/**
 * Session lineage helper for the PI adapter.
 *
 * PI exposes a `ReadonlySessionManager` with `getHeader()` that returns the
 * header for the current session. The header carries `parentSession` which is
 * the path to the parent session's file (not a session id). Because the core
 * `HostAdapter` only asks for the root session id reachable from a starting
 * id, we walk best-effort: when the current request matches the session
 * manager's current session we return its ultimate parent-less ancestor's id
 * (falling back to the current id when the lineage chain cannot be resolved).
 *
 * This is intentionally conservative. PI's read-only API does not expose a
 * way to look up arbitrary session headers by id, so for any sessionId that
 * isn't the currently-active one we return the input id unchanged. That keeps
 * the `runIn: "main"` semantics sane: the current session resolves to its
 * root, everything else resolves to itself.
 */
import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
/** Test-only: clear the resolution cache so each case starts fresh. */
export declare function resetSessionLineageCacheForTests(): void;
/**
 * P3-2: same justification as in `adapter.ts` — use the SDK's
 * `ReadonlySessionManager` shape by indexing `ExtensionContext["sessionManager"]`
 * (its only public surface) rather than a structural mirror.
 */
type ReadonlySessionManager = ExtensionContext["sessionManager"];
/**
 * Return the root session id reachable from `currentSessionId`.
 *
 * Walks `sessionManager.getHeader().parentSession` when it points to a file
 * path we can read; otherwise returns the starting id. Best-effort by design.
 */
export declare function getRootSessionId(currentSessionId: string, sessionManager: ReadonlySessionManager | undefined): string;
export {};