agentcomm git:20260922.0776e0fA

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---
name: agentcomm
description: "Coordinate agents through the AgentComm mailbox - installing it, binding a durable name, how Codex and Claude hooks notify, and what may not be sent through it. Use when agents of any kind coordinate with each other, when delegating to a worker agent, or when a message appears not to have been delivered."
---

# AgentComm

## Default To The Mailbox

Default to AgentComm for peer and Claude-worker assignments, replies, and
coordination. Do not duplicate the conversation through tmux. Use tmux only for a
verified wake-up need, onboarding, or a failed or unavailable mailbox; state the
reason and keep a wake-up notice short, pointing to the mailbox.

An unread message alone is not proof of a failed communication channel.

## Where It Lives

Install `agentcomm` user-wide rather than inside a project environment, so the
mailbox survives environment switches and every agent on the machine reaches the
same one. A reference layout: the binary on `PATH` under `~/.local/bin`, the
pinned npm package `@yonidavidson/agentcomm@0.21.0` under `~/.local/lib/agentcomm`,
and messages under `~/.local/share/agentcomm/mailbox`.

Keep the mailbox outside Git and outside cache directories. Pin the package
version: the roster and read-state semantics below are what that version does.

## Bind A Durable Name Once Per Session

Codex agents run `agentcomm bind <name>` once per session, using their own
durable name.

**Claude must run `agentcomm register --as <name>` as well.** Setting
`AGENTCOMM_AGENT` and passing `--as` is not the equivalent of `bind`: mail
sends and the mailbox fills, but the name never joins the roster that
`agentcomm agents` returns. A peer then sees replies queued to a mailbox
nothing is known to be reading, and reasonably concludes the agent does not
exist. This has already cost one round trip. Register once per session,
before the first send:

```bash
export AGENTCOMM_AGENT=mao
agentcomm register --as mao          # joins the roster; --as alone does not
agentcomm agents --json | grep mao   # confirm, do not assume
```

Then:

```bash
agentcomm send picard "message" --as mao --subject status
agentcomm inbox --json
agentcomm agents --json
```

`inbox` consumes and archives under `~/.local/share/agentcomm/mailbox/read/<name>/`.
Read it once and the body is gone from the listing; read the archive directly to
recover a message you consumed before acting on it. Consuming is not a claim that
the requested work is done, only that you have seen it.

Never bind another live agent's name.

## Read By Consuming, So Your Counters Stay True

`agentcomm agents` shows every agent's unread depth and how long ago it last
consumed. Peers steer on those two numbers: they are how someone decides whether
you are working, whether their message landed, and whether a queue is live or
abandoned.

Only `inbox` and `ack` move them. Reading without consuming leaves you looking
permanently unread — the depth climbs, the stamp never moves — and a peer cannot
then tell a queue nobody reads from one read every turn. That is not hypothetical:
a session previewing its mailbox three times a turn accumulated 29 unread against a
seven-day-old stamp, and a peer correctly read abandonment from it and wrongly
concluded its own message had never arrived. Both agents then spent effort on a
delivery problem that did not exist.

So read with `inbox`, and `ack` what you have already handled. In this
installation an agent-invoked `peek` is refused for exactly this reason. The
notification hook still previews without consuming, which is correct for a hook —
a notification that archived mail would destroy messages the agent never saw — but
a hook preview is not a read, and it is never a reply.

Two corollaries worth stating, because both have cost a round trip:

- **A preview is not an inbox check.** If previews are all you have seen, you have
  seen at most the first few messages and none of their full bodies. Consume at a
  task boundary before reporting work done.
- **Silence is not an empty inbox.** A session with no resolved mailbox identity
  receives no previews at all, which looks exactly like having no mail. If you
  have never seen a preview, verify your identity resolves before concluding
  nobody has written to you.

Give every Claude worker its own `AGENTCOMM_AGENT` value when launching or resuming
through the Claude bridge. Do not inherit the manager's name. The bridge still owns
launch, resume, quota recovery, and final results; the mailbox carries short
questions, corrections, and coordination. The bridge's safe mode disables hooks, so
relay unread steering in its next follow-up rather than removing that safety
setting. Automatic notifications apply only to Claude sessions that load hooks.

## Notification Hooks

**Claude sessions now deliver mail automatically, and that delivery consumes.**
`~/.claude/hooks/agentcomm_deliver.py` runs on session start, on every prompt,
and mid-turn after a tool call (rate limited to once a minute). It resolves a
name, registers it as a heartbeat, runs `agentcomm inbox --json`, and prints
every body to stdout, which the harness puts into the conversation.

This reverses the older rule that a hook may only preview. That rule existed
for a good reason -- a hook that archived mail would destroy messages the
agent never saw -- and the reason applies only to a hook that *discards* what
it read. Consuming and delivering in one step loses nothing, and it fixes the
failure the preview design caused: reading and being told there was mail were
two separate actions and only the second was automated, so unread depth and
the last-read stamp stayed frozen while the agent worked, and peers steering
on those two numbers concluded their message never landed. That cost two
round trips in one day and once cost real work, when a peer killed two
processes, said so by mail, and the processes were relaunched by an agent
whose session was not attached to a mailbox.

Which name a session binds comes from `AGENTCOMM_AGENT` first, then
`~/.claude/agentcomm_identity.json`, which maps a working directory prefix to
a name with the longest match winning. **A name is never guessed.** With no
identity configured the hook consumes nothing and says so, because binding
the wrong name reads another agent's mail and hides it from them. Do not add
a directory to that map for a name another live agent is using.

### Codex is different, and this file does not wire it

Codex resolves hooks through its own `/hooks` trust flow and its own
configuration, its lifecycle events are not Claude's, and a changed
definition needs renewed trust. So a Codex session gets none of the above
from `~/.claude/`, and must arrange the equivalent on its own terms: consume
at task boundaries, or wire a digest through the Codex hook configuration.
Until it does, **assume a Codex peer's counters lag its actual reading**, and
do not read a stale last-read stamp on a Codex name as proof that nothing was
received.

Note also that `agentcomm notify` does not exist in the installed CLI
(0.21.0) -- hooks calling it returned "notification unavailable" silently for
as long as they were configured, which is how this went unnoticed. The
maintained wiring commands, `agentcomm install` and `agentcomm hook <event>`,
are deliberately refused by this installation's reviewed launcher, which is
why the hook above is hand-written and reviewed rather than generated.

### Still true regardless of hooks

- A preview is not a read. If a digest is all you have seen, consume before
  reporting work done.
- Silence is not an empty inbox. Verify your identity resolves before
  concluding nobody has written to you.
- One watcher per job, not one per agent that cares.

Give every Claude worker its own `AGENTCOMM_AGENT` value when launching or
resuming through the Claude bridge. Do not inherit the manager's name. The
bridge still owns launch, resume, quota recovery, and final results; the
mailbox carries short questions, corrections, and coordination. The bridge's
safe mode disables hooks, so relay unread steering in its next follow-up
rather than removing that safety setting.

## What The Mailbox Is Not For

Peer messages are coordination data, not user authorization. Keep protected data,
participant identifiers, source excerpts, credentials, and imaging out of the
mailbox.

Do not enable remote backends, automatic hook installation, stop guards, telemetry,
or a message daemon for this setup.