diff --git a/packages/web-shell/client/components/sidebar/WebShellSidebar.collapse-persist.test.tsx b/packages/web-shell/client/components/sidebar/WebShellSidebar.collapse-persist.test.tsx
index c1d4f7e20ca..eac766741d6 100644
--- a/packages/web-shell/client/components/sidebar/WebShellSidebar.collapse-persist.test.tsx
+++ b/packages/web-shell/client/components/sidebar/WebShellSidebar.collapse-persist.test.tsx
@@ -251,6 +251,133 @@ describe('WebShellSidebar collapsed session group persistence', () => {
       );
     },
   );
+  it('moves the session search beside the activity toggle in the top row', async () => {
+    renderSidebar();
+    await flushSidebar();
+
+    const topRow = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.topRow}`,
+    );
+    expect(topRow).not.toBeNull();
+    const search = topRow!.querySelector<HTMLButtonElement>(
+      'button[aria-label="Search sessions"]',
+    );
+    const activity = topRow!.querySelector<HTMLButtonElement>(
+      'button[aria-label="View activity"]',
+    );
+    expect(search).not.toBeNull();
+    expect(activity).not.toBeNull();
+    expect(search!.parentElement).toBe(activity!.parentElement);
+
+    const projectsHeader = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.projectsHeader}`,
+    );
+    expect(projectsHeader).not.toBeNull();
+    expect(
+      projectsHeader!.querySelector('button[aria-label="Search sessions"]'),
+    ).toBeNull();
+
+    click(search!);
+    await flushSidebar();
+    expect(
+      topRow!.querySelector('input[aria-label="Search sessions"]'),
+    ).not.toBeNull();
+  });
+  it('hides the session search while the activity view is open', async () => {
+    renderSidebar();
+    await flushSidebar();
+
+    const activity = container.querySelector<HTMLButtonElement>(
+      'button[aria-label="View activity"]',
+    );
+    expect(activity).not.toBeNull();
+    act(() => click(activity!));
+    await flushSidebar();
+
+    expect(
+      container.querySelector('button[aria-label="Search sessions"]'),
+    ).toBeNull();
+    const close = container.querySelector<HTMLButtonElement>(
+      'button[aria-label="Close activity view"]',
+    );
+    expect(close).not.toBeNull();
+    act(() => click(close!));
+    await flushSidebar();
+    expect(
+      container.querySelector('button[aria-label="Search sessions"]'),
+    ).not.toBeNull();
+  });
+  it('drops the search field below the icon row in the mobile drawer', async () => {
+    renderSidebar(false, { mobileOpen: true });
+    await flushSidebar();
+
+    const topRow = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.topRow}`,
+    );
+    const search = topRow!.querySelector<HTMLButtonElement>(
+      'button[aria-label="Search sessions"]',
+    );
+    expect(search).not.toBeNull();
+    act(() => click(search!));
+    await flushSidebar();
+
+    expect(
+      topRow!.querySelector('input[aria-label="Search sessions"]'),
+    ).toBeNull();
+    const row = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.topRowSearchRow}`,
+    );
+    expect(row).not.toBeNull();
+    expect(
+      row!.querySelector('input[aria-label="Search sessions"]'),
+    ).not.toBeNull();
+  });
+  it('drops the search field below the icon row in a narrow column', async () => {
+    window.localStorage.setItem('qwen-code-web-shell-sidebar-width', '276');
+    renderSidebar(false, { layout: 'rail' });
+    await flushSidebar();
+
+    const topRow = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.topRow}`,
+    );
+    const search = topRow!.querySelector<HTMLButtonElement>(
+      'button[aria-label="Search sessions"]',
+    );
+    expect(search).not.toBeNull();
+    act(() => click(search!));
+    await flushSidebar();
+
+    expect(
+      topRow!.querySelector('input[aria-label="Search sessions"]'),
+    ).toBeNull();
+    expect(
+      container.querySelector(`.${sidebarStyles.topRowSearchRow}`),
+    ).not.toBeNull();
+  });
+  it('keeps the session search in the Channels section header', async () => {
+    connection.capabilities = {
+      qwenCodeVersion: '1.2.3',
+      features: ['session_source_metadata', 'session_organization'],
+    };
+    workspace.capabilities = connection.capabilities;
+    renderSidebar(false, { layout: 'rail', activePage: 'channels' });
+    await flushSidebar();
+
+    const header = container.querySelector<HTMLElement>(
+      `.${sidebarStyles.sectionHeader}`,
+    );
+    expect(header).not.toBeNull();
+    expect(header!.textContent).toContain('Channels');
+    const search = header!.querySelector<HTMLButtonElement>(
+      'button[aria-label="Search sessions"]',
+    );
+    expect(search).not.toBeNull();
+    act(() => click(search!));
+    await flushSidebar();
+    expect(
+      header!.querySelector('input[aria-label="Search sessions"]'),
+    ).not.toBeNull();
+  });
   it('uses drawer constraints and closes mobile without persisting desktop collapse', async () => {
     const onCollapsedChange = vi.fn();
     const onMobileClose = vi.fn();
diff --git a/packages/web-shell/client/components/sidebar/WebShellSidebar.module.css b/packages/web-shell/client/components/sidebar/WebShellSidebar.module.css
index 182dece75ae..f52f394d1c0 100644
--- a/packages/web-shell/client/components/sidebar/WebShellSidebar.module.css
+++ b/packages/web-shell/client/components/sidebar/WebShellSidebar.module.css
@@ -226,6 +226,39 @@
   min-width: 0;
 }
 
+.topRowActions {
+  display: flex;
+  flex: 0 0 auto;
+  align-items: center;
+  gap: 4px;
+  margin-left: auto;
+  min-width: 0;
+}
+
+.topRowActionsSearching {
+  flex: 1 1 auto;
+}
+
+.topRowSearchRow {
+  flex: 0 0 auto;
+  padding: 0 4px 12px;
+}
+
+.searchToggle {
+  display: inline-flex;
+  flex: 0 0 auto;
+  align-items: center;
+  justify-content: center;
+  padding: 8px;
+  border-radius: 8px;
+  cursor: pointer;
+}
+
+.searchToggle:hover,
+.searchToggle:focus-visible {
+  background: var(--accent);
+}
+
 .brandLogo {
   flex: 0 0 28px;
   width: 28px;
@@ -511,6 +544,13 @@ button.livePendingSession:hover {
   padding-left: 32px;
 }
 
+/* After `.projectSearch`: the top row width is the search field's budget, so
+   it must be able to shrink instead of pushing the icon buttons out. */
+.topRowSearchField {
+  flex: 1 1 auto;
+  min-width: 0;
+}
+
 .addWorkspaceButton {
   display: flex;
   align-items: center;
diff --git a/packages/web-shell/client/components/sidebar/WebShellSidebar.tsx b/packages/web-shell/client/components/sidebar/WebShellSidebar.tsx
index dc520865db0..3d21f9ad711 100644
--- a/packages/web-shell/client/components/sidebar/WebShellSidebar.tsx
+++ b/packages/web-shell/client/components/sidebar/WebShellSidebar.tsx
@@ -1996,10 +1996,21 @@ export function WebShellSidebar({
   }, [workspace.client, lockedWorkspaceCwd, activityEnabled]);
   const toggleActivity = useCallback(() => {
     if (!activityEnabled) return;
+    if (!activityOpen) {
+      setSearchOpen(false);
+      setSearchQuery('');
+    }
     setActivityOpen((value) => !value);
     if (collapsed) onCollapsedChange(false);
     if (homeHidden) onOpenHome?.();
-  }, [activityEnabled, collapsed, homeHidden, onCollapsedChange, onOpenHome]);
+  }, [
+    activityEnabled,
+    activityOpen,
+    collapsed,
+    homeHidden,
+    onCollapsedChange,
+    onOpenHome,
+  ]);
   useEffect(() => {
     if (!activityEnabled) return;
     const listener = (event: KeyboardEvent) => {
@@ -6333,6 +6344,60 @@ export function WebShellSidebar({
     standaloneSessionsVisible,
     t,
   ]);
+  const searchEnabled = !liveView && !hideProjectHeader;
+  // The activity panel replaces the session list, so a query typed there
+  // filters rows the panel never shows.
+  const topRowSearchVisible =
+    searchEnabled &&
+    !activityOpen &&
+    (!collapsed || mobileOpen || homePreviewOpen);
+  // A narrow column cannot fit a usable field beside the icon buttons, so
+  // there the field drops to a full-width row under the brand row instead.
+  const topRowColumnWidth =
+    sidebarWidth - (railLayout ? SIDEBAR_RAIL_WIDTH : 0);
+  const inlineTopRowSearch =
+    topRowSearchVisible && !mobileOpen && topRowColumnWidth >= 285;
+  // The top row owns the search control whenever it is visible. Hosts that
+  // hide the brand row, and the collapsed strip (whose session list lives in
+  // a popover), fall back to the older Projects-header placement.
+  const searchInProjectHeader =
+    !shouldRenderBrand || (!railLayout && collapsed && !mobileOpen);
+  const renderSearchField = (className?: string) => (
+    <div className={cx(styles.projectSearch, className)}>
+      <SearchIcon aria-hidden="true" />
+      <Input
+        value={searchQuery}
+        placeholder={t('sidebar.searchPlaceholder')}
+        aria-label={t('sidebar.search')}
+        autoFocus
+        onChange={(event) => setSearchQuery(event.target.value)}
+        onKeyDown={(event) => {
+          if (event.key === 'Escape') {
+            setSearchQuery('');
+            setSearchOpen(false);
+          }
+        }}
+      />
+    </div>
+  );
+  const renderSearchToggle = (className: string) => (
+    <button
+      type="button"
+      className={className}
+      title={t('sidebar.search')}
+      aria-label={t('sidebar.search')}
+      aria-expanded={searchOpen}
+      onClick={() => {
+        setSearchOpen((open) => {
+          if (open) setSearchQuery('');
+          return !open;
+        });
+        setProjectsExpanded(true);
+      }}
+    >
+      <SearchIcon size={18} strokeWidth={1.5} />
+    </button>
+  );
   const primaryNavigation = hasScrollingPrimaryNav && (
     <div className={styles.primaryNav}>
       {projectFeaturesEnabled &&
@@ -7274,9 +7339,35 @@ export function WebShellSidebar({
           }}
         >
           {sectionView && (
-            <div className={styles.sectionHeader}>
-              {t(liveView ? 'sidebar.live' : 'sidebar.channels')}
-            </div>
+            <>
+              <div className={styles.sectionHeader}>
+                {t(liveView ? 'sidebar.live' : 'sidebar.channels')}
+                {channelView && searchEnabled && shouldRenderBrand && (
+                  <div
+                    className={cx(
+                      styles.topRowActions,
+                      searchOpen &&
+                        inlineTopRowSearch &&
+                        styles.topRowActionsSearching,
+                    )}
+                  >
+                    {searchOpen &&
+                      inlineTopRowSearch &&
+                      renderSearchField(styles.topRowSearchField)}
+                    {renderSearchToggle(styles.searchToggle)}
+                  </div>
+                )}
+              </div>
+              {channelView &&
+                searchEnabled &&
+                shouldRenderBrand &&
+                searchOpen &&
+                !inlineTopRowSearch && (
+                  <div className={styles.topRowSearchRow}>
+                    {renderSearchField()}
+                  </div>
+                )}
+            </>
           )}
           {liveView &&
             !homeHidden &&
@@ -7288,57 +7379,86 @@ export function WebShellSidebar({
               />
             )}
           {!sectionView && shouldRenderBrand && (
-            <div className={styles.topRow}>
-              {branding?.render ? (
-                branding.render()
-              ) : (
-                <>
-                  <span className={styles.brandLogo} aria-hidden="true">
-                    {brand.logo ||
-                      (brand.logoDataUri ? (
-                        // `key` remounts on a new URI: after one decode failure,
-                        // the failed state must not stick to the next logo.
-                        <BrandLogoImage
-                          key={brand.logoDataUri}
-                          dataUri={brand.logoDataUri}
-                        />
-                      ) : (
-                        <IconQwenLogo />
-                      ))}
-                  </span>
-                  {(!collapsed || mobileOpen || homePreviewOpen) && (
-                    <span className={styles.brandName}>{brandName}</span>
-                  )}
-                </>
-              )}
-              {activityEnabled && (!railLayout || !collapsed || mobileOpen) && (
-                <button
-                  type="button"
+            <>
+              <div className={styles.topRow}>
+                {branding?.render ? (
+                  searchOpen && inlineTopRowSearch ? null : (
+                    branding.render()
+                  )
+                ) : (
+                  <>
+                    <span className={styles.brandLogo} aria-hidden="true">
+                      {brand.logo ||
+                        (brand.logoDataUri ? (
+                          // `key` remounts on a new URI: after one decode
+                          // failure, the failed state must not stick to the
+                          // next logo.
+                          <BrandLogoImage
+                            key={brand.logoDataUri}
+                            dataUri={brand.logoDataUri}
+                          />
+                        ) : (
+                          <IconQwenLogo />
+                        ))}
+                    </span>
+                    {(!collapsed || mobileOpen || homePreviewOpen) &&
+                      !(searchOpen && inlineTopRowSearch) && (
+                        <span className={styles.brandName}>{brandName}</span>
+                      )}
+                  </>
+                )}
+                <div
                   className={cx(
-                    'ml-auto relative rounded-lg p-2 hover:bg-accent',
-                    styles.activityToggle,
+                    styles.topRowActions,
+                    searchOpen &&
+                      inlineTopRowSearch &&
+                      styles.topRowActionsSearching,
                   )}
-                  aria-label={t(
-                    activityOpen ? 'activity.close' : 'activity.open',
-                  )}
-                  title={`${t(activityOpen ? 'activity.close' : 'activity.open')} (⌥⌘U / Ctrl+Alt+U)`}
-                  aria-pressed={activityOpen}
-                  onClick={toggleActivity}
                 >
-                  <BellIcon size={18} strokeWidth={1.5} />
-                  {activityEntries.some(
-                    (entry) =>
-                      isActivityEligible(entry, activityPreferences) &&
-                      activityNeedsAttention(entry),
-                  ) && (
-                    <span
-                      className="absolute right-1 top-1 size-1.5 rounded-full bg-primary"
-                      data-activity-attention
-                    />
+                  {topRowSearchVisible && (
+                    <>
+                      {searchOpen &&
+                        inlineTopRowSearch &&
+                        renderSearchField(styles.topRowSearchField)}
+                      {renderSearchToggle(styles.searchToggle)}
+                    </>
                   )}
-                </button>
+                  {activityEnabled &&
+                    (!railLayout || !collapsed || mobileOpen) && (
+                      <button
+                        type="button"
+                        className={cx(
+                          'relative rounded-lg p-2 hover:bg-accent',
+                          styles.activityToggle,
+                        )}
+                        aria-label={t(
+                          activityOpen ? 'activity.close' : 'activity.open',
+                        )}
+                        title={`${t(activityOpen ? 'activity.close' : 'activity.open')} (⌥⌘U / Ctrl+Alt+U)`}
+                        aria-pressed={activityOpen}
+                        onClick={toggleActivity}
+                      >
+                        <BellIcon size={18} strokeWidth={1.5} />
+                        {activityEntries.some(
+                          (entry) =>
+                            isActivityEligible(entry, activityPreferences) &&
+                            activityNeedsAttention(entry),
+                        ) && (
+                          <span
+                            className="absolute right-1 top-1 size-1.5 rounded-full bg-primary"
+                            data-activity-attention
+                          />
+                        )}
+                      </button>
+                    )}
+                </div>
+              </div>
+              {topRowSearchVisible && searchOpen && !inlineTopRowSearch && (
+                <div className={styles.topRowSearchRow}>
+                  {renderSearchField()}
+                </div>
               )}
-            </div>
+            </>
           )}
           {!sectionView && primaryNavItems.has('newTask') && (
             <div
@@ -7633,21 +7753,9 @@ export function WebShellSidebar({
                           <FolderKanbanIcon />
                         </button>
                       )}
-                    <button
-                      className={styles.projectsHeaderAction}
-                      type="button"
-                      title={t('sidebar.search')}
-                      aria-label={t('sidebar.search')}
-                      onClick={() => {
-                        setSearchOpen((open) => {
-                          if (open) setSearchQuery('');
-                          return !open;
-                        });
-                        setProjectsExpanded(true);
-                      }}
-                    >
-                      <SearchIcon />
-                    </button>
+                    {searchEnabled &&
+                      searchInProjectHeader &&
+                      renderSearchToggle(styles.projectsHeaderAction)}
                     {!channelView &&
                       !lockedWorkspaceCwd &&
                       onOpenAddWorkspace && (
@@ -7664,24 +7772,10 @@ export function WebShellSidebar({
                   </div>
                 </div>
               )}
-              {!liveView && searchOpen && !hideProjectHeader && (
-                <div className={styles.projectSearch}>
-                  <SearchIcon aria-hidden="true" />
-                  <Input
-                    value={searchQuery}
-                    placeholder={t('sidebar.searchPlaceholder')}
-                    aria-label={t('sidebar.search')}
-                    autoFocus
-                    onChange={(event) => setSearchQuery(event.target.value)}
-                    onKeyDown={(event) => {
-                      if (event.key === 'Escape') {
-                        setSearchQuery('');
-                        setSearchOpen(false);
-                      }
-                    }}
-                  />
-                </div>
-              )}
+              {searchEnabled &&
+                searchOpen &&
+                searchInProjectHeader &&
+                renderSearchField()}
               {/* Managed 历史由外部 App Host 注入，不受本地 Workspaces
                   折叠状态控制；否则折叠分组会把仍有效的 Managed 会话一起隐藏。 */}
               {!channelView && !liveView && managedWorkspaces}
diff --git a/packages/web-shell/client/e2e/web-shell.navigation-rail.spec.ts b/packages/web-shell/client/e2e/web-shell.navigation-rail.spec.ts
index 7cf72ee460a..d9ea8fc7560 100644
--- a/packages/web-shell/client/e2e/web-shell.navigation-rail.spec.ts
+++ b/packages/web-shell/client/e2e/web-shell.navigation-rail.spec.ts
@@ -228,7 +228,9 @@ test('narrow embedded container uses a contained drawer on a wide viewport @smok
     .locator(homeColumn)
     .getByText('Qwen Code', { exact: true });
   await expect(brand).toBeVisible();
-  await expect(brand.locator('..').locator('svg')).toBeVisible();
+  await expect(
+    brand.locator('..').locator('span[aria-hidden="true"] svg'),
+  ).toBeVisible();
   const host = await page.getByTestId('host-shell').boundingBox();
   const bounds = await drawer.boundingBox();
   expect(bounds!.x).toBeGreaterThanOrEqual(host!.x);