fix(app): count what the subagents pill's mark is showing

The pill drew the most urgent state of the fan-out next to the size of
the fan-out. Two questions, one pill, 8pt apart: a spinning ring beside
"2 subagents" reads as two agents running when one is. The mark is the
thing the eye lands on, so its state gets read onto whatever number is
next to it.

While anything is happening the pill now names that state and counts the
children in it — "1 running", "2 failed" — and falls back to naming the
total once nothing is. The total is a tap away in the panel, and the
running count is the number worth glancing at anyway.

Label and mark are built by one function so they cannot disagree; the
call site takes both or neither. Every non-done bucket gets copy, not
just the two that are reachable today, because needs_input and attention
become reachable the moment a subagent row carries requiresAttention,
and the failure mode is silently the bug this commit fixes.

packages/app/src/subagents/track-presentation.test.ts

@@ -1,7 +1,8 @@
-import { describe, expect, it } from "vitest";
+import { beforeAll, describe, expect, it } from "vitest";
+import { i18n } from "@/i18n/i18next";
 import type { PaseoSubagentRow, ProviderSubagentRow, SubagentRow } from "./select";
 import {
-  aggregateSubagentStatusBucket,
+  buildSubagentPillPresentation,
   buildSubagentRowPresentationData,
   countFinishedSubagents,
   resolveRowLabel,
@@ -23,28 +24,57 @@ function row(
   };
 }
 
-describe("aggregateSubagentStatusBucket", () => {
-  it("has no bucket without rows", () => {
-    expect(aggregateSubagentStatusBucket([])).toBeNull();
+describe("buildSubagentPillPresentation", () => {
+  // The real instance, so a label that names a key nobody added renders as that key and fails.
+  beforeAll(async () => {
+    if (!i18n.isInitialized) {
+      await i18n.init();
+    }
+    await i18n.changeLanguage("en");
   });
 
-  it("has no bucket when every child is done", () => {
-    expect(aggregateSubagentStatusBucket([row({ id: "a" }), row({ id: "b" })])).toBeNull();
+  const pill = (rows: SubagentRow[]) => buildSubagentPillPresentation(i18n.t, rows);
+
+  it("counts the children that are running, not the fan-out", () => {
+    expect(pill([row({ id: "a" }), row({ id: "b", status: "running" })])).toEqual({
+      label: "1 running",
+      statusBucket: "running",
+    });
   });
 
-  it("reports running when any child is running", () => {
+  it("counts every child in the state it reports", () => {
     expect(
-      aggregateSubagentStatusBucket([row({ id: "a" }), row({ id: "b", status: "running" })]),
-    ).toBe("running");
+      pill([
+        row({ id: "a", status: "running" }),
+        row({ id: "b", status: "running" }),
+        row({ id: "c" }),
+      ]),
+    ).toEqual({ label: "2 running", statusBucket: "running" });
   });
 
-  it("ranks a failed child above a running one", () => {
+  it("ranks a failed child above a running one, and counts the failures", () => {
     expect(
-      aggregateSubagentStatusBucket([
+      pill([
         row({ id: "a", status: "running" }),
         row({ id: "b", status: "error", requiresAttention: true }),
+        row({ id: "c", status: "error" }),
       ]),
-    ).toBe("failed");
+    ).toEqual({ label: "2 failed", statusBucket: "failed" });
+  });
+
+  it("names what it opens once every child is done", () => {
+    expect(pill([row({ id: "a" }), row({ id: "b" })])).toEqual({
+      label: "2 subagents",
+      statusBucket: null,
+    });
+  });
+
+  it("keeps the singular for a lone child", () => {
+    expect(pill([row({ id: "a" })])).toEqual({ label: "1 subagent", statusBucket: null });
+  });
+
+  it("has nothing to mark without rows", () => {
+    expect(pill([])).toEqual({ label: "0 subagents", statusBucket: null });
   });
 });