Fan Out

Fan-Out

Overview

This skill distributes work across multiple subagents with unified status tracking. It creates a to-do list, spawns subagents, maintains a live discussion post of task status, steers subagents when they encounter known issues, and summarizes outputs when complete. Subagents can be spawned asynchronously to complete tasks in parallel.

Requirements

• todo MCP server — used for task list creation and item tracking. See haliphax-openclaw/todo-mcp-server.

When to Use

• User provides multiple tasks ("help me do X, Y, and Z")
• A to-do list exists and each item should become an independent subagent
• Long-running tasks benefit from parallel execution rather than sequential
• Need unified tracking and summary of multiple workers

Workflow

Step 1: Accept Input

• tasks: Bullet list or comma-separated list of task descriptions
• async: Whether the tasks should be completed asynchronously (parallel subagents)

For item names in the to-do list, use the task content directly.

Step 2: Create To-Do List

For the list ID:

• Use current agentId if working on agent-specific tasks
• Generate a project slug based on task content
• Create new list with descriptive slug

For the list name:

• Use a short description of the project

Create new list:

mcporter call todo.todo_list_create key=<list_id> name="<name>"

Add items:

mcporter call todo.todo_item_add key=<list_id> content="<task description>"

Each item returns a unique item_id for tracking.

Step 3: Spawn Subagents Asynchronously

For each to-do item, spawn a subagent using sessions_spawn:

sessions_spawn(
  task="<task description>",
  label="fanout-<list_id>-<item_short_id>",
  runtime="subagent",
  mode="run",
  cleanup="keep"  # Keep for status polling
)

Key settings:

• runtime="subagent" - Spawns isolated subagent session
• mode="run" - One-shot execution
• cleanup="keep" - Retain session for status checks
• label - Trackable identifier for steering/polling

Store mapping: item_id → session_key

Step 4: Maintain Live Status Post

Post the initial status to a single message, then edit that same message in-place as tasks progress. Do not add new messages for each update—edit the original to keep the channel clean. When a task completes, the status post reflecting this is enough. Save additional output for the summary.

Track:

• All tasks and their current status (pending/running/completed/failed)
• Elapsed time for each task
• Errors or blockers encountered

Format as a list with emoji for status:

**Fan-Out Status: some-list-id**

- 🕰️ task-id-1 (1m13s)
- ⚡️ task-id-2 (15s)
- ❌ task-id-3 (5m3s)
- ✅ task-id-4 (8s)
- 🚫 task-id-5 (10m)

Emoji key:

• 🕰️ pending (not started)
• ⚡️ running
• 🚫 canceled
• ❌ failed
• ✅ succeeded

Edit this same message periodically as subagents progress.

Step 5: Poll and Steer Subagents

Poll status:

subagents(action="list", recentMinutes=10)

For each subagent, check:

• Is it still running?
• Did it encounter a known issue the parent agent can help with?
• Has it exceeded expected time?

Steering: If a subagent is blocked on something the parent agent has context for:

subagents(
  action="steer",
  target="<session_key>",
  message="<guidance based on parent agent context>"
)

Examples:

• "Use the todo MCP server: mcporter call todo.todo_list_create key=..."
• "The repo is at /path/to/repo - don't re-clone it"
• "Credentials are in env vars, not in code"

Step 6: Aggregate Results

When all subagents complete (or are killed for inactivity):

1. Collect outputs:

   • Poll each session for final status
   • Fetch session history if needed

2. Summarize:

   • Group by status (success/failed/canceled/timeout)
   • Include individual task durations and total duration
   • Extract key outputs from each
   • Note any patterns or common blockers

3. Final report:

   **Fan-Out Complete: <list_id>**
   
   **✅ Succeeded (<n>):**
   - <task> (<duration>): <result summary>
   
   **❌ Failed (<n>):**
   - <task> (<duration>): <error>
   
   **🚫 Canceled (<n>):**
   - <task> (<duration>): <reason>
   
   **Total Duration:** <time>
   

Example Usage

Tasks to fan out:

• Fix bug in auth module
• Update README
• Run tests

Execution flow:

1. Create list (agent generates name)
2. Spawn subagents for each task (in parallel if async is requested)
3. Post initial status to channel
4. Poll every 5-10s for updates
5. If subagent encounters issues, steer it with context
6. When all complete, post summary

Key Commands Reference

Note: You may need to supply additional arguments to mcporter (such as --config to specify the configuration file path).

Best Practices

• Use descriptive list_id that links to project/task
• Keep task descriptions clear and actionable
• Set reasonable cleanup="keep" for status tracking
• Execute tasks in parallel whenever possible to save time
• Poll every 5-10s for updates (native subagents)
• Use progressive backoff when monitoring ACP subagents doing complex work (e.g. 20s → 40s → 60s → 120s, capped at 2 minutes)
• Edit status post in-place—never add new messages for updates
• Steer proactively when you see common blockers
• Always aggregate results at the end