diff --git a/packages/tui/src/routes/session/index.tsx b/packages/tui/src/routes/session/index.tsx
index d9db6d26a4..e2ece2fbd5 100644
--- a/packages/tui/src/routes/session/index.tsx
+++ b/packages/tui/src/routes/session/index.tsx
@@ -2262,7 +2262,7 @@ export function formatSubagentToolcalls(count: number) {
 }
 
 export function formatSubagentTitle(agent: string, description: string, background: boolean) {
-  return `${agent} Subagent${background ? " (background)" : ""} — ${description}`
+  return `${agent} Subagent — ${description}${background ? " [background]" : ""}`
 }
 
 export function formatSubagentRetry(attempt: number, message: string) {
diff --git a/packages/tui/test/cli/tui/inline-tool-wrap-snapshot.test.tsx b/packages/tui/test/cli/tui/inline-tool-wrap-snapshot.test.tsx
index 31b05ebcf1..f9a657ecc4 100644
--- a/packages/tui/test/cli/tui/inline-tool-wrap-snapshot.test.tsx
+++ b/packages/tui/test/cli/tui/inline-tool-wrap-snapshot.test.tsx
@@ -175,7 +175,7 @@ describe("TUI inline tool wrapping", () => {
   test("keeps background state attached to the subagent identity", () => {
     expect(formatSubagentTitle("Explore", "Inspect renderer", false)).toBe("Explore Subagent — Inspect renderer")
     expect(formatSubagentTitle("Explore", "Inspect renderer", true)).toBe(
-      "Explore Subagent (background) — Inspect renderer",
+      "Explore Subagent — Inspect renderer [background]",
     )
   })