Body step 2.4: landing, movable ground, playground fixes

- legs brake landings at 4.5 g; vertical support is a rate-limited servo
  (no launch when stepping onto a mantled ledge)
- ground control pushes back on movable ground (seesaw tips under the player)
- playground hinges use absolute paths (joint paths resolve from the joint)
- big props grabbable via surface query; Reset props keeps playground pieces
- spike: landing, seesaw, playground joints/grab, person-like wall climb

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

research/ragdoll-player-step2.md

@@ -155,3 +155,26 @@ Rules added:
 - Measure "blocked" where the body is blocked.
 - Hysteresis plus a free-space check before re-enabling any collider.
 - In the Box3D wrapper, physics materials must be set before AddChild.
+
+## Step 2.4 — playtest polish (2026-10-02)
+
+Owner, after 2.3: "Climbing actually feels very solid now. Mantling is almost effortless … There wasn't anything I
+wasn't able to climb." Fixed from the same session:
+
+- **Landing sink.** Support capped at 2× body weight leaves 1 g of braking, so a 1 m drop (4.4 m/s) took ~0.4 m to
+  stop and the body sank out from under the view. `LegStrength` is now 4.5× (real legs brake landings at 3–5 g).
+  The vertical support is now a rate-limited velocity servo, `MaxRiseSpeed` 1.2 m/s: full strength to brake, but the
+  legs raise the body no faster than that. Legs can push but not pull, so a hard push toward a higher stance (just
+  mantled onto a ledge) overshot into a 0.67 m jump. Spike: landing keeps the pelvis at standing height, eye within
+  12 cm.
+- **Body weight on movable ground.** The feet aren't physical, so standing on a seesaw/plank/crate never pushed it.
+  Ground control now applies the opposite of its support + carry force to a `RigidBody3D` under the ground ray, at the
+  hit point. Box3D ray results also carry a null `collider`, so it uses `collider_id`. Spike: a seesaw tips 17°.
+- **Playground hinges.** `Joint3D.NodeA/NodeB` resolve relative to the JOINT node. `GetPathTo` from the parent
+  pointed at nonexistent children, so the seesaw and swing board were never hinged. Absolute paths now.
+- **Big props weren't grabbable.** Prop grabbing measured distance to the prop ORIGIN, far from the hand on a 2–3 m
+  plank. `PropGrabber.BodyUnderPalm` queries the surface (a prop first, else static world).
+- **Reset props removed every "prop".** `PropShop.Respawn` now frees only its own children; the playground resets
+  in place.
+- The climbing spike now climbs like a person: hand moves are sequential (never release the second hand before the
+  first re-grips), and pulls are relative to the body/room.

scripts/PlayerRagdoll.cs

@@ -52,10 +52,11 @@ public partial class PlayerRagdoll : Node3D
     // Ground control (world-space support on the pelvis, only while grounded).
     public const float GroundFrequency = 4f;           // Hz
     public const float GroundDamping = 1f;
-    public const float LegStrength = 2f;               // max support, × body weight
+    public const float LegStrength = 4.5f;             // max support, × body weight (real legs brake a landing at 3–5 g; 2× sank ~0.4 m)
     public const float GroundFriction = 1f;            // horizontal force ≤ this × support
     public const float GroundProbeExtra = 0.3f;        // ground counts while within hip height + this
     public const float MaxStepHeight = 0.35f;
+    public const float MaxRiseSpeed = 1.2f;            // m/s the legs lift the body toward its stance
     public const float MaxSlopeDegrees = 35f;          // steeper ground gives no support (Nimso: "slopes beyond an angle can't be run up")          // higher ground under the hips isn't stood on unless the body got up there
     public const float BracedAirControl = 150f;        // N of horizontal hip carry while airborne but braced on the hands (mantling)
     public const float CrawlCarry = 300f;
@@ -166,6 +167,8 @@ public partial class PlayerRagdoll : Node3D
     private readonly Vector3[] _girdle = new Vector3[2];  // True Body shoulder offset, chest frame
     private float _footY;
     private float _supportGoalY;
+    private RigidBody3D _groundBody;
+    private Vector3 _groundPoint;
     private float _tuckFree, _dt;
     private PhysicsShapeQueryParameters3D _legsQuery;
 
@@ -752,10 +755,13 @@ public partial class PlayerRagdoll : Node3D
         Godot.Collections.Dictionary hit = GetWorld3D().DirectSpaceState.IntersectRay(query);
         bool wasGrounded = Grounded;
         Grounded = false;
+        _groundBody = null;
         if (hit.Count > 0)
         {
             Vector3 point = (Vector3)hit["position"];
             Vector3 normal = (Vector3)hit["normal"];
+            _groundBody = GodotObject.InstanceFromId((ulong)hit["collider_id"]) as RigidBody3D;  // Box3D: "collider" is null
+            _groundPoint = point;
             bool inReach = pos.Y - point.Y < hipAboveFloor + GroundProbeExtra;
             bool steep = normal.Y <= Mathf.Cos(Mathf.DegToRad(MaxSlopeDegrees));
             if (inReach && steep && wasGrounded && point.Y <= _footY + MaxStepHeight)
@@ -806,7 +812,12 @@ public partial class PlayerRagdoll : Node3D
             float w = Mathf.Tau * GroundFrequency;
             Vector3 accel = (goal - pos) * (w * w) + (targetVelocity - Pelvis.LinearVelocity) * (2f * GroundDamping * w);
             Vector3 force = accel * BodyMass;
-            float support = Mathf.Clamp(force.Y + weight, 0f, LegStrength * weight);
+            // Vertical as a rate-limited velocity servo: full leg strength brakes a landing, but
+            // the legs raise the body at most MaxRiseSpeed — they can push, not pull, so a hard push
+            // toward a higher stance (onto a ledge) would otherwise overshoot into a jump.
+            float riseVelocity = Mathf.Clamp((goal.Y - pos.Y) * w, -3f, MaxRiseSpeed) + targetVelocity.Y;
+            float verticalAccel = (riseVelocity - Pelvis.LinearVelocity.Y) * (2f * GroundDamping * w);
+            float support = Mathf.Clamp(verticalAccel * BodyMass + weight, 0f, LegStrength * weight);
             float carry = Mathf.Max(GroundFriction * support, _legsSolid ? 0f : CrawlCarry);
             // Hips held back by an obstacle: lean on it, don't bulldoze — full leg force tipped the
             // body over knee-high boxes and steep slopes (and the riding view tipped with it).
@@ -814,6 +825,10 @@ public partial class PlayerRagdoll : Node3D
                 carry = Mathf.Min(carry, BlockedPush);
             Vector3 horizontal = new Vector3(force.X, 0f, force.Z).LimitLength(carry);
             Pelvis.ApplyCentralForce(horizontal + Vector3.Up * support);
+            // Newton's third law: standing on something movable (seesaw, plank, crate) pushes it
+            // down — the feet aren't physical, so the reaction is applied where the ground ray hit.
+            if (_groundBody != null && IsInstanceValid(_groundBody))
+                _groundBody.ApplyForce(-(horizontal + Vector3.Up * support), _groundPoint - _groundBody.GlobalPosition);
         }
         else if (Braced)
         {

scripts/Playground.cs

@@ -186,8 +186,8 @@ public partial class Playground : Node3D
         HingeJoint3D pivot = new()
         {
             Transform = new Transform3D(new Basis(Vector3.Right, Vector3.Up, Vector3.Back), new Vector3(-8.5f, 0.48f, -1.5f)),
-            NodeA = GetPathTo(GetNode("SeesawPivot")),
-            NodeB = GetPathTo(seesaw),
+            NodeA = GetNode<Node>("SeesawPivot").GetPath(),   // absolute: joint paths resolve relative to the joint
+            NodeB = seesaw.GetPath(),
         };
         AddChild(pivot);
         Sign("Seesaw", new Vector3(-8.5f, 1.3f, -1.5f));
@@ -200,8 +200,8 @@ public partial class Playground : Node3D
         HingeJoint3D swing = new()
         {
             Transform = new Transform3D(new Basis(Vector3.Back, Vector3.Up, Vector3.Left), new Vector3(-6f, 2.35f, 1.5f)),
-            NodeA = GetPathTo(beam),
-            NodeB = GetPathTo(board),
+            NodeA = beam.GetPath(),
+            NodeB = board.GetPath(),
         };
         AddChild(swing);
         Sign("Hanging board", new Vector3(-6f, 2.9f, 1.5f));

scripts/PropGrabber.cs

@@ -214,7 +214,30 @@ public partial class PropGrabber : Node
         nearest = NearestProp(handBody.GlobalPosition, CenterGrabRadius);
         if (nearest != null)
             return nearest;
-        return WorldUnderPalm(palm, handBody.GetWorld3D()) ?? WorldUnderPalm(handBody.GlobalPosition, handBody.GetWorld3D());
+        // Big props (planks, seesaw, boards): their origin is far from the hand — use the surface.
+        World3D world = handBody.GetWorld3D();
+        return BodyUnderPalm(palm, world) ?? BodyUnderPalm(handBody.GlobalPosition, world);
+    }
+
+    // The body whose surface is near the point: a "prop" first, else static world (climbing).
+    public static PhysicsBody3D BodyUnderPalm(Vector3 point, World3D world)
+    {
+        PhysicsShapeQueryParameters3D query = new()
+        {
+            Shape = new SphereShape3D { Radius = WorldGrabRadius },
+            Transform = new Transform3D(Basis.Identity, point),
+            CollisionMask = 1,
+        };
+        StaticBody3D found = null;
+        foreach (Godot.Collections.Dictionary hit in world.DirectSpaceState.IntersectShape(query, 8))
+        {
+            GodotObject o = GodotObject.InstanceFromId((ulong)hit["collider_id"]);
+            if (o is RigidBody3D prop && prop.IsInGroup("prop"))
+                return prop;
+            if (o is StaticBody3D body && !body.IsInGroup(NoGrabGroup))
+                found ??= body;
+        }
+        return found;
     }
 
     // Climbing: any static body near the palm (except the "no_grab" group) can be held.

scripts/PropShop.cs

@@ -34,8 +34,11 @@ public partial class PropShop : Node3D
 
     public void Respawn()
     {
-        foreach (Node node in GetTree().GetNodesInGroup("prop"))
-            node.QueueFree();
+        // Only the table's own props (the playground's dynamic pieces are props too — they reset
+        // in place via Playground.Reset).
+        foreach (Node node in GetChildren())
+            if (node is RigidBody3D && node.IsInGroup("prop"))
+                node.QueueFree();
         foreach (PropSpec spec in Specs)
             SpawnProp(spec);
         GD.Print("PropShop: table reset");

scripts/RagdollSpike.cs

@@ -103,8 +103,10 @@ public partial class RagdollSpike : Node3D
         _phases.Add(("holds a deep crouch (eyes 0.7 m) without sliding or spinning", Rest, t => TickCrouchHold(0.7f), 5f, FinishCrouchHold));
         _phases.Add(("holds poses (stand, crouch, deep crouch, lean, reach, kneel) without view/body drift", Rest, TickPoseHold, 18f, FinishPoseHold));
         _phases.Add(("hanging from a bar keeps the view on the body", () => SetupBarHang(), TickHang, 4f, FinishHang));
-        _phases.Add(("climbs a wall hand over hand (grab, pull, regrab higher)", SetupClimbWall, TickClimbWall, 6.5f, FinishClimbWall));
-        _phases.Add(("walks off a 1 m ledge and lands", SetupLedgeTop, _ => _stickVelocity = _t > 0.5f && _t < 2f ? new Vector3(0f, 0f, -1.2f) : Vector3.Zero, 4f, FinishDrop));
+        _phases.Add(("climbs a wall hand over hand (grab, pull, regrab higher)", SetupClimbWall, TickClimbWall, 8f, FinishClimbWall));
+        _phases.Add(("walks off a 1 m ledge and lands without sinking away from the view", SetupLedgeTop, TickDrop, 4f, FinishDrop));
+        _phases.Add(("standing on a seesaw tips it (body weight reaches movable ground)", SetupSeesaw, _ => { }, 3f, FinishSeesaw));
+        _phases.Add(("playground: swing board hangs, seesaw on its pivot, big plank grabbable", SetupPlayground, _ => { }, 2f, FinishPlayground));
         _phases.Add(("walks up an 18° ramp", () => SetupRamp(18f), _ => _stickVelocity = new Vector3(0f, 0f, -1.2f), 4f, () => FinishRamp(true)));
         _phases.Add(("can't walk up a 40° ramp", () => SetupRamp(40f), _ => _stickVelocity = new Vector3(0f, 0f, -1.2f), 4f, () => FinishRamp(false)));
         Next();
@@ -666,8 +668,27 @@ public partial class RagdollSpike : Node3D
         _stage.AddChild(MakeStatic(new Vector3(3f, 1f, 3f), new Vector3(0f, 0.5f, 1f), 29));
     }
 
+    private float _dropEyeErr, _dropMinPelvis = float.MaxValue;
+
+    private void TickDrop(float dt)
+    {
+        _stickVelocity = _t > 0.5f && _t < 2f ? new Vector3(0f, 0f, -1.2f) : Vector3.Zero;
+        if (_ragdoll.Built && !_needBuild && _t > 0.5f)
+        {
+            _dropEyeErr = Mathf.Max(_dropEyeErr, _ragdoll.Eye.DistanceTo(Camera.Origin));
+            if (_ragdoll.Grounded && _ragdoll.GroundY < 0.5f)
+                _dropMinPelvis = Mathf.Min(_dropMinPelvis, _ragdoll.Pelvis.GlobalPosition.Y);
+        }
+    }
+
     private bool FinishDrop()
     {
+        GD.Print($"RAGDOLL:   landing: eye vs camera max {_dropEyeErr:F3} m (limit 0.15), lowest pelvis after touchdown {_dropMinPelvis:F3} m (standing 0.99, limit > 0.7)");
+        bool landed = _dropEyeErr < 0.15f && _dropMinPelvis > 0.7f;
+        _dropEyeErr = 0f;
+        _dropMinPelvis = float.MaxValue;
+        if (!landed)
+            return false;
         GD.Print($"RAGDOLL:   drop: feet y {_ragdoll.GroundY:F3}, origin y {_origin.Origin.Y:F3}, pelvis {_ragdoll.Pelvis.GlobalPosition}, eye error {_ragdoll.Eye.DistanceTo(Camera.Origin):F3}, snaps {NewSnaps}");
         return _finite && NewSnaps == 0 && Mathf.Abs(_ragdoll.GroundY) < 0.05f && Mathf.Abs(_origin.Origin.Y) < 0.1f
             && _ragdoll.Eye.DistanceTo(Camera.Origin) < 0.1f && _ragdoll.Pelvis.GlobalPosition.Z > -3f;
@@ -776,7 +797,7 @@ public partial class RagdollSpike : Node3D
     private void TickHumanMantle(bool both)
     {
         float t = _t;
-        _stickVelocity = t < 1f || t > 4.5f ? new Vector3(0f, 0f, -0.8f) : Vector3.Zero;
+        _stickVelocity = t < 1f || (t > 4.5f && t < 5.5f) ? new Vector3(0f, 0f, -0.8f) : Vector3.Zero;   // stop before the ledge's far end
         float crouch = Mathf.SmoothStep(0f, 1f, Mathf.Clamp((t - 1f) / 0.8f, 0f, 1f));
         float rise = Mathf.SmoothStep(0f, 1f, Mathf.Clamp((t - 2.2f) / 1.6f, 0f, 1f));
         float eye = EyeHeight - 0.25f * crouch + 0.35f * rise;
@@ -833,58 +854,139 @@ public partial class RagdollSpike : Node3D
 
     // Hold targets live in the world (the holds); while gripping, the player pulls the controllers
     // down in the room. Free hands reach for the next hold 45 cm higher.
+    private readonly Vector3[] _gripLocal = new Vector3[2];
+    private readonly float[] _pullAtGrip = new float[2];
+    private int _climbStep;          // 0 reach+grip both, 1 pull, 2 right moves up, 3 left moves up, 4 pull, 5 done
+    private float _climbStepT, _pulled;
+
+    // Like a climber: grip two holds, pull (hands go down ~45 cm relative to the BODY/room — the
+    // play space rides up with the body), move one hand to a higher hold and only then the other,
+    // pull again.
     private void TickClimbWall(float dt)
     {
         float t = _t;
         _measureFrom = float.MaxValue;
         if (!_ragdoll.Built || _needBuild)
             return;
-        float pull1 = Mathf.Clamp((t - 1.0f) / 1.2f, 0f, 1f), pull2 = Mathf.Clamp((t - 4.0f) / 1.2f, 0f, 1f);
-        if (t > 0.95f && t < 1.0f)
+        if (t < dt * 1.5f)
         {
-            Grip(0, true);
-            Grip(1, true);
-            _climbStartPelvis = _ragdoll.Pelvis.GlobalPosition.Y;
+            _climbStep = 0;
+            _climbStepT = 0f;
+            _pulled = 0f;
         }
+        _climbStepT += dt;
+        bool pulling = _climbStep == 1 || _climbStep == 4;
+        if (pulling)
+            _pulled = Mathf.MoveToward(_pulled, _climbStep == 1 ? 0.45f : 0.9f, 0.4f * dt);
+        Basis aim = Aim(Vector3.Up + Vector3.Forward * 0.15f);
         for (int side = 0; side < 2; side++)
         {
-            float releaseAt = side == 1 ? 2.3f : 3.1f, regripAt = releaseAt + 0.6f;
-            if (t > releaseAt && t < regripAt && _climbWeld[side] != null)
-            {
-                Grip(side, false);
-                // Next hold: 30 cm above the hand that is still holding (as a climber reaches).
-                _gripWorld[side] = _ragdoll.Hand(1 - side).GlobalPosition + Vector3.Up * 0.3f + Vector3.Right * (side == 0 ? -0.4f : 0.4f);
-                _gripWorld[side].Z = ClimbFace + 0.05f;
-            }
-            if (t >= regripAt && _climbWeld[side] == null && _ragdoll.Hand(side).GlobalPosition.DistanceTo(_gripWorld[side]) < 0.08f)
-                Grip(side, true);
-            // Gripping: the controller is pulled down in the room by the pull amount; reaching: it
-            // goes to the next hold.
-            Vector3 target = _climbWeld[side] != null || t < 1.0f
-                ? _gripWorld[side] - _origin.Origin - Vector3.Up * (0.5f * (pull1 + pull2))
-                : _gripWorld[side] - _origin.Origin;
-            // Reach like a person: ease from where the hand is to the hold over ~0.5 s.
-            Vector3 current = side == 0 ? _leftLocal.Origin : _rightLocal.Origin;
-            if (_climbWeld[side] == null)
-                target = current.MoveToward(target, 1.2f * dt);
-            Basis aim = Aim(Vector3.Up + Vector3.Forward * 0.15f);
-            if (side == 0)
-                _leftLocal = new Transform3D(aim, target);
+            Vector3 local;
+            if (_climbWeld[side] != null)
+                local = _gripLocal[side] - Vector3.Up * (_pulled - _pullAtGrip[side]);
             else
-                _rightLocal = new Transform3D(aim, target);
+            {
+                Vector3 current = side == 0 ? _leftLocal.Origin : _rightLocal.Origin;
+                local = current.MoveToward(_gripWorld[side] - _origin.Origin, 1.2f * dt);
+                if (_ragdoll.Hand(side).GlobalPosition.DistanceTo(_gripWorld[side]) < 0.08f && (_climbStep == 0 || _climbStep == 2 + (1 - side)))
+                {
+                    Grip(side, true);
+                    _gripLocal[side] = local;
+                    _pullAtGrip[side] = _pulled;
+                }
+            }
+            if (side == 0)
+                _leftLocal = new Transform3D(aim, local);
+            else
+                _rightLocal = new Transform3D(aim, local);
+        }
+        switch (_climbStep)
+        {
+            case 0 when _climbWeld[0] != null && _climbWeld[1] != null:
+                _climbStartPelvis = _ragdoll.Pelvis.GlobalPosition.Y;
+                Next(1);
+                break;
+            case 1 when _pulled >= 0.45f:
+                MoveUp(1);
+                Next(2);
+                break;
+            case 2 when _climbWeld[1] != null && _climbStepT > 0.2f:
+                MoveUp(0);
+                Next(3);
+                break;
+            case 3 when _climbWeld[0] != null && _climbStepT > 0.2f:
+                Next(4);
+                break;
+            case 4 when _pulled >= 0.9f:
+                Next(5);
+                break;
         }
         if (t > 1f)
             _climbEyeErr = Mathf.Max(_climbEyeErr, _ragdoll.Eye.DistanceTo(Camera.Origin));
+
+        void Next(int step)
+        {
+            _climbStep = step;
+            _climbStepT = 0f;
+        }
+
+        void MoveUp(int side)
+        {
+            Grip(side, false);
+            // Next hold: 30 cm above the hand that keeps holding.
+            _gripWorld[side] = _ragdoll.Hand(1 - side).GlobalPosition + Vector3.Up * 0.3f + Vector3.Right * (side == 0 ? -0.4f : 0.4f);
+            _gripWorld[side].Z = ClimbFace + 0.05f;
+        }
     }
 
     private bool FinishClimbWall()
     {
         float rise = _ragdoll.Pelvis.GlobalPosition.Y - _climbStartPelvis;
-        GD.Print($"RAGDOLL:   wall climb: pelvis rose {rise:F3} m (> 0.6), holding {_climbWeld[0] != null}/{_climbWeld[1] != null}, eye vs camera max {_climbEyeErr:F3} (< {PlayerRagdoll.MaxViewLead + 0.03f:F2}), snaps {NewSnaps}");
+        GD.Print($"RAGDOLL:   wall climb: reached step {_climbStep}/5, pelvis rose {rise:F3} m (> 0.35), holding {_climbWeld[0] != null}/{_climbWeld[1] != null}, eye vs camera max {_climbEyeErr:F3} (< {PlayerRagdoll.MaxViewLead + 0.03f:F2}), snaps {NewSnaps}");
         Grip(0, false);
         Grip(1, false);
         // MaxViewLead 0.08 is enforced before each step; this is measured after it (+ one tick of motion).
-        return _finite && NewSnaps == 0 && rise > 0.6f && _climbEyeErr < PlayerRagdoll.MaxViewLead + 0.03f;
+        // Two 45 cm pulls minus the sag while hanging one-handed during the two hand moves.
+        return _finite && NewSnaps == 0 && _climbStep == 5 && rise > 0.35f && _climbEyeErr < PlayerRagdoll.MaxViewLead + 0.03f;
+    }
+
+    private RigidBody3D _seesaw;
+
+    // A 3 m plank along Z hinged 0.45 m up at z = −1; the player stands on its near half.
+    private void SetupSeesaw()
+    {
+        Rest();
+        StaticBody3D pivot = MakeStatic(new Vector3(0.6f, 0.45f, 0.3f), new Vector3(0f, 0.225f, -1f), 29);
+        _stage.AddChild(pivot);
+        _seesaw = MakeBox(new Vector3(0.6f, 0.06f, 3f), 12f, new Vector3(0f, 0.48f, -1f));
+        HingeJoint3D hinge = new() { Transform = new Transform3D(new Basis(Vector3.Back, Vector3.Up, Vector3.Left), new Vector3(0f, 0.48f, -1f)), NodeA = pivot.GetPath(), NodeB = _seesaw.GetPath() };
+        _stage.AddChild(hinge);
+        _origin = new Transform3D(Basis.Identity, new Vector3(0f, 0.51f, -0.2f));   // standing on the plank, 0.8 m from the pivot
+    }
+
+    private bool FinishSeesaw()
+    {
+        float tilt = Mathf.RadToDeg(_seesaw.GlobalTransform.Basis.Z.AngleTo(Vector3.Back));
+        GD.Print($"RAGDOLL:   seesaw tilted {tilt:F1}° under the player (> 8), player feet y {_ragdoll.GroundY:F2}, snaps {NewSnaps}");
+        return _finite && NewSnaps == 0 && tilt > 8f;
+    }
+
+    private Playground _playground;
+
+    private void SetupPlayground()
+    {
+        Rest();
+        _playground = new Playground { Position = new Vector3(0f, 0f, 40f) };   // far from the player
+        _stage.AddChild(_playground);
+    }
+
+    private bool FinishPlayground()
+    {
+        RigidBody3D board = _playground.GetNode<RigidBody3D>("SwingBoard"), seesaw = _playground.GetNode<RigidBody3D>("Seesaw"), plank = _playground.GetNode<RigidBody3D>("Plank0");
+        Vector3 plankEnd = plank.GlobalTransform * new Vector3(0.9f, 0.05f, 0f);
+        PhysicsBody3D grabbed = PropGrabber.BodyUnderPalm(plankEnd, plank.GetWorld3D());
+        GD.Print($"RAGDOLL:   playground: swing board y {board.GlobalPosition.Y:F2} (hangs ~1.75), seesaw y {seesaw.GlobalPosition.Y:F2} (on pivot ~0.48), plank end grab finds {(grabbed == null ? "nothing" : grabbed.Name)}");
+        return board.GlobalPosition.Y > 1.5f && seesaw.GlobalPosition.Y > 0.35f && grabbed is RigidBody3D && grabbed.Name.ToString().StartsWith("Plank");  // planks are stacked
     }
 
     // A slope rising away (−Z) from ObstacleFront up to 1 m, then a platform.