import type { ContextReader } from "#context/key.js";
import type { HarnessSessionBase, SessionStateMap } from "#harness/types.js";
import { type SessionProjection } from "#protocol/session-projection.js";
import type { MessageStreamEvent, UnstampedMessageStreamEvent } from "#protocol/message.js";
export declare function enterSessionProjection(ctx: ContextReader, state: SessionStateMap | undefined): void;
/** Enters the stored projection unless this step already did. */
export declare function ensureSessionProjection(ctx: ContextReader, state: SessionStateMap | undefined): void;
/** The projection as of the last event the current step published. */
export declare function currentProjection(ctx?: ContextReader | undefined): SessionProjection;
/** The step's live projection, or the session's stored one when no step entered it. */
export declare function projectionFor(ctx: ContextReader, state: SessionStateMap | undefined): SessionProjection;
export declare function recordPublishedEvent(ctx: ContextReader, event: MessageStreamEvent | UnstampedMessageStreamEvent): void;
/** Records the session a transition the step published produced. */
export declare function recordAppliedSession(ctx: ContextReader, session: HarnessSessionBase): void;
/** The session the step's last applied transition produced, if it applied any. */
export declare function appliedSession<T extends HarnessSessionBase>(ctx: ContextReader): T | undefined;
export declare function saveSessionProjection<T extends HarnessSessionBase>(session: T, ctx: ContextReader): T;
/**
 * The session saves the lifecycle its steps read. Calls and tasks are for the stream's readers,
 * which fold them from the events, and their outputs can be large, so the checkpoint omits them.
 */
export declare function saveProjection<T extends HarnessSessionBase>(session: T, projection: SessionProjection): T;
/** The projection one step reads and folds what it publishes into. */
export interface StepProjection {
    read(): SessionProjection;
    /** Folds an event no publish sink folded: the step runs without one. */
    record(event: UnstampedMessageStreamEvent): void;
}
/**
 * A step's projection: the context's live one, which the publish sink folds, or, for a step
 * that runs without a context, a detached one the step folds itself.
 */
export declare function stepProjection(ctx: ContextReader | undefined, state: SessionStateMap | undefined): StepProjection;