/**
 * TaskStore interface — abstraction over persistent state for MCP background tasks.
 *
 * Mirrors the elicitation store design: reads/writes + pub/sub for cross-node
 * result unblocking and cancel signaling.
 *
 * @module task/store/task.store
 */
import type { TaskRecord } from '../task.types';
/** Callback invoked when a task reaches a terminal status. */
export type TaskTerminalCallback = (record: TaskRecord) => void;
/** Callback invoked when a task has been asked to cancel. */
export type TaskCancelCallback = () => void;
/** Unsubscribe handle returned by subscribe* methods. */
export type TaskUnsubscribe = () => Promise<void>;
/** Result of a paginated list operation. */
export interface TaskListPage {
    tasks: TaskRecord[];
    nextCursor?: string;
}
export interface TaskStore {
    /**
     * Persist a newly-created task record. The store SHOULD honor `expiresAt`
     * as TTL for automatic cleanup. Must fail if a record with the same
     * `taskId` already exists (taskId collisions are a bug upstream).
     */
    create(record: TaskRecord): Promise<void>;
    /**
     * Fetch a task record. Returns `null` if:
     *  - the task does not exist
     *  - the task has expired
     *  - `sessionId` does not match the record's session (hard auth binding)
     */
    get(taskId: string, sessionId: string): Promise<TaskRecord | null>;
    /**
     * Apply a partial patch. Returns the updated record, or `null` if the task
     * no longer exists / belongs to a different session. Implementations should
     * treat this as a read-modify-write (no external CAS requirement).
     */
    update(taskId: string, sessionId: string, patch: Partial<TaskRecord>): Promise<TaskRecord | null>;
    /**
     * Delete a task record. No-op if not found.
     */
    delete(taskId: string, sessionId: string): Promise<void>;
    /**
     * List tasks owned by `sessionId`, paginated.
     * Cursor format is opaque to callers; implementations define their own.
     */
    list(sessionId: string, opts?: {
        cursor?: string;
        pageSize?: number;
    }): Promise<TaskListPage>;
    /**
     * Subscribe for a one-shot terminal notification on the given task.
     * Called once the store observes a terminal status.
     */
    subscribeTerminal(taskId: string, sessionId: string, cb: TaskTerminalCallback): Promise<TaskUnsubscribe>;
    /**
     * Publish a terminal state change. MUST be called after the backing record
     * has been updated to a terminal status.
     */
    publishTerminal(record: TaskRecord): Promise<void>;
    /**
     * Subscribe for cancellation signals. Used by the node running the task to
     * react to a `tasks/cancel` that arrived at a different node.
     */
    subscribeCancel(taskId: string, sessionId: string, cb: TaskCancelCallback): Promise<TaskUnsubscribe>;
    /**
     * Broadcast a cancellation signal. The authoritative state transition to
     * `cancelled` still happens in the flow layer via `update()`.
     */
    publishCancel(taskId: string, sessionId: string): Promise<void>;
    /** Optional teardown hook called during server shutdown. */
    destroy?(): Promise<void>;
}
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