Method finalize

packages/utils/src/lib/wal-sharded.ts:353–391

* Finalize all shards by merging them into a single output file. * Recovers all records from all shards, validates no errors, and writes merged result. * Idempotent: returns early if already finalized or cleaned. * @throws Error if custom finalizer method throws

(opt?: Record<string, unknown>)

   * @throws Error if custom finalizer method throws
   */
  finalize(opt?: Record<string, unknown>) {
    if (this.#state !== 'active') {
      return;
    }

    // Ensure base directory exists before calling shardFiles()
    ensureDirectoryExistsSync(this.#dir);

    const lastRecovery = this.shardFiles().map(f => ({
      file: f,
      result: new WriteAheadLogFile({
        file: f,
        codec: this.#format.codec,
      }).recover(),
    }));

    const records = lastRecovery.flatMap(({ result }) => result.records);

    if (this.#debug) {
      this.#lastRecovery = lastRecovery;
    }

    ensureDirectoryExistsSync(path.dirname(this.getFinalFilePath()));

    try {
      fs.writeFileSync(
        this.getFinalFilePath(),
        this.#format.finalizer(filterValidRecords(records), opt),
      );
    } catch (error) {
      throw extendError(
        error,
        'Could not finalize sharded wal. Finalizer method in format throws.',
        { appendOriginalMessage: true },
      );
    }

    this.#state = 'finalized';
  }

  /**
   * Cleanup shard files by removing them from disk.