Function readTaskOutput

apps/vis/server/src/lib/task-store.ts:121–151

(
  agentDir: string,
  taskId: string,
  offset: number,
  maxBytes: number,
)

 * Mirrors agent-core's `readTaskOutputBytes` so large logs page identically.
 */
export async function readTaskOutput(
  agentDir: string,
  taskId: string,
  offset: number,
  maxBytes: number,
): Promise<TaskOutputWindow> {
  const start = Math.max(0, Math.trunc(offset));
  const limit = Math.max(0, Math.trunc(maxBytes));
  let handle;
  try {
    handle = await open(taskOutputFile(agentDir, taskId), 'r');
  } catch {
    return { offset: start, nextOffset: start, size: 0, content: '', eof: true };
  }
  try {
    const size = (await handle.stat()).size;
    if (limit === 0 || start >= size) {
      return { offset: start, nextOffset: start, size, content: '', eof: start >= size };
    }
    const length = Math.min(limit, size - start);
    const buffer = Buffer.allocUnsafe(length);
    const { bytesRead } = await handle.read(buffer, 0, length, start);
    const content = buffer.toString('utf-8', 0, bytesRead);
    const nextOffset = start + bytesRead;
    return { offset: start, nextOffset, size, content, eof: nextOffset >= size };
  } catch {
    return { offset: start, nextOffset: start, size: 0, content: '', eof: true };
  } finally {
    await handle.close();
  }
}

// ── normalization (ported from agent-core/agent/background/persist.ts) ───────