import type { SpawnOptions } from "../execution/deps.js";
import type { HarnessEvent } from "../execution/events.js";
export declare const OBSERVER_ENV = "HCN_OBSERVER";
export declare const INVOCATION_ID_ENV = "HCN_INVOCATION_ID";
type Env = Readonly<Record<string, string | undefined>>;
/** The observer command from the environment, or null when no observer is
 * enabled. Decided from the string alone: the variable must be non-empty
 * and absolute. No filesystem work happens here - a path that does not
 * name a spawnable file fails later, asynchronously, and silently. The
 * check uses `isAbsolute` so a value like `/tmp/../tmp/observer` keeps
 * enabling the observer: the previous `resolve(value) === value` form
 * rejected those (and any value that resolves to itself through `..`),
 * disabling observation and the invocation-ID export on a string the
 * caller plainly intended as absolute. */
export declare const observerCommand: (env: Env) => string | null;
export interface RunObserver {
    readonly enabled: boolean;
    /** The pid of the spawned observer child, or null when there is
     * none to name: no observer enabled, the spawn failed, or launched
     * not yet called. The value survives the child's exit (ChildProcess.pid
     * keeps the last pid), so a caller can still wait on the child after
     * the stream ends. */
    readonly pid: number | null;
    /** Adds `HCN_INVOCATION_ID` over the caller's env on the launch spawn;
     * returns the options untouched when no observer is enabled. Call on
     * the first harness spawn only - later spawns (the approval helper)
     * carry none of this. */
    harnessEnv(opts: SpawnOptions, invocationId: string): SpawnOptions;
    /** Spawns the observer command and writes the `started` record. Call
     * in a `finally` so a harness spawn that throws is still covered.
     * Never throws. */
    launched(invocationId: string, at: string): void;
    /** Streams one run event, unless it is droppable or observation has
     * ended. A `done` event ends the stream. Fire-and-forget; never
     * throws. */
    event(event: HarnessEvent): void;
    /** Ends the stream. Idempotent; never throws. */
    end(): void;
}
/** The run observer for one `hcn run` invocation. Inert unless
 * `HCN_OBSERVER` enables it. */
export declare const createRunObserver: (harness: string, cwd: string | undefined) => RunObserver;
export {};
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