type StoragePort = Pick<Storage, 'getItem' | 'setItem'>;
const KEY = 'akashic_savedClinicianCheckout_v1';
const digest = (value: unknown): value is string => typeof value === 'string' && /^[a-f0-9]{64}$/.test(value);

// Hashes only; retain uncertain purchases across reload without keeping role details or checkout secrets.
export function claimSavedClinicianCheckout(storage: StoragePort, scope: string, initialize: boolean): void {
    const refused = () => new Error('The checkout result is not confirmed here. Check billing before another purchase.');
    if (!digest(scope)) throw refused();
    const raw = storage.getItem(KEY);
    let held: string[];
    if (raw === null) {
        if (!initialize) throw refused();
        held = [];
    } else {
        let value: unknown;
        try { value = JSON.parse(raw); } catch { throw refused(); }
        if (!value || typeof value !== 'object' || Array.isArray(value)) throw refused();
        const record = value as Record<string, unknown>;
        if (record.v !== 1 || Object.keys(record).some(key => !['v', 'held'].includes(key))
            || !Array.isArray(record.held) || record.held.length > 20 || !record.held.every(digest)
            || new Set(record.held).size !== record.held.length) throw refused();
        held = record.held;
    }
    if (held.includes(scope) || held.length >= 20) throw refused();
    const next = JSON.stringify({ v: 1, held: [...held, scope] });
    storage.setItem(KEY, next);
    if (storage.getItem(KEY) !== next) throw refused();
}