Function resolve_agent_name_at_boundary 

pub(crate) async fn resolve_agent_name_at_boundary(
    client: &Client,
    local_url: &str,
    auth_key: &str,
    name: &str,
) -> Result<Option<String>>

Identity M3 (spec §5): resolve a typed agent name at the boundary — the only place a name is turned into a UID — before a tool stores it. Ok(Some(uid)) when exactly one identified agent matches; Ok(None) when none does, the match has no UID, or the srv predates the endpoint (the tool then sends the name and the server records the miss). Err in two cases, both of which fail the tool call: the name is ambiguous — the error lists the candidates so the model can retry by uid (§5.2) — or the resolver could not answer (a store fault, any other non-2xx, an unreadable or unexpected response), where sending the bare name would skip the ambiguity check. See interpret_resolve_response.