[]{}<>\t"

# ----------------------------------------------
# Enhanced Pane Awareness Configuration for tmux
# ----------------------------------------------
#
# The following configurations provide a more nuanced view of the
# processes running inside the tmux panes:
#
# 1. Primary Conditional for `zsh` Command:
#    - The format checks if the command being executed in the pane is
#      `zsh`. If it is, it applies specific formatting.
#
# 2. Path Formatting for `zsh`:
#    - Two transformations are applied:
#        a. Substitutes the home directory with `~`.
#        b. Extracts the basename of the current path.
#
#      Result: If you're in `/home/user/documents`, it displays
#              `documents`.
#              If in `/home/user`, it displays `~`.
#
# 3. Formatting for Other Commands:
#    - Displays the current command.
#    - Checks if the current path is not the home directory.
#      - If it's not, it appends the basename of the
#      - pane_current_path in brackets.
#      - If in the home directory, just displays the command name
#      - without brackets.
#
# For instance, with a command like `emacs`:
#     - In `/projects/ai`: The display is `emacs(ai)`.
#     - In `/home/user`: The display is just `emacs`.
setw -g window-status-format "#F<#I:#{?#{==:#{pane_current_command},zsh},#{s|$HOME|~|;s|.*/||:pane_current_path},#{pane_current_command}#{?#{!=:#{pane_current_path},$HOME},(#{s|.*/||:pane_current_path}),}}>"
setw -g window-status-current-format "#F<#I:#{?#{==:#{pane_current_command},zsh},#{s|$HOME|~|;s|.*/||:pane_current_path},#{pane_current_command}#{?#{!=:#{pane_current_path},$HOME},(#{s|.*/||:pane_current_path}),}}>"

# Set the status line background to dark green and foreground to
# bright yellow.
set-option -g status-style bg=darkgreen,fg=brightyellow

# Set the message area background to bright yellow and foreground to
# black.
set-option -g message-style bg=brightyellow,fg=black

# Mode styles (like copy mode) are set to 'yellow' background and
# 'black' foreground for clarity and distinction from normal panes.
setw -g mode-style 'bg=yellow,fg=black'

set-option -g window-status-activity-style bg=grey25
set-option -g window-status-current-style bg=darkgreen,fg=brightwhite,bold,reverse
set-option -g window-status-last-style fg=orange,bold
set-option -g window-status-style bg=darkgreen,fg=brightwhite

# Set the inactive pane border's foreground to a muted green and
# background to default.
set-option -g pane-border-style 'fg=darkgreen,bg=default'

# Set the active pane border's foreground to yellow and background to
# default.
set-option -g pane-active-border-style 'fg=yellow,bg=default'


# Source the tmux-extras.conf file if it exists.
if-shell -b '[[ -f "$HOME/.tmux-extras.conf" ]]' {
  source ~/.tmux-extras.conf
}