Bring the drop position into .NET and add the DOM hit test

app/MindWork AI Studio/Tools/JsRuntimeExtensions.cs

@@ -71,6 +71,40 @@ public static class JsRuntimeExtensions
         return await jsRuntime.TryInvokeVoidAsync(identifier, args);
     }
 
+    /// <summary>
+    /// Calls a JavaScript function which returns a value, unless the circuit is known to be disconnected.
+    /// </summary>
+    /// <remarks>
+    /// The two parts of the result answer two different questions, and callers must keep them apart.
+    /// Whether the browser ran the function at all comes first: a call which never arrived says nothing
+    /// about the page, so nobody may act on an answer they did not get. What the function returned is the
+    /// second question, and there a null is a legitimate answer -- it means the browser looked and found
+    /// nothing.
+    /// </remarks>
+    /// <param name="jsRuntime">The JS runtime to call.</param>
+    /// <param name="circuitState">The circuit of the caller.</param>
+    /// <param name="identifier">The name of the JavaScript function.</param>
+    /// <param name="args">The arguments for the JavaScript function.</param>
+    /// <returns>Whether the browser ran the function, and what it returned.</returns>
+    public static async ValueTask<(bool WasInvoked, TValue? Value)> TryInvokeAsync<TValue>(this IJSRuntime jsRuntime, CircuitStateService circuitState, string identifier, params object?[]? args)
+    {
+        if (!circuitState.IsConnected)
+        {
+            LOGGER.LogDebug("The JS call '{Identifier}' was skipped because the browser connection of the circuit '{CircuitId}' is down.", identifier, circuitState.CircuitId);
+            return (false, default);
+        }
+
+        try
+        {
+            return (true, await jsRuntime.InvokeAsync<TValue>(identifier, args));
+        }
+        catch (Exception exception)
+        {
+            LogInvocationFailure(exception, identifier);
+            return (false, default);
+        }
+    }
+
     /// <summary>
     /// Calls a function of a JavaScript module which returns nothing, and tolerates a circuit which is
     /// already gone. See the remarks on the JS runtime variant of this method.

app/MindWork AI Studio/Tools/Rust/DropPosition.cs

@@ -0,0 +1,13 @@
+namespace AIStudio.Tools.Rust;
+
+/// <summary>
+/// The cursor position of a drag and drop event.
+/// </summary>
+/// <remarks>
+/// The coordinates are viewport-relative CSS pixels, on every platform. The Rust runtime has already
+/// dealt with the platform differences -- device pixels on Windows, logical points on macOS and Linux --
+/// so these numbers can be handed to the browser for a hit test without any further conversion.
+/// </remarks>
+/// <param name="X">The distance from the left edge of the viewport, in CSS pixels.</param>
+/// <param name="Y">The distance from the top edge of the viewport, in CSS pixels.</param>
+public readonly record struct DropPosition(double X, double Y);

app/MindWork AI Studio/Tools/Rust/TauriEvent.cs

@@ -5,7 +5,8 @@ namespace AIStudio.Tools.Rust;
 /// </summary>
 /// <param name="EventType">The type of the Tauri event.</param>
 /// <param name="Payload">The payload of the Tauri event.</param>
-public readonly record struct TauriEvent(TauriEventType EventType, List<string> Payload)
+/// <param name="Position">Where the cursor was, for the drag and drop events which know it.</param>
+public readonly record struct TauriEvent(TauriEventType EventType, List<string> Payload, DropPosition? Position = null)
 {
     /// <summary>
     /// Attempts to parse the first payload element as a shortcut.
@@ -29,6 +30,28 @@ public readonly record struct TauriEvent(TauriEventType EventType, List<string>
         return TryParseSnakeCase(this.Payload[0], out shortcut);
     }
 
+    /// <summary>
+    /// Reads the cursor position of a drag and drop event.
+    /// </summary>
+    /// <remarks>
+    /// The coordinates are viewport-relative CSS pixels, ready for a hit test in the browser. Only the
+    /// drag and drop events carry them, which is why the caller has to ask instead of assuming.
+    /// </remarks>
+    /// <param name="x">The distance from the left edge of the viewport, in CSS pixels.</param>
+    /// <param name="y">The distance from the top edge of the viewport, in CSS pixels.</param>
+    /// <returns>True if the event carried a position, false otherwise.</returns>
+    public bool TryGetDropPosition(out double x, out double y)
+    {
+        x = 0.0;
+        y = 0.0;
+        if (this.Position is not { } position)
+            return false;
+
+        x = position.X;
+        y = position.Y;
+        return true;
+    }
+
     /// <summary>
     /// Reads a portal shortcut change and its effective display name.
     /// </summary>

app/MindWork AI Studio/Tools/Rust/TauriEventType.cs

@@ -13,6 +13,7 @@ public enum TauriEventType
     WINDOW_NOT_FOCUSED,
 
     FILE_DROP_HOVERED,
+    FILE_DROP_OVER,
     FILE_DROP_DROPPED,
     FILE_DROP_CANCELED,
 

app/MindWork AI Studio/Tools/Services/RustService.Events.cs

@@ -46,7 +46,14 @@ public partial class RustService
                                 and not TauriEventType.UNKNOWN
                                 and not TauriEventType.PING)
                         {
-                            this.logger!.LogDebug("Received Tauri event {EventType} with {NumPayloadItems} payload items.", tauriEvent.EventType, tauriEvent.Payload.Count);
+                            //
+                            // Log every event but the drag-over ones: those arrive about ten times per
+                            // second for as long as a drag lasts, and one line each would bury everything
+                            // else in the log.
+                            //
+                            if(tauriEvent.EventType is not TauriEventType.FILE_DROP_OVER)
+                                this.logger!.LogDebug("Received Tauri event {EventType} with {NumPayloadItems} payload items.", tauriEvent.EventType, tauriEvent.Payload.Count);
+
                             await MessageBus.INSTANCE.SendMessage(null, Event.TAURI_EVENT_RECEIVED, tauriEvent);
                         }
                     }