Author a terminal theme¶

A custom theme is a small TOML or JSON file. It starts from one of the built-in themes, then changes only the parts you name. Colossus loads theme files when the terminal starts.

1. Find a theme folder¶

In the terminal UI, enter:

/theme list

The Custom theme search locations section shows the folders Colossus reads. If your active configuration is .colossus/config.yaml in a repository, use .colossus/themes/ in that repository. Create the folder if it does not exist. For another configuration location, use its adjacent themes/ folder or the user theme folder shown by /theme list.

2. Save a theme file¶

Create midnight.toml in that folder with this content:

schemaVersion = 1
name = "midnight"
base = "default"
title = "Colossus Midnight"
caret = "›"
continuation = "…"
spinner = "arc"

[prompt]
left = "#9BB7FF"
indicator = "#9BB7FF"

[styles.assistant]
foreground = "#E6E9FF"

[styles.tool]
foreground = "#79C0FF"
bold = true

[styles.warning]
foreground = "#FFD479"
bold = true

schemaVersion must be 1. Use a unique theme name made of letters, digits, and underscores. Colors use #RRGGBB. Unspecified colors and text styles inherit the base theme.

You can also set [prompt] colors for right and continuation; add [styles.activity], [styles.thinking], [styles.success], [styles.error], or [styles.meta]. Each style accepts foreground, bold, dim, and italic. Available spinners are dots, line, arc, bouncingBar, and aesthetic.

3. Reload and select it¶

Exit and restart the terminal UI so Colossus reads the new file. Then enter:

/theme list
/theme validate
/theme preview midnight
/theme midnight

The list should include midnight, validation should report the loaded library as valid, and the preview should show its colors without applying them. The final command saves it as your active theme. You can also select it in the /theme browser.

When you edit an already selected custom theme, restart Colossus and select the theme again. The active preference keeps the previously selected version until you reselect it. If Colossus reports an invalid theme while starting, check the TOML syntax, theme name, color values, and folder shown by /theme list.