fix: polish agent voice controls

tests/browser/agent-voice-hydration.e2e.ts

@@ -83,3 +83,48 @@ test("speech recognition writes final transcript into the prompt", async ({ page
 
   await expect(page.getByPlaceholder("输入调度问题，Agent 将通过后端会话流式响应")).toHaveValue("检查城南泵站水位");
 });
+
+test("speech recognition pulse stays transparent across its loop boundary", async ({ page }) => {
+  await page.addInitScript(() => {
+    Object.defineProperty(window, "SpeechRecognition", {
+      configurable: true,
+      value: class SpeechRecognition {
+        start() {}
+
+        stop() {}
+
+        abort() {}
+      }
+    });
+  });
+  await page.goto("/", { waitUntil: "domcontentloaded" });
+
+  await page.getByRole("button", { name: "语音输入" }).click();
+
+  const pulse = page.locator('[data-slot="voice-input-pulse"]');
+  await expect(pulse).toBeVisible();
+  const seamOpacity = await pulse.evaluate((element) => {
+    const animation = element
+      .getAnimations()
+      .find((candidate) =>
+        (candidate.effect as KeyframeEffect | null)
+          ?.getKeyframes()
+          .some((keyframe) => keyframe.opacity !== undefined)
+      );
+    if (!animation?.effect) {
+      throw new Error("Voice input pulse opacity animation was not found");
+    }
+
+    animation.pause();
+    const duration = Number(animation.effect.getTiming().duration);
+    animation.currentTime = duration - 1;
+    const before = Number(window.getComputedStyle(element).opacity);
+    animation.currentTime = duration + 1;
+    const after = Number(window.getComputedStyle(element).opacity);
+
+    return { before, after };
+  });
+
+  expect(seamOpacity.before).toBeLessThan(0.02);
+  expect(seamOpacity.after).toBeLessThan(0.02);
+});