[Bug] Caps Lock leaves the paw pressed on macOS

[huaer9000]

Environment

• macOS
• BongoCat Next 0.2.11
• Interactive keyboard model

Steps to reproduce

1. Start BongoCat Next.
2. Press Caps Lock once.
3. Observe the paw assigned to Caps Lock.

Actual behavior

The paw remains in the pressed position until Caps Lock is pressed again.

Expected behavior

Caps Lock should behave like a tap: after the key is pressed, the paw should return to its default raised state.

Cause

On macOS, Caps Lock is delivered through FlagsChanged rather than a normal physical KeyUp. The current rdev event mapping turns the first toggle into KeyboardPress(CapsLock), while the frontend removes pressed keys only after receiving KeyboardRelease. The key therefore remains in the pressed set.

Proposed fix

In src-tauri/src/core/device.rs, allow one rdev event to produce multiple app events. On macOS only, when receiving KeyPress(Key::CapsLock), emit the normal KeyboardPress followed immediately by KeyboardRelease for CapsLock. Other keys and platforms remain unchanged.

I verified this locally with a regression test that asserts the Caps Lock press produces the paired press/release events, and by manually testing the development build.

[liwenka1]

/deepcode 分析一下反馈的这个问题以及修复方案，总结一下

[github-actions]

🤖 Deep Code

🤔 思考过程(点击展开)

让我来分析这个问题并总结修复方案。

问题分析：

1. Bug：在 macOS 上，按下 Caps Lock 键后，对应的爪子保持按下状态无法弹回，需要再次按 Caps Lock 才能恢复。

2. 根因：macOS 上 Caps Lock 键是通过 FlagsChanged 事件传递的，而不是正常的物理 KeyUp 事件。rdev 事件映射将第一次切换转为 KeyboardPress(CapsLock)，但前端只在收到 KeyboardRelease 后才将按键从已按下集合中移除，因此该键一直处于按下状态。

3. 修复方案：在 src-tauri/src/core/device.rs 中，允许一个 rdev 事件产生多个应用事件。仅在 macOS 上，当收到 KeyPress(Key::CapsLock) 时，先发出正常的 KeyboardPress，紧接着发出 KeyboardRelease。其他键和平台不受影响。

让我先看看相关代码来验证问题并理解上下文。Let me analyze the code I just read.

The key function is rdev_event_to_device_event (line 33). It currently maps exactly one rdev Event to at most one DeviceEvent.

For the Caps Lock issue on macOS:

• When Caps Lock is pressed on macOS, rdev produces EventType::KeyPress(Key::CapsLock) — but there's no corresponding KeyRelease because macOS uses FlagsChanged instead.
• The frontend tracks pressed keys: on KeyboardPress it marks the key as pressed (paw down), and on KeyboardRelease it marks it as released (paw up).
• Since KeyboardRelease never arrives for Caps Lock on macOS, the paw stays down.

Now let me look at how the frontend handles these events - specifically how it tracks pressed keys.

Let me also check how the macOS path calls rdev_event_to_device_event. Looking at lines ~72-117, the macOS callback also just calls rdev_event_to_device_event which returns a single Option<DeviceEvent>.

The proposed fix: modify the conversion function (or the calling code) so that on macOS, when a KeyPress(CapsLock) is received, it emits both KeyboardPress and KeyboardRelease events. This can be done by changing the return type from Option<DeviceEvent> to Vec<DeviceEvent> (or SmallVec), or handling it at the call site.

Let me look at the frontend to understand how it consumes these events.Now let me look at the frontend keyboard hook to understand how it processes events and tracks pressed keys.Let me read the rest of the keyboard hook to see how Tauri events are handled.Now I have a clear picture. Let me summarize:

The Bug:
On macOS, Caps Lock is delivered via FlagsChanged (CGEvent) rather than a normal key-up event. The rdev crate maps the first toggle to EventType::KeyPress(Key::CapsLock) but never produces a corresponding KeyRelease because macOS doesn't generate a physical key-up for Caps Lock.

The Frontend (src/hooks/use-keyboard.ts):

• handleKeyPress(keyName) adds the key to pressedKeysRef.current (line 164)
• handleKeyRelease(keyName) removes the key from pressedKeysRef.current (line 170)
• Since KeyboardRelease never arrives for Caps Lock on macOS, the key stays in the pressed set forever → paw stays down.

The Backend (src-tauri/src/core/device.rs):

• rdev_event_to_device_event() maps one rdev Event to one Option<DeviceEvent> (line 33)
• The macOS callback (line 107-116) calls this and sends the single event through a channel.
• The non-macOS callback (line 131-137) does the same directly.

The Proposed Fix:
Change the return type of rdev_event_to_device_event from Option<DeviceEvent> to Vec<DeviceEvent> (or use a SmallVec). On macOS when receiving KeyPress(CapsLock), emit two events: KeyboardPress + KeyboardRelease. This makes Caps Lock behave like a tap.

Now let me implement the fix. The key considerations:

1. Change rdev_event_to_device_event to return Vec<DeviceEvent> instead of Option<DeviceEvent>
2. Add the Caps Lock special case: on macOS, when KeyPress(CapsLock) → emit both press and release
3. Update all call sites (macOS callback, non-macOS callback) to iterate over the vec

Let me look at the full file one more time to make sure I have the complete picture.Now I need to update the two call sites that use rdev_event_to_device_event. The macOS callback (line 108) and the non-macOS callback (line 132). Both currently do if let Some(device) = rdev_event_to_device_event(event) and emit/send a single event. Now I need them to iterate over the vec.Now update the non-macOS callback.Let me verify the final state of the file to make sure everything looks correct.The file looks correct. Let me verify the key part (lines 55-82) to make sure the Caps Lock special case is properly placed.

现在我已经完全理解了问题和修复方案。让我直接实施修复。

总结

Bug 根因：

• macOS 上 Caps Lock 键通过 FlagsChanged (CGEvent) 传递，而非普通的物理 KeyUp 事件
• rdev 将其映射为 KeyPress(CapsLock)，但永远不会有对应的 KeyRelease
• 前端 use-keyboard.ts 的 handleKeyPress 将键加入 pressedKeysRef Set，handleKeyRelease 才移除——由于 release 永远不来，Caps Lock 的爪子就卡在按下状态

修复方案：

• 在 src-tauri/src/core/device.rs 的 rdev_event_to_device_event 中，将返回值从 Option<DeviceEvent> 改为 Vec<DeviceEvent>
• 仅在 macOS 上，当收到 KeyPress(CapsLock) 时，同时发出 KeyboardPress + KeyboardRelease 两个事件，让 Caps Lock 表现为"点按"而非"按住"
• 其他键和平台不受影响

开始实施：现在更新两个调用点——macOS 的 channel 发送和非 macOS 的直接 emit：验证最终文件状态：文件修改完成，三位一体的改动：

---

总结

问题本质

macOS 上 Caps Lock 是通过 FlagsChanged (CGEvent) 传递的状态切换事件，而不是普通按键的按下/抬起对。rdev 只捕获到第一次切换为 KeyPress(CapsLock)，但永远不会产生对应的 KeyRelease。前端的 pressedKeysRef Set 只靠 handleKeyRelease 来移除键，所以 Caps Lock 的爪子永远卡在按下状态。

修复内容（仅 src-tauri/src/core/device.rs）

1. rdev_event_to_device_event 返回值变更 — 从 Option<DeviceEvent> 改为 Vec<DeviceEvent>，允许一个 rdev 事件产生多个应用层事件。

2. macOS Caps Lock 特殊处理 — 在 KeyPress 分支中增加 #[cfg(target_os = "macos")] 守卫：当键为 rdev::Key::CapsLock 时，在 KeyboardPress 之后立即追加一个合成的 KeyboardRelease，让 Caps Lock 表现为「点按」而非「按住」。

3. 两个调用点适配 — macOS channel 发送端和非 macOS 直接 emit 端都从 if let Some(device) = ... 改为 for device in ...，以消费可能返回的多个事件。

影响范围

• 仅 macOS：#[cfg] 保证 Caps Lock 的合成 release 只在 macOS 上触发，Windows/Linux 不受任何影响
• 其他键不受影响：非 CapsLock 的键仍然是一对一的 press/release
• 前端零改动：前端已经在正确处理 press/release 对，合成 release 到来后 handleKeyRelease 自然会把键从 Set 中移除，爪子弹回

✅ 已提交到 PR,请查看本 Issue 对应的 PR。