subagents publish their model and effort as headers on every row, and the swarm shows them

The subagent daemon stamps Swarm-Model and Swarm-Effort on each row it
publishes. The list endpoint reads them off the newest row it already fetches,
so a long-running subagent keeps them past the stream's 24 hour window, and the
terminal page's menu and the agent panel's list show them beside the name.

swarm-wire/src/subagent_term.rs

@@ -32,6 +32,16 @@ const SUBAGENT_TOKEN: &str = "sub";
 /// its last output.
 pub const MAX_AGE: std::time::Duration = std::time::Duration::from_hours(24);
 
+/// The message header carrying the model a subagent runs, on every row it
+/// publishes. Absent when the subagent runs the harness's default model, which
+/// is no value to name. The list endpoint reads it off the newest row, so a
+/// subagent that runs for longer than [`MAX_AGE`] still shows it.
+pub const HEADER_MODEL: &str = "Swarm-Model";
+
+/// The message header carrying a subagent's reasoning effort, published with
+/// [`HEADER_MODEL`].
+pub const HEADER_EFFORT: &str = "Swarm-Effort";
+
 /// The stream holding `agent`'s subagent rows: `term-sub-<agent>`.
 #[must_use]
 pub fn stream_name(agent: &str) -> String {