Point it at your folders. It keeps your place.

    private save(): Promise<void> {
        // Snapshot is taken inside run() at write time (last-serialise-wins is
        // the correct semantics here), and every write is chained so that two
        // concurrent saves cannot race on a shared temp file. The second arg to
        // .then keeps the chain alive even after a prior write rejects.
        const run = () => this.persistSnapshot(this.data);
        this.writeQueue = this.writeQueue.then(run, run);
        return this.writeQueue;
    }

    private async persistSnapshot(snapshot: DbSchema): Promise<void> {
        const tmp = `${this.filePath}.${process.pid}.${Date.now()}.${Math.random().toString(36).slice(2)}.tmp`;
        try {
            const content = JSON.stringify(snapshot, null, 2);
            const fh = await fs.open(tmp, 'w');
            try {
                await fh.writeFile(content, 'utf-8');
                await fh.sync();
            } finally { await fh.close(); }
            await this.renameWithRetry(tmp, this.filePath);
        } catch (err) {
            await fs.unlink(tmp).catch(() => {});
            // (logging removed)
            throw err;
        }
    }

    /** Await all writes currently queued. Safe to call from before-quit. */
    flushWrites(): Promise<void> {
        return this.writeQueue;
    }