import type { TaskState, TaskStatus } from './task-state.js';
/**
 * In-memory task store with FSM-validated state transitions.
 *
 * This is the single source of truth for task state. It enforces the FSM at
 * the data layer — illegal transitions are rejected before any mutation occurs.
 *
 * Terminal tasks can be evicted by age to prevent unbounded memory growth.
 */
export declare class TaskStore {
    private readonly tasks;
    /** Store a new task. Overwrites if the ID already exists. */
    create(task: TaskState): void;
    /** Retrieve a task by its unique ID. */
    get(id: string): TaskState | undefined;
    /** Linear scan for a task matching the given session ID. */
    getBySessionId(sessionId: string): TaskState | undefined;
    /** Return all tasks as an array. */
    getAll(): TaskState[];
    /**
     * Transition a task to a new status.
     *
     * Returns `true` if the transition was valid and applied, `false` if the
     * task was not found or the transition is illegal per the FSM.
     */
    updateStatus(id: string, next: TaskStatus): boolean;
    /**
     * Apply a partial update to a task. If the update includes a `status`
     * change, the FSM is validated first — an illegal transition causes the
     * entire update to be rejected (returns `undefined`).
     */
    update(id: string, updates: Partial<TaskState>): TaskState | undefined;
    /** Remove a task by ID. Returns `true` if it existed. */
    delete(id: string): boolean;
    /**
     * Remove terminal tasks whose `updatedAt` timestamp is older than
     * `maxAgeMs` milliseconds from now.
     *
     * Returns the number of tasks evicted.
     */
    evict(maxAgeMs: number): number;
    /** Remove all tasks. */
    clear(): void;
    /** Return the number of stored tasks. */
    size(): number;
}