feat(video): add inline volume control to MessageInlineVideo

- Add mute toggle button (Volume2/VolumeX icons) to the custom control bar.
- Add an always-visible inline straight-line volume slider on desktop;
  mobile keeps mute toggle only and relies on system volume keys.
- Slider at 0 auto-mutes; unmuting from zero restores volume to 1.
- Sync isMuted/volume state via the video volumechange event.

Verified in browser at /browse?type=video: drag slider updates
video.volume, mute toggle preserves volume across on/off.

.unipi/docs/fix/2026-06-07-video-volume-control-fix.md

@@ -0,0 +1,40 @@
+---
+title: "影片播放音量调整按钮 — Quick Fix"
+type: quick-fix
+date: 2026-06-07
+---
+
+# 影片播放音量调整按钮 — Quick Fix
+
+## Bug
+`MessageInlineVideo` 的自定义控制条只有播放/暂停、进度条、全屏按钮，缺少音量控制。用户无法在播放器内静音或调节音量。
+
+## Root Cause
+功能缺失。原生 `<video>` 控件被关闭以统一 iOS Safari 体验，但替代实现没有补回音量控制。
+
+## Fix
+在底部控制条「剩余时间」与「全屏按钮」之间加入音量控制：
+
+- 静音切换按钮（`Volume2` / `VolumeX`），点击直接 toggle `video.muted`，桌面、移动均可用。
+- 桌面端始终可见的内联直线音量滑块（`<input type="range">`，0~1，step 0.05），紧贴喇叭按钮右侧；不再用 hover 弹出，调音量像 YouTube 一样直接拖一条直线。
+- 滑到 0 自动静音；从 0 解除静音时自动恢复到 1，避免「点开还是没声音」的体验。
+- 新增 `isMuted` / `volume` state，监听 `volumechange` 与初始挂载同步，确保按钮图标与滑块位置始终一致。
+- 移动端只显示静音按钮，音量大小让系统音量键负责。
+
+### Files Modified
+- `src/components/messageStream/MessageInlineVideo.tsx` — 引入 `Volume2/VolumeX` 图标、新增音量 state / `volumechange` 监听 / `toggleMute` / `handleVolumeChange`，在控制条加入音量按钮 + hover 音量滑块。
+
+## Verification
+- `npx tsc --noEmit` 通过（严格模式 + 未使用变量检查）。
+- `npm run format` 通过。
+- `npm test` 全部 49 测试通过。
+- 浏览器实测 `/browse?type=video`：
+  - 拖滑块 0.3：`video.volume=0.3`，slider 同步 0.3 ✓
+  - 点喇叭按钮：`muted=true`，slider 显示 0 ✓
+  - 再点：`muted=false`，volume 保留 0.3 ✓
+  - 滑块拖到 0：`muted=true`、`volume=0` ✓
+
+## Notes
+- 仅修改 `MessageInlineVideo`，全屏播放器 `VideoPlayer.tsx` 复用同一组件，因此全屏模式同时获得音量控制。
+- 没有改变 `autoPlay` 默认行为；如未来 iOS autoplay 受限，可考虑默认 `muted` 起播再由用户点按钮解除。
+- 滑块在移动端隐藏（仅 `md:` 以上显示），移动端通过按钮 + 系统音量键操作，避免在小气泡里拥挤。

src/components/messageStream/MessageInlineVideo.tsx

@@ -1,4 +1,4 @@
-import { Maximize2, Pause, Play } from "lucide-react";
+import { Maximize2, Pause, Play, Volume2, VolumeX } from "lucide-react";
 import {
   useCallback,
   useEffect,
@@ -121,6 +121,8 @@ export function MessageInlineVideo({
   const [currentTime, setCurrentTime] = useState(initialTime);
   const [duration, setDuration] = useState(attachment.durationSec ?? 0);
   const [isScrubbing, setIsScrubbing] = useState(false);
+  const [isMuted, setIsMuted] = useState(false);
+  const [volume, setVolume] = useState(1);
   // When we programmatically seek (e.g. syncing the playhead back from the
   // fullscreen overlay) the progress fill should jump straight to the watched
   // position instead of sweeping up from its old width via the CSS transition.
@@ -150,6 +152,10 @@ export function MessageInlineVideo({
       setCurrentTime(v.currentTime);
       onTimeUpdate?.(v.currentTime);
     };
+    const onVolume = () => {
+      setIsMuted(v.muted);
+      setVolume(v.volume);
+    };
     const onMeta = () => {
       if (Number.isFinite(v.duration)) setDuration(v.duration);
       if (initialTime > 0) {
@@ -165,12 +171,15 @@ export function MessageInlineVideo({
     v.addEventListener("timeupdate", onTime);
     v.addEventListener("seeked", onSeeked);
     v.addEventListener("loadedmetadata", onMeta);
+    v.addEventListener("volumechange", onVolume);
+    onVolume();
     return () => {
       v.removeEventListener("play", onPlay);
       v.removeEventListener("pause", onPause);
       v.removeEventListener("timeupdate", onTime);
       v.removeEventListener("seeked", onSeeked);
       v.removeEventListener("loadedmetadata", onMeta);
+      v.removeEventListener("volumechange", onVolume);
     };
   }, [initialTime, onTimeUpdate]);
 
@@ -181,6 +190,22 @@ export function MessageInlineVideo({
     else v.pause();
   }, []);
 
+  const toggleMute = useCallback(() => {
+    const v = videoRef.current;
+    if (!v) return;
+    // Unmuting at zero volume would leave the user with silence; restore to full.
+    if (v.muted && v.volume === 0) v.volume = 1;
+    v.muted = !v.muted;
+  }, []);
+
+  const handleVolumeChange = useCallback((next: number) => {
+    const v = videoRef.current;
+    if (!v) return;
+    const clamped = Math.max(0, Math.min(1, next));
+    v.volume = clamped;
+    v.muted = clamped === 0;
+  }, []);
+
   const seekToClientX = useCallback((clientX: number) => {
     const el = scrubRef.current;
     const v = videoRef.current;
@@ -367,6 +392,38 @@ export function MessageInlineVideo({
           -{formatClock(remaining)}
         </span>
 
+        <div className="flex shrink-0 items-center gap-2">
+          <button
+            type="button"
+            onClick={(e) => {
+              e.stopPropagation();
+              toggleMute();
+            }}
+            className={`flex shrink-0 items-center justify-center text-white transition hover:scale-105 ${t.btn}`}
+            aria-label={isMuted || volume === 0 ? "Unmute" : "Mute"}
+          >
+            {isMuted || volume === 0 ? (
+              <VolumeX className={t.btnIcon} strokeWidth={2.2} />
+            ) : (
+              <Volume2 className={t.btnIcon} strokeWidth={2.2} />
+            )}
+          </button>
+          {/* Always-visible inline straight-line volume slider (desktop only;
+              on touch devices users rely on the mute toggle + system volume). */}
+          <input
+            type="range"
+            min={0}
+            max={1}
+            step={0.05}
+            value={isMuted ? 0 : volume}
+            onChange={(e) => handleVolumeChange(Number(e.target.value))}
+            onClick={(e) => e.stopPropagation()}
+            onPointerDown={(e) => e.stopPropagation()}
+            aria-label="Volume"
+            className="hidden h-1 w-20 cursor-pointer appearance-none rounded-full bg-white/30 accent-white md:block"
+          />
+        </div>
+
         {hideFullscreen ? null : (
           <button
             type="button"