/**
 * Terminal identity and background detection.
 *
 * Covers cavekit-terminal-blend R1 (background luminance detection via OSC 11,
 * COLORFGBG, and CAVE_TERM_BG override) and R2 (terminal program identity).
 */
import type { ProcessTerminal } from "./terminal.js";
export type TerminalProgram = "ghostty" | "iterm2" | "apple-terminal" | "kitty" | "wezterm" | "alacritty" | "vte" | "tmux" | "screen" | "linux-console" | "cmux" | "windows-terminal" | "vscode" | "unknown";
export type Multiplexer = "tmux" | "screen" | "none";
export type BackgroundClassification = "dark" | "light";
export interface TerminalIdentity {
    program: TerminalProgram;
    /** Outer host terminal when running under a multiplexer. */
    hostProgram?: TerminalProgram;
    version?: string;
    multiplexer: Multiplexer;
    isSsh: boolean;
    raw: Record<string, string | undefined>;
}
export interface TerminalBackground {
    r: number;
    g: number;
    b: number;
    /** Relative luminance per WCAG 2.x (0-1). */
    luminance: number;
    classification: BackgroundClassification;
    source: "osc11" | "colorfgbg" | "override";
}
export interface ProbeResult {
    identity: TerminalIdentity;
    background: TerminalBackground | null;
    /** Final classification — always a concrete value (falls back to "dark"). */
    classification: BackgroundClassification;
}
export declare function detectTerminalIdentity(env?: NodeJS.ProcessEnv): TerminalIdentity;
/** WCAG 2.x relative luminance from sRGB 0-255 components. */
export declare function relativeLuminance(r: number, g: number, b: number): number;
/**
 * Query the terminal's background color. Tries CAVE_TERM_BG override, then OSC 11,
 * then COLORFGBG. Returns null when no signal is available. Total wall time capped
 * by timeoutMs (default 200ms for the OSC 11 part; env lookups are instant).
 */
export declare function queryTerminalBackground(terminal: ProcessTerminal | null, timeoutMs?: number, env?: NodeJS.ProcessEnv): Promise<TerminalBackground | null>;
/**
 * Standalone OSC 11 query that works before the TUI has started.
 *
 * Briefly installs its own stdin listener in raw mode, writes the OSC 11
 * query, waits up to `timeoutMs` for the response, then restores stdin.
 * Returns null on timeout / non-TTY / parse failure.
 *
 * Use this during startup when we need the background classification before
 * theme init but haven't yet constructed a ProcessTerminal.
 */
export declare function queryOsc11Standalone(timeoutMs?: number): Promise<TerminalBackground | null>;
/**
 * One-call probe: identity + background + final classification (with "dark" fallback).
 * The classification field is always concrete per R1.
 */
export declare function probeTerminal(options: {
    terminal?: ProcessTerminal | null;
    timeoutMs?: number;
    env?: NodeJS.ProcessEnv;
    /** Whether to run the standalone OSC 11 query (needs raw stdin). Default: true when no terminal is supplied. */
    useStandaloneOsc?: boolean;
}): Promise<ProbeResult>;
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