/**
 * The client contract for the Herdr viewer pane. The Pi session owns the workflow server and the
 * client version, so it resolves the `piw` client once and hands the pane an absolute path plus
 * these variables. A pane then draws one run, checks nothing about `PATH`, and starts no server.
 */
export declare const PIW_BIN_ENV = "PIW_BIN";
export declare const PIW_SOCKET_ENV = "PIW_SOCKET";
export declare const PIW_NO_AUTOSTART_ENV = "PIW_NO_AUTOSTART";
export type PiwClientSource = "PIW_BIN" | "package" | "PATH";
export type PiwClientInspection = {
    ok: true;
    path: string;
    source: PiwClientSource;
    version: string;
    expectedVersion: string;
} | {
    ok: false;
    kind: "missing" | "mismatch";
    message: string;
};
export type PiwVersionCheck = {
    compatible: true;
    version: string;
} | {
    compatible: false;
    reason: string;
};
export type PiwClientOptions = {
    env?: NodeJS.ProcessEnv;
    packageRoot?: string;
    platform?: NodeJS.Platform;
    arch?: string;
    readVersion?: (file: string) => string | undefined;
};
/**
 * crates.io owns the client binary. The version check binds that distribution to this package, so
 * the failure message names the one command that resolves it.
 */
export declare function installHint(expectedVersion: string): string;
export declare function piwPackageRoot(): string;
export declare function piwPlatformPackageName(platform?: NodeJS.Platform, arch?: string): string | undefined;
export declare function piwBinaryNames(platform?: NodeJS.Platform): [string, ...string[]];
export declare function piwPackageBinaryPath(root: string, platform?: NodeJS.Platform, arch?: string): string | undefined;
export declare function piwPackageVersion(root?: string): string | undefined;
/** Tolerates a `piw ` prefix, a tab, and a leading `v`, so every client build reports a version. */
export declare function parsePiwVersion(output: string | undefined): string | undefined;
export declare function checkPiwVersion(actual: string | undefined, expected: string, clientPath: string): PiwVersionCheck;
export declare function isExecutableFile(file: string): boolean;
export declare function pathEntries(env?: NodeJS.ProcessEnv): string[];
export declare function findOnPath(name: string, env?: NodeJS.ProcessEnv): string | undefined;
export declare function readPiwVersion(file: string): string | undefined;
/**
 * Resolve the client once. Resolution order: an explicit `PIW_BIN`; the package-local platform
 * binary when a platform package is installed; then the first `piw` on `PATH`, which keeps the
 * behavior of a machine with no package-local binary. An explicit `PIW_BIN` that is unusable is a
 * loud failure rather than a silent `PATH` fallback.
 */
export declare function inspectPiwClient(options?: PiwClientOptions): PiwClientInspection;
export declare function piwPaneEnvironment(clientPath: string, socketPath?: string): string[];