lightweight variant (#1)

Reviewed-on: #1
Co-authored-by: Aleksandr Neychev <alexnejchev73@gmail.com>

CursorLang.Core/Services/ICapsLockHotkeyService.cs

@@ -0,0 +1,29 @@
+namespace CursorLang.Core.Services;
+
+/// <summary>
+/// Intercepts Caps Lock at the system level and splits the presses into short and
+/// long ones. What to do with them is up to the subscribers.
+/// </summary>
+public interface ICapsLockHotkeyService
+{
+    /// <summary>A short press: the key was released before the hold threshold.</summary>
+    event EventHandler? Tapped;
+
+    /// <summary>The hold threshold has passed, the key is still held.</summary>
+    event EventHandler? HoldStarted;
+
+    /// <summary>The hold is over: the key was released.</summary>
+    event EventHandler? HoldEnded;
+
+    /// <summary>Whether the hook is installed right now.</summary>
+    bool IsRunning { get; }
+
+    /// <summary>
+    /// Starts intercepting. Must be called from the user interface thread:
+    /// a system keyboard hook works only on a thread with a message loop.
+    /// </summary>
+    void Start();
+
+    /// <summary>Removes the hook, giving the key its usual behaviour back.</summary>
+    void Stop();
+}