Method append

src/agent/scratchpad.ts:452–454

* Append-only write

(entry: ScratchpadEntry)

   * Append-only write
   */
  private append(entry: ScratchpadEntry): void {
    appendFileSync(this.filepath, JSON.stringify(entry) + '\n');
  }

  /**
   * Parse and validate a single JSONL line. Returns null for malformed or invalid entries.