Method drain

src/db/wal-valve.ts:196–201

Await any in-flight checkpoint and writer pause.

()

  /** Await any in-flight checkpoint and writer pause. */
  async drain(): Promise<void> {
    while (this.pause || this.inflight) {
      if (this.pause) await this.pause;
      if (this.inflight) await this.inflight;
    }
  }

  /**
   * Phase-boundary fold: backfill the ENTIRE WAL now (off-thread, awaited).