stack/skills/ms-communications/SKILL.md

name, description, disable-model-invocation

name	description	disable-model-invocation
ms-communications	Use this skill whenever sending a message to, or receiving one from, another Mosaic agent.	false

ms-communications

Agent-to-agent messaging: one channel, one addressing grammar, honest triage. Messages are transport. The durable record lives in run records, issues, and SESSIONS.md, never in a pane that scrolls away.

Channel

• tools/tmux/agent-send.sh is the only send path. It prepends the preamble, submits reliably (bracketed paste, Enter flush, draft detection), and ships itself over ssh for remote targets. Never raw tmux send-keys; that is how messages die as unsubmitted drafts.
• Your own session output is not a send path either. A reply composed as assistant prose, however well formatted, delivers nothing to the recipient's pane; a hand-written preamble in prose is decoration, not delivery. A reply exists only once agent-send.sh has run, and its exit code is the delivery receipt. No rc, no send.

Preamble

Preamble is prepended to the message when using the agent-send.sh script. Check the script for usage instructions.

[<src_host>:<src_session> -> <dst_host>:<dst_session>] <message>
[<src> -> <dst> class=<CLASS>] <message>     # with triage class

• Non-Fleet seats use the default docket.

• Fleet seats use the named socket: -L mosaic-fleet (or MOSAIC_TMUX_SOCKET). Fleet traffic stays off the user's default tmux server.

• Address durable fleet seats exactly: =coder0, not a prefix that might match two sessions.

• Tool spec and internals: tools/tmux/README.md

• host is hostname -s of the sender's machine; session is the tmux session name. agent-send.sh writes the preamble for you. Two rules carry the protocol:

1. Replying? Flip it: [<dst> -> <src>] .... Answer under your own lane. The tool performs the flip: aim your send at the original sender's session (agent-send.sh -s <src_session> -C <class>) and it writes the flipped preamble for you. Never write the bracket line yourself.
2. A preamble-less cross-agent message is malformed. If you receive one, ask the sender to resend before acting on it.

Triage classes

Class	Meaning	Recipient behavior
(absent)	fail-safe default	treat as actionable
actionable	decision, blocker, or gate	act, then reply
human	from a human operator	deliver; respond promptly
reaction	emoji or ack	note it; no reply expected
terminal-log	log-only noise	file it; never act
digest	machine-wake, coalescible	batch; wake and continue

Class honestly. Never downgrade a question you want answered to terminal-log.

Etiquette

1. Write for a context-wiped reader. Preamble plus body must carry the ask, the evidence (run id, issue number, path), and any deadline. The recipient has no "as I mentioned earlier".
2. One topic per message. Two asks in one paste is how the second gets lost.
3. Reply, even when the reply is "ACK, on it" or "cannot, reason follows". Silence is not an ack. A refusal with a reason is recoverable; a guess is not.
4. No secrets. Messages land in scrollback, logs, and possibly comms daemons.
5. Waiting on a condition? Arm agent-watch on the condition, not a poll of a colleague's pane. Waiting on a seat? Message them (see ms-watch).

Receiving

1. Read the preamble first. Confirm you are the dst. Note the src.
2. Triage by class (table above). actionable or absent: act now, or reply why not.
3. Reply by sending: invoke agent-send.sh aimed at the sender's session; the tool writes the flipped preamble. Cite the run id or issue you acted on. Formatting the reply into your own output without running the tool leaves the sender with nothing; that is a dropped reply, not a late one.

Delivery mechanics

• Exit codes: 0 delivered or queued, 1 target not found, 2 still draft, 3 usage error, 4 ambiguous socket (the session name exists on more than one tmux server; disambiguate with -L).
• A refusal is evidence. Diagnose it; do not route around it with raw send-keys.
• rc=2 from an agent-watch delivery means the text reached your pane as a draft. Go read the pane; auto-submit-drafts.sh flushes stable drafts.

When not to message

• Waiting on yourself: do the next thing.
• Facts that must survive the exchange belong in the run record, the issue, or SESSIONS.md. A message that matters gets persisted where the record lives.