fix(webui): correct activity duration display

webui/src/tests/agent-activity-cluster.test.tsx

@@ -359,6 +359,20 @@ describe("AgentActivityCluster", () => {
     expect(screen.getByText("Thought for 12s")).toBeInTheDocument();
   });
 
+  it("labels mixed tool activity as work instead of thought", () => {
+    render(
+      <AgentActivityCluster
+        messages={activityMessages()}
+        isTurnStreaming={false}
+        hasBodyBelow
+        turnLatencyMs={12_400}
+      />,
+    );
+
+    expect(screen.getByText("Worked for 12s")).toBeInTheDocument();
+    expect(screen.queryByText("Thought for 12s")).not.toBeInTheDocument();
+  });
+
   it("omits the duration when completed history has no reliable timing", () => {
     render(
       <AgentActivityCluster

webui/src/tests/thread-messages.test.tsx

@@ -308,10 +308,47 @@ describe("ThreadMessages", () => {
 
     render(<ThreadMessages messages={messages} isStreaming={false} />);
     expect(screen.queryByRole("button", { name: /^thinking$/i })).not.toBeInTheDocument();
-    expect(screen.getByText("Thought for 9s")).toBeInTheDocument();
+    expect(screen.getByText("Worked for 9s")).toBeInTheDocument();
     expect(screen.getByText("final answer")).toBeInTheDocument();
   });
 
+  it("uses final turn latency when an earlier reasoning segment has its own latency", () => {
+    const messages: UIMessage[] = [
+      {
+        id: "r1",
+        role: "assistant",
+        content: "",
+        reasoning: "plan",
+        reasoningStreaming: false,
+        latencyMs: 3_000,
+        createdAt: 1,
+      },
+      {
+        id: "t1",
+        role: "tool",
+        kind: "trace",
+        content: "shell()",
+        traces: ["shell()"],
+        createdAt: 2,
+      },
+      {
+        id: "a1",
+        role: "assistant",
+        content: "done",
+        latencyMs: 20_000,
+        createdAt: 3,
+      },
+    ];
+
+    const units = buildDisplayUnits(messages);
+
+    expect(units[0].type === "activity" ? units[0].turnLatencyMs : undefined).toBe(20_000);
+
+    render(<ThreadMessages messages={messages} isStreaming={false} />);
+    expect(screen.getByText("Worked for 20s")).toBeInTheDocument();
+    expect(screen.queryByText("Worked for 3s")).not.toBeInTheDocument();
+  });
+
   it("keeps late activity after the live assistant answer while streaming", () => {
     const messages: UIMessage[] = [
       {
@@ -626,8 +663,8 @@ describe("ThreadMessages", () => {
 
     render(<ThreadMessages messages={messages} isStreaming={false} />);
 
-    expect(screen.getByText("Thought for 15s")).toBeInTheDocument();
-    expect(screen.queryByText("Thought for 0s")).not.toBeInTheDocument();
+    expect(screen.getByText("Worked for 15s")).toBeInTheDocument();
+    expect(screen.queryByText("Worked for 0s")).not.toBeInTheDocument();
   });
 
   it("shows copy only on the last assistant slice before the next user turn", () => {