diff --git a/features/agent/components/agent-message-details.tsx b/features/agent/components/agent-message-details.tsx
index 4fbbc8a..917ab9c 100644
--- a/features/agent/components/agent-message-details.tsx
+++ b/features/agent/components/agent-message-details.tsx
@@ -37,6 +37,8 @@ type TodoStatus = AgentTodoUpdate["todos"][number]["status"];
 type PermissionStatus = AgentPermissionRequest["status"];
 type QuestionStatus = AgentQuestionRequest["status"];
 
+const STREAMING_PROGRESS_LIMIT = 3;
+
 const progressStatusMeta: Record<ProgressStatus, { label: string; className: string; dotClassName: string }> = {
   running: {
     label: "进行中",
@@ -155,7 +157,7 @@ export function AgentMessageProgress({
     return null;
   }
 
-  return <ProgressList progress={progress} running={running} />;
+  return <ProgressList key={running ? "running" : "settled"} progress={progress} running={running} />;
 }
 
 function AgentNestedBlock({
@@ -198,30 +200,35 @@ function AnimatedDetailItem({ children }: { children: ReactNode }) {
 
 function ProgressList({ progress, running }: { progress: AgentChatProgress[]; running: boolean }) {
   const [expanded, setExpanded] = useState(false);
-  const visibleProgress = expanded ? progress : progress.slice(-1);
-  const listMode = expanded ? "expanded" : "summary";
+  const visibleProgress = running
+    ? progress.slice(-STREAMING_PROGRESS_LIMIT)
+    : expanded
+      ? progress
+      : [];
+  const listMode = running ? "streaming" : expanded ? "expanded" : "collapsed";
 
   return (
     <div className="agent-panel-nested rounded-xl p-2.5">
       <button
         type="button"
-        className="flex w-full items-center gap-2 text-left text-xs font-semibold text-slate-600"
-        aria-expanded={expanded}
+        className="flex w-full items-center gap-2 text-left text-xs font-semibold text-slate-600 disabled:cursor-default"
+        aria-expanded={running || expanded}
+        disabled={running}
         onClick={() => setExpanded((current) => !current)}
       >
         <ListTree size={16} className="shrink-0 text-blue-700" aria-hidden="true" />
         <span>执行进度</span>
         <span className="flex-1" />
         <span className="shrink-0 font-normal text-slate-400">
-          {expanded
-            ? `全部 ${progress.length} 条`
-            : running
-              ? "当前步骤"
+          {running
+            ? `最近 ${Math.min(progress.length, STREAMING_PROGRESS_LIMIT)} 条`
+            : expanded
+              ? `全部 ${progress.length} 条`
               : `共 ${progress.length} 条`}
         </span>
         <ChevronDown
           size={14}
-          className={cn("shrink-0 text-slate-400 transition-transform", expanded && "rotate-180")}
+          className={cn("shrink-0 text-slate-400 transition-transform", !running && expanded && "rotate-180")}
           aria-hidden="true"
         />
       </button>
@@ -229,7 +236,7 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
         {visibleProgress.length ? (
           <motion.ol
             key={listMode}
-            aria-label={expanded ? "全部执行进度" : "当前执行进度"}
+            aria-label={!running && expanded ? "全部执行进度" : "最近执行进度"}
             className="mt-2 space-y-1.5 overflow-hidden"
             initial={{ height: 0, opacity: 0 }}
             animate={{ height: "auto", opacity: 1 }}
@@ -240,7 +247,7 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
               {visibleProgress.map((item) => (
                 <motion.li
                   key={item.id}
-                  className="grid min-h-7 grid-cols-[16px_1fr_auto] items-start gap-2 text-xs"
+                  className="grid h-12 grid-cols-[16px_minmax(0,1fr)_auto] items-start gap-2 overflow-hidden text-xs"
                   initial={{ opacity: 0, y: 4 }}
                   animate={{ opacity: 1, y: 0 }}
                   exit={{ opacity: 0, y: -2 }}
@@ -252,10 +259,18 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
                       "mt-0.5 h-3.5 w-3.5 rounded-full border transition-colors duration-150",
                       progressStatusMeta[item.status].dotClassName
                     )}
-                    animate={item.status === "running" ? { opacity: [0.45, 1, 0.45] } : { opacity: 1 }}
+                    animate={
+                      item.status === "running"
+                        ? { opacity: [0.45, 1, 0.45], scale: 1 }
+                        : item.status === "error"
+                          ? { opacity: [0.55, 1, 1], scale: [1, 1.28, 1] }
+                          : { opacity: 1, scale: 1 }
+                    }
                     transition={
                       item.status === "running"
                         ? { duration: 1.2, ease: "easeInOut", repeat: Infinity }
+                        : item.status === "error"
+                          ? { duration: 0.28, ease: agentEase }
                         : { duration: 0.14 }
                     }
                   />
@@ -264,7 +279,7 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
                       {item.title}
                     </span>
                     {item.detail ? (
-                      <span className="block line-clamp-2 whitespace-pre-wrap leading-5 text-slate-500">
+                      <span className="block truncate leading-5 text-slate-500" title={item.detail}>
                         {item.detail}
                       </span>
                     ) : null}
@@ -272,14 +287,23 @@ function ProgressList({ progress, running }: { progress: AgentChatProgress[]; ru
                   <AnimatePresence initial={false} mode="wait">
                     <motion.span
                       key={item.status}
+                      data-progress-status={item.status}
                       className={cn(
                         "min-w-12 rounded-full px-2 py-0.5 text-center font-semibold",
                         progressStatusMeta[item.status].className
                       )}
                       initial={{ opacity: 0 }}
-                      animate={{ opacity: 1 }}
+                      animate={
+                        item.status === "error"
+                          ? { opacity: [0, 1, 1], x: [0, -2, 2, -1, 0] }
+                          : { opacity: 1, x: 0 }
+                      }
                       exit={{ opacity: 0 }}
-                      transition={{ duration: 0.14 }}
+                      transition={
+                        item.status === "error"
+                          ? { duration: 0.24, ease: agentEase }
+                          : { duration: 0.14 }
+                      }
                     >
                       {progressStatusMeta[item.status].label}
                     </motion.span>
diff --git a/features/agent/components/agent-operational-brief.tsx b/features/agent/components/agent-operational-brief.tsx
index 857f261..b25d121 100644
--- a/features/agent/components/agent-operational-brief.tsx
+++ b/features/agent/components/agent-operational-brief.tsx
@@ -28,7 +28,7 @@ export function AgentOperationalBrief({
 
   return (
     <div className="agent-panel-control rounded-2xl p-3">
-      <div className="flex items-start justify-between gap-3">
+      <div className="flex items-start gap-3">
         <div className="min-w-0">
           <div className="flex items-center gap-2">
             <span className={cn("h-2 w-2 rounded-full", brief.statusDotClassName)} />
@@ -38,9 +38,6 @@ export function AgentOperationalBrief({
             {brief.task}
           </p>
         </div>
-        <span className="shrink-0 rounded-full bg-violet-100 px-2 py-1 text-xs font-semibold text-violet-700">
-          Agent 推断
-        </span>
       </div>
 
       <dl className="mt-3 grid grid-cols-3 gap-2">
diff --git a/tests/browser/agent-streaming-stability.e2e.ts b/tests/browser/agent-streaming-stability.e2e.ts
index 20fc1d1..5986baf 100644
--- a/tests/browser/agent-streaming-stability.e2e.ts
+++ b/tests/browser/agent-streaming-stability.e2e.ts
@@ -7,6 +7,8 @@ const STREAM_CHUNK_DELAY_MS = 20;
 
 let streamServer: Server;
 let streamServerUrl: string;
+let failProgress: (() => void) | null = null;
+let releaseStream: (() => void) | null = null;
 
 test.beforeAll(async () => {
   streamServer = createServer((_request, response) => {
@@ -36,6 +38,30 @@ test.beforeAll(async () => {
         started_at: Date.now()
       }
     });
+    send({
+      type: "data-progress",
+      id: "inspect-rainfall",
+      data: {
+        id: "inspect-rainfall",
+        phase: "evidence",
+        status: "completed",
+        title: "正在核对降雨过程与汇水区响应关系",
+        detail: "读取最近十二小时分钟级降雨序列，并检查每个汇水区的响应延迟是否处于合理范围。",
+        started_at: Date.now()
+      }
+    });
+    send({
+      type: "data-progress",
+      id: "inspect-level",
+      data: {
+        id: "inspect-level",
+        phase: "evidence",
+        status: "completed",
+        title: "正在核对液位连续性",
+        detail: "排除缺测与异常峰值。",
+        started_at: Date.now()
+      }
+    });
     send({
       type: "data-todo_update",
       id: "stream-stability-plan",
@@ -53,24 +79,11 @@ test.beforeAll(async () => {
     send({ type: "text-start", id: "answer" });
 
     let index = 0;
-    const timer = setInterval(() => {
+    let timer: ReturnType<typeof setInterval> | null = null;
+    const sendNextTextChunk = () => {
       const delta = chunks[index];
       if (delta !== undefined) {
         index += 1;
-        if (index === 3) {
-          send({
-            type: "data-progress",
-            id: "assess-risk",
-            data: {
-              id: "assess-risk",
-              phase: "analysis",
-              status: "running",
-              title: "正在判断溢流风险",
-              detail: "结合流量突变与液位趋势形成判断。",
-              started_at: Date.now()
-            }
-          });
-        }
         send({ type: "text-delta", id: "answer", delta });
         send({
           type: "data-stream_token",
@@ -84,7 +97,10 @@ test.beforeAll(async () => {
         return;
       }
 
-      clearInterval(timer);
+      if (timer) {
+        clearInterval(timer);
+        timer = null;
+      }
       send({
         type: "data-progress",
         id: "assess-risk",
@@ -100,9 +116,50 @@ test.beforeAll(async () => {
       send({ type: "text-end", id: "answer" });
       send({ type: "finish", finishReason: "stop" });
       response.end();
-    }, STREAM_CHUNK_DELAY_MS);
+    };
 
-    response.on("close", () => clearInterval(timer));
+    while (index < 3 && index < chunks.length) {
+      sendNextTextChunk();
+    }
+    send({
+      type: "data-progress",
+      id: "assess-risk",
+      data: {
+        id: "assess-risk",
+        phase: "analysis",
+        status: "running",
+        title: "正在判断溢流风险",
+        detail: "结合流量突变与液位趋势形成判断。",
+        started_at: Date.now()
+      }
+    });
+
+    failProgress = () => {
+      send({
+        type: "data-progress",
+        id: "inspect-level",
+        data: {
+          id: "inspect-level",
+          phase: "evidence",
+          status: "error",
+          title: "液位连续性核对失败",
+          detail: "监测数据读取超时。",
+          ended_at: Date.now()
+        }
+      });
+    };
+
+    releaseStream = () => {
+      if (!timer) {
+        timer = setInterval(sendNextTextChunk, STREAM_CHUNK_DELAY_MS);
+      }
+    };
+
+    response.on("close", () => {
+      if (timer) {
+        clearInterval(timer);
+      }
+    });
   });
 
   await new Promise<void>((resolve) => streamServer.listen(0, "127.0.0.1", resolve));
@@ -204,13 +261,55 @@ test("stream completion and the plan card remain positionally stable", async ({
   });
 
   await sendButton.click();
+  const liveProgress = page.getByRole("list", { name: "最近执行进度" });
+  await expect(liveProgress.getByText("正在判断溢流风险", { exact: true })).toBeVisible();
+  await expect(liveProgress.locator("li")).toHaveCount(3);
+  await expect(liveProgress.getByText("正在分析运行上下文", { exact: true })).toHaveCount(0);
+
+  const liveProgressRowHeights = await liveProgress.locator("li").evaluateAll((rows) =>
+    rows.map((row) => row.getBoundingClientRect().height)
+  );
+  expect(liveProgressRowHeights.every((height) => Math.abs(height - 48) <= 0.01)).toBe(true);
+
+  await page.evaluate(() => {
+    const state = window as typeof window & { __agentFailureMotionObserved?: boolean };
+    const startedAt = performance.now();
+    state.__agentFailureMotionObserved = false;
+
+    const sample = () => {
+      const badge = document.querySelector<HTMLElement>('[data-progress-status="error"]');
+      if (badge && getComputedStyle(badge).transform !== "none") {
+        state.__agentFailureMotionObserved = true;
+      }
+      if (!state.__agentFailureMotionObserved && performance.now() - startedAt < 1_000) {
+        requestAnimationFrame(sample);
+      }
+    };
+
+    requestAnimationFrame(sample);
+  });
+  triggerProgressFailure();
+  await expect(liveProgress.getByText("液位连续性核对失败", { exact: true })).toBeVisible();
+  await expect.poll(() =>
+    page.evaluate(() =>
+      (window as typeof window & { __agentFailureMotionObserved?: boolean }).__agentFailureMotionObserved ?? false
+    )
+  ).toBe(true);
+  resumeStream();
+
   await expect(page.getByText("分析完成", { exact: true }).filter({ visible: true }).first()).toBeVisible({
     timeout: 10_000
   });
   const progressToggle = page.getByRole("button", { name: /执行进度/ }).filter({ visible: true }).first();
-  await expect(progressToggle).toContainText("共 2 条");
-  await expect(page.getByText("溢流风险判断完成", { exact: true }).filter({ visible: true }).first()).toBeVisible();
-  await page.waitForTimeout(400);
+  await expect(progressToggle).toContainText("共 4 条");
+  await expect(page.getByRole("list", { name: "最近执行进度" })).toHaveCount(0);
+  await expect(page.getByText("溢流风险判断完成", { exact: true }).filter({ visible: true })).toHaveCount(0);
+  await expect.poll(async () =>
+    page.evaluate(() => {
+      const scroll = document.querySelector<HTMLElement>(".agent-conversation-scroll");
+      return scroll ? Math.abs((scroll.scrollHeight - scroll.clientHeight) - scroll.scrollTop) : Number.POSITIVE_INFINITY;
+    })
+  ).toBeLessThanOrEqual(2);
 
   const samples = await page.evaluate(() =>
     (window as typeof window & {
@@ -259,6 +358,7 @@ test("stream completion and the plan card remain positionally stable", async ({
   ).toBeLessThanOrEqual(2);
 
   await progressToggle.click();
+  await expect(page.getByRole("list", { name: "全部执行进度" }).locator("li")).toHaveCount(4);
   await expect(page.getByText("正在分析运行上下文", { exact: true }).filter({ visible: true }).first()).toBeVisible();
 });
 
@@ -282,3 +382,23 @@ function splitIntoCodePointChunks(content: string, chunkSize: number) {
   }
   return chunks;
 }
+
+function resumeStream() {
+  if (!releaseStream) {
+    throw new Error("Stream checkpoint was not reached");
+  }
+
+  const resume = releaseStream;
+  releaseStream = null;
+  resume();
+}
+
+function triggerProgressFailure() {
+  if (!failProgress) {
+    throw new Error("Progress failure checkpoint was not reached");
+  }
+
+  const fail = failProgress;
+  failProgress = null;
+  fail();
+}