Subagents in the CLI (harness spec 3.3.0): the model, capacity, the offer, /context

- A task subagent or a team member runs on the session's model unless the
  person named another in this session's own messages (team/subagents.ts;
  engine.personSaid reads every prompt and mid-turn message, compacted ones
  included). Not named: refused; an agent file's own model is not used.
- Another model on the session's one-model server is refused; a one-request
  session model is not its own subagent, and nothing else is picked.
- The team is offered when a model could serve: the session's with two
  slots, or any usable model off its one-model server; the size note adds
  team_own when the session's model cannot serve its own.
- "Subagents" in /effort, /team, /settings and the config schema; the status
  bar reads "agents 3/4 · 2 subagents working".
- /context: used of the window, one bar by category, each category's share,
  what is free, and "N until auto-compact".
- Conformance runner for the subagents area (26 cases); helper -> task.

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

src/team/subagents.ts

@@ -0,0 +1,101 @@
+// Subagents (harness spec 3.3.0, harness/subagents.md): which model a subagent — a task subagent or
+// a team's member — runs on, and whether subagents are offered at all. The rules alone, without an
+// engine: the conformance area `subagents` drives them, and the app (spawn, team_add) asks them.
+import { LOOP } from "../harness.ts"
+import type { Message } from "../provider/types.ts"
+import { parallelFrom, type Capacity } from "./team.ts"
+
+export const SUBAGENTS = LOOP.subagents
+const TEXTS = SUBAGENTS.texts
+
+/** A model the person may use: its served id (the ref), its id at its connection, its display name. */
+export interface ModelInfo {
+  ref: string
+  id?: string
+  name?: string
+  capacity: Capacity
+}
+
+const escape = (s: string) => s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")
+const BEFORE = new RegExp(`${SUBAGENTS.named.before}$`, "u")
+const AFTER = new RegExp(`^(?:${SUBAGENTS.named.after})`, "u")
+
+/** The names a model goes by: the served id, the part after its provider, the display name. */
+export function namesOf(m: Pick<ModelInfo, "ref" | "id" | "name">): string[] {
+  const out = [m.ref]
+  if (m.id) out.push(m.id)
+  const slash = m.ref.lastIndexOf("/")
+  if (slash >= 0) out.push(m.ref.slice(slash + 1))
+  if (m.name?.trim()) out.push(m.name.trim())
+  return [...new Set(out.filter(Boolean))]
+}
+
+/** Whether `name` occurs in `text` as a whole word, without case (subagents.md §2). White space in
+ *  the name matches any run of white space. */
+export function occursAsWord(text: string, name: string): boolean {
+  const pattern = name
+    .trim()
+    .split(/\s+/)
+    .map(escape)
+    .join("\\s+")
+  if (!pattern) return false
+  const re = new RegExp(pattern, "giu")
+  for (let m = re.exec(text); m; m = re.exec(text)) {
+    const before = text.slice(0, m.index)
+    const after = text.slice(m.index + m[0].length)
+    if (!BEFORE.test(before) && !AFTER.test(after)) return true
+    re.lastIndex = m.index + 1
+  }
+  return false
+}
+
+/** Whether the person named the model in any of the messages they typed. */
+export function named(m: Pick<ModelInfo, "ref" | "id" | "name">, said: readonly string[]): boolean {
+  const names = namesOf(m)
+  return said.some((t) => names.some((n) => occursAsWord(t, n)))
+}
+
+/** What the person typed in a session, oldest first: their prompts and what they sent mid-turn
+ *  (after `steerMark`) — never a note, a job's or a team's marked message, or a machine turn. */
+export function personTexts(messages: readonly Message[], steerMark: string): string[] {
+  const out: string[] = []
+  for (const m of messages) {
+    if (m.role !== "user" || m.machine) continue
+    const first = m.parts[0]
+    if (!first || first.type !== "text") continue
+    if (m.turn === false) {
+      if (first.text.startsWith(steerMark)) out.push(first.text.slice(steerMark.length).trim())
+      continue
+    }
+    out.push(first.text)
+  }
+  return out
+}
+
+/** Whether a model can be its own session's subagent: it serves two requests at once, or has no limit. */
+export function servesOwn(c: Capacity): boolean {
+  return parallelFrom(c) >= 2
+}
+
+/** subagents.md §4: whether subagents are offered for a session on `session`, given the models the
+ *  person may use, and whether the session's model can serve its own. */
+export function offer(session: ModelInfo, models: readonly ModelInfo[], subagents = true): { offered: boolean; own: boolean } {
+  const own = servesOwn(session.capacity)
+  const group = session.capacity.group
+  const other = models.some((m) => m.ref !== session.ref && (group === undefined || m.capacity.group !== group))
+  return { offered: subagents && (own || other), own }
+}
+
+/** subagents.md §2, §3: the model a subagent runs on — the session's, or `wanted` (already resolved
+ *  to a model the person may use) — or the refusal, word for word. */
+export function subagentModel(session: ModelInfo, wanted: ModelInfo | undefined, said: readonly string[]): { model: string } | { refused: string } {
+  const m = wanted ?? session
+  if (m.ref !== session.ref) {
+    if (!named(m, said)) return { refused: TEXTS.not_named }
+    const group = session.capacity.group
+    if (group !== undefined && m.capacity.group === group) return { refused: TEXTS.same_group }
+    return { model: m.ref }
+  }
+  if (!servesOwn(session.capacity)) return { refused: TEXTS.one_request }
+  return { model: session.ref }
+}