/**
 * Three-tier color engine for the terminal UI design system.
 *
 * Automatically detects terminal color capability and degrades gracefully:
 *   truecolor (24-bit RGB) → 256-color → 16 ANSI → no color
 *
 * Respects NO_COLOR, COLORTERM, and TERM environment variables.
 */
import type { ColorTokens } from "./tokens.ts";
export type ColorDepth = "none" | "ansi16" | "ansi256" | "truecolor";
/**
 * Detect the terminal's maximum supported color depth.
 * Checks environment variables in order of specificity.
 */
export declare function detectColorDepth(): ColorDepth;
/**
 * Check if the current environment supports truecolor.
 */
export declare function supportsTrueColor(): boolean;
/**
 * Check if the current environment supports any color.
 */
export declare function supportsColor(): boolean;
export interface ColorTheme {
    /** Current detected color depth */
    readonly depth: ColorDepth;
    /**
     * Apply a foreground color token to text.
     * @param tokenName - Name of the semantic token
     * @param text - Text to color
     * @returns Styled text string
     */
    fg(tokenName: keyof ColorTokens["fg"], text: string): string;
    /**
     * Apply a background color token to text.
     * @param tokenName - Name of the semantic token
     * @param text - Text to color
     * @returns Styled text string (with bg color + fg reset)
     */
    bg(tokenName: keyof ColorTokens["bg"], text: string): string;
    /**
     * Apply bold to text.
     */
    bold(text: string): string;
    /**
     * Apply italic to text.
     */
    italic(text: string): string;
    /**
     * Apply underline to text.
     */
    underline(text: string): string;
    /**
     * Reset all styles.
     */
    reset(text: string): string;
    /**
     * Combine multiple styles.
     * Example: theme.compose(theme.bold, (t) => theme.fg('accent', t))
     */
    compose(...styles: Array<(text: string) => string>): (text: string) => string;
}
/**
 * Create a ColorTheme from a palette and detected color depth.
 */
export declare function createColorTheme(tokens: ColorTokens, depth?: ColorDepth): ColorTheme;
/**
 * Create a function that applies a foreground token.
 */
export declare function fgFn(theme: ColorTheme, token: keyof ColorTokens["fg"]): (text: string) => string;
/**
 * Create a function that applies a background token.
 */
export declare function bgFn(theme: ColorTheme, token: keyof ColorTokens["bg"]): (text: string) => string;
/**
 * Create a function that applies bold + foreground.
 */
export declare function boldFgFn(theme: ColorTheme, token: keyof ColorTokens["fg"]): (text: string) => string;
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