Harness spec 3.3.0: subagents — the word, the model, capacity, the offer

- "Subagent" in every text a person or a model reads; "helper" retired
  (the team area's step helper_done is now task_done).
- A subagent runs on the session's model unless the person named another
  in this session's own messages; task's and team_add's `model` is refused
  otherwise. No setting chooses a subagent's model.
- Capacity: another model on the session's model's one-model server is
  refused; the session's model as its own subagent needs parallel >= 2 or
  no limit; no fallback.
- The agents {min, max} setting is shown as Subagents, offered when a model
  could serve; context.note.team_own when the session's model cannot.
- subagents.md, loop.json subagents, conformance/subagents.json (26 cases).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/conformance.ts

@@ -272,7 +272,7 @@ export const AREAS: Record<string, (c: Case) => unknown> = {
         case "finish":
           team.finish(by, st.reply ?? "", st.reason ?? "stop")
           return { delivered: delivered() }
-        case "helper_done":
+        case "task_done":
           team.helperDoneBy(by)
           return null
         case "set":