Glossary¶

This page defines the terms the documentation uses, each with one meaning.

A2A: The Agent2Agent protocol. Agent Kourier speaks A2A 1.0 over JSON-RPC, and A2A 0.3 to an agent whose card is a 0.3 card, and needs an agent that streams.
Actor: Who a turn is from, as the agent sees it: the agentkourier.dev/actor metadata (id, platform, and name and email when the chat platform knows them) and the prefix at the start of the text. It is information for the agent, never authorization (Agent contract).
Agent Substrate: The runtime kagent 1.0 runs every agent session on. It needs the Kubernetes pod-certificate APIs, which most clusters do not serve (Connect a kagent agent).
AgentBackend: The resource that names an A2A endpoint and the dialect to speak to it. Owned by the platform team.
Binding: The resource that connects one agent to one channel, with the service identity every turn runs as. Owned by an application team.
Binding identity: The one service identity, a bearer token or a user ID, that every turn of a Binding runs as, chat or alert. The person who wrote a message is carried as attribution, never as the identity.
Channel: A place in a chat platform where people post, named by its ID. One channel takes at most one Binding per connection.
ChatConnection: The resource that connects Agent Kourier to one chat platform workspace, with the Secret that holds its tokens. Owned by the platform team.
Context: The A2A contextId that a session maps to. Agent Kourier resumes the same context for every turn of a thread.
Cooldown: For a botMessage trigger with thread.by: key: the window after an investigation starts in which another fire of the same key adds a note and starts no turn.
Dialect: The per-backend part of the A2A client: URL layout, card location, identity header and how a pause is read. a2a is generic; kagent-v1 adds kagent's human-in-the-loop extension.
Digest line: One line at the top level of a channel that counts the alerts a trigger's limits stopped in a window.
Epoch: With Postgres, the leadership number in the database. A replica that takes the Lease increments it, and every write transaction checks it, so a deposed leader's writes fail. This is the fencing of a leader.
Failover: The standby taking the Lease after the leader stops, is lost or is paused past its renew deadline, and running the same recovery as a restart.
Front door: A proxy in front of an agent runtime that verifies the Binding's token and strips the headers that select a user. Required in front of kagent.
Interaction: A pause in which the agent waits for a person: a question (ask-user), or a kagent-v1 tool approval when the Binding enables interactions.toolApprovals. A generic A2A structured pause is unusable.
Investigation: A session that a trigger or an alert started rather than a person.
Kind full tier: The local kind cluster that make e2e-full-up builds from a checkout of the repository, with kagent 1.0, Agent Substrate, a front door and an OIDC issuer (Dex) in it. The sre-triage recipe's agent runs on it.
Lease: The Kubernetes Lease, <fullname>-leader, that the replicas on Postgres hold to elect the leader. The leader renews it; a standby takes it a lease duration after the last renewal it saw.
Leader: With Postgres, the one replica that does Agent Kourier's work, chosen by a Kubernetes Lease. Its writes are fenced by an epoch in the database.
Message field: One of text, title, link, body, footer and fallback: what a trigger's match, exclude and extract read. text is the message's top-level text. The others are the heading, the heading's URL, the main text, the small print and the plain-text summary of the message's structured part (Slack: its first legacy attachment).
Outbox: The durable table of posts Agent Kourier means to make. A post is recorded before it is sent, so a crash between sending and recording is found and not posted twice.
Platform: A chat platform behind the chat.Platform interface. Slack is the one platform in v1.
Post: A message Agent Kourier writes into a channel or thread.
Redaction: Taking secrets out of text before it is shown, stored, logged or sent to an agent.
Reply queue: The durable queue of thread replies that wait for the agent's active task to end.
Sender: Who posted a message a botMessage trigger reads, named by from.id and from.kind. A message matches only when both are equal to the sender's.
Session: The conversation between a thread and an agent context, stored by Agent Kourier. A thread is a session.
Standby: With Postgres, a replica that does not hold the Lease. It is Ready, serves health and metrics, does no work and waits to take the Lease.
Thread: A message and its replies. Agent Kourier owns a thread it started, or one it was mentioned in.
Trigger: A rule in a Binding's chat.triggers that decides what starts a turn: mention, or botMessage for another bot's posts.
Turn: One message to the agent and the task that answers it. A session's turns run one at a time, in order.
Untrusted block: Text from people or other bots that reaches an agent, framed as data inside a tagged block that says it is never instructions.