Configuration Reference

File location: ~/.config/crt/config.toml

The config directory can be overridden via the CRT_CONFIG_DIR environment variable (must be an absolute path). If the config file is absent, CRT starts with all defaults. If the file contains a parse error, CRT logs a warning and falls back to all defaults. Unknown fields are silently ignored. Partial configs use defaults for every omitted field; fields within a section that are omitted also use their defaults.

[shell]

Field	Type	Default	Description
`program`	`string` (optional)	user’s login shell, then `/bin/zsh` (macOS) or `/bin/bash` (Linux)	Absolute path to the shell binary to launch.
`args`	`string[]`	`[]`	Arguments passed to the shell.
`working_directory`	`string` (optional)	user’s home directory	Starting working directory for the shell.
`semantic_prompts`	`bool`	`false`	Inject OSC 133 shell hooks for command success/failure detection. Not required when using starship, oh-my-zsh, or p10k, which emit OSC 133 natively.

[font]

Field	Type	Default	Description
`family`	`string[]`	`["MesloLGS NF", "JetBrains Mono", "Fira Code", "SF Mono", "Menlo"]`	Font families in preference order. The first family found on the system is used. Custom fonts can be placed in `~/.config/crt/fonts/`, which is searched before system fonts. Falls back to an embedded font if no listed family is found.
`size`	`float`	`14.0`	Base font size in points.
`line_height`	`float`	`1.5`	Line height multiplier. `1.0` = no extra spacing; `1.5` = 50% additional vertical space between lines.

[window]

Field	Type	Default	Description
`columns`	`integer`	`80`	Initial terminal width in character columns.
`rows`	`integer`	`24`	Initial terminal height in character rows.
`title`	`string`	`"CRT Terminal"`	Window title bar text.
`fullscreen`	`bool`	`false`	Start in fullscreen mode.

[theme]

Field	Type	Default	Description
`name`	`string`	`"synthwave"` (release builds); `"nyancat"` (debug builds)	Theme name to load. CRT looks for `~/.config/crt/themes/{name}.css`. All 19 built-in themes are pre-installed in that directory. Custom themes can be added as additional `.css` files.

[cursor]

Field	Type	Default	Description
`style`	`"block"` \| `"bar"` \| `"underline"`	`"block"`	Cursor shape.
`blink`	`bool`	`true`	Whether the cursor blinks.
`blink_interval_ms`	`integer`	`530`	Blink period in milliseconds.

[bell]

Field	Type	Default	Description
`visual`	`bool`	`true`	Enable visual bell (screen flash on terminal bell character `\a`).
`flash_duration_ms`	`integer`	`100`	Duration of the visual flash in milliseconds.
`flash_intensity`	`float`	`0.3`	Intensity of the flash overlay. Range: `0.0` (invisible) to `1.0` (full white).

[[keybindings.bindings]]

Each entry in the bindings array is a table with three fields:

Field	Type	Required	Description
`key`	`string`	yes	Key name. Single character keys are specified literally (`"t"`, `"w"`, `"c"`). Special keys use names: `"equal"`, `"minus"`, `"0"`–`"9"`, `"[`“`,` ”]“`,` “F1”`–`“F12”`.
`mods`	`string[]`	no (default `[]`)	Modifier keys. Valid values: `"super"` (Cmd on macOS, Win on Linux), `"shift"`, `"ctrl"`, `"alt"`.
`action`	`string`	yes	Action to perform. See table below.

Available Actions

Action	Description
`new_tab`	Open a new tab.
`close_tab`	Close the active tab (closes the window if only one tab is open).
`next_tab`	Switch to the next tab.
`prev_tab`	Switch to the previous tab.
`select_tab1` – `select_tab9`	Switch directly to tab 1 through 9 by position.
`increase_font_size`	Increase font size by one step.
`decrease_font_size`	Decrease font size by one step.
`reset_font_size`	Reset font size to the value in `[font].size`.
`toggle_fullscreen`	Toggle fullscreen mode.
`copy`	Copy selected text to the clipboard.
`paste`	Paste from the clipboard.
`quit`	Quit the application.

Keybindings Replacement Behavior

When a [[keybindings.bindings]] array is present in config.toml, it replaces the entire default binding list. There is no merge. To keep all default bindings while adding one more, reproduce all defaults plus the new entry.

Default Keybindings

Shortcut	Action
`Cmd+T`	`new_tab`
`Cmd+W`	`close_tab`
`Cmd+Shift+[`	`prev_tab`
`Cmd+Shift+]`	`next_tab`
`Cmd+1` – `Cmd+9`	`select_tab1` – `select_tab9`
`Cmd+=`	`increase_font_size`
`Cmd+-`	`decrease_font_size`
`Cmd+0`	`reset_font_size`
`Cmd+C`	`copy`
`Cmd+V`	`paste`
`Cmd+Q`	`quit`

Complete Example config.toml

# ~/.config/crt/config.toml
# All fields shown with their default values.
# Uncomment and modify any setting you want to change.

[shell]
# program = "/bin/zsh"
# args = ["-l"]
# working_directory = "/Users/you"
# semantic_prompts = false

[font]
family = [
    "MesloLGS NF",
    "JetBrains Mono",
    "Fira Code",
    "SF Mono",
    "Menlo",
]
size = 14.0
line_height = 1.5

[window]
columns = 80
rows = 24
title = "CRT Terminal"
fullscreen = false

[theme]
name = "synthwave"

[cursor]
style = "block"
blink = true
blink_interval_ms = 530

[bell]
visual = true
flash_duration_ms = 100
flash_intensity = 0.3

# Custom keybindings. WARNING: this list REPLACES the defaults entirely.
# If you define this section, reproduce all shortcuts you want to keep.
[keybindings]
bindings = [
    # Tab management
    { key = "t",   mods = ["super"],          action = "new_tab"   },
    { key = "w",   mods = ["super"],          action = "close_tab" },
    { key = "[",   mods = ["super", "shift"], action = "prev_tab"  },
    { key = "]",   mods = ["super", "shift"], action = "next_tab"  },

    # Tab selection
    { key = "1", mods = ["super"], action = "select_tab1" },
    { key = "2", mods = ["super"], action = "select_tab2" },
    { key = "3", mods = ["super"], action = "select_tab3" },
    { key = "4", mods = ["super"], action = "select_tab4" },
    { key = "5", mods = ["super"], action = "select_tab5" },
    { key = "6", mods = ["super"], action = "select_tab6" },
    { key = "7", mods = ["super"], action = "select_tab7" },
    { key = "8", mods = ["super"], action = "select_tab8" },
    { key = "9", mods = ["super"], action = "select_tab9" },

    # Font size
    { key = "equal", mods = ["super"], action = "increase_font_size" },
    { key = "minus", mods = ["super"], action = "decrease_font_size" },
    { key = "0",     mods = ["super"], action = "reset_font_size"    },

    # Clipboard
    { key = "c", mods = ["super"], action = "copy"  },
    { key = "v", mods = ["super"], action = "paste" },

    # Application
    { key = "q", mods = ["super"], action = "quit" },
]

Config Directory Layout

~/.config/crt/
├── config.toml          # Main configuration file
├── themes/              # Theme CSS files (built-in themes live here)
│   ├── synthwave.css
│   ├── dracula.css
│   └── my-theme.css     # Custom themes go here
├── fonts/               # Optional: custom font files (searched before system fonts)
│   └── MyFont.ttf
└── profile-*.log        # Profiling logs (written when profiling is active)