swarm: list subagents from their published run state

The subagents list reads each subagent's status from the subagent-status
bucket and reports its state, when it began and the exit status. A subagent
with no status keeps the newest-row lookup, so an older daemon lists as before.
The swarm UI uses the state when there is one and the row-age guess otherwise.

frontend/packages/swarm-ui/src/agent/terminal/SubagentTerms.tsx

@@ -1,8 +1,9 @@
 // <SubagentTerms> — an agent's subagents, under its own terminal preview in
 // an opened agent card on `AgentsPage`. The list is `GET /api/agents/{name}/subagents`:
 // the subagents the swarm queue holds terminal rows for, each with the
-// publish time of its newest row. Newest first, with a ticking age beside
-// the name; one quiet for `STALE_S` is dimmed. Subagents are spawned on
+// state its daemon published, or else the publish time of its newest row.
+// Newest first, with a ticking age beside the name; one that is not running
+// is dimmed (`isDimmed`, `subagent-list.ts`). Subagents are spawned on
 // demand, so `useSubagentList` refetches it. Picking one shows its
 // terminal in `AgentTermPreview`, expand-to-tab included. Read-only like the
 // agent's own: subagents take no input.
@@ -12,7 +13,13 @@ import { useEffect, useState } from "preact/hooks";
 import { ApiErrorPanel } from "@hive/shared/api-error-panel.js";
 import { Badge } from "@hive/shared/badge.js";
 import { AgentTermPreview } from "./AgentTermPreview.js";
-import { STALE_S, runLabel, stillListed } from "./subagent-list.js";
+import {
+  isDimmed,
+  lastActive,
+  runLabel,
+  stateLabel,
+  stillListed,
+} from "./subagent-list.js";
 import { useSubagentList } from "./useSubagentList.js";
 import { RelativeTime } from "../../ui/relative-time/RelativeTime.js";
 import "./SubagentTerms.css";
@@ -42,10 +49,11 @@ export function SubagentTerms({ agentName }: { agentName: string }) {
       <div class="ui-subagent-terms-list">
         <span class="ui-subagent-terms-heading">subagents</span>
         {subagents?.map((sub) => {
-          const { name, last_row_unix } = sub;
+          const { name } = sub;
           const runs = runLabel(sub);
-          const stale =
-            last_row_unix !== null && nowS - last_row_unix > STALE_S;
+          const active = lastActive(sub);
+          const status = stateLabel(sub);
+          const stale = isDimmed(sub, nowS);
           return (
             <span
               key={name}
@@ -63,9 +71,10 @@ export function SubagentTerms({ agentName }: { agentName: string }) {
                 onClick={() => setPicked(name === selected ? null : name)}
               />
               {runs && <span class="ui-subagent-terms-age">{runs}</span>}
-              {last_row_unix !== null && (
+              {status && <span class="ui-subagent-terms-age">{status}</span>}
+              {active !== null && (
                 <span class="ui-subagent-terms-age">
-                  <RelativeTime epochMs={last_row_unix * 1000} />
+                  <RelativeTime epochMs={active * 1000} />
                 </span>
               )}
             </span>

frontend/packages/swarm-ui/src/agent/terminal/SubagentsMenu.tsx

@@ -3,8 +3,8 @@
 // its own terminal page. On a subagent's page the current one is marked and the
 // list starts with a way back to the agent's own terminal. The list is the
 // same `GET /api/agents/{name}/subagents` as the one under the preview, and
-// "running" means the same too: a row published within `STALE_S`
-// (`subagent-list.ts`). Quiet subagents are listed below, dimmed, so a finished
+// "running" means the same too: what the subagent's daemon says, or without
+// that a row published within `STALE_S` (`subagent-list.ts`). Quiet subagents are listed below, dimmed, so a finished
 // one can still be opened.
 //
 // With `onSplit` the entries are buttons that put the subagent's terminal
@@ -22,9 +22,11 @@ import { Popover } from "../../ui/popover/Popover.js";
 import { RelativeTime } from "../../ui/relative-time/RelativeTime.js";
 import { termPaths } from "./term-paths.js";
 import {
+  lastActive,
   runLabel,
   runningLabel,
   splitRunning,
+  stateLabel,
   type Subagent,
 } from "./subagent-list.js";
 import { useSubagentList } from "./useSubagentList.js";
@@ -51,9 +53,12 @@ function Entry({
           {runLabel(sub)}
         </span>
       )}
-      {sub.last_row_unix !== null && (
+      {stateLabel(sub) && (
+        <span class="ui-subagents-menu-age">{stateLabel(sub)}</span>
+      )}
+      {lastActive(sub) !== null && (
         <span class="ui-subagents-menu-age">
-          <RelativeTime epochMs={sub.last_row_unix * 1000} />
+          <RelativeTime epochMs={(lastActive(sub) ?? 0) * 1000} />
         </span>
       )}
     </>

frontend/packages/swarm-ui/src/agent/terminal/subagent-list.ts

@@ -12,6 +12,21 @@ export interface Subagent {
   model: string | null;
   /** Its reasoning effort; `null` when not readable. */
   effort: string | null;
+  /**
+   * Whether it runs, as its daemon published it: `stale` is a running status
+   * the daemon stopped refreshing. `null` (or absent) for a subagent whose
+   * daemon publishes no status, which is judged by its newest row instead.
+   */
+  state?: "running" | "finished" | "stale" | null;
+  /** Unix seconds when it entered `state`; `null` with `state`. */
+  since_unix?: number | null;
+  /** The process's exit status once it finished by itself. */
+  exit?: number | null;
+}
+
+/** When a subagent was last heard from: its newest row, else its status. */
+export function lastActive(sub: Subagent): number | null {
+  return sub.last_row_unix ?? sub.since_unix ?? null;
 }
 
 /**
@@ -23,23 +38,55 @@ export function runLabel(sub: Pick<Subagent, "model" | "effort">): string {
   return [sub.model, sub.effort].filter((v) => v).join(" · ");
 }
 
-/** A subagent quiet for longer than this is no longer counted as running. */
+/**
+ * A subagent whose daemon publishes no status, quiet for longer than this, is
+ * no longer counted as running.
+ */
 export const STALE_S = 15 * 60;
 
 /**
- * Whether a subagent counts as running: it published a row within
- * [`STALE_S`]. The controller reports only when the newest row was published,
- * so this is a guess. A subagent that is thinking quietly drops out, and one
- * that finished stays in until the window passes.
+ * Whether a subagent counts as running. The daemon's own status decides when
+ * there is one. Without it this is a guess from the newest row: published
+ * within [`STALE_S`], so a subagent thinking quietly drops out and one that
+ * finished stays in until the window passes.
  */
 export function isRunning(sub: Subagent, nowS: number): boolean {
+  const state = sub.state ?? null;
+  if (state !== null) return state === "running";
   return sub.last_row_unix !== null && nowS - sub.last_row_unix <= STALE_S;
 }
 
-/** Newest row first; a subagent whose time could not be read sorts last. */
+/**
+ * Whether the list dims a subagent: its daemon says it is not running, or,
+ * with no status, its newest row is older than [`STALE_S`]. A subagent whose
+ * time could not be read is not dimmed, as nothing says it has stopped.
+ */
+export function isDimmed(sub: Subagent, nowS: number): boolean {
+  const state = sub.state ?? null;
+  if (state !== null) return state !== "running";
+  return sub.last_row_unix !== null && nowS - sub.last_row_unix > STALE_S;
+}
+
+/**
+ * A word for a state that is neither running nor unknown, to show beside the
+ * subagent: `finished`, or `stopped reporting` for a stale status. Empty
+ * when running or when the daemon published no status.
+ */
+export function stateLabel(sub: Subagent): string {
+  switch (sub.state ?? null) {
+    case "finished":
+      return "finished";
+    case "stale":
+      return "stopped reporting";
+    default:
+      return "";
+  }
+}
+
+/** Newest first; a subagent whose time could not be read sorts last. */
 export function byRecency(a: Subagent, b: Subagent): number {
-  const ta = a.last_row_unix ?? -Infinity;
-  const tb = b.last_row_unix ?? -Infinity;
+  const ta = lastActive(a) ?? -Infinity;
+  const tb = lastActive(b) ?? -Infinity;
   if (ta !== tb) return tb > ta ? 1 : -1;
   return a.name.localeCompare(b.name);
 }