paseo/packages/cli/src/commands/agent/attach.ts

import type { Command } from "commander";

export function addAttachOptions(cmd: Command): Command {
  return cmd
    .description("Attach to a running agent's output stream")
    .argument("<id>", "Agent ID (or prefix)");
}
import { connectToDaemon, getDaemonHost } from "../../utils/client.js";
import { fetchProjectedTimelineItems } from "../../utils/timeline.js";
import type {
  DaemonClient,
  AgentStreamMessage,
  AgentStreamEventPayload,
  AgentTimelineItem,
} from "@getpaseo/server";

export interface AgentAttachOptions {
  host?: string;
  [key: string]: unknown;
}

/**
 * Format and print a timeline item to the terminal
 */
function printTimelineItem(item: AgentTimelineItem): void {
  switch (item.type) {
    case "assistant_message":
      // Print assistant text directly
      process.stdout.write(item.text);
      break;

    case "reasoning":
      // Print reasoning in a muted color if available
      console.log(`\n[Reasoning] ${item.text}`);
      break;

    case "tool_call": {
      const toolName = item.name;
      const status = item.status ?? "started";
      console.log(`\n[Tool: ${toolName}] ${status}`);
      break;
    }

    case "todo": {
      const completed = item.items.filter((i) => i.completed).length;
      const total = item.items.length;
      console.log(`\n[Todo] ${completed}/${total} completed`);
      break;
    }

    case "error":
      console.error(`\n[Error] ${item.message}`);
      break;

    case "user_message":
      console.log(`\n[User] ${item.text}`);
      break;

    default:
      // Unknown item type, skip
      break;
  }
}

/**
 * Format and print a stream event to the terminal
 */
function printStreamEvent(event: AgentStreamEventPayload): void {
  switch (event.type) {
    case "timeline":
      // Print the timeline item
      printTimelineItem(event.item);
      break;

    case "permission_requested":
      console.log(`\n[Permission Required] ${event.request.name}`);
      if (event.request.description) {
        console.log(`  ${event.request.description}`);
      }
      break;

    case "permission_resolved":
      console.log(`\n[Permission ${event.resolution.behavior}]`);
      break;

    case "turn_failed":
      console.error(`\n[Turn Failed] ${event.error}`);
      break;

    case "attention_required":
      console.log(`\n[Attention Required: ${event.reason}]`);
      break;

    default:
      // Other event types are internal
      break;
  }
}

/**
 * Attach to a running agent's output stream
 */
export async function runAttachCommand(
  id: string,
  options: AgentAttachOptions,
  _command: Command,
): Promise<void> {
  const host = getDaemonHost({ host: options.host as string | undefined });

  if (!id) {
    console.error("Error: Agent ID required");
    console.error("Usage: paseo attach <id>");
    process.exit(1);
  }

  let client: DaemonClient;
  try {
    client = await connectToDaemon({ host: options.host as string | undefined });
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err);
    console.error(`Error: Cannot connect to daemon at ${host}: ${message}`);
    console.error("Start the daemon with: paseo daemon start");
    process.exit(1);
  }

  try {
    const fetchResult = await client.fetchAgent(id);
    if (!fetchResult) {
      console.error(`Error: No agent found matching: ${id}`);
      console.error("Use `paseo ls` to list available agents");
      await client.close();
      process.exit(1);
    }
    const resolvedId = fetchResult.agent.id;

    // Print header
    console.log(`Attaching to agent ${resolvedId.substring(0, 7)}...`);
    console.log(`(Press Ctrl+C to detach)\n`);

    // Print existing output from timeline fetch.
    try {
      const timelineItems = await fetchProjectedTimelineItems({
        client,
        agentId: resolvedId,
      });
      for (const item of timelineItems) {
        printTimelineItem(item);
      }
    } catch (error) {
      console.warn("Warning: failed to fetch existing timeline", error);
    }

    // Subscribe to new events
    const unsubscribe = client.on("agent_stream", (msg: unknown) => {
      const message = msg as AgentStreamMessage;
      if (message.type !== "agent_stream") return;
      if (message.payload.agentId !== resolvedId) return;

      printStreamEvent(message.payload.event);
    });

    // Handle Ctrl+C to detach gracefully
    let detached = false;
    const detach = () => {
      if (detached) return;
      detached = true;

      console.log("\n\nDetaching from agent...");
      unsubscribe();
      client
        .close()
        .then(() => {
          process.exit(0);
        })
        .catch(() => {
          process.exit(1);
        });
    };

    process.on("SIGINT", detach);
    process.on("SIGTERM", detach);

    // Keep the process alive
    await new Promise(() => {
      // Wait indefinitely until interrupted
    });
  } catch (err) {
    await client.close().catch(() => {});
    const message = err instanceof Error ? err.message : String(err);
    console.error(`Error: Failed to attach to agent: ${message}`);
    process.exit(1);
  }
}