export type RuntimeSessionEvictReason = "idle_timeout" | "stale" | "replaced" | "disposed";
/** Public upper bound for opaque canonical-history version tokens. */
export declare const CONVERSATION_HISTORY_VERSION_MAX_BYTES = 512;
export declare function assertConversationHistoryVersion(value: unknown): asserts value is string;
export interface RuntimeSessionRecord {
    modelKey?: string;
    /** Process-local budget and one-shot boundary; never serialized. */
    recovery?: {
        failureUsed: boolean;
        nextOutcome?: "cancelled" | "failed";
    };
    readonly conversationId: string;
    readonly providerSessionId: string;
    providerSessionRevision?: number;
    /** Canonical host-history version this warm handle has consumed. */
    historyVersion?: string;
    readonly createdAt: number;
    lastActivityAt: number;
    busy: boolean;
}
export interface RuntimeSessionSnapshot {
    readonly modelKey?: string;
    readonly conversationId: string;
    readonly providerSessionId: string;
    readonly providerSessionRevision?: number;
    readonly historyVersion?: string;
    readonly createdAt: number;
    readonly lastActivityAt: number;
    readonly busy: boolean;
}
export interface RuntimeSessionStoreOptions {
    readonly idleTimeoutMs: number;
    readonly onEvict?: (record: RuntimeSessionRecord, reason: RuntimeSessionEvictReason) => void | Promise<void>;
    readonly now?: () => number;
}
export interface RuntimeSessionStore {
    /**
     * Returns the live record for a conversation and marks it busy, or
     * undefined when there is no session, another run already holds it, or it
     * idled out (lazy wall-clock check covers stalled timers). Busy records are
     * never evicted here — a session executing a turn must not be torn down.
     */
    acquire(conversationId: string): RuntimeSessionRecord | undefined;
    /** No-op unless `record` is still the conversation's live record. */
    release(conversationId: string, record: RuntimeSessionRecord): boolean | void;
    /**
     * Upsert. A differing stored id is evicted first with reason "replaced" —
     * unless that record is busy under another run (`owner` is the caller's
     * acquired record), in which case the save is skipped: the in-flight run's
     * session must not be disposed out from under it.
     */
    save(conversationId: string, providerSessionId: string, owner?: RuntimeSessionRecord, providerSessionRevision?: number, historyVersion?: string, modelKey?: string, recovery?: RuntimeSessionRecord["recovery"]): void;
    /**
     * When `providerSessionId` is given, evicts only if it still matches the
     * stored record — a stale-resume eviction must not retire a session some
     * other run replaced it with.
     */
    evict(conversationId: string, reason: RuntimeSessionEvictReason, providerSessionId?: string): Promise<void>;
    /** Forget only this process's mapping after the runtime handle was refreshed explicitly. */
    forget(conversationId: string, providerSessionId?: string): boolean;
    /** Read-only snapshot for detached status and diagnostics. */
    list?(): readonly RuntimeSessionSnapshot[];
    /** Evicts everything and latches the store shut: later save/acquire no-op. */
    disposeAll(): Promise<void>;
}
export interface RuntimeSessionStoreWithSnapshot extends RuntimeSessionStore {
    release(conversationId: string, record: RuntimeSessionRecord): boolean;
    list(): readonly RuntimeSessionSnapshot[];
}
export declare function createRuntimeSessionStore(options: RuntimeSessionStoreOptions): RuntimeSessionStoreWithSnapshot;
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