Colour policy

Colour modes

Mode	Rust	Node	Behaviour
Auto	ColorMode::Auto	color: 'auto' (default)	Styles only when writing to an interactive terminal and NO_COLOR is not set
Always	ColorMode::Always	color: 'always'	Styles regardless of the destination
Never	ColorMode::Never	color: 'never'	Plain text – for tests, snapshots and logs

NO_COLOR follows the no-color.org convention: when it is set, Auto emits no styles.

Which stream

In Rust, create the console for the stream you write to, so Auto checks the right terminal:

use runemark::{ColorMode, Console};

let out = Console::stdout(ColorMode::Auto); // results
let err = Console::stderr(ColorMode::Auto); // progress and diagnostics

In Node, rendering returns strings and your code writes them. isTerminal overrides the detection when you know better, for example in a test harness:

const { RunemarkConsole } = require('@casoon/runemark')

const console = new RunemarkConsole({ color: 'auto', isTerminal: false })

Symbols

Status symbols use Unicode by default. Choose ASCII for terminals or logs that cannot display it: SymbolTheme in Rust, symbols: 'ascii' in Node.

Width

runemark never queries the terminal itself. Pass a known width and reports adapt: narrow layouts stack summary metrics and wrap finding messages with a hanging indent.

use runemark::{ColorMode, Console, RenderOptions, Report, Verdict};

let report = Report::new("Site audit", Verdict::Info);
let output = report.render_with_options(
    Console::stdout(ColorMode::Auto),
    RenderOptions::new().with_width(80),
);

report.render({ width: process.stdout.columns })

Deterministic output

With Never, identical input produces identical text: no escape sequences, no terminal-dependent behaviour. That is the mode for golden tests and snapshots.