/**
 * `createD1PrewarmClaimStore` — the cross-isolate half of
 * `createSandboxPrewarmer`'s single-flight, implemented once.
 *
 * WHY THIS SHIPS HERE. `SandboxPrewarmerOptions.claim` is REQUIRED and has no
 * default, which is correct — the unsafe behaviour must be said out loud. But
 * "required with no implementation" is how five products end up hand-rolling
 * five subtly different atomic leases, and a lease that is subtly wrong is
 * indistinguishable from one that works until two tabs leak a box. Every
 * agent-app product deploys to Cloudflare Workers with a D1 binding, so the
 * store is the same code in all of them: it is mechanism, not domain, and it
 * belongs beside the prewarmer.
 *
 * The measured stake (staging-sandbox, 2026-07-28): two concurrent
 * `POST /v1/sandboxes` with an identical name BOTH returned HTTP 201 and left
 * two running boxes. The platform does not dedupe by name, so nothing below
 * this line is defensive programming — an unclaimed race genuinely doubles
 * spend.
 *
 * ── ATOMICITY IS THE WHOLE POINT ───────────────────────────────────────────
 * `acquire` is ONE statement. A `SELECT` followed by an `INSERT` is exactly the
 * race this exists to close: both isolates read "free", both write, both warm.
 * The upsert's `DO UPDATE ... WHERE expires_at <= now` means an unexpired claim
 * makes the conflict path a no-op, and `RETURNING` then yields no row — so the
 * loser learns it lost from the same statement that would have made it the
 * winner. `RETURNING` is used rather than `meta.changes` because a no-op upsert
 * reporting `changes: 0` is a SQLite detail, whereas "no row came back" is the
 * statement telling you directly.
 *
 * ── STRUCTURAL, NOT A DEPENDENCY ───────────────────────────────────────────
 * The binding is taken as the narrow shape actually used (`prepare().bind()`,
 * `.first()`, `.run()`), per the package's structural-over-hard-dep rule. No
 * `@cloudflare/workers-types` import, so `/sandbox` stays importable in a plain
 * node test. A real `D1Database` satisfies it.
 *
 * ── THE TABLE IS THE PRODUCT'S MIGRATION, NOT A LAZY CREATE ────────────────
 * The store never runs DDL. A `CREATE TABLE IF NOT EXISTS` on every project
 * open costs a round trip on the exact path this feature exists to keep fast,
 * and it hides schema drift instead of failing on it. `PREWARM_CLAIM_TABLE_DDL`
 * is exported so a product pastes it into a real migration. If the table is
 * missing, `acquire` throws — and the prewarmer treats a throwing claim as a
 * failed warm: it records the failure, emits `onEvent({type:'failed'})`, and
 * degrades to the lazy path. Fail-closed and loud, never a silent double-warm.
 */
/** The columns and statements this store uses, and nothing else. A real
 *  `D1Database` structurally satisfies it. */
export interface PrewarmClaimD1Like {
    prepare(query: string): {
        bind(...values: unknown[]): {
            first<T = Record<string, unknown>>(): Promise<T | null>;
            run(): Promise<unknown>;
        };
    };
}
export interface D1PrewarmClaimStoreOptions {
    /** Defaults to `sandbox_prewarm_claims`. Must be a bare SQL identifier — it
     *  is interpolated, because a table name cannot be a bound parameter. */
    table?: string;
    /** Clock seam for tests. */
    now?(): number;
}
export declare const DEFAULT_PREWARM_CLAIM_TABLE = "sandbox_prewarm_claims";
/** Paste into a migration. `expires_at` is epoch MILLISECONDS, matching
 *  `Date.now()`, so no unit conversion sits between the lease and its clock. */
export declare const PREWARM_CLAIM_TABLE_DDL = "CREATE TABLE IF NOT EXISTS sandbox_prewarm_claims (\n  key TEXT PRIMARY KEY,\n  expires_at INTEGER NOT NULL\n)";
/**
 * A `PrewarmClaimStore` backed by one D1 table.
 *
 * ```ts
 * const prewarmer = createSandboxPrewarmer(shell, {
 *   claim: createD1PrewarmClaimStore(env.DB),
 *   mode: 'create-or-resume',
 * })
 * ```
 */
export declare function createD1PrewarmClaimStore(db: PrewarmClaimD1Like, options?: D1PrewarmClaimStoreOptions): {
    acquire(key: string, ttlSeconds: number): Promise<boolean>;
    release(key: string): Promise<void>;
    isHeld(key: string): Promise<boolean>;
};