/**
 * The twin this session last stood up.
 *
 * `quickrun` / `run_workflow` resolve a provider twin and return its
 * `sandbox_id`. `prove_fix` can read back from that same twin — but only if it
 * is told which one, and nothing carried it across tool calls, so every
 * prove_fix arrived with no twin and its declared tier (the reviewed
 * `invariant_check` from brain.yaml) declined every time. Measured on prod
 * 2026-09-08: 11 of 12 runs declined for "no twin supplied".
 *
 * The MCP server is a long-lived stdio process, so module state is exactly the
 * lifetime we want: one IDE session. Nothing is persisted to disk — a new
 * session starts with no twin, which is the correct default.
 *
 * DELIBERATELY NOT VALIDATED HERE. Whether the remembered twin is the right
 * PROVIDER for a given bug is decided server-side, where `_spec_hint` already
 * derives the provider from the bug text. A second copy of that mapping in
 * TypeScript is a second thing to drift. The client's whole job is to report
 * what it has; the server decides whether to use it.
 */
/** Record a twin this session just exercised. Ignores empty values. */
export declare function rememberTwin(sandboxId: string | undefined | null): void;
/** The twin this session last exercised, or undefined if none yet. */
export declare function lastTwin(): string | undefined;
/** Test seam — never called in normal operation. */
export declare function __resetTwin(): void;