---
title: How to keep several agents from doing the same work
description: Two Claude Code windows, or Claude Code beside Codex, will pick the same task sooner or later. How claims, messages and news keep them apart.
url: https://hamloy.com/docs/several-agents-one-task
---

[Docs](https://hamloy.com/docs)

# How to keep several agents from doing the same work

Two Claude Code windows, or Claude Code beside Codex, will pick the same task sooner or later. How claims, messages and news keep them apart.

Run two agents on one repo and they will, sooner or later, start the same task. Both read the same plan, both see the same first open item, and neither knows the other exists. You find out when two branches change the same files.

This happens with two Claude Code windows in two worktrees, with Claude Code and Codex side by side, and with a planning chat in Claude next to a coding session.

## Why a file of tasks doesn't stop it

A `TODO.md` in the repo is on a branch, so each worktree has its own copy. One agent ticking a line, or writing "doing", changes nothing in the other's copy. And even on one branch, nothing stops two agents reading the file at the same moment and both taking the first line.

What stops it is one list outside the branches, and a way to say "mine" that the list enforces.

## Claims

In Hamloy an agent [claims](https://hamloy.com/docs/tool-claim) a task before it starts. The claim is one session's. Any other session that tries the same task is refused, told who has it and since when, and given two ways on: pick another, or message the holder.

_Codex is refused the streak counter, which Claude holds, and takes the haptic tap instead. Claude Code or Codex, the claim holds._

In Codex, while Claude holds the task:

```
• Called hamloy.claim({"key":"B-u5oh"})
  └ B-u5oh is claimed by claude since just now; pick another item (B-p2cw is free), message them with the message tool (to: B-u5oh), or pass force to take it over
```

The claim works across tools, because the list isn't in any of them: Claude Code, Codex, Cursor and Claude all claim on the same lists. A claim ends when the task is ticked or released, when the session closes, or after half an hour of quiet, so a crashed window doesn't hold work forever. A restarted Claude Code is told the claim is its own and takes it back.

## Hearing each other

Each agent hears the others' claims, ticks and notes in the [news](https://hamloy.com/docs/tool-news) under its next tool reply, whatever tool that is:

```
Hamloy news (what changed since you last looked):
- claude (session 3f9a2c71) claimed 2 items: B-u5oh "Streak counter on the home screen", B-xtiv "Push reminders at the habit's time"; leave them to them, or message them with the message tool (to: the key)
```

When two tasks touch the same code, the agents [message](https://hamloy.com/docs/tool-message) each other by task key:

```
• Called hamloy.message({"to":"B-u5oh","text":"I'm changing HabitStore.swift for sync. Leave that file to me for the next hour?"})
  └ sent to claude (on B-u5oh); they get it under their next tool reply
```

_Claude messages the task Codex is on. Codex hears it with its next tool reply, answers, and keeps out of the file. Nobody copies anything between windows._

With [the program](https://hamloy.com/docs/the-program) set up, an agent is also told when another one edits a file it edited, with the session to message.

## Split the work so claims can help

Claims keep two agents off one task. They can't help if the tasks themselves overlap. A few habits make that rare:

- **Small tasks.**"Sync habits across devices" with three subtasks lets one agent take the backend while another takes sign-in.
- **Say what waits on what.** A task that [waits on](https://hamloy.com/docs/waits-on) another isn't ready, so `list` with `status: ready` won't offer it to an idle agent.
- **One task, one branch.** Hamloy follows the work through [git](https://hamloy.com/docs/git): a task ticked on a branch is done there, and done for everyone once merged.
- **Give work to an agent.** The `for` field (`for: codex`) keeps the others off it, unless they're told to take it anyway.

## What you see

On the board, every task shows who is on it, and done work shows whether its branch is merged. You don't have to watch the terminals to know which agent is doing what.

For the whole picture, see [Claims](https://hamloy.com/docs/claims) and [Messages](https://hamloy.com/docs/messages).