Sessions and resources

export interface HarnessIdentity {
    userId: string;
    tenantId: string;
}

export interface HarnessSessionLease {
    read(): HarnessSessionSnapshot;
    commit(snapshot: Omit<HarnessSessionSnapshot, "revision">): void;
    release(): void;
}

export interface HarnessSessionSnapshot {
    conversations?: Record<string, ChatMessage[]>;
    history: ChatMessage[];
    state: Record<string, unknown>;
    revision: number;
    replayable: boolean;
}

export interface HarnessSessionStore {
    readonly guarantees: {
        durable: boolean;
        compareAndSwap: boolean;
        singleWriter: "process" | "distributed";
    };
    acquire(identity: HarnessIdentity, sessionId: string): Promise<HarnessSessionLease>;
}

export interface ScopedResource<T = unknown> {
    value: T;
    ownership: "host" | "runtime";
    dispose?: () => Promise<void>;
}

export interface SessionResourceLease<T> {
    value: T;
    release: () => Promise<void>;
}

/** Session resources live until explicit closeSession; run resources use their returned lease. */
export declare class HarnessResourcePool {
    acquire<T>(identity: HarnessIdentity, sessionId: string, id: string, scope: "host" | "session" | "run", initialize: () => Promise<ScopedResource<T>>): Promise<SessionResourceLease<T>>;
    closeSession(identity: HarnessIdentity, sessionId: string): Promise<readonly string[]>;
}

export declare class HarnessSessionConflict extends Error {
    readonly code = "session_conflict";
    constructor();
}

/** One writer per scoped session; deliberately rejects rather than silently interleaving. */
export declare class InMemoryHarnessSessionStore implements HarnessSessionStore {
    readonly guarantees: {
        durable: boolean;
        compareAndSwap: boolean;
        singleWriter: "process";
    };
    acquire(identity: HarnessIdentity, sessionId: string): Promise<HarnessSessionLease>;
    /** Imported display-only transcripts are readable but never represented as complete replay state. */
    importLegacy(identity: HarnessIdentity, sessionId: string, history: ChatMessage[]): void;
}