From 11582ab62b8c29ef2175bdd7837ae61ac29116c4 Mon Sep 17 00:00:00 2001
From: Igor Velho <velhoi@ryanair.com>
Date: Mon, 24 Aug 2026 14:45:51 +0100
Subject: [PATCH] test: add failing test for subagent cost index builder

---
 .../chat/work-status/subagentCost.test.ts       | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 packages/ui/src/components/chat/work-status/subagentCost.test.ts

diff --git a/packages/ui/src/components/chat/work-status/subagentCost.test.ts b/packages/ui/src/components/chat/work-status/subagentCost.test.ts
new file mode 100644
index 00000000..be6bf4e1
--- /dev/null
+++ b/packages/ui/src/components/chat/work-status/subagentCost.test.ts
@@ -0,0 +1,17 @@
+import { describe, expect, test } from 'bun:test';
+import type { Session } from '@opencode-ai/sdk/v2';
+import { buildChildrenIndex } from './subagentCost';
+
+function makeSession(id: string, cost: number, parentID?: string): Session {
+  return { id, cost, parentID } as unknown as Session;
+}
+
+describe('buildChildrenIndex', () => {
+  test('groups sessions by parentID', () => {
+    const root = makeSession('root', 1);
+    const childA = makeSession('a', 2, 'root');
+    const childB = makeSession('b', 3, 'root');
+    const index = buildChildrenIndex([root, childA, childB]);
+    expect(index.get('root')).toEqual([childA, childB]);
+  });
+});