diff --git a/tests/frontend_task_progress.test.mjs b/tests/frontend_task_progress.test.mjs
new file mode 100644
index 0000000..bd69082
--- /dev/null
+++ b/tests/frontend_task_progress.test.mjs
@@ -0,0 +1,51 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  applyProgressAction,
+  progressActionsFromToolCalls,
+} from "../web/static/js/progress.js";
+
+test("update_step without title preserves title from the existing plan", () => {
+  const initial = applyProgressAction([], {
+    action: "set_plan",
+    steps: [
+      { id: "s1", title: "理解需求", status: "in_progress" },
+      { id: "s2", title: "实现功能", status: "pending" },
+    ],
+  });
+
+  const updated = applyProgressAction(initial, {
+    action: "update_step",
+    step: { id: "s1", status: "completed" },
+  });
+
+  assert.deepEqual(updated, [
+    { id: "s1", title: "理解需求", status: "completed" },
+    { id: "s2", title: "实现功能", status: "pending" },
+  ]);
+});
+
+test("tool calls can apply progress updates on top of previous task progress", () => {
+  const previous = [
+    { id: "s1", title: "理解需求", status: "in_progress" },
+    { id: "s2", title: "实现功能", status: "pending" },
+  ];
+  const toolCalls = [{
+    function: {
+      name: "task_progress",
+      arguments: JSON.stringify({
+        action: "update_step",
+        step: { id: "s1", status: "completed" },
+      }),
+    },
+  }];
+
+  const result = progressActionsFromToolCalls(toolCalls, previous);
+
+  assert.equal(result.sawProgress, true);
+  assert.deepEqual(result.steps, [
+    { id: "s1", title: "理解需求", status: "completed" },
+    { id: "s2", title: "实现功能", status: "pending" },
+  ]);
+});
diff --git a/web/static/dev.html b/web/static/dev.html
index 3be0391..4402aaf 100644
--- a/web/static/dev.html
+++ b/web/static/dev.html
@@ -466,6 +466,16 @@
   }
   .task-progress .tp-text { overflow-wrap: anywhere; line-height: 1.45; }
   .task-progress .tp-step.completed .tp-text { color: var(--muted); text-decoration: line-through; }
+  #task-progress-dock {
+    flex-shrink: 0; display: none;
+    padding: 8px 12px; border-top: 1px solid var(--border);
+    background: #fff;
+  }
+  #task-progress-dock.show { display: block; }
+  #task-progress-dock .task-progress {
+    margin-top: 0; border-color: rgba(192,57,43,0.22);
+    background: linear-gradient(180deg, #fff, #fffafa);
+  }
   /* media tool 摘要 banner(model / size / cost / elapsed,折叠态也可见) */
   .tool-banner {
     display: inline-flex; flex-wrap: wrap; gap: 6px;
@@ -1030,6 +1040,7 @@
     <div id="chat-meta"><span class="muted">(未选中任务)</span></div>
     <div id="wd-concurrent-warn" style="display:none;"></div>
     <div id="chat-stream"><div class="empty">请在左侧选一个任务</div></div>
+    <div id="task-progress-dock"></div>
     <form id="chat-form" style="display:none;">
       <textarea id="chat-input" placeholder="输入消息…(Enter 发送,Shift+Enter 换行,Ctrl+V 可粘贴文件)"></textarea>
       <div class="row">
diff --git a/web/static/js/chat.js b/web/static/js/chat.js
index 6988fd4..0e35412 100644
--- a/web/static/js/chat.js
+++ b/web/static/js/chat.js
@@ -14,6 +14,7 @@ import { logout } from "./auth.js";
 import { openFilePreview, openPasteFilePreview, closePreviewIfShowing } from "./preview.js";
 import { loadFiles, scheduleFilesRefresh, uploadFiles, formatUploadProgress } from "./files.js";
 import { toolActivityLabel, _workingDirName, extractMediaBanner, extractArtifactRels, renderArtifactBarHtml, upgradeMediaArtifacts, ARTIFACT_PRODUCING_TOOLS, _flushMediaArtifactCache } from "./media.js";
+import { applyProgressAction, cloneProgressSteps, progressActionsFromToolCalls } from "./progress.js";
 
 export async function loadModels() {
   try {
@@ -237,6 +238,7 @@ export async function selectTask(tid) {
     refreshConcurrentWarnings();  // 同 wd 其他 task 活跃软警告 — 后台 fire-and-forget
   } catch (e) {
     if (e.status === 401) { logout(); return; }
+    renderTaskProgressDock([]);
     $("chat-stream").innerHTML = `<div class="empty">加载失败:${escapeHtml(e.message)}</div>`;
   }
 }
@@ -415,6 +417,7 @@ function renderLiveRunIfVisible() {
   const wrap = $("chat-stream");
   const card = run.card || createLiveAssistantCard(run);
   if (run.body && run.acc) run.body.innerHTML = renderMd(run.acc);
+  renderProgressInto(card, run.progressSteps || []);
   if (card.parentElement !== wrap) wrap.appendChild(card);
   wrap.scrollTop = wrap.scrollHeight;
   setActionMode(run.cancelling ? "cancelling" : "streaming");
@@ -434,6 +437,7 @@ function ensureRunningTaskSubscribed(taskId, url) {
     body: null,
     cancelling: state.taskMeta && state.taskMeta.run_status === "cancelling",
     workingDir: state.taskMeta && state.taskMeta.working_dir,
+    progressSteps: cloneProgressSteps(state.taskProgressByTask.get(taskId)),
   };
   state.liveRuns.set(taskId, run);
   state.streaming = true;
@@ -445,54 +449,6 @@ function setRunHint(run, text) {
   if (state.taskId === run.taskId) $("chat-hint").textContent = text;
 }
 
-function normalizeProgressStatus(status) {
-  return ["pending", "in_progress", "completed"].includes(status) ? status : "pending";
-}
-
-function normalizeProgressStep(step) {
-  if (!step || typeof step !== "object") return null;
-  const id = String(step.id || "").trim();
-  const title = String(step.title || "").trim();
-  const status = normalizeProgressStatus(step.status);
-  if (!id || !title) return null;
-  return { id, title, status };
-}
-
-function applyProgressAction(progress, args) {
-  if (!args || typeof args !== "object") return progress;
-  const action = args.action || "";
-  if (action === "clear") return [];
-  if (action === "set_plan") {
-    const steps = Array.isArray(args.steps) ? args.steps.map(normalizeProgressStep).filter(Boolean) : [];
-    return steps;
-  }
-  if (action === "update_step") {
-    const raw = args.step;
-    if (!raw || typeof raw !== "object") return progress;
-    const id = String(raw.id || "").trim();
-    if (!id) return progress;
-    let found = false;
-    const next = progress.map((s) => {
-      if (s.id !== id) return s;
-      found = true;
-      return {
-        id: s.id,
-        title: String(raw.title || s.title || "").trim(),
-        status: normalizeProgressStatus(raw.status || s.status),
-      };
-    }).filter(s => s.title);
-    if (!found && raw.title) {
-      next.push({
-        id,
-        title: String(raw.title).trim(),
-        status: normalizeProgressStatus(raw.status),
-      });
-    }
-    return next;
-  }
-  return progress;
-}
-
 function renderProgressHtml(steps) {
   if (!Array.isArray(steps) || !steps.length) return "";
   const mark = (status) => status === "completed" ? "✓" : (status === "in_progress" ? "…" : "");
@@ -519,10 +475,29 @@ function renderProgressInto(card, steps) {
   }
 }
 
+function renderTaskProgressDock(steps) {
+  const dock = $("task-progress-dock");
+  if (!dock) return;
+  if (!Array.isArray(steps) || !steps.length) {
+    dock.innerHTML = "";
+    dock.classList.remove("show");
+    return;
+  }
+  dock.innerHTML = renderProgressHtml(steps);
+  dock.classList.add("show");
+}
+
+function setTaskProgress(taskId, steps) {
+  const normalized = cloneProgressSteps(steps);
+  if (taskId) state.taskProgressByTask.set(taskId, normalized);
+  if (state.taskId === taskId) renderTaskProgressDock(normalized);
+}
+
 function renderMessages(msgs) {
   const wrap = $("chat-stream");
   wrap.innerHTML = "";
   if (!msgs.length) {
+    setTaskProgress(state.taskId, []);
     wrap.innerHTML = `<div class="empty">(暂无消息 · 在下方输入开始对话)</div>`;
     renderLiveRunIfVisible();
     return;
@@ -533,6 +508,7 @@ function renderMessages(msgs) {
   // chip 去重:同一路径在 tool 结果里挂过 inline 图后,assistant 正文 echo 同路径不再重挂。
   // chronological 遍历,首次出现保留(tool 结果常在前),后续重复过滤掉。
   const seenRels = new Set();
+  let currentProgressSteps = [];
   const pickFresh = (rels) => {
     const fresh = [];
     for (const r of rels) {
@@ -591,8 +567,8 @@ function renderMessages(msgs) {
     }
     if (Array.isArray(p.tool_calls) && p.tool_calls.length) {
       const wd = _workingDirName(state.taskMeta && state.taskMeta.working_dir);
-      let progressSteps = [];
-      let sawProgress = false;
+      const progressResult = progressActionsFromToolCalls(p.tool_calls, currentProgressSteps);
+      currentProgressSteps = progressResult.steps;
       for (const tc of p.tool_calls) {
         const fn = (tc.function && tc.function.name) || "?";
         let argsObj = {};
@@ -602,8 +578,6 @@ function renderMessages(msgs) {
           args = JSON.stringify(argsObj, null, 2);
         } catch (e) { args = (tc.function && tc.function.arguments) || ""; }
         if (fn === "task_progress") {
-          progressSteps = applyProgressAction(progressSteps, argsObj);
-          sawProgress = true;
           continue;
         }
         const label = toolActivityLabel(fn, argsObj);
@@ -614,13 +588,14 @@ function renderMessages(msgs) {
           ${renderArtifactBarHtml(rels, isProducer)}
         `;
       }
-      if (sawProgress) html += renderProgressHtml(progressSteps);
+      if (progressResult.sawProgress) html += renderProgressHtml(currentProgressSteps);
     }
     card.innerHTML = html;
     highlightIn(card);
     wrap.appendChild(card);
   }
   wrap.scrollTop = wrap.scrollHeight;
+  setTaskProgress(state.taskId, currentProgressSteps);
   upgradeMediaArtifacts(wrap);
   renderLiveRunIfVisible();
 }
@@ -839,6 +814,7 @@ async function sendMessage() {
       body: asstCard.querySelector(".body"),
       cancelling: false,
       workingDir: state.taskMeta && state.taskMeta.working_dir,
+      progressSteps: cloneProgressSteps(state.taskProgressByTask.get(taskId)),
     };
     state.liveRuns.set(taskId, run);
     state.streaming = true;
@@ -1027,6 +1003,7 @@ function handleSseEvent(ev, asstCard, ctx) {
     const argsStr = typeof args === "string" ? args : JSON.stringify(args, null, 2);
     if (fn === "task_progress") {
       ctx.progressSteps = applyProgressAction(ctx.progressSteps || [], args);
+      setTaskProgress(ctx.taskId, ctx.progressSteps);
       renderProgressInto(asstCard, ctx.progressSteps);
       return;
     }
@@ -1145,6 +1122,7 @@ async function deleteTask(tid, name, nMsg) {
       renderConcurrentWarning();
       $("chat-meta").innerHTML = `<span class="muted">(未选中任务)</span>`;
       $("chat-stream").innerHTML = `<div class="empty">请在左侧选一个任务</div>`;
+      renderTaskProgressDock([]);
       $("chat-form").style.display = "none";
       $("btn-done").disabled = true;
       $("btn-abandon").disabled = true;
diff --git a/web/static/js/progress.js b/web/static/js/progress.js
new file mode 100644
index 0000000..12a5c34
--- /dev/null
+++ b/web/static/js/progress.js
@@ -0,0 +1,73 @@
+// Task progress state helpers. Kept DOM-free so Node tests can cover the
+// "update_step without title" merge behavior used by the Web UI.
+
+export function cloneProgressSteps(steps) {
+  return Array.isArray(steps) ? steps.map(s => ({ ...s })) : [];
+}
+
+export function normalizeProgressStatus(status) {
+  return ["pending", "in_progress", "completed"].includes(status) ? status : "pending";
+}
+
+export function normalizeProgressStep(step) {
+  if (!step || typeof step !== "object") return null;
+  const id = String(step.id || "").trim();
+  const title = String(step.title || "").trim();
+  const status = normalizeProgressStatus(step.status);
+  if (!id || !title) return null;
+  return { id, title, status };
+}
+
+export function applyProgressAction(progress, args) {
+  const current = cloneProgressSteps(progress);
+  if (!args || typeof args !== "object") return current;
+  const action = args.action || "";
+  if (action === "clear") return [];
+  if (action === "set_plan") {
+    return Array.isArray(args.steps) ? args.steps.map(normalizeProgressStep).filter(Boolean) : [];
+  }
+  if (action === "update_step") {
+    const raw = args.step;
+    if (!raw || typeof raw !== "object") return current;
+    const id = String(raw.id || "").trim();
+    if (!id) return current;
+    let found = false;
+    const next = current.map((s) => {
+      if (s.id !== id) return s;
+      found = true;
+      return {
+        id: s.id,
+        title: String(raw.title || s.title || "").trim(),
+        status: normalizeProgressStatus(raw.status || s.status),
+      };
+    }).filter(s => s.title);
+    if (!found && raw.title) {
+      next.push({
+        id,
+        title: String(raw.title).trim(),
+        status: normalizeProgressStatus(raw.status),
+      });
+    }
+    return next;
+  }
+  return current;
+}
+
+export function progressActionsFromToolCalls(toolCalls, baseSteps = []) {
+  let steps = cloneProgressSteps(baseSteps);
+  let sawProgress = false;
+  if (!Array.isArray(toolCalls)) return { steps, sawProgress };
+  for (const tc of toolCalls) {
+    const fn = (tc && tc.function && tc.function.name) || "";
+    if (fn !== "task_progress") continue;
+    let args = {};
+    try {
+      args = JSON.parse((tc.function && tc.function.arguments) || "{}");
+    } catch (e) {
+      args = {};
+    }
+    steps = applyProgressAction(steps, args);
+    sawProgress = true;
+  }
+  return { steps, sawProgress };
+}
diff --git a/web/static/js/state.js b/web/static/js/state.js
index 06813fb..cdfbdea 100644
--- a/web/static/js/state.js
+++ b/web/static/js/state.js
@@ -28,6 +28,7 @@ export const state = {
   evtSrc: null,
   streaming: false,      // 兼容旧判断:任一 task 是否在流式中
   liveRuns: new Map(),   // task_id -> 当前浏览器会话内运行中的回复卡/累计文本
+  taskProgressByTask: new Map(),  // task_id -> 历史消息重放后的当前进度步骤
   // task list 滚动加载 + 筛选
   taskPage: 0,           // 已加载到的最后一页(0 = 未加载)
   taskPageSize: 20,