From cc013c96808e68ca99338841dd2ba997076e826d Mon Sep 17 00:00:00 2001
From: TYY-2005 <tyy1659579788@gmail.com>
Date: Fri, 23 Oct 2026 11:24:26 +0800
Subject: [PATCH] fix(frontend): classify thinking-only token steps correctly
 (#7175)

* fix(frontend): classify thinking-only token steps correctly

* docs(frontend): explain thinking-only token step classification

---------

Co-authored-by: TYY-2005 <334029581+TYY-2005@users.noreply.github.com>
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
---
 frontend/src/core/messages/usage-model.ts     |  5 ++--
 .../unit/core/messages/usage-model.test.ts    | 23 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/frontend/src/core/messages/usage-model.ts b/frontend/src/core/messages/usage-model.ts
index 2290716022..11dd05604c 100644
--- a/frontend/src/core/messages/usage-model.ts
+++ b/frontend/src/core/messages/usage-model.ts
@@ -3,7 +3,7 @@ import type { Message } from "@langchain/langgraph-sdk";
 import type { Translations } from "@/core/i18n/locales/types";
 
 import { getUsageMetadata, type TokenUsage } from "./usage";
-import { hasContent } from "./utils";
+import { extractContentFromMessage } from "./utils";
 
 export type TokenUsageInlineMode = "off" | "per_turn" | "step_debug";
 
@@ -166,7 +166,8 @@ export function buildTokenDebugSteps(
     }
 
     if (actionLabels.length === 0) {
-      if (hasContent(message)) {
+      // Thinking-only blocks (Anthropic) carry no visible answer content.
+      if (extractContentFromMessage(message).length > 0) {
         actionLabels.push(t.tokenUsage.finalAnswer);
       } else {
         actionLabels.push(t.common.thinking);
diff --git a/frontend/tests/unit/core/messages/usage-model.test.ts b/frontend/tests/unit/core/messages/usage-model.test.ts
index f9354268f4..68156ecad9 100644
--- a/frontend/tests/unit/core/messages/usage-model.test.ts
+++ b/frontend/tests/unit/core/messages/usage-model.test.ts
@@ -127,6 +127,29 @@ test("uses generic todo labels when backend attribution is absent", () => {
   ]);
 });
 
+test("labels Anthropic thinking-only blocks as thinking", () => {
+  const messages = [
+    {
+      id: "ai-thinking",
+      type: "ai",
+      content: [{ type: "thinking", thinking: "Still checking." }],
+      usage_metadata: {
+        input_tokens: 20,
+        output_tokens: 5,
+        total_tokens: 25,
+      },
+    },
+  ] as unknown as Message[];
+
+  expect(buildTokenDebugSteps(messages, enUS)).toEqual([
+    expect.objectContaining({
+      messageId: "ai-thinking",
+      label: "Thinking",
+      sharedAttribution: false,
+    }),
+  ]);
+});
+
 test("marks multi-action AI steps as shared attribution", () => {
   const messages = [
     {