diff --git a/packages/ui/src/__tests__/session-history-working-mark.test.tsx b/packages/ui/src/__tests__/session-history-working-mark.test.tsx
new file mode 100644
index 0000000000..9df348a4f4
--- /dev/null
+++ b/packages/ui/src/__tests__/session-history-working-mark.test.tsx
@@ -0,0 +1,86 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { parseHTML } from 'linkedom';
+import { renderToStaticMarkup } from 'react-dom/server';
+import type { SessionSummary } from '@maka/core/session';
+import { LocaleProvider } from '../locale-context.js';
+import { SessionHistoryList } from '../session-history-list.js';
+import { SessionRailProvider, type SessionRailData } from '../session-rail-context.js';
+
+function Rail(props: Partial<SessionRailData> & { sessions: readonly SessionSummary[] }) {
+  const data: SessionRailData = {
+    groupVariant: 'conversation',
+    onSelectSession: () => undefined,
+    ...props,
+  };
+  return (
+    <LocaleProvider locale="en">
+      <SessionRailProvider data={data}>
+        <SessionHistoryList />
+      </SessionRailProvider>
+    </LocaleProvider>
+  );
+}
+
+const session: SessionSummary = {
+  id: 'session-1',
+  name: 'Release notes',
+  isFlagged: false,
+  isArchived: false,
+  labels: [],
+  hasUnread: false,
+  status: 'active',
+  backend: 'ai-sdk',
+  llmConnectionSlug: 'test-connection',
+  connectionLocked: true,
+  model: 'test-model',
+  permissionMode: 'ask',
+};
+
+test('the responding row’s signal carries the working mark', () => {
+  const dom = parseHTML(
+    renderToStaticMarkup(
+      <Rail sessions={[{ ...session, status: 'running', runningTurnIds: ['turn-1'] }]} />,
+    ),
+  );
+  assert.equal(
+    dom.document.querySelector('.maka-session-row-signal')?.getAttribute('data-working'),
+    'true',
+  );
+});
+
+test('a persisted running row keeps the working mark without live turns', () => {
+  const dom = parseHTML(
+    renderToStaticMarkup(<Rail sessions={[{ ...session, status: 'running' }]} />),
+  );
+  assert.equal(
+    dom.document.querySelector('.maka-session-row-signal')?.getAttribute('data-working'),
+    'true',
+  );
+});
+
+test('a settled row carries no working mark', () => {
+  const dom = parseHTML(renderToStaticMarkup(<Rail sessions={[session]} />));
+  const signal = dom.document.querySelector('.maka-session-row-signal');
+  assert.ok(signal, 'the signal gutter always renders');
+  assert.equal(signal.getAttribute('data-working'), null);
+});
diff --git a/packages/ui/src/session-history-list.tsx b/packages/ui/src/session-history-list.tsx
index 924e235868..306952fde3 100644
--- a/packages/ui/src/session-history-list.tsx
+++ b/packages/ui/src/session-history-list.tsx
@@ -797,7 +797,14 @@ const SessionNavRow = memo(function SessionNavRow(props: {
         // whether or not it has a dot, so state reads as one column down the
         // rail instead of a mark that drifts with each title's length.
         icon={
-          <span className="maka-session-row-signal">
+          <span
+            className="maka-session-row-signal"
+            // The working cue's hook: `styles.css` wraps the dot in a spinning
+            // arc keyed on this attribute (static ring under reduced motion).
+            // `isPulsing` is exactly "a turn is working" — live responding and
+            // the persisted running fallback both set it.
+            data-working={signal?.isPulsing ? 'true' : undefined}
+          >
             {signal ? (
               <StatusDot
                 variant={signal.variant}
diff --git a/packages/ui/src/styles.css b/packages/ui/src/styles.css
index b90f8794e5..fe577b9031 100644
--- a/packages/ui/src/styles.css
+++ b/packages/ui/src/styles.css
@@ -1342,3 +1342,32 @@
 .maka-choice-panel:focus-visible { outline: var(--focus-ring-width) solid var(--focus-ring); outline-offset: var(--focus-ring-offset); }
 
 .maka-choice-hint { margin: 8px 0; }
+
+/* ---------------------------------------------------------------------------
+   Session rail working cue.
+
+   The 8px dot's own opacity breathe reads as "settled" in peripheral vision,
+   and `prefers-reduced-motion` removes even that (apache/maka#5519). While a
+   turn is working, the signal gutter wraps the dot in a spinning arc — the
+   rotation is the in-progress cue when motion is fine, and the arc itself is
+   the non-motion mark when it is not.
+--------------------------------------------------------------------------- */
+
+.maka-session-row-signal { display: inline-flex; position: relative; }
+
+.maka-session-row-signal[data-working='true']::after {
+  content: '';
+  position: absolute;
+  inset: -3px;
+  border-radius: 999px;
+  border: 1.5px solid transparent;
+  border-top-color: var(--accent);
+  animation: maka-spin 0.9s linear infinite;
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .maka-session-row-signal[data-working='true']::after {
+    animation: none;
+    border-color: color-mix(in oklch, var(--accent) 55%, transparent);
+  }
+}