feat(movement): wire server RunRate into player MotionInterpreter

Parse ForwardSpeed from UpdateMotion (0xF74C) InterpretedMotionState.
Feed server-echoed RunRate into the player's MotionInterpreter so
get_state_velocity produces the correct speed. Previously hardcoded
at 1.0 (4.0 m/s), now matches character's Run skill.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/AcDream.App/Input/PlayerMovementController.cs

@@ -115,6 +115,18 @@ public sealed class PlayerMovementController
         _motion = new MotionInterpreter(_body);
     }
 
+    /// <summary>
+    /// Apply a server-echoed run rate (ForwardSpeed from UpdateMotion) to the
+    /// player's MotionInterpreter. The server broadcasts the real RunRate
+    /// derived from the character's Run skill; wiring it here ensures
+    /// get_state_velocity produces the correct speed instead of the default 1.0.
+    /// </summary>
+    public void ApplyServerRunRate(float forwardSpeed)
+    {
+        _motion.InterpretedState.ForwardSpeed = forwardSpeed;
+        _motion.apply_current_movement(cancelMoveTo: false, allowJump: false);
+    }
+
     public void SetPosition(Vector3 pos, uint cellId)
     {
         _body.Position = pos;

src/AcDream.App/Rendering/GameWindow.cs

@@ -952,6 +952,18 @@ public sealed class GameWindow : IDisposable
         if (!newCycleIsGood)
             return;
 
+        // Wire server-echoed RunRate into the player's MotionInterpreter.
+        // The server broadcasts the character's real Run-skill-derived ForwardSpeed
+        // in UpdateMotion; without this the player would always move at 4.0 m/s
+        // (ForwardSpeed = 1.0 hardcoded in MotionInterpreter defaults).
+        if (_playerController is not null
+            && update.Guid == _playerServerGuid
+            && update.MotionState.ForwardSpeed.HasValue
+            && update.MotionState.ForwardSpeed.Value > 0f)
+        {
+            _playerController.ApplyServerRunRate(update.MotionState.ForwardSpeed.Value);
+        }
+
         // Sequencer path
         if (ae.Sequencer is not null)
         {

src/AcDream.Core.Net/Messages/CreateObject.cs

@@ -109,7 +109,7 @@ public static class CreateObject
     /// Nullified Statue of a Drudge, which is rendered in the wrong pose
     /// if you only consult the MotionTable's default style.
     /// </summary>
-    public readonly record struct ServerMotionState(ushort Stance, ushort? ForwardCommand);
+    public readonly record struct ServerMotionState(ushort Stance, ushort? ForwardCommand, float? ForwardSpeed = null);
 
     /// <summary>
     /// Server instruction to replace the surface texture at
@@ -479,6 +479,7 @@ public static class CreateObject
             p += 2;
 
             ushort? forwardCommand = null;
+            float? forwardSpeed = null;
 
             // 0 = Invalid is the only union variant we care about for static
             // entities. Walking/turning entities use the other variants but
@@ -513,13 +514,21 @@ public static class CreateObject
                     forwardCommand = BinaryPrimitives.ReadUInt16LittleEndian(mv.Slice(p));
                     p += 2;
                 }
-                // Remaining fields (SideStep, Turn, speeds, commands list,
-                // align) are deliberately not parsed — we already have what
-                // the resolver needs and the outer length tells the caller
-                // where MovementData ends.
+                // SidestepCommand (0x4) — skip
+                if ((flags & 0x4u) != 0) { if (mv.Length - p < 2) goto done; p += 2; }
+                // TurnCommand (0x8) — skip
+                if ((flags & 0x8u) != 0) { if (mv.Length - p < 2) goto done; p += 2; }
+                // ForwardSpeed (0x10)
+                if ((flags & 0x10u) != 0)
+                {
+                    if (mv.Length - p < 4) goto done;
+                    forwardSpeed = BinaryPrimitives.ReadSingleLittleEndian(mv.Slice(p));
+                    p += 4;
+                }
+                done:;
             }
 
-            return new ServerMotionState(currentStyle, forwardCommand);
+            return new ServerMotionState(currentStyle, forwardCommand, forwardSpeed);
         }
         catch
         {

src/AcDream.Core.Net/Messages/UpdateMotion.cs

@@ -102,6 +102,7 @@ public static class UpdateMotion
             pos += 2;
 
             ushort? forwardCommand = null;
+            float? forwardSpeed = null;
 
             if (movementType == 0)
             {
@@ -130,9 +131,21 @@ public static class UpdateMotion
                     forwardCommand = BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(pos));
                     pos += 2;
                 }
+                // SidestepCommand (0x4) — skip
+                if ((flags & 0x4u) != 0) { if (body.Length - pos < 2) goto done; pos += 2; }
+                // TurnCommand (0x8) — skip
+                if ((flags & 0x8u) != 0) { if (body.Length - pos < 2) goto done; pos += 2; }
+                // ForwardSpeed (0x10)
+                if ((flags & 0x10u) != 0)
+                {
+                    if (body.Length - pos < 4) goto done;
+                    forwardSpeed = BinaryPrimitives.ReadSingleLittleEndian(body.Slice(pos));
+                    pos += 4;
+                }
+                done:;
             }
 
-            return new Parsed(guid, new CreateObject.ServerMotionState(currentStyle, forwardCommand));
+            return new Parsed(guid, new CreateObject.ServerMotionState(currentStyle, forwardCommand, forwardSpeed));
         }
         catch
         {