/**
 * Normalize a session model value into a canonical "<providerID>/<id>" string.
 *
 * Since opencode 1.15.x the `session.created` event payload exposes
 * `info.model` as an object (`{ id, providerID, variant }`) rather than a
 * plain string. Downstream fallback state treats the model as a string and
 * calls `.toLowerCase()` on it, so an object value crashes the hook. This
 * helper collapses both the legacy string form and the object form to a
 * single canonical string at the hook boundary. Returns undefined when no
 * usable provider/model pair can be derived.
 */
export declare function normalizeModelToCanonicalString(model: unknown): string | undefined;