swarm: list an agent's bash tasks from their published status

GET /api/agents/{name}/bash-tasks reads the agent's keys of the bash-task-status
bucket and reports each task's state, command and times, with a live task whose
daemon stopped reporting as stale. The swarm UI shows them in a background tasks
section of the agent card, running ones first. The task output stays unread.

frontend/packages/swarm-ui/test/bash-tasks.test.mjs

@@ -0,0 +1,69 @@
+// What the bash task list means: which tasks are live, the words for a state,
+// the order, and the count. Run by `npm test`, which imports the `.ts` module
+// as it is.
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import {
+  isLive,
+  runningTasksLabel,
+  sortTasks,
+  stateWord,
+} from "../src/agent/terminal/bash-tasks.ts";
+
+const task = (name, state, created, exit = null) => ({
+  task: name,
+  state,
+  cmd: "make",
+  created_unix: created,
+  since_unix: created + 1,
+  exit,
+});
+
+test("only a queued or running task, still reporting, is live", () => {
+  assert.equal(isLive(task("a", "pending", 1)), true);
+  assert.equal(isLive(task("a", "running", 1)), true);
+  for (const s of ["stale", "done", "timed_out", "interrupted", "killed"]) {
+    assert.equal(isLive(task("a", s, 1)), false, s);
+  }
+});
+
+test("the state word says what the age counts from", () => {
+  assert.equal(stateWord(task("a", "pending", 1)), "queued");
+  assert.equal(stateWord(task("a", "running", 1)), "started");
+  assert.equal(stateWord(task("a", "stale", 1)), "stopped reporting");
+  assert.equal(stateWord(task("a", "done", 1, 0)), "finished");
+  assert.equal(stateWord(task("a", "done", 1)), "finished");
+  assert.equal(stateWord(task("a", "done", 1, 2)), "exited 2");
+  assert.equal(stateWord(task("a", "timed_out", 1)), "timed out");
+  assert.equal(stateWord(task("a", "interrupted", 1)), "interrupted");
+  assert.equal(stateWord(task("a", "killed", 1)), "killed");
+});
+
+test("live tasks come first, each group newest first, ties by id", () => {
+  const list = [
+    task("old-done", "done", 10),
+    task("new-done", "done", 50),
+    task("old-run", "running", 20),
+    task("new-run", "running", 60),
+    task("b", "running", 40),
+    task("a", "running", 40),
+  ];
+  assert.deepEqual(
+    sortTasks(list).map((t) => t.task),
+    ["new-run", "a", "b", "old-run", "new-done", "old-done"],
+  );
+});
+
+test("the count names the live tasks only", () => {
+  assert.equal(runningTasksLabel([]), "0 running tasks");
+  assert.equal(runningTasksLabel([task("a", "running", 1)]), "1 running task");
+  assert.equal(
+    runningTasksLabel([
+      task("a", "running", 1),
+      task("b", "pending", 1),
+      task("c", "done", 1),
+      task("d", "stale", 1),
+    ]),
+    "2 running tasks",
+  );
+});