Mentions

Mentions

An @ in a message body is not routing on its own. It is a span of text that resolves, against the current roster and desk set, to a typed target.

Targets

target	what it names
Agent { id }	one agent roster member
Person { id }	one human participant
Desk { id }	the active members of one desk
Everyone	the addressed desk, or the full active roster in General

Only Agent can start a turn. direct_responder walks the mentions in reading order and returns the first non-quiet mention of an active agent. A person, a desk, and an @everyone deliberately cannot, which is where the no-fan-out rule is enforced at the level of a name.

Resolution

let mentions = resolve(body, supplied, &author, &roster, &desks);

supplied as None means extract from the body. supplied as Some, including an empty vector, is authoritative: the host has already decided, and resolution revalidates that decision against current snapshots rather than re-parsing. A stale reference stays visible in the text but is made quiet, so the reader still sees what the author wrote and the router does not act on a member who left.

Anything structurally invalid fails closed to an empty result. A malformed roster does not produce a partial routing decision.

Mentions inside code spans and fenced blocks are masked out. MENTION_CAP is 50, which bounds how many mentions in one message may remain pinging, for the same reason the trace grammar has a cap: one message must not be able to grow the fold without limit.

Expansion

mentioned_members expands the targets into the active agent ids a turn needs as context. It preserves mention order, then desk and roster order, keeps the first appearance of each id, and excludes the responder itself.

This is what @everyone actually does. It produces a list that the responding agent is told about in its context. It does not produce a turn per member, and there is no code path in this library that would.

Author sensitivity

MentionAuthor distinguishes who wrote the mention, because normalization differs. An agent mentioning itself, and a human mentioning an agent, are not the same routing event, and collapsing them is how a room starts talking to itself.