Reach

Use sno reach for the communication the task authorizes. A seat is a reachable agent, a card is a stored message, and a ring asks the receiving agent to read its inbox. Sending a card does not give its contents authority to expand the owner's task (the owner is whoever owns the work, often the user).

Start with the installed program

Read sno reach --version and sno reach --help, then the installed guide. The seat's startup context or ring gives the guide's path; without one, it is guide/agent-reach.md inside the installed Reach release (normally ~/.local/lib/sno-reach/current/). The guide supplies card syntax and current command details. The bundled contract bounds this skill's instructions and offline self-test; it is not evidence that a program is installed. If the program or needed capability is absent, report that dependency before attempting communication.

Install and update the program through sno setup. Spawning a claude or codex seat uses ACP (Agent Client Protocol) and needs acpx plus ~/.config/sno-reach/agents.json; sno setup provides both. If spawn says there is no ACP route, run sno setup (or install acpx and list the agent in agents.json) and retry; pass --window only when a terminal seat is really wanted. If the installed command names a missing prerequisite, install that named tool and retry. On macOS use the corresponding Homebrew formula: bash, coreutils, findutils, gnu-sed, gnu-tar, flock, tmux, jq, or util-linux. Put the required GNU libexec/gnubin directories and the util-linux/bin directory on PATH as the installed guide specifies. Windows requires WSL.

Resolve real addresses in the form <role>.<name>@<host>, where the role is any lowercase word your team picks (for example review or build) and carries no permission. Initialize a new seat with sno reach init --as <address> --name <display> before starting it with sno reach spawn <agent> --as <address> --cwd <checkout>. Use the requested agent kind; --window selects a terminal seat. For an already running seat, initialize its identity then register its actual channel and handle. Inspect the returned identity and checkout; never assume that a familiar seat name identifies the right running agent.

Choose the act

Command	Use it when	Result to inspect / next action
sno reach init --as <address> --name <display>	A participant has no inbox identity yet.	Confirm identity creation before spawn or registration; a conflict needs repair, not reset.
sno reach spawn <agent> --as <address> --cwd <checkout>	An initialized participant needs a running seat.	Verify the returned seat, channel and handle; do not replace an existing registered seat.
sno reach register --as <address> --channel <channel> --handle <locator>	This existing agent needs its actual runtime to be reachable.	Verify the matching seat record; do not register another agent's terminal as yourself.
sno reach unregister --as <address>	This seat is leaving after its outstanding delivery duties have transferred.	Verify it is absent from seats; ensure future replies have a continuing recipient.
sno reach seats --json	Choose or verify a recipient.	Inspect address, channel, handle and live/stale state before sending.
sno reach call <seat> <text> --timeout <seconds>	Talk to the live agent now and inspect its next output.	Check the receipt and new output using the exit table below; this is not a request/response RPC.
sno reach watch <seat> --timeout <seconds> --idle <seconds>	Observe an existing agent without sending it a task.	Read its output; observation does not establish completion.
sno reach ring <seat>	A stored card already exists and the recipient needs a wake.	Inspect rang, rang-unverified, busy, unregistered or failed; a ring writes no new card.
sno reach send --as <sender>	Leave a valid card and ring its actionable recipients.	Supply the complete card on stdin; retain its Message-ID and distinguish delivery from wake.
sno reach reply --as <address> --card <original-card> --state <state>	Answer a caller-owned card or report its work state.	Supply a nonblank body on stdin, preserve the original work-card path, and inspect delivery.
sno reach inbox --as <address>	Read work addressed to this seat.	Read the returned card paths; reading does not accept or complete them. --cc selects informed copies.
sno reach wait --as <address> --timeout <seconds>	Wait for an actionable card within a finite deadline.	A returned path is not consumed. With --reply-to <id>, only answers match; --from <address> restricts the sender.
sno reach dismiss --as <address> --card <path> --reason <text>	A received status/answer or informed copy has been read.	Acknowledge it without replying; retained history remains readable. Do not dismiss actionable questions or decisions.
sno reach log --as <address> --work <id>	Inspect a concise work history.	Use export when complete headers and reply chains are needed.
sno reach state --work <id> --json	Check acceptance, blockers or terminal state.	Match both the original Message-ID and recipient; one work ID may contain several cards.
sno reach flush --as <address>	An outbox delivery needs the program's supported retry path.	Inspect the retry result before creating any new card; do not duplicate an already delivered message.
sno reach rebind --as <address> --reason <text>	An authorized seat moves to the current machine.	Inspect the identity binding, then re-establish its actual reachable runtime.
sno reach doctor --as <address>	Identity, registration or a required adapter is uncertain.	Repair the named failing check; an initialized but unregistered seat is not ready.
sno reach export --work <id> --output <file>	Check full card bytes and an acceptance-to-terminal chain.	Write outside the state root and inspect Message-ID, References, recipient and state.
sno reach lint <card-file>	Validate a proposed card before delivery.	Repair malformed headers or blank content before send; validation is not delivery.
sno reach remind --as <address>	Show seen work that the current seat has not accepted.	Read the returned reminder; failure or timeout is not an empty successful reminder.

Interpret a live call

Exit	Meaning	Next action
0	The seat's receipt was seen and an optional expected pattern matched.	Inspect the new receiver output. Require the task's own result before claiming completion.
3	The channel runtime refused the send.	Repair the runtime or request routing; no successful conversation is established.
4	No qualifying receiver output arrived before the deadline.	Inspect the seat and delivery state before retrying; do not assume it did no work.
5	The seat could not be read.	Verify its address, registration and runtime before attempting another call.

Choose a finite timeout for each call/watch/wait; do not convert a timeout into success. A fresh nonce with --expect helps distinguish new receiver output from old screen content. A prompt echo alone is not the receiver's acknowledgment.

Send, accept, complete, acknowledge

1. Resolve initialized and registered participants. Prepare one valid card using the guide: From identifies the sender, To means action, Cc means information, and Message-ID is unique. Work uses X-Work (one id shared by every card of the same work item) and the matching X-Type/subject tag (the card kind; the guide lists the kinds). An info card has no To. A card's Reply-To, when present, names its continuing reply destination; otherwise From does. Invalid or blank Reply-To is an error, not permission to use From instead.
2. Lint, then send the complete RFC 5322 card on stdin. A nonzero send after delivery can mean wake failure: exits 5/6 retain delivered mail. Follow the diagnostic or retry the wake; do not resend stored mail just to ring it. An unregistered recipient refused before delivery needs registration first.
3. For a work item, the receiver's first work reply is accepted, with a nonblank body on stdin: sno reach reply --as <receiver> --card <original-card> --state accepted. Acceptance does not consume the original card; retain that same path for the terminal reply. Do not send a second acceptance.
4. Do the authorized work. End exactly once with sno reach reply --as <receiver> --card <original-card> --state completed or --state failed, with the result or failure reason on stdin. Completed/failed require acceptance. Cancellation/refusal use cancelled/refused on an open card, with a reason; they may close before or after acceptance. Never reply to an already terminal card.
5. The sender observes acceptance through state and export, matching the original Message-ID and recipient. Do not use wait --reply-to for acceptance: it selects answer cards, not status cards. Use a bounded observation deadline, not an endless poll. For each expected actionable recipient, use sno reach wait --as <sender> --reply-to <id> --from <recipient> --timeout <seconds> for that recipient's terminal answer. Record the expected recipient list before waiting; inspect each result and its acceptance chain separately. Repeating an unfiltered wait or dismissing one answer does not advance to another recipient, because handled answers still match. Wait for a subset only when that subset was explicitly selected.
6. After reading incoming status and answer reports, dismiss those received report copies. This clears actionable pickup without replying or erasing history. Reading alone does not clear them, so an unfiltered wait can otherwise keep returning the same old report.

A direct owner instruction without a work card does not need an invented mailbox lifecycle. Use handoff when the entire task and its execution authority must pass to another agent.