# Glossary > **Reference** (informative) · **For:** everyone One-line definitions of the terms used across these docs and the spec. The base terminology is [SPEC §1](/spec/#1-scope-and-terminology); each entry links to its home. - **Agent file / persona**, a `.cotal/agents/.md` file: AgentCard-shaped identity and channel grants in the frontmatter, with the Markdown body as the agent's persona (appended system prompt). [agent-files.md](/agent-files/) - **Agent node**: an instance whose `kind` is `agent`, as opposed to a plain `endpoint` such as an observer or dashboard. [SPEC §1](/spec/#1-scope-and-terminology) - **Anycast**: a delivery mode addressed to a service **role**, delivered to one of its consumers (load-balanced). [SPEC §4](/spec/#4-delivery-modes) - **Attention**, an advisory per-instance receive preference in presence: a global mode (`open` / `dnd` / `focus`) and per-channel overrides (`quiet` / `muted`). It shapes what wakes an agent, not what the broker delivers or authorizes. [SPEC §6](/spec/#6-presence-and-discovery) - **Broker**: the message router for a space; v0 assumes a single trusted broker. [SPEC §1](/spec/#1-scope-and-terminology) - **Channel**: a named, dotted, hierarchical multicast topic within a space. [SPEC §7](/spec/#7-channels) - **Channel registry**: the per-space store of channel config (`replay`, `replayWindow`, `deliveryClass`, `description`, `instructions`), keyed by channel name. [SPEC §7](/spec/#7-channels) - **Connector**: an adapter that bridges an agent harness (Claude Code, OpenCode, Hermes, …) to the mesh, exposing the `cotal_*` tools. [connect-claude.md](/connect-claude/) - **Control plane**: the request/reply layer on `ctl` subjects plus the infra roles behind it (the manager and the delivery daemon) that provision and supervise a mesh. [architecture.md](/architecture/) - **Delivery class (`live` / `durable`)**, a channel's per-channel delivery guarantee: `live` is at-most-once; `durable` adds a per-member backstop (at-least-once within retention). Distinct from delivery *mode*. [SPEC §4](/spec/#4-delivery-modes), [channels-and-permissions.md](/channels-and-permissions/) - **Delivery daemon (Plane-3)**, the server-side component providing the durable backstop: fan-out writer, trusted reader, and membership registry. [delivery-daemon.md](/delivery-daemon/) - **Delivery modes**, the three addressing axes: multicast (channel), unicast (instance), and anycast (role). Exactly one per message. [SPEC §4](/spec/#4-delivery-modes) - **Direct message / unicast**: a message addressed to one named instance's inbox. [SPEC §4](/spec/#4-delivery-modes) - **Durable backstop**: the per-subscriber store that retains `durable`-channel posts (and authorized `live`-channel `@mention` copies) until the member has seen them. [SPEC §4](/spec/#4-delivery-modes), [delivery-daemon.md](/delivery-daemon/) - **Endpoint**: a connected participant, identified by a stable instance id; the general term for any instance, agent or not. [SPEC §1](/spec/#1-scope-and-terminology) - **History / replay**: retained channel messages backfilled to a joiner when a channel's `replay` is on, bounded to the reader's ACL and optionally to `replayWindow`. [SPEC §7](/spec/#7-channels) - **Instance (id)**: a connected participant; its **id** is a stable per-connection identifier (in the auth binding, an Ed25519 nkey public key) used identically as sender, presence key, and durable name. [SPEC §2](/spec/#2-identity) - **Join link**: a `cotal://` / `cotals://` URL encoding broker host, space, optional credential, and optional channels, the onboarding half of the contract. [SPEC §10](/spec/#10-connection-and-onboarding) - **Manager**, the agent supervisor and provisioner host: spawns and manages agent nodes over a pluggable runtime, and pre-creates the durables and membership records agents can't create themselves. [run-a-mesh.md](/run-a-mesh/) - **Manifest**, `cotal.yaml` (`kind: Mesh`): the declarative, channel-centric description of a team's channels, agents, and access, launched with one command. [manifest.md](/manifest/) - **Mention**: a lowercased peer name in a message's `mentions`; a wake hint that, on a `live` channel, also routes a durable copy to each mentioned target authorized to read the channel. [SPEC §4](/spec/#4-delivery-modes), [§5](/spec/#5-envelopes) - **Mesh**, a running Cotal deployment: a broker, a space, and the peers coordinating in it. [what-is-cotal.md](/what-is-cotal/) - **Multicast**: a delivery mode delivered to every subscriber of a channel. [SPEC §4](/spec/#4-delivery-modes) - **Observer**: a read-only profile that reads chat, history, presence, and the channel registry, but cannot publish and cannot see DMs. [SPEC §9](/spec/#9-nats--jetstream-security-and-authorization) - **Presence**, the per-space directory keyed by instance id: each peer's card, status, activity, attention, and heartbeat timestamp. [SPEC §6](/spec/#6-presence-and-discovery) - **Profile (`agent` / `observer` / `admin`)**: a default-deny credential class defining what subjects, streams, durables, and KV keys a credential may touch. [SPEC §9](/spec/#9-nats--jetstream-security-and-authorization), [Appendix B](/spec/#appendix-b-profile-acls) - **Provisioner**: the privileged, signing-capable role that mints scoped credentials and writes the durables and membership records agents cannot write themselves. [SPEC §7](/spec/#7-channels), [Appendix B](/spec/#appendix-b-profile-acls) - **Role / service**: a named anycast target a group of agents share; a message to the role reaches one of them. [SPEC §1](/spec/#1-scope-and-terminology), [§4](/spec/#4-delivery-modes) - **Runtime (`pty` / `tmux` / `cmux`)**, how the manager runs each agent process: the built-in pty, or tmux/cmux via extensions. [run-a-mesh.md](/run-a-mesh/) - **Space**: an isolated coordination context and tenant boundary; one space maps to one NATS account. [SPEC §1](/spec/#1-scope-and-terminology), [spaces.md](/spaces/) - **Spawn capability**, the `spawn` control-plane capability in an agent file: grants publish to the privileged control subject so the agent may start or despawn peers. [agent-files.md](/agent-files/) - **Trusted reader**: the privileged component that reads the mixed durable backstop on an agent's behalf and re-authorizes each entry (current ACL and membership) before delivering it. [delivery-daemon.md](/delivery-daemon/), [SPEC §8](/spec/#8-nats--jetstream-binding)