Body step 2.1: climbing, mantling, crawling, legs, playground, 144 Hz

- Step rule + lower-body collider: no walking onto tables, steps <= 0.35 m
- Structural hand strength: two-hand mantle/pull-up works, one hand can't
- Arms aim from the physical shoulder horizontally, keep True Body pose vertically
- Crawl pose, crawl carry, 35 deg slope limit, ground feed-forward ignores
  play-space corrections (fixes a runaway feedback loop)
- Grab static world (climbing), procedural visual legs
- Playground sandbox; menu strength slider, spectator (old drag) and turn toggles
- Physics 144 Hz with interpolation; legacy chase-body spikes pin 90 Hz
- RagdollSpike: 27 phases incl. mantle, pull-up, crawl, ledge drop, ramps

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

scripts/AnchorMoveMode.cs

@@ -1,7 +1,12 @@
 using Godot;
 
+// The old grab-the-air movement. Since the ragdoll player (body step 2) it is only the SPECTATOR
+// mode (menu → Player → Spectator), where there is no body; off by default. Known issues kept as-is
+// (owner, 2026-10-02): two-hand turning isn't 2-anchor based, simultaneous two-hand moves act weird.
 public partial class AnchorMoveMode : Node
 {
+    public static bool Enabled;
+
     private const float GripThreshold = 0.6f;
 
     private XROrigin3D _origin;
@@ -25,6 +30,13 @@ public partial class AnchorMoveMode : Node
 
     public override void _Process(double delta)
     {
+        if (!Enabled)
+        {
+            _wasTwoHand = false;
+            _leftPrev = _left.Position;
+            _rightPrev = _right.Position;
+            return;
+        }
         bool leftGrip = _left.GetFloat("grip") > GripThreshold && !PropGrabber.IsGrabbing(_left);
         bool rightGrip = _right.GetFloat("grip") > GripThreshold && !PropGrabber.IsGrabbing(_right);
 

scripts/ArmSpike.cs

@@ -73,6 +73,9 @@ public partial class ArmSpike : Node3D
 
     public override void _Ready()
     {
+        // Legacy chase bodies (PhysicsHands/Torso/Arms) were tuned at 90 Hz; the project runs 144 Hz
+        // since body step 2, so this regression pins their design rate.
+        Engine.PhysicsTicksPerSecond = 90;
         StaticBody3D floor = new() { CollisionMask = 0b11101 };
         floor.AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = new Vector3(20f, 0.1f, 20f) }, Position = new Vector3(0f, -0.05f, 0f) });
         AddChild(floor);

scripts/BodySpike.cs

@@ -53,6 +53,9 @@ public partial class BodySpike : Node3D
 
     public override void _Ready()
     {
+        // Legacy chase bodies (PhysicsHands/Torso/Arms) were tuned at 90 Hz; the project runs 144 Hz
+        // since body step 2, so this regression pins their design rate.
+        Engine.PhysicsTicksPerSecond = 90;
         BuildWorld();
         _head = new Node3D { Position = new Vector3(0f, 1.6f, 0f) };
         AddChild(_head);

scripts/CollapseSpike.cs

@@ -58,6 +58,9 @@ public partial class CollapseSpike : Node3D
 
     public override void _Ready()
     {
+        // Legacy chase bodies (PhysicsHands/Torso/Arms) were tuned at 90 Hz; the project runs 144 Hz
+        // since body step 2, so this regression pins their design rate.
+        Engine.PhysicsTicksPerSecond = 90;
         // A real profile is measured standing once (T-pose) and does not shrink when seated:
         // every scenario, seated or not, uses the same standing 1.65 m-eye profile.
         BodyProfile.Current = BodyProfile.Estimate(1.65f);

scripts/GrabSpike.cs

@@ -89,6 +89,9 @@ public partial class GrabSpike : Node3D
 
     public override void _Ready()
     {
+        // Legacy chase bodies (PhysicsHands/Torso/Arms) were tuned at 90 Hz; the project runs 144 Hz
+        // since body step 2, so this regression pins their design rate.
+        Engine.PhysicsTicksPerSecond = 90;
         StaticBody3D floor = new() { Position = new Vector3(0, -0.5f, 0) };
         floor.AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = new Vector3(20, 1, 20) } });
         AddChild(floor);

scripts/Main.cs

@@ -14,6 +14,8 @@ public partial class Main : Node3D
     [Export]
     public int MaximumRefreshRate { get; set; } = 90;
 
+    public const int PhysicsRate = 144;
+
     private OpenXRInterface _xrInterface;
     private bool _xrIsFocused;
 
@@ -70,7 +72,10 @@ public partial class Main : Node3D
             currentRefreshRate = newRate;
         }
 
-        Engine.PhysicsTicksPerSecond = (int)currentRefreshRate;
+        // Physics runs at a fixed PhysicsRate (the ragdoll's joints like small steps), decoupled from
+        // the display; physics interpolation smooths rendering (XR origin subtree excluded — the
+        // runtime and locomotion place it every frame).
+        Engine.PhysicsTicksPerSecond = PhysicsRate;
     }
 
     private void OnSessionVisible()

scripts/MainMenu.cs

@@ -18,6 +18,9 @@ public partial class MainMenu : PanelContainer
     public event Action PingRequested;
     public event Action CloseRequested;
     public event Action Clicked;
+    public event Action<bool> SpectatorToggled;
+    public event Action<bool> SmoothTurnToggled;
+    public event Action<float> StrengthChanged;
 
     public TabContainer Tabs { get; private set; }
     public Button ReturnToSpawnButton { get; private set; }
@@ -27,6 +30,9 @@ public partial class MainMenu : PanelContainer
     public Button CloseButton { get; private set; }
     public Button HeaderCloseButton { get; private set; }
     public HSlider ClickVolumeSlider { get; private set; }
+    public HSlider StrengthSlider { get; private set; }
+    public Button SpectatorButton { get; private set; }
+    public Button TurnModeButton { get; private set; }
     public ScrollContainer LogScroll { get; private set; }
 
     private Label _fpsLabel;
@@ -116,6 +122,39 @@ public partial class MainMenu : PanelContainer
         _calibrationStatus.AddThemeColorOverride("font_color", new Color(0.6f, 0.6f, 0.65f));
         calibRow.AddChild(_calibrationStatus);
         player.AddChild(calibRow);
+
+        // Nimso's single strength value: every muscle and the hand guides scale with it.
+        HBoxContainer strengthRow = new();
+        strengthRow.AddThemeConstantOverride("separation", 20);
+        Label strengthLabel = new() { Text = "Strength 1.00×", VerticalAlignment = VerticalAlignment.Center, CustomMinimumSize = new Vector2(220, 0) };
+        strengthRow.AddChild(strengthLabel);
+        StrengthSlider = new HSlider
+        {
+            MinValue = 0.25,
+            MaxValue = 3,
+            Step = 0.05,
+            Value = 1,
+            SizeFlagsHorizontal = SizeFlags.ExpandFill,
+            SizeFlagsVertical = SizeFlags.ShrinkCenter,
+            CustomMinimumSize = new Vector2(0, 48),
+            FocusMode = FocusModeEnum.None,
+        };
+        StrengthSlider.ValueChanged += v =>
+        {
+            strengthLabel.Text = $"Strength {v:0.00}×";
+            StrengthChanged?.Invoke((float)v);
+        };
+        strengthRow.AddChild(StrengthSlider);
+        player.AddChild(strengthRow);
+
+        HBoxContainer modeRow = new();
+        modeRow.AddThemeConstantOverride("separation", 16);
+        TurnModeButton = MakeToggle("Turning: snap", "Turning: smooth", on => SmoothTurnToggled?.Invoke(on));
+        modeRow.AddChild(TurnModeButton);
+        // Spectator: no body; fly around by grabbing the air (the old drag movement).
+        SpectatorButton = MakeToggle("Spectator: off", "Spectator: on (grab-fly)", on => SpectatorToggled?.Invoke(on));
+        modeRow.AddChild(SpectatorButton);
+        player.AddChild(modeRow);
         Tabs.AddChild(player);
 
         // World
@@ -180,6 +219,25 @@ public partial class MainMenu : PanelContainer
         return page;
     }
 
+    private Button MakeToggle(string offText, string onText, Action<bool> changed)
+    {
+        Button button = new()
+        {
+            Text = offText,
+            ToggleMode = true,
+            CustomMinimumSize = new Vector2(0, ButtonHeight),
+            SizeFlagsHorizontal = SizeFlags.ExpandFill,
+            FocusMode = FocusModeEnum.None,
+        };
+        button.Toggled += on =>
+        {
+            button.Text = on ? onText : offText;
+            Clicked?.Invoke();
+            Callable.From(() => changed(on)).CallDeferred();
+        };
+        return button;
+    }
+
     private Button MakeButton(string text, Action action)
     {
         Button button = new()

scripts/MenuSpike.cs

@@ -302,6 +302,20 @@ public partial class MenuSpike : Node3D
         await TouchPress(1, Center(_menu.RecalibrateButton));
         Check("touch: Recalibrate called once", stub.Calls == 1, $"(calls={stub.Calls})");
 
+        // 7b) Player-page toggles: spectator and smooth turn fire with the new state.
+        bool? spectator = null, smooth = null;
+        _menu.SpectatorToggled += on => spectator = on;
+        _menu.SmoothTurnToggled += on => smooth = on;
+        await TouchPress(1, TabCenter(0));
+        await TouchPress(1, Center(_menu.SpectatorButton));
+        await TouchPress(1, Center(_menu.TurnModeButton));
+        await Frame(3);
+        Check("touch: spectator toggled on", spectator == true, $"({spectator})");
+        Check("touch: smooth turn toggled on", smooth == true, $"({smooth})");
+        await TouchPress(1, Center(_menu.SpectatorButton));
+        await Frame(3);
+        Check("touch: spectator toggled back off", spectator == false, $"({spectator})");
+
         // 8) Header Close via touch.
         await TouchPress(1, Center(_menu.HeaderCloseButton));
         Check("touch: Close fired once", _close == 1, $"(count={_close})");

scripts/PlayerRagdoll.cs

@@ -33,6 +33,14 @@ public partial class PlayerRagdoll : Node3D
     // Hand guide (chest→hand drive): pulls the hand onto the controller; capped so the arm,
     // not the guide, carries real loads.
     public const float HandGuideKp = 40f, HandGuideForce = 40f, HandGuideMaxSpeed = 10f;
+    // STRUCTURAL strength: force along the arm (straight arm pressing on a ledge, hanging from a
+    // bar, carrying a bucket at your side) goes through bone and is strong; force across the arm
+    // needs muscle torque and stays at HandGuideForce. Cap = lerp(base, structural, alignment).
+    // Two arms ≈ 1.2 × body weight → two hands mantle/pull up, one can't (Nimso).
+    public const float HandStructuralForce = 400f;
+    public const float StructuralDeadband = 0.03f;
+    // Nimso's one global strength value: scales every muscle and the hand guides (menu slider).
+    public static float Strength = 1f;
     public const float HandGuideAngularKp = 40f, HandGuideTorque = 25f;
     // Ground control (world-space support on the pelvis, only while grounded).
     public const float GroundFrequency = 4f;           // Hz
@@ -40,6 +48,18 @@ public partial class PlayerRagdoll : Node3D
     public const float LegStrength = 2f;               // max support, × body weight
     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 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;              // N: the torso lies on the floor in a crawl; knees/hands would push (not simulated)
+    public const float TorsoFriction = 0.3f;           // clothing on floor: lets a crawl slide
+    // Lower-body collider: a box from the hips down to MaxStepHeight above the feet, so knee-high
+    // obstacles block walking (no walking over tables) while lower steps pass under it. It slides
+    // up into the torso when crouching and switches off when crawling (Nimso: legs don't snag).
+    public const float LegsMass = 6f;
+    public const float LegsKp = 30f, LegsForce = 3000f, LegsTorque = 400f;
+    public const float LegsOffAbove = 0.25f;           // collider disabled once slid this far above the hips
+    public const float MantleLift = 0.08f;             // braced + hips this far above the support goal = being lifted (legs tuck)
     // Balance: an implicit torque-capped motor from a world anchor to the pelvis (explicit torques
     // let the arms' reaction torques set the whole trunk swinging).
     public const float BalanceKp = 10f;
@@ -48,6 +68,8 @@ public partial class PlayerRagdoll : Node3D
     // Play-space reconciliation.
     public const float CameraRadius = 0.03f;           // sphere swept from the head's eye to the camera
     public const float FreeSlack = 0.2f;               // camera may lead an unobstructed (lagging/held) head by this much
+    public const float AirSlack = 0.05f;               // climbing/hanging (braced): the view rides the body tightly
+    public const float FallSlack = 0.25f;              // free airborne: brief ground loss (sliding off a steep slope) mustn't sink the view
     public const float GroundFollowRate = 8f;
     public const float ResetDistance = 1.5f;           // pelvis this far from its target → snap the whole body to the pose
     // Geometry.
@@ -92,8 +114,9 @@ public partial class PlayerRagdoll : Node3D
         public HingeJoint3D Elbow;
         public Drive Shoulder, Guide;
         public float UpperLen, ForeLen;
-        public RigidBody3D Held;
         public float PrevFlexTarget = -1f;
+        public float GuideCap = HandGuideForce;
+        public PhysicsBody3D Held;
     }
 
     public RigidBody3D Pelvis { get; private set; }
@@ -101,7 +124,11 @@ public partial class PlayerRagdoll : Node3D
     public RigidBody3D Head { get; private set; }
     public bool Built { get; private set; }
     public bool Grounded { get; private set; }
-    public float GroundY { get; private set; }
+    public float GroundY => _footY;
+    public bool Braced { get; private set; }             // a hand touches or holds static world
+    // Really climbing: a hand holds static world, or the arms are lifting the body (mantle).
+    public bool Climbing => Built && (_arms[0].Held is StaticBody3D || _arms[1].Held is StaticBody3D || _lifted);
+    public RigidBody3D Legs { get; private set; }
     public Vector3 Eye => Head.GlobalTransform * _eyeLocal;
     public BodyProfile Profile { get; private set; }
     public int Snaps { get; private set; }               // safety resets (NaN / too far) — should stay 0
@@ -115,6 +142,14 @@ public partial class PlayerRagdoll : Node3D
     private Vector3 _pelvisCenterLocal, _chestCenterLocal, _headCenterLocal; // from each body's proximal joint, in its basis
     private readonly Dictionary<RigidBody3D, Transform3D> _targets = new();
     private readonly Vector3[] _girdle = new Vector3[2];  // True Body shoulder offset, chest frame
+    private float _footY;
+    private float _supportGoalY;
+    private bool _lifted;
+    private float _legsHeight;
+    private Drive _legsDrive;
+    private bool _legsSolid = true;
+    private ProceduralLegs _legVisuals;
+    private float _appliedStrength = 1f;
     private Vector3 _pelvisTargetPrev;
     private bool _havePelvisPrev;
 
@@ -157,14 +192,21 @@ public partial class PlayerRagdoll : Node3D
         _eyeLocal -= headCenterFromPivot;             // eye relative to the head body's centre
 
         Color skin = new(0.85f, 0.72f, 0.6f), shirt = new(0.3f, 0.45f, 0.7f), pants = new(0.25f, 0.27f, 0.32f);
-        Pelvis = MakeBody("Pelvis", new BoxShape3D { Size = pelvisSize }, (0.142f + 0.139f + 0.322f) * m, BodyLayer, WorldMask, pants,
+        Pelvis = MakeBody("Pelvis", new BoxShape3D { Size = pelvisSize }, (0.142f + 0.139f + 0.322f) * m - LegsMass, BodyLayer, WorldMask, pants,
             c * new Transform3D(Basis.Identity, hip + _pelvisCenterLocal));
+        float standingHip = pose.PelvisTarget.Y - (pose.Eye.Y - p.EyeHeight);
+        _legsHeight = Mathf.Max(0.2f, standingHip - MaxStepHeight);
+        Legs = MakeBody("Legs", new BoxShape3D { Size = new Vector3(0.28f * s, _legsHeight, 0.2f * s) }, LegsMass, BodyLayer, WorldMask, pants,
+            c * new Transform3D(Basis.Identity, hip - new Vector3(0f, _legsHeight * 0.5f, 0f)), visible: false);
+        _footY = pose.Eye.Y - p.EyeHeight;
         Chest = MakeBody("Chest", new BoxShape3D { Size = chestSize }, 0.216f * m, BodyLayer, WorldMask, shirt,
             c * new Transform3D(Basis.Identity, lumbar + _chestCenterLocal));
         Head = MakeBody("Head", new BoxShape3D { Size = HeadSize * s }, 0.081f * m, BodyLayer, WorldMask, skin,
             c * new Transform3D(Basis.Identity, neckPivot + headCenterFromPivot));
         // The neck: a box hanging under the head, same body.
         Vector3 neckCenter = (neckBase + neckPivot) * 0.5f - (neckPivot + headCenterFromPivot);
+        foreach (RigidBody3D torso in new[] { Pelvis, Chest, Head, Legs })
+            torso.PhysicsMaterialOverride = new PhysicsMaterial { Friction = TorsoFriction };
         Head.AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = new Vector3(0.09f * s, _neckLen, 0.09f * s) }, Position = neckCenter });
         MeshInstance3D neckMesh = new() { Mesh = new BoxMesh { Size = new Vector3(0.09f * s, _neckLen, 0.09f * s) }, Position = neckCenter };
         neckMesh.SetSurfaceOverrideMaterial(0, new StandardMaterial3D { AlbedoColor = skin, Roughness = 0.6f });
@@ -175,6 +217,10 @@ public partial class PlayerRagdoll : Node3D
         StaticBody3D anchor = new() { Name = "BalanceAnchor", CollisionLayer = 0, CollisionMask = 0 };
         AddChild(anchor);
         _balance = MakeDrive(anchor, Pelvis, Pelvis.GlobalTransform, 0f, BalanceTorque);
+        _legsDrive = MakeDrive(Pelvis, Legs, c * new Transform3D(Basis.Identity, hip), LegsForce, LegsTorque);
+        _legVisuals = new ProceduralLegs { Name = "LegVisuals" };
+        AddChild(_legVisuals);
+        _legVisuals.Setup(Pelvis, -_pelvisCenterLocal, p.Stature, pants, new Color(0.15f, 0.15f, 0.17f));
         _balanceCap = BalanceTorque;
 
         _spine = MakeBall(Pelvis, Chest, c * lumbar, c.Basis * TwistAlong(Vector3.Up), Mathf.DegToRad(60f), Mathf.DegToRad(35f), SpineKp, SpineTorque);
@@ -217,6 +263,9 @@ public partial class PlayerRagdoll : Node3D
 
         Built = true;
         _havePelvisPrev = false;
+        _appliedStrength = 1f;
+        _legsSolid = true;
+        ApplyStrength();
         SnapToPose(pose, left, right);
         GD.Print($"PlayerRagdoll: built for stature {p.Stature:F2} m (arm {p.UpperArm:F3}+{p.Forearm:F3} m, {_bodies.Count} bodies)");
     }
@@ -249,11 +298,11 @@ public partial class PlayerRagdoll : Node3D
         return new Basis(x, boneDir, x.Cross(boneDir));
     }
 
-    private RigidBody3D MakeBody(string name, Shape3D shape, float mass, uint layer, uint mask, Color color, Transform3D at)
+    private RigidBody3D MakeBody(string name, Shape3D shape, float mass, uint layer, uint mask, Color color, Transform3D at, bool visible = true)
     {
-        RigidBody3D body = new() { Name = name, Mass = mass, CollisionLayer = layer, CollisionMask = mask, Transform = at };
+        RigidBody3D body = new() { Name = name, Mass = mass, CollisionLayer = layer, CollisionMask = mask, Transform = at, ContactMonitor = true, MaxContactsReported = 4 };
         body.AddChild(new CollisionShape3D { Shape = shape });
-        if (shape is BoxShape3D box && layer != 0)
+        if (shape is BoxShape3D box && layer != 0 && visible)
         {
             MeshInstance3D mesh = new() { Mesh = new BoxMesh { Size = box.Size } };
             mesh.SetSurfaceOverrideMaterial(0, new StandardMaterial3D { AlbedoColor = color, Roughness = 0.6f });
@@ -337,14 +386,17 @@ public partial class PlayerRagdoll : Node3D
     // World transform every body should have in the True Body pose. The trunk is rebuilt top-down
     // through the physical chain (upper chest → lumbar → hips) so a leaning chest doesn't drag
     // the head off the camera; the hips take part of the crouch lean (hip hinge).
-    private void ComputeTargets(TrueBodySolver s, Transform3D left, Transform3D right)
+    private void ComputeTargets(TrueBodySolver s, Transform3D left, Transform3D right, bool physicalArms = false, float dt = 0f)
     {
         Basis chest = s.ChestBasis;
-        Basis pelvis = s.YawBasis * new Basis(Vector3.Right, -s.Lean * PelvisLeanShare);
+        // Hips take half of a crouch lean, all of it in a crawl (keeps them off the floor).
+        float share = Mathf.Lerp(PelvisLeanShare, 1f, Mathf.Clamp((s.Lean - TrueBodySolver.ChestLeanMax) / 0.5f, 0f, 1f));
+        Basis pelvis = s.YawBasis * new Basis(Vector3.Right, -s.Lean * share);
         Vector3 lumbar = s.UpperChest - chest.Y * (_trunk - _lumbar);
         Vector3 hip = lumbar - pelvis.Y * _lumbar;
         _targets[Pelvis] = new Transform3D(pelvis, hip + pelvis * _pelvisCenterLocal);
         _targets[Chest] = new Transform3D(chest, lumbar + chest * _chestCenterLocal);
+        _targets[Legs] = new Transform3D(s.YawBasis, hip - Vector3.Up * (_legsHeight * 0.5f));  // snap pose only; LegsDrive steps it
         // Head + neck pivot at the neck base: orient like the camera, tilted by the small extra
         // rotation that puts the body's eye on the camera (the True Body bends the neck at two points).
         Vector3 eyeDir = s.HeadBasis * _neckBaseToEye;
@@ -368,9 +420,33 @@ public partial class PlayerRagdoll : Node3D
             _targets[a.Upper] = new Transform3D(BoneBasis(up, hinge), sh + up * (a.UpperLen * 0.5f));
             _targets[a.Fore] = new Transform3D(BoneBasis(fore, hinge), el + fore * (a.ForeLen * 0.5f));
             _targets[a.Hand] = (side == 0 ? left : right).Orthonormalized();
+
+            if (physicalArms)
+            {
+                // Re-aim the arm from the PHYSICAL shoulder. Horizontally the body may be held away from
+                // the camera (pressed against a ledge, leaning over a table): the arm reaches for the
+                // real hand. Vertically a sagging body keeps its arm pose (the aim point moves with
+                // the shoulder), so straight real arms stay straight virtual arms — pillars that hold
+                // you up when crawling or press you up a ledge (the hand guide adds the rest).
+                Transform3D chestPhys = Chest.GlobalTransform.Orthonormalized();
+                Vector3 shPhys = chestPhys * (a.Shoulder.AnchorA + _girdle[side]);
+                Transform3D ctrl = _targets[a.Hand];
+                Vector3 aim = ctrl * new Vector3(0f, 0f, WristOffset) + Vector3.Up * (shPhys.Y - sh.Y);
+                ArmSolver solver = _armSolvers[side];
+                solver.Solve(shPhys, aim, chestPhys.Basis, chestPhys.Basis.X * (side == 0 ? -1f : 1f),
+                    ctrl.Basis, a.UpperLen, a.ForeLen, dt);
+                Vector3 d = solver.Wrist - shPhys;
+                Vector3 h = d.LengthSquared() > 1e-8f ? solver.Pole.Cross(d.Normalized()) : chestPhys.Basis.X;
+                h = h.LengthSquared() > 1e-8f ? h.Normalized() : chestPhys.Basis.X;
+                Vector3 u = (solver.Elbow - shPhys).Normalized(), f = (solver.Wrist - solver.Elbow).Normalized();
+                _targets[a.Upper] = new Transform3D(BoneBasis(u, h), shPhys + u * (a.UpperLen * 0.5f));
+                _targets[a.Fore] = new Transform3D(BoneBasis(f, h), solver.Elbow + f * (a.ForeLen * 0.5f));
+            }
         }
     }
 
+    private readonly ArmSolver[] _armSolvers = { new(), new() };
+
     public Transform3D Target(RigidBody3D body) => _targets.TryGetValue(body, out Transform3D t) ? t : body.GlobalTransform;
 
     // ---------------------------------------------------------------- per tick
@@ -379,7 +455,7 @@ public partial class PlayerRagdoll : Node3D
     {
         if (!Built)
             return;
-        ComputeTargets(s, left, right);
+        ComputeTargets(s, left, right, physicalArms: true, dt);
         foreach (RigidBody3D b in _bodies)
         {
             if (BodyMath.ResetIfNonFinite(b, Target(b), "PlayerRagdoll"))
@@ -401,14 +477,20 @@ public partial class PlayerRagdoll : Node3D
 
         Muscle(_spine, _targets[Pelvis].Basis, _targets[Chest].Basis, dt);
         Muscle(_neck, _targets[Chest].Basis, _targets[Head].Basis, dt);
+        if (Strength != _appliedStrength)
+            ApplyStrength();
+        Braced = false;
         for (int side = 0; side < 2; side++)
         {
             Arm a = _arms[side];
             ShoulderDrive(a, side, dt);
             ElbowMuscle(a, dt);
             HandGuide(a, _targets[a.Hand], side == 0 ? leftVelocity : rightVelocity);
+            Braced |= IsBraced(a);
         }
         GroundControl(pelvisTarget, floorY, dt);
+        LegsDrive(s);
+        _legVisuals.Tick(_footY, Grounded, !_legsSolid, s.YawBasis, dt);
     }
 
     // Muscle = PD on the joint's relative rotation toward the relative rotation of the two TARGET
@@ -461,6 +543,72 @@ public partial class PlayerRagdoll : Node3D
         a.Elbow.SetParam(HingeJoint3D.Param.MotorTargetVelocity, HingeSign * w);
     }
 
+    private void ApplyStrength()
+    {
+        _appliedStrength = Strength;
+        float k = Mathf.Max(0.05f, Strength);
+        SetAngularCap(_spine.Joint, SpineTorque * k);
+        SetAngularCap(_neck.Joint, NeckTorque * k);
+        foreach (Arm a in _arms)
+        {
+            SetAngularCap(a.Shoulder.Joint, ShoulderTorque * k);
+            SetAngularCap(a.Guide.Joint, HandGuideTorque * k);
+            a.Elbow.SetParam(HingeJoint3D.Param.MotorMaxImpulse, ElbowTorque * k);
+        }
+    }
+
+    private static void SetAngularCap(Generic6DofJoint3D j, float cap)
+    {
+        j.SetParamX(Generic6DofJoint3D.Param.AngularMotorForceLimit, cap);
+        j.SetParamY(Generic6DofJoint3D.Param.AngularMotorForceLimit, cap);
+        j.SetParamZ(Generic6DofJoint3D.Param.AngularMotorForceLimit, cap);
+    }
+
+    private static void SetLinearCap(Generic6DofJoint3D j, float cap)
+    {
+        j.SetParamX(Generic6DofJoint3D.Param.LinearMotorForceLimit, cap);
+        j.SetParamY(Generic6DofJoint3D.Param.LinearMotorForceLimit, cap);
+        j.SetParamZ(Generic6DofJoint3D.Param.LinearMotorForceLimit, cap);
+    }
+
+    // A hand pressing on or holding static world (a ledge, a wall, a grabbed bar).
+    private static bool IsBraced(Arm a)
+    {
+        if (a.Held is StaticBody3D)
+            return true;
+        foreach (Node3D n in a.Hand.GetCollidingBodies())
+            if (n is StaticBody3D)
+                return true;
+        return false;
+    }
+
+    // The lower-body collider hangs from the actual hips, its bottom never below a step above the
+    // feet; once it would have to slide far up into the torso (deep crouch, crawl) it stops colliding.
+    private void LegsDrive(TrueBodySolver s)
+    {
+        Transform3D pelvis = Pelvis.GlobalTransform;
+        Vector3 hip = pelvis * (-_pelvisCenterLocal);
+        float minCenter = _footY + MaxStepHeight + _legsHeight * 0.5f;
+        float center = Mathf.Max(hip.Y - _legsHeight * 0.5f, minCenter);
+        // Tucked: deep crouch/crawl, or being lifted by the arms (mantling — the knee comes up).
+        _lifted = Braced && Pelvis.GlobalPosition.Y > _supportGoalY + MantleLift;
+        bool solid = center + _legsHeight * 0.5f < hip.Y + LegsOffAbove && !_lifted;
+        if (solid != _legsSolid)
+        {
+            _legsSolid = solid;
+            // The shape itself is disabled: Box3D keeps existing contacts when only the layer changes.
+            Legs.GetChild<CollisionShape3D>(0).SetDeferred(CollisionShape3D.PropertyName.Disabled, !solid);
+        }
+        if (!solid)
+            center = hip.Y;   // tucked into the pelvis, out of the way
+        Vector3 desired = new(hip.X, center, hip.Z);
+        Quaternion frameA = Rot(Pelvis) * _legsDrive.FrameA;
+        SetLinearVelocity(_legsDrive.Joint, frameA.Inverse() * ((desired - Legs.GlobalPosition) * LegsKp));
+        Quaternion target = (Rot(Pelvis) * _legsDrive.FrameA).Inverse() * (s.YawBasis.GetRotationQuaternion() * _legsDrive.FrameB);
+        Quaternion current = frameA.Inverse() * (Rot(Legs) * _legsDrive.FrameB);
+        SetAngularVelocity(_legsDrive.Joint, (BodyMath.RotationError(target, current) * LegsKp).LimitLength(MuscleMaxSpin));
+    }
+
     // Shoulder = one drive: its linear motor keeps the humeral head on the chest's shoulder point
     // shifted by the True Body girdle offset (shrug/protraction), its angular motor is the
     // shoulder muscle (same PD + feed-forward as Muscle, parent = chest).
@@ -474,7 +622,8 @@ public partial class PlayerRagdoll : Node3D
         SetLinearVelocity(d.Joint, frameA.Inverse() * (err * GirdleKp));
 
         Quaternion current = frameA.Inverse() * (Rot(a.Upper) * d.FrameB);
-        Quaternion target = (_targets[Chest].Basis.Orthonormalized().GetRotationQuaternion() * d.FrameA).Inverse()
+        // Arm targets are solved from the physical chest, so the physical chest is the parent frame.
+        Quaternion target = (chest.Basis.GetRotationQuaternion() * d.FrameA).Inverse()
             * (_targets[a.Upper].Basis.Orthonormalized().GetRotationQuaternion() * d.FrameB);
         Vector3 ff = d.HasPrev && dt > 0f ? (BodyMath.RotationError(target, d.PrevTarget) / dt).LimitLength(MuscleMaxSpin) : Vector3.Zero;
         d.PrevTarget = target;
@@ -488,12 +637,24 @@ public partial class PlayerRagdoll : Node3D
         Transform3D chest = Chest.GlobalTransform;
         Vector3 anchor = chest * a.Guide.AnchorA;
         Vector3 anchorVelocity = Chest.LinearVelocity + Chest.AngularVelocity.Cross(anchor - Chest.GlobalPosition);
-        Vector3 desired = (targetVelocity + (target.Origin - a.Hand.GlobalPosition) * HandGuideKp).LimitLength(HandGuideMaxSpeed);
+        Vector3 err = target.Origin - a.Hand.GlobalPosition;
+        Vector3 desired = (targetVelocity + err * HandGuideKp).LimitLength(HandGuideMaxSpeed);
         Quaternion frameA = Rot(Chest) * a.Guide.FrameA;
+        Vector3 shoulder = a.Upper.GlobalTransform * a.Shoulder.AnchorB;
+        Vector3 axis = a.Hand.GlobalPosition - shoulder;
+        // Axial share of the error, with a 3 cm floor so a nearly-reached target's noisy error
+        // direction can't flip a held load into "structural".
+        float align = axis.LengthSquared() > 1e-8f ? Mathf.Abs(err.Dot(axis.Normalized())) / (err.Length() + StructuralDeadband) : 0f;
+        float cap = Mathf.Lerp(HandGuideForce, HandStructuralForce, align) * Mathf.Max(0.05f, Strength);
+        if (Mathf.Abs(cap - a.GuideCap) > 1f)
+        {
+            a.GuideCap = cap;
+            SetLinearCap(a.Guide.Joint, cap);
+        }
         SetLinearVelocity(a.Guide.Joint, frameA.Inverse() * (desired - anchorVelocity));
         // Angular: hand rotation onto the controller rotation, as a relative spin vs the chest.
-        Vector3 err = BodyMath.RotationError(target.Basis.GetRotationQuaternion(), Rot(a.Hand));
-        Vector3 wWorld = (err * HandGuideAngularKp).LimitLength(MuscleMaxSpin * 2f) - Chest.AngularVelocity;
+        Vector3 rotErr = BodyMath.RotationError(target.Basis.GetRotationQuaternion(), Rot(a.Hand));
+        Vector3 wWorld = (rotErr * HandGuideAngularKp).LimitLength(MuscleMaxSpin * 2f) - Chest.AngularVelocity;
         SetAngularVelocity(a.Guide.Joint, frameA.Inverse() * wWorld);
     }
 
@@ -506,20 +667,42 @@ public partial class PlayerRagdoll : Node3D
         float hipAboveFloor = target.Origin.Y - floorY;
         var query = PhysicsRayQueryParameters3D.Create(pos, pos + Vector3.Down * (hipAboveFloor + GroundProbeExtra + 0.5f), WorldMask);
         Godot.Collections.Dictionary hit = GetWorld3D().DirectSpaceState.IntersectRay(query);
+        bool wasGrounded = Grounded;
         Grounded = false;
         if (hit.Count > 0)
         {
             Vector3 point = (Vector3)hit["position"];
             Vector3 normal = (Vector3)hit["normal"];
-            if (pos.Y - point.Y < hipAboveFloor + GroundProbeExtra && normal.Y > 0.6f)
+            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)
             {
+                // The foot of a too-steep slope: keep standing on the ground we're on (the legs
+                // collider stops us); dropping support here would collapse the body.
                 Grounded = true;
-                GroundY = point.Y;
+            }
+            else if (inReach && !steep)
+            {
+                // Step rule: ground more than a step above the feet is only stood on once the
+                // hips are already well above it (climbed/mantled/landed there) — otherwise it's an
+                // obstacle the legs collider holds us back from, and the feet stay where they were.
+                // Higher ground climbed onto must be under the hips' back edge too (not just a
+                // pelvis centre hanging over the lip).
+                bool clear = point.Y <= _footY + MaxStepHeight || GroundBehindAt(pos, point.Y);
+                bool reachable = point.Y <= _footY + MaxStepHeight
+                    || ((!wasGrounded || !_legsSolid || pos.Y - point.Y > 0.6f * hipAboveFloor) && clear);
+                Grounded = true;
+                if (reachable)
+                    _footY = point.Y;
             }
         }
 
-        Vector3 targetVelocity = _havePelvisPrev && dt > 0f ? (target.Origin - _pelvisTargetPrev) / dt : Vector3.Zero;
-        _pelvisTargetPrev = target.Origin;
+        // Feed-forward from the GOAL (pose + ground offset): when the play-space floor follows the
+        // ground, the pose target and the ground offset move by the same amount in opposite
+        // directions — differentiating the pose alone would launch the body.
+        Vector3 goalNow = target.Origin + Vector3.Up * (_footY - floorY);
+        Vector3 targetVelocity = _havePelvisPrev && dt > 0f ? (goalNow - _pelvisTargetPrev) / dt : Vector3.Zero;
+        _pelvisTargetPrev = goalNow;
         _havePelvisPrev = true;
         if (targetVelocity.Length() > 10f)
             targetVelocity = Vector3.Zero;
@@ -529,13 +712,25 @@ public partial class PlayerRagdoll : Node3D
         {
             // Pose heights are relative to the tracking floor; stand on the ground actually under us.
             Vector3 goal = target.Origin + Vector3.Up * (GroundY - floorY);
+            _supportGoalY = goal.Y;
             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);
-            Vector3 horizontal = new Vector3(force.X, 0f, force.Z).LimitLength(GroundFriction * support);
+            float carry = Mathf.Max(GroundFriction * support, _legsSolid ? 0f : CrawlCarry);
+            Vector3 horizontal = new Vector3(force.X, 0f, force.Z).LimitLength(carry);
             Pelvis.ApplyCentralForce(horizontal + Vector3.Up * support);
         }
+        else if (Braced)
+        {
+            // Hanging/mantling on the hands: the hips still drift after the head a little, so you can
+            // shift your weight over a ledge you're pressing yourself up onto.
+            Vector3 lead = target.Origin - pos;
+            lead.Y = 0f;
+            Vector3 v = Pelvis.LinearVelocity;
+            v.Y = 0f;
+            Pelvis.ApplyCentralForce(((lead * 20f - v * 8f) * BodyMass).LimitLength(BracedAirControl));
+        }
 
         Vector3 rotErr = BodyMath.RotationError(target.Basis.GetRotationQuaternion(), Rot(Pelvis));
         Vector3 spin = (rotErr * BalanceKp).LimitLength(MuscleMaxSpin);
@@ -576,20 +771,44 @@ public partial class PlayerRagdoll : Node3D
             float[] fractions = GetWorld3D().DirectSpaceState.CastMotion(_cameraQuery);
             float safe = fractions.Length > 0 ? fractions[0] : 1f;
             if (safe < 1f)
+            {
                 correction = -lead * (1f - safe);
-            else if (lead.Length() > FreeSlack)
-                correction = -lead * (1f - FreeSlack / lead.Length());
+                // Only a climbing body drags the view vertically through geometry; otherwise a
+                // camera-to-eye line grazing a slope would sink the view (and with it the pose).
+                if (!Climbing)
+                    correction.Y = 0f;
+            }
+            else
+            {
+                float slack = Grounded ? FreeSlack : Climbing ? AirSlack : FallSlack;
+                if (lead.Length() > slack)
+                    correction = -lead * (1f - slack / lead.Length());
+            }
         }
         if (Grounded)
         {
             correction.Y = 0f;
             correction.Y += (GroundY - floorY) * (1f - Mathf.Exp(-dt * GroundFollowRate));
         }
+        // The pose target moves with the play space: a correction is not intended motion, so it
+        // must not show up in ground control's feed-forward (that loop ran away at 7 m/s).
+        _pelvisTargetPrev += correction;
         return correction;
     }
 
     private PhysicsShapeQueryParameters3D _cameraQuery;
 
+    // Second ground ray 12 cm behind the hips (toward the body's back): ground at least `groundY`.
+    private bool GroundBehindAt(Vector3 pelvisPos, float groundY)
+    {
+        Vector3 back = Pelvis.GlobalTransform.Basis.Z;
+        back.Y = 0f;
+        back = back.LengthSquared() > 1e-6f ? back.Normalized() * 0.12f : Vector3.Zero;
+        var query = PhysicsRayQueryParameters3D.Create(pelvisPos + back, pelvisPos + back + Vector3.Down * 3f, WorldMask);
+        Godot.Collections.Dictionary hit = GetWorld3D().DirectSpaceState.IntersectRay(query);
+        return hit.Count > 0 && ((Vector3)hit["position"]).Y > groundY - 0.05f;
+    }
+
     public void TeleportBy(Transform3D delta)
     {
         if (!Built)
@@ -601,6 +820,9 @@ public partial class PlayerRagdoll : Node3D
             b.AngularVelocity = delta.Basis * b.AngularVelocity;
         }
         _pelvisTargetPrev = delta * _pelvisTargetPrev;
+        _footY += delta.Origin.Y;
+        foreach (RigidBody3D b in _bodies)
+            b.ResetPhysicsInterpolation();
     }
 
     public void SnapToPose(TrueBodySolver s, Transform3D left, Transform3D right)
@@ -620,11 +842,13 @@ public partial class PlayerRagdoll : Node3D
             a.Hand.GlobalTransform = new Transform3D(hb, s.Wrist[side] - hb * new Vector3(0f, 0f, WristOffset));
         }
         _havePelvisPrev = false;
+        foreach (RigidBody3D b in _bodies)
+            b.ResetPhysicsInterpolation();
     }
 
     // Collision exceptions between a held prop and that arm's segments (its hand is excluded by
     // the grab weld itself) — a forearm wrapped around a held object must not fight it.
-    public void SetHeld(int side, RigidBody3D prop)
+    public void SetHeld(int side, PhysicsBody3D prop)
     {
         if (!Built)
             return;

scripts/PlayerRig.cs

@@ -38,6 +38,21 @@ public partial class PlayerRig : Node
     private bool _rebuild = true;
 
     public PlayerRagdoll Ragdoll => _ragdoll;
+    public static bool Spectator { get; private set; }
+
+    // Spectator = no body (fly with the old grab-drag movement); leaving it rebuilds the body at
+    // the current pose.
+    public static void SetSpectator(bool on)
+    {
+        Spectator = on;
+        AnchorMoveMode.Enabled = on;
+        if (_instance == null)
+            return;
+        if (on)
+            _instance._ragdoll.Clear();
+        _instance._rebuild = true;
+        GD.Print($"PlayerRig: spectator {(on ? "on" : "off")}");
+    }
 
     public static RigidBody3D GetHandBody(XRController3D controller)
     {
@@ -46,7 +61,7 @@ public partial class PlayerRig : Node
         return _instance._ragdoll.Hand(controller == _instance._left ? 0 : 1);
     }
 
-    public static void SetHeld(XRController3D controller, RigidBody3D prop)
+    public static void SetHeld(XRController3D controller, PhysicsBody3D prop)
     {
         if (_instance != null)
             _instance._ragdoll.SetHeld(controller == _instance._left ? 0 : 1, prop);
@@ -65,7 +80,9 @@ public partial class PlayerRig : Node
             _trueBody.ExternallySolved = true;
             TrueBody.ShowDebug = false;
         }
-        _ragdoll = new PlayerRagdoll { Name = "Ragdoll" };
+        // PlayerRig itself is excluded from physics interpolation (ghosts follow controllers per
+        // frame); the body is simulated, so it interpolates.
+        _ragdoll = new PlayerRagdoll { Name = "Ragdoll", PhysicsInterpolationMode = PhysicsInterpolationModeEnum.On };
         AddChild(_ragdoll);
         BodyProfile.Changed += _ => _rebuild = true;
         for (int i = 0; i < 2; i++)
@@ -93,8 +110,11 @@ public partial class PlayerRig : Node
     {
         float dt = (float)delta;
         BodyProfile profile = BodyProfile.Current;
-        if (profile == null)
+        if (profile == null || Spectator)
+        {
+            _haveLastOrigin = false;
             return;
+        }
 
         // 1. Someone else moved the play space discretely: bring the body along.
         Transform3D origin = _origin.GlobalTransform;

scripts/Playground.cs

@@ -0,0 +1,243 @@
+using Godot;
+using System.Collections.Generic;
+
+// The body-physics sandbox (Nimso-sandbox style), built in code around the spawn/table area:
+//   EAST  — mantling ledges (0.3 … 1.5 m), a 1 m platform with stairs, a walkable 18° ramp and a
+//           too-steep 40° one, a climbing wall with holds onto a 2.4 m top, a pull-up bar, monkey bars.
+//   WEST  — physics toys: a plank bridge on two blocks (walk on it / knock it off), loose planks,
+//           a seesaw, a hanging swing board (grab it and hang), a crate pyramid, a heavy box,
+//           barrels, a balance beam.
+//   SOUTH — a crawl tunnel (0.6 m clearance), a duck-under bar (1.2 m) and a doorway.
+// Static pieces are world (layer 1) and grabbable for climbing (PropGrabber grabs any static body
+// not in "no_grab"); dynamic pieces are "prop"s (grab/push) and come back with Reset().
+public partial class Playground : Node3D
+{
+    private readonly List<(RigidBody3D Body, Transform3D Start)> _dynamic = new();
+    private const uint WorldLayer = 1, WorldMask = 0b11101, PropMask = 0b11101;
+
+    private static readonly Color Concrete = new(0.62f, 0.62f, 0.6f), Wood = new(0.72f, 0.55f, 0.33f),
+        DarkWood = new(0.5f, 0.36f, 0.2f), Metal = new(0.45f, 0.47f, 0.52f), Hold = new(0.9f, 0.45f, 0.15f),
+        Blue = new(0.3f, 0.45f, 0.75f), Green = new(0.35f, 0.6f, 0.35f), Red = new(0.7f, 0.25f, 0.2f);
+
+    public override void _Ready()
+    {
+        BuildEast();
+        BuildWest();
+        BuildSouth();
+    }
+
+    public void Reset()
+    {
+        foreach (var (body, start) in _dynamic)
+        {
+            if (!IsInstanceValid(body))
+                continue;
+            body.GlobalTransform = start;
+            body.LinearVelocity = Vector3.Zero;
+            body.AngularVelocity = Vector3.Zero;
+            body.ResetPhysicsInterpolation();
+        }
+    }
+
+    // ---------------------------------------------------------------- builders
+
+    private StaticBody3D Block(string name, Vector3 size, Vector3 center, Color color, Basis? basis = null)
+    {
+        StaticBody3D body = new() { Name = name, CollisionLayer = WorldLayer, CollisionMask = WorldMask, Transform = new Transform3D(basis ?? Basis.Identity, center) };
+        body.AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = size } });
+        body.AddChild(Mesh(new BoxMesh { Size = size }, color));
+        AddChild(body);
+        return body;
+    }
+
+    private StaticBody3D Bar(string name, Vector3 from, Vector3 to, float radius, Color color)
+    {
+        Vector3 axis = to - from;
+        float len = axis.Length();
+        Vector3 y = axis / len;
+        Vector3 x = Mathf.Abs(y.Y) < 0.99f ? Vector3.Up.Cross(y).Normalized() : Vector3.Right;
+        StaticBody3D body = new() { Name = name, CollisionLayer = WorldLayer, CollisionMask = WorldMask, Transform = new Transform3D(new Basis(x, y, x.Cross(y)), (from + to) * 0.5f) };
+        body.AddChild(new CollisionShape3D { Shape = new CylinderShape3D { Radius = radius, Height = len } });
+        body.AddChild(Mesh(new CylinderMesh { TopRadius = radius, BottomRadius = radius, Height = len, RadialSegments = 12 }, color));
+        AddChild(body);
+        return body;
+    }
+
+    private RigidBody3D Prop(string name, Shape3D shape, Mesh mesh, float mass, Vector3 center, Color color, Basis? basis = null, float friction = 0.8f)
+    {
+        RigidBody3D body = new()
+        {
+            Name = name,
+            Mass = mass,
+            Transform = new Transform3D(basis ?? Basis.Identity, center),
+            CollisionMask = PropMask,
+            ContactMonitor = true,
+            MaxContactsReported = 4,
+            PhysicsMaterialOverride = new PhysicsMaterial { Friction = friction, Bounce = 0.05f },
+        };
+        body.AddToGroup("prop");
+        body.AddChild(new CollisionShape3D { Shape = shape });
+        body.AddChild(Mesh(mesh, color));
+        AddChild(body);
+        _dynamic.Add((body, body.GlobalTransform));
+        return body;
+    }
+
+    private RigidBody3D BoxProp(string name, Vector3 size, float mass, Vector3 center, Color color, Basis? basis = null) =>
+        Prop(name, new BoxShape3D { Size = size }, new BoxMesh { Size = size }, mass, center, color, basis);
+
+    private static MeshInstance3D Mesh(Mesh mesh, Color color)
+    {
+        MeshInstance3D m = new() { Mesh = mesh };
+        m.SetSurfaceOverrideMaterial(0, new StandardMaterial3D { AlbedoColor = color, Roughness = 0.75f });
+        return m;
+    }
+
+    private void Sign(string text, Vector3 at)
+    {
+        AddChild(new Label3D
+        {
+            Text = text,
+            FontSize = 96,
+            PixelSize = 0.002f,
+            OutlineSize = 12,
+            Billboard = BaseMaterial3D.BillboardModeEnum.FixedY,
+            Position = at,
+        });
+    }
+
+    // ---------------------------------------------------------------- zones
+
+    private void BuildEast()
+    {
+        // Mantling ledges: walk up to one, put both hands on it and press yourself up.
+        float[] heights = { 0.3f, 0.6f, 0.9f, 1.2f, 1.5f };
+        for (int i = 0; i < heights.Length; i++)
+        {
+            float h = heights[i];
+            Block($"Ledge{h:0.0}", new Vector3(1.2f, h, 1.2f), new Vector3(4.5f + i * 1.9f, h * 0.5f, -8f), Concrete);
+            Sign($"{h:0.0} m", new Vector3(4.5f + i * 1.9f, h + 0.35f, -7.3f));
+        }
+        Sign("Mantle: both hands on the ledge, push down", new Vector3(8.3f, 2.4f, -8f));
+
+        // Platform 1 m high with stairs (0.17 m risers) on the south side and ramps on the north.
+        Block("Platform", new Vector3(3f, 1f, 3f), new Vector3(8f, 0.5f, -1.5f), Concrete);
+        for (int i = 0; i < 5; i++)
+        {
+            float top = 0.17f * (i + 1);
+            Block($"Stair{i}", new Vector3(1.2f, top, 0.3f), new Vector3(8f, top * 0.5f, 0.15f + (4 - i) * 0.3f), Concrete.Lightened(0.1f));
+        }
+        float walkable = Mathf.DegToRad(18f);
+        float rampLen = 1f / Mathf.Sin(walkable);
+        // Negative X rotation lifts the slab's +Z end, which touches the platform's north edge.
+        Block("RampWalkable", new Vector3(1.2f, 0.1f, rampLen), new Vector3(7f, 0.5f, -3f - Mathf.Cos(walkable) * rampLen * 0.5f),
+            Green, new Basis(Vector3.Right, -walkable));
+        float steep = Mathf.DegToRad(40f);
+        float steepLen = 1f / Mathf.Sin(steep);
+        Block("RampSteep", new Vector3(1.2f, 0.1f, steepLen), new Vector3(9f, 0.5f, -3f - Mathf.Cos(steep) * steepLen * 0.5f),
+            Red, new Basis(Vector3.Right, -steep));
+        Sign("18° ramp", new Vector3(7f, 1.6f, -4.5f));
+        Sign("40° (too steep)", new Vector3(9f, 1.6f, -4.5f));
+
+        // Climbing wall: holds on the west face, top at 2.4 m to climb onto.
+        Block("ClimbWall", new Vector3(1.5f, 2.4f, 3f), new Vector3(12.25f, 1.2f, -1.5f), Concrete.Darkened(0.15f));
+        RandomNumberGenerator rng = new() { Seed = 5 };
+        for (float y = 0.4f; y < 2.35f; y += 0.35f)
+        {
+            for (int k = 0; k < 4; k++)
+            {
+                float z = -2.7f + k * 0.8f + rng.RandfRange(-0.15f, 0.15f);
+                Block("Hold", new Vector3(0.08f, 0.06f, 0.22f), new Vector3(11.46f, y + rng.RandfRange(-0.06f, 0.06f), z), Hold);
+            }
+        }
+        Sign("Climbing wall: grip the holds", new Vector3(11f, 3f, -1.5f));
+
+        // Pull-up bar and monkey bars.
+        Bar("PostA", new Vector3(5f, 0f, 2.5f), new Vector3(5f, 2.25f, 2.5f), 0.05f, Metal);
+        Bar("PostB", new Vector3(6.4f, 0f, 2.5f), new Vector3(6.4f, 2.25f, 2.5f), 0.05f, Metal);
+        Bar("PullUpBar", new Vector3(5f, 2.1f, 2.5f), new Vector3(6.4f, 2.1f, 2.5f), 0.025f, Metal);
+        Sign("Pull-up bar", new Vector3(5.7f, 2.6f, 2.5f));
+        Bar("MonkeyRailL", new Vector3(5f, 2.25f, 4.5f), new Vector3(10f, 2.25f, 4.5f), 0.04f, Metal);
+        Bar("MonkeyRailR", new Vector3(5f, 2.25f, 5.1f), new Vector3(10f, 2.25f, 5.1f), 0.04f, Metal);
+        foreach (float x in new[] { 5f, 10f })
+            foreach (float z in new[] { 4.5f, 5.1f })
+                Bar("MonkeyPost", new Vector3(x, 0f, z), new Vector3(x, 2.25f, z), 0.05f, Metal);
+        for (float x = 5.4f; x < 9.8f; x += 0.4f)
+            Bar("Rung", new Vector3(x, 2.2f, 4.5f), new Vector3(x, 2.2f, 5.1f), 0.022f, Metal);
+        Sign("Monkey bars", new Vector3(7.5f, 2.8f, 4.8f));
+    }
+
+    private void BuildWest()
+    {
+        // Plank bridge: two blocks with a loose 9 kg plank across — walk on it, or knock it off.
+        Block("BridgeBlockA", new Vector3(1f, 0.8f, 1f), new Vector3(-4.5f, 0.4f, -5f), Concrete);
+        Block("BridgeBlockB", new Vector3(1f, 0.8f, 1f), new Vector3(-8f, 0.4f, -5f), Concrete);
+        BoxProp("BridgePlank", new Vector3(3.4f, 0.06f, 0.4f), 9f, new Vector3(-6.25f, 0.83f, -5f), Wood);
+        Sign("Plank bridge", new Vector3(-6.25f, 1.6f, -5f));
+
+        // Loose planks to pick up, carry, lean, swing (light enough to wield, long enough to lever).
+        for (int i = 0; i < 3; i++)
+            BoxProp($"Plank{i}", new Vector3(2f, 0.04f, 0.2f), 4f, new Vector3(-5f, 0.02f + i * 0.045f, -2.6f + i * 0.05f), Wood.Lightened(0.05f * i),
+                new Basis(Vector3.Up, 0.1f * i));
+
+        // Seesaw: a plank hinged on a pivot block.
+        Block("SeesawPivot", new Vector3(0.3f, 0.45f, 0.5f), new Vector3(-8.5f, 0.225f, -1.5f), Metal);
+        RigidBody3D seesaw = BoxProp("Seesaw", new Vector3(3.2f, 0.06f, 0.45f), 12f, new Vector3(-8.5f, 0.48f, -1.5f), DarkWood);
+        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),
+        };
+        AddChild(pivot);
+        Sign("Seesaw", new Vector3(-8.5f, 1.3f, -1.5f));
+
+        // Swing board: a 10 kg board hinged at its top edge from a 2.4 m beam — grab it and hang.
+        Bar("SwingPostA", new Vector3(-5f, 0f, 1.5f), new Vector3(-5f, 2.45f, 1.5f), 0.05f, Metal);
+        Bar("SwingPostB", new Vector3(-7f, 0f, 1.5f), new Vector3(-7f, 2.45f, 1.5f), 0.05f, Metal);
+        StaticBody3D beam = Bar("SwingBeam", new Vector3(-5f, 2.4f, 1.5f), new Vector3(-7f, 2.4f, 1.5f), 0.05f, Metal);
+        RigidBody3D board = BoxProp("SwingBoard", new Vector3(1.2f, 1.2f, 0.05f), 10f, new Vector3(-6f, 1.75f, 1.5f), Wood);
+        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),
+        };
+        AddChild(swing);
+        Sign("Hanging board", new Vector3(-6f, 2.9f, 1.5f));
+
+        // Crate pyramid (4 kg each), a heavy 25 kg box, barrels.
+        Vector3 basePos = new(-9.5f, 0f, 2f);
+        int n = 0;
+        for (int row = 0; row < 3; row++)
+            for (int col = 0; col < 3 - row; col++)
+                BoxProp($"Crate{n++}", Vector3.One * 0.4f, 4f, basePos + new Vector3((col + row * 0.5f) * 0.42f, 0.2f + row * 0.401f, 0f), Wood.Darkened(0.1f));
+        BoxProp("HeavyBox", Vector3.One * 0.7f, 25f, new Vector3(-9f, 0.35f, 4f), Blue);
+        for (int i = 0; i < 2; i++)
+            Prop($"Barrel{i}", new CylinderShape3D { Radius = 0.28f, Height = 0.85f }, new CylinderMesh { TopRadius = 0.28f, BottomRadius = 0.28f, Height = 0.85f }, 12f,
+                new Vector3(-7.5f + i * 0.7f, 0.425f, 4.5f), Red);
+
+        // Balance beam.
+        Block("BalanceBeam", new Vector3(0.12f, 0.3f, 4f), new Vector3(-11f, 0.15f, -2f), DarkWood);
+        Sign("Balance beam", new Vector3(-11f, 1.1f, -2f));
+    }
+
+    private void BuildSouth()
+    {
+        // Crawl tunnel: 0.6 m clearance, 3 m long.
+        Block("TunnelRoof", new Vector3(1.4f, 0.1f, 3f), new Vector3(-2.5f, 0.65f, 7f), Concrete);
+        Block("TunnelWallL", new Vector3(0.1f, 0.6f, 3f), new Vector3(-3.15f, 0.3f, 7f), Concrete);
+        Block("TunnelWallR", new Vector3(0.1f, 0.6f, 3f), new Vector3(-1.85f, 0.3f, 7f), Concrete);
+        Sign("Crawl tunnel (0.6 m)", new Vector3(-2.5f, 1.2f, 5.3f));
+
+        // Duck-under bar at 1.2 m and a doorway (1.9 × 0.8 m).
+        Bar("DuckPostA", new Vector3(1f, 0f, 7f), new Vector3(1f, 1.3f, 7f), 0.05f, Metal);
+        Bar("DuckPostB", new Vector3(2.6f, 0f, 7f), new Vector3(2.6f, 1.3f, 7f), 0.05f, Metal);
+        Bar("DuckBar", new Vector3(1f, 1.25f, 7f), new Vector3(2.6f, 1.25f, 7f), 0.03f, Metal);
+        Sign("Duck under (1.2 m)", new Vector3(1.8f, 1.8f, 7f));
+        Block("DoorL", new Vector3(0.2f, 2.1f, 0.3f), new Vector3(4.1f, 1.05f, 7f), Wood);
+        Block("DoorR", new Vector3(0.2f, 2.1f, 0.3f), new Vector3(5.1f, 1.05f, 7f), Wood);
+        Block("DoorTop", new Vector3(1.2f, 0.2f, 0.3f), new Vector3(4.6f, 2.0f, 7f), Wood);
+        Sign("Doorway", new Vector3(4.6f, 2.5f, 7f));
+    }
+}

scripts/Playground.cs.uid

@@ -0,0 +1 @@
+uid://dg665wra8wjhg

scripts/ProceduralLegs.cs

@@ -0,0 +1,227 @@
+using Godot;
+
+// Visual procedural legs for the ragdoll player (Nimso: "a very basic procedural leg system", feet
+// "don't actually hold the player up" — ground control does). Feet stay planted on the ground and
+// step, alternating, when the hips move or turn away from them; the stride leads with the body's
+// velocity. Airborne the feet hang under the hips; low (crawling) they trail behind. Knees bend
+// forward via a 2-bone solve. Physics-tick state (PlayerRagdoll.Step calls Tick), drawn in
+// _Process from the interpolated pelvis. No collision — the lower-body collider is separate.
+public partial class ProceduralLegs : Node3D
+{
+    public const float ThighRatio = 0.245f, ShinRatio = 0.246f, AnkleRatio = 0.039f;   // Winter, × stature
+    public const float HipHalfWidth = 0.09f;
+    public const float StanceHalfWidth = 0.11f;
+    public const float StepTrigger = 0.2f;          // m from the ideal spot
+    public const float StepTurnTrigger = 0.6f;      // rad
+    public const float StepLead = 0.25f;            // s of velocity the new foothold leads by
+    public const float StepTimeSlow = 0.32f, StepTimeFast = 0.2f;
+    public const float StepHeight = 0.09f;
+    public const float SettleTime = 0.4f;           // standing still this long → the trailing foot squares up
+
+    private struct Foot
+    {
+        public Vector3 Planted, From, To;
+        public float Yaw, FromYaw, ToYaw;
+        public float T;           // step progress 0..1 (1 = planted)
+        public Vector3 Current;
+        public float CurrentYaw;
+    }
+
+    private readonly Foot[] _feet = new Foot[2];
+    private readonly MeshInstance3D[] _thigh = new MeshInstance3D[2], _shin = new MeshInstance3D[2], _foot = new MeshInstance3D[2];
+    private RigidBody3D _pelvis;
+    private Vector3 _hipLocal;       // pelvis-body-local hip centre
+    private float _thighLen, _shinLen, _ankle, _scale;
+    private bool _initialized;
+    private int _lastStepped;
+    private float _stillTime;
+
+    public void Setup(RigidBody3D pelvis, Vector3 hipLocal, float stature, Color pants, Color shoes)
+    {
+        _pelvis = pelvis;
+        _hipLocal = hipLocal;
+        _thighLen = ThighRatio * stature;
+        _shinLen = ShinRatio * stature;
+        _ankle = AnkleRatio * stature;
+        _scale = stature / 1.75f;
+        PhysicsInterpolationMode = PhysicsInterpolationModeEnum.Off;  // meshes are placed every frame
+        TopLevel = true;
+        for (int i = 0; i < 2; i++)
+        {
+            _thigh[i] = MakeMesh(new Vector3(0.13f * _scale, 1f, 0.14f * _scale), pants);
+            _shin[i] = MakeMesh(new Vector3(0.1f * _scale, 1f, 0.11f * _scale), pants);
+            _foot[i] = MakeMesh(new Vector3(0.1f * _scale, 0.07f * _scale, 0.25f * _scale), shoes);
+        }
+        _initialized = false;
+    }
+
+    private MeshInstance3D MakeMesh(Vector3 size, Color color)
+    {
+        MeshInstance3D m = new() { Mesh = new BoxMesh { Size = size } };
+        m.SetSurfaceOverrideMaterial(0, new StandardMaterial3D { AlbedoColor = color, Roughness = 0.7f });
+        AddChild(m);
+        return m;
+    }
+
+    private Vector3 Hip(Transform3D pelvis, int side) =>
+        pelvis * (_hipLocal + new Vector3(side == 0 ? -HipHalfWidth * _scale : HipHalfWidth * _scale, 0f, 0f));
+
+    private static float YawOf(Basis b)
+    {
+        Vector3 f = -b.Z;
+        return Mathf.Atan2(-f.X, -f.Z);
+    }
+
+    // groundY = where the feet stand (ground control's foot level); crawl = legs collider off.
+    public void Tick(float groundY, bool grounded, bool crawl, Basis yawBasis, float dt)
+    {
+        if (_pelvis == null)
+            return;
+        Transform3D pelvis = _pelvis.GlobalTransform;
+        Vector3 velocity = _pelvis.LinearVelocity;
+        velocity.Y = 0f;
+        float yaw = YawOf(yawBasis);
+        Vector3 back = yawBasis.Z;
+
+        for (int i = 0; i < 2; i++)
+        {
+            Vector3 hip = Hip(pelvis, i);
+            Vector3 side = yawBasis.X * (i == 0 ? -1f : 1f);
+            Vector3 ideal = new Vector3(hip.X, groundY, hip.Z) + side * (StanceHalfWidth - HipHalfWidth) * _scale;
+            if (crawl)
+                ideal += back * (_thighLen + _shinLen) * 0.8f;
+            if (!_initialized)
+            {
+                _feet[i] = new Foot { Planted = ideal, Current = ideal, To = ideal, Yaw = yaw, CurrentYaw = yaw, ToYaw = yaw, T = 1f };
+                continue;
+            }
+
+            ref Foot f = ref _feet[i];
+            if (!grounded)
+            {
+                // Hanging: feet dangle under the hips, a little forward, and replant on landing.
+                Vector3 hang = hip + Vector3.Down * (_thighLen + _shinLen) * 0.92f - back * 0.08f;
+                f.Current = f.Current.Lerp(hang, 1f - Mathf.Exp(-dt * 10f));
+                f.CurrentYaw = Mathf.LerpAngle(f.CurrentYaw, yaw, 1f - Mathf.Exp(-dt * 10f));
+                f.Planted = f.Current;
+                f.T = 1f;
+                continue;
+            }
+
+            if (f.T < 1f)
+            {
+                float speed = velocity.Length();
+                float duration = Mathf.Lerp(StepTimeSlow, StepTimeFast, Mathf.Clamp(speed / 2.5f, 0f, 1f));
+                f.T = Mathf.Min(1f, f.T + dt / duration);
+                f.To = new Vector3(f.To.X, groundY, f.To.Z);
+                float k = Mathf.SmoothStep(0f, 1f, f.T);
+                f.Current = f.From.Lerp(f.To, k) + Vector3.Up * (Mathf.Sin(Mathf.Pi * f.T) * (StepHeight + 0.03f * speed));
+                f.CurrentYaw = Mathf.LerpAngle(f.FromYaw, f.ToYaw, k);
+                if (f.T >= 1f)
+                {
+                    f.Planted = f.To;
+                    f.Yaw = f.ToYaw;
+                }
+            }
+            else
+            {
+                f.Planted = new Vector3(f.Planted.X, Mathf.MoveToward(f.Planted.Y, groundY, dt * 2f), f.Planted.Z);
+                f.Current = f.Planted;
+                f.CurrentYaw = f.Yaw;
+            }
+        }
+
+        if (!_initialized)
+        {
+            _initialized = true;
+            return;
+        }
+        if (!grounded)
+            return;
+
+        // One foot at a time: step the foot that is farthest from where it should be.
+        if (_feet[0].T >= 1f && _feet[1].T >= 1f)
+        {
+            float speed = velocity.Length();
+            _stillTime = speed < 0.05f ? _stillTime + dt : 0f;
+            int pick = -1;
+            float worst = 0f;
+            for (int i = 0; i < 2; i++)
+            {
+                Vector3 hip = Hip(pelvis, i);
+                Vector3 side = yawBasis.X * (i == 0 ? -1f : 1f);
+                Vector3 ideal = new Vector3(hip.X, groundY, hip.Z) + side * (StanceHalfWidth - HipHalfWidth) * _scale;
+                if (crawl)
+                    ideal += back * (_thighLen + _shinLen) * 0.8f;
+                float off = new Vector2(_feet[i].Planted.X - ideal.X, _feet[i].Planted.Z - ideal.Z).Length();
+                float turn = Mathf.Abs(Mathf.AngleDifference(_feet[i].Yaw, yaw));
+                bool need = off > StepTrigger * _scale || turn > StepTurnTrigger || (_stillTime > SettleTime && off > 0.06f);
+                float score = off + turn * 0.2f + (i == _lastStepped ? -0.01f : 0f);
+                if (need && score > worst)
+                {
+                    worst = score;
+                    pick = i;
+                }
+            }
+            if (pick >= 0)
+            {
+                Vector3 hip = Hip(pelvis, pick);
+                Vector3 side = yawBasis.X * (pick == 0 ? -1f : 1f);
+                Vector3 to = new Vector3(hip.X, groundY, hip.Z) + side * (StanceHalfWidth - HipHalfWidth) * _scale + velocity * StepLead;
+                if (crawl)
+                    to += back * (_thighLen + _shinLen) * 0.8f;
+                ref Foot f = ref _feet[pick];
+                f.From = f.Planted;
+                f.FromYaw = f.Yaw;
+                f.To = to;
+                f.ToYaw = yaw;
+                f.T = 0f;
+                _lastStepped = pick;
+                _stillTime = 0f;
+            }
+        }
+    }
+
+    public override void _Process(double delta)
+    {
+        if (_pelvis == null || !_initialized || !IsInstanceValid(_pelvis))
+            return;
+        Transform3D pelvis = _pelvis.GetGlobalTransformInterpolated();
+        Vector3 forward = -pelvis.Basis.Z;
+        forward.Y = 0f;
+        forward = forward.LengthSquared() > 1e-6f ? forward.Normalized() : Vector3.Forward;
+        for (int i = 0; i < 2; i++)
+        {
+            Vector3 hip = Hip(pelvis, i);
+            Vector3 ankle = _feet[i].Current + Vector3.Up * _ankle;
+            // 2-bone solve, knee bending forward.
+            Vector3 d = ankle - hip;
+            float reach = _thighLen + _shinLen;
+            float len = Mathf.Clamp(d.Length(), 0.05f, reach * 0.999f);
+            Vector3 dir = d.LengthSquared() > 1e-8f ? d.Normalized() : Vector3.Down;
+            ankle = hip + dir * len;
+            float along = (_thighLen * _thighLen - _shinLen * _shinLen + len * len) / (2f * len);
+            float radius = Mathf.Sqrt(Mathf.Max(_thighLen * _thighLen - along * along, 0f));
+            Vector3 pole = forward - dir * forward.Dot(dir);
+            pole = pole.LengthSquared() > 1e-6f ? pole.Normalized() : forward;
+            Vector3 knee = hip + dir * along + pole * radius;
+            Place(_thigh[i], hip, knee);
+            Place(_shin[i], knee, ankle);
+            Basis footBasis = new Basis(Vector3.Up, _feet[i].CurrentYaw);
+            _foot[i].GlobalTransform = new Transform3D(footBasis, _feet[i].Current + Vector3.Up * (0.035f * _scale) + footBasis * new Vector3(0f, 0f, -0.06f * _scale));
+        }
+    }
+
+    private static void Place(MeshInstance3D mesh, Vector3 from, Vector3 to)
+    {
+        Vector3 seg = to - from;
+        float len = seg.Length();
+        if (len < 1e-4f)
+            return;
+        Vector3 y = seg / len;
+        Vector3 x = Mathf.Abs(y.Y) < 0.99f ? Vector3.Up.Cross(y).Normalized() : Vector3.Right;
+        Vector3 z = x.Cross(y);
+        // Box mesh is 1 m tall along Y: stretch it to the segment.
+        mesh.GlobalTransform = new Transform3D(new Basis(x, y * len, z), (from + to) * 0.5f);
+    }
+}

scripts/ProceduralLegs.cs.uid

@@ -0,0 +1 @@
+uid://bwbp1b87b5qxx

scripts/PropGrabber.cs

@@ -11,6 +11,8 @@ public partial class PropGrabber : Node
     private const float BreakTime = 0.25f;
     private const float BreakDistanceBoth = 0.4f;
     private const float GripRipDistance = 0.8f;
+    private const float WorldGrabRadius = 0.05f;   // palm sphere for grabbing static world (ledges, bars, holds)
+    public const string NoGrabGroup = "no_grab";   // static bodies that can't be grabbed (the floor)
 
     private static PropGrabber _instance;
 
@@ -18,7 +20,7 @@ public partial class PropGrabber : Node
     private XRController3D _right;
     private PhysicsArms _arms;
 
-    private readonly RigidBody3D[] _held = new RigidBody3D[2];
+    private readonly PhysicsBody3D[] _held = new PhysicsBody3D[2];  // a prop, or static world (climbing)
     private readonly ConeTwistJoint3D[] _joints = new ConeTwistJoint3D[2];
     private readonly Vector3[] _localAnchor = new Vector3[2];
     private readonly uint[] _grabSeq = new uint[2];
@@ -59,7 +61,7 @@ public partial class PropGrabber : Node
 
         if (grip && !_gripPrev[hand] && _held[hand] == null)
         {
-            RigidBody3D prop = FindProp(controller, hand);
+            PhysicsBody3D prop = FindProp(controller, hand);
             RigidBody3D handBody = PhysicsHands.GetBody(controller);
             if (prop != null && handBody != null)
             {
@@ -68,26 +70,27 @@ public partial class PropGrabber : Node
                 Vector3 pivot = PalmPoint(handBody, hand);
                 _joints[hand] = MakeWeld(handBody, prop, pivot, RigidWeldBias);
                 _localAnchor[hand] = prop.GlobalTransform.AffineInverse() * pivot;
-                _arms?.SetHeld(hand, prop);
+                _arms?.SetHeld(hand, prop as RigidBody3D);
                 PlayerRig.SetHeld(controller, prop);
-                GD.Print($"PropGrabber: grabbed '{prop.Name}' ({prop.Mass:0.###} kg, {(hand == 0 ? "left" : "right")}{(_held[other] == prop ? ", two-handed" : "")})");
+                string what = prop is RigidBody3D rb ? $"{rb.Mass:0.###} kg" : "static world";
+                GD.Print($"PropGrabber: grabbed '{prop.Name}' ({what}, {(hand == 0 ? "left" : "right")}{(_held[other] == prop ? ", two-handed" : "")})");
             }
         }
 
         if (!grip && _held[hand] != null)
         {
-            RigidBody3D prop = _held[hand];
+            PhysicsBody3D prop = _held[hand];
             _held[hand] = null;
             DestroyJoint(hand);
-            if (IsInstanceValid(prop))
-                GD.Print($"PropGrabber: released '{prop.Name}' at {prop.LinearVelocity.Length():F2} m/s");
+            if (prop is RigidBody3D released && IsInstanceValid(released))
+                GD.Print($"PropGrabber: released '{released.Name}' at {released.LinearVelocity.Length():F2} m/s");
         }
         _gripPrev[hand] = grip;
     }
 
     private void HoldUpdate(XRController3D controller, int hand, float delta)
     {
-        RigidBody3D body = _held[hand];
+        PhysicsBody3D body = _held[hand];
         if (body == null)
             return;
         if (!IsInstanceValid(body))
@@ -148,7 +151,7 @@ public partial class PropGrabber : Node
         }
     }
 
-    private int PrimaryHand(RigidBody3D body)
+    private int PrimaryHand(PhysicsBody3D body)
     {
         int primary = -1;
         for (int hand = 0; hand < 2; hand++)
@@ -159,7 +162,7 @@ public partial class PropGrabber : Node
         return primary;
     }
 
-    private ConeTwistJoint3D MakeWeld(RigidBody3D handBody, RigidBody3D prop, Vector3 pivot, float bias)
+    private ConeTwistJoint3D MakeWeld(RigidBody3D handBody, PhysicsBody3D prop, Vector3 pivot, float bias)
     {
         ConeTwistJoint3D weld = new()
         {
@@ -175,7 +178,7 @@ public partial class PropGrabber : Node
         return weld;
     }
 
-    private void BreakGrip(int hand, RigidBody3D body, string reason)
+    private void BreakGrip(int hand, PhysicsBody3D body, string reason)
     {
         if (_held[hand] != body)
             return;
@@ -199,7 +202,7 @@ public partial class PropGrabber : Node
 
     private static float PalmOffset(int hand) => hand == 0 ? PalmGrabOffset : -PalmGrabOffset;
 
-    private RigidBody3D FindProp(XRController3D controller, int hand)
+    private PhysicsBody3D FindProp(XRController3D controller, int hand)
     {
         RigidBody3D handBody = PhysicsHands.GetBody(controller);
         if (handBody == null)
@@ -208,7 +211,27 @@ public partial class PropGrabber : Node
         RigidBody3D nearest = NearestProp(palm, GrabRadius);
         if (nearest != null)
             return nearest;
-        return NearestProp(handBody.GlobalPosition, CenterGrabRadius);
+        nearest = NearestProp(handBody.GlobalPosition, CenterGrabRadius);
+        if (nearest != null)
+            return nearest;
+        return WorldUnderPalm(palm, handBody.GetWorld3D());
+    }
+
+    // Climbing: any static body touching the palm (except the "no_grab" group) can be held.
+    private static StaticBody3D WorldUnderPalm(Vector3 palm, World3D world)
+    {
+        PhysicsShapeQueryParameters3D query = new()
+        {
+            Shape = new SphereShape3D { Radius = WorldGrabRadius },
+            Transform = new Transform3D(Basis.Identity, palm),
+            CollisionMask = 1,
+        };
+        foreach (Godot.Collections.Dictionary hit in world.DirectSpaceState.IntersectShape(query, 8))
+        {
+            if (hit["collider"].AsGodotObject() is StaticBody3D body && !body.IsInGroup(NoGrabGroup))
+                return body;
+        }
+        return null;
     }
 
     private RigidBody3D NearestProp(Vector3 point, float radius)

scripts/RagdollSpike.cs

@@ -57,6 +57,17 @@ public partial class RagdollSpike : Node3D
         _phases.Add(("12 kg held at arm's length sags more", () => SetupWeight(close: false), _ => { }, 3f, () => FinishWeight(close: false)));
         _phases.Add(("teleport + snap turn carry the body", Rest, TickTeleport, 2f, FinishTeleport));
         _phases.Add(("random motion soak", Rest, TickRandom, 8f, FinishSoak));
+        _phases.Add(("a knee-high box blocks walking (no stepping onto it)", () => SetupObstacle(0.6f), _ => _stickVelocity = new Vector3(0f, 0f, -1.5f), 3f, FinishBlockedLow));
+        _phases.Add(("a table can't be walked over", SetupTableObstacle, _ => _stickVelocity = new Vector3(0f, 0f, -1.5f), 3f, FinishBlockedLow));
+        _phases.Add(("walks up a 0.25 m step", () => SetupObstacle(0.25f, 8f), _ => _stickVelocity = new Vector3(0f, 0f, -1.2f), 3f, FinishStep));
+        _phases.Add(("two-handed mantle onto a 0.9 m ledge", () => SetupObstacle(0.9f), t => TickMantle(both: true), 6f, () => FinishMantle(true)));
+        _phases.Add(("one hand can't mantle", () => SetupObstacle(0.9f), t => TickMantle(both: false), 6f, () => FinishMantle(false)));
+        _phases.Add(("two-handed pull-up on a grabbed bar", () => SetupBarHang(), t => TickPullUp(both: true), 3.5f, () => FinishPullUp(true)));
+        _phases.Add(("one-handed pull-up is weaker", () => SetupBarHang(), t => TickPullUp(both: false), 3.5f, () => FinishPullUp(false)));
+        _phases.Add(("crawls through a 0.6 m tunnel", SetupTunnel, TickCrawl, 7f, FinishCrawl));
+        _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(("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();
     }
 
@@ -448,6 +459,198 @@ public partial class RagdollSpike : Node3D
         return _finite && NewSnaps == 0 && _maxEyeErr < 0.05f && _maxHandErr < 0.06f;
     }
 
+    // ---------------------------------------------------------------- obstacles, mantling, climbing, crawling
+
+    private const float ObstacleFront = -0.55f;
+
+    // A box from ObstacleFront 2 m deep (wide), `height` tall.
+    private void SetupObstacle(float height, float depth = 2f)
+    {
+        Rest();
+        _stage.AddChild(MakeStatic(new Vector3(3f, height, depth), new Vector3(0f, height * 0.5f, ObstacleFront - depth * 0.5f), 29));
+    }
+
+    private void SetupTableObstacle()
+    {
+        Rest();
+        _stage.AddChild(MakeStatic(new Vector3(1.4f, 0.05f, 0.8f), new Vector3(0f, 0.725f, ObstacleFront - 0.4f), 29));
+        foreach (float x in new[] { -0.65f, 0.65f })
+            foreach (float z in new[] { ObstacleFront - 0.05f, ObstacleFront - 0.75f })
+                _stage.AddChild(MakeStatic(new Vector3(0.06f, 0.7f, 0.06f), new Vector3(x, 0.35f, z), 29));
+    }
+
+    private bool FinishBlockedLow()
+    {
+        GD.Print($"RAGDOLL:   obstacle front z {ObstacleFront}: pelvis z {_ragdoll.Pelvis.GlobalPosition.Z:F3}, feet y {_ragdoll.GroundY:F3}, origin y {_origin.Origin.Y:F3}, camera min z {_minCamZ:F3}, snaps {NewSnaps}");
+        return _finite && NewSnaps == 0 && _ragdoll.GroundY < 0.1f && _origin.Origin.Y < 0.1f && _ragdoll.Pelvis.GlobalPosition.Z > ObstacleFront - 0.3f;
+    }
+
+    private bool FinishStep()
+    {
+        GD.Print($"RAGDOLL:   step: feet y {_ragdoll.GroundY:F3}, origin y {_origin.Origin.Y:F3}, pelvis z {_ragdoll.Pelvis.GlobalPosition.Z:F3}, snaps {NewSnaps}");
+        return _finite && NewSnaps == 0 && Mathf.Abs(_ragdoll.GroundY - 0.25f) < 0.03f && _origin.Origin.Y > 0.2f && _ragdoll.Pelvis.GlobalPosition.Z < ObstacleFront - 0.3f;
+    }
+
+    private float _maxPelvisRise, _lastRise;
+
+    // Put both hands on the ledge, press down (controllers sink as the real arms straighten), then
+    // walk forward onto it.
+    // Walk up to the ledge (the legs collider stops you), hands on top just ahead, press down.
+    private void TickMantle(bool both)
+    {
+        float t = _t;
+        _stickVelocity = t < 1f ? new Vector3(0f, 0f, -0.8f) : t > 3.5f ? new Vector3(0f, 0f, -0.8f) : Vector3.Zero;
+        float down = Mathf.Clamp((t - 1.6f) / 1.5f, 0f, 1f);
+        float y = t < 1.6f ? Mathf.Lerp(1.0f, 0.95f, Mathf.Clamp(t - 1f, 0f, 0.6f) / 0.6f) : Mathf.Lerp(0.95f, 0.35f, down);
+        // Hands just past the ledge edge (aimed in the room, like a real player looking at it).
+        float z = t < 1f ? -0.4f : ObstacleFront - 0.1f - _origin.Origin.Z;
+        Vector3 l = new(-0.22f, y, z), r = new(0.22f, y, z);
+        _rightLocal = new Transform3D(Aim(Vector3.Down + Vector3.Forward * 0.3f), r);
+        _leftLocal = both ? new Transform3D(Aim(Vector3.Down + Vector3.Forward * 0.3f), l) : new Transform3D(Basis.Identity, new Vector3(-0.2f, 1.0f, -0.3f));
+        if (t > 3.6f)
+        {
+            // Up and walking on: hands come back to the body like a real player's.
+            _leftLocal = new Transform3D(Basis.Identity, new Vector3(-0.2f, 1.0f, -0.3f));
+            _rightLocal = new Transform3D(Basis.Identity, new Vector3(0.2f, 1.0f, -0.3f));
+        }
+        if (_ragdoll.Built && !_needBuild)
+            _maxPelvisRise = Mathf.Max(_maxPelvisRise, _ragdoll.Pelvis.GlobalPosition.Y - 0.99f);
+    }
+
+    private bool FinishMantle(bool both)
+    {
+        GD.Print($"RAGDOLL:   mantle ({(both ? "two hands" : "one hand")}): pelvis rose up to {_maxPelvisRise:F3} m, feet y {_ragdoll.GroundY:F3}, origin y {_origin.Origin.Y:F3}, snaps {NewSnaps}");
+        bool onTop = _ragdoll.GroundY > 0.85f && _origin.Origin.Y > 0.8f;
+        _lastRise = _maxPelvisRise;
+        _maxPelvisRise = 0f;
+        return _finite && NewSnaps == 0 && (both ? onTop : !onTop && _lastRise < 0.25f);
+    }
+
+    private StaticBody3D _bar;
+    private const float BarY = 1.95f, BarHangZ = -0.15f;
+    private float _barPelvisStart;
+    private bool _barGrabbed;
+
+    private void SetupBarHang()
+    {
+        Rest();
+        _bar = new StaticBody3D { Position = new Vector3(0f, BarY, BarHangZ), CollisionMask = 29 };
+        _bar.AddChild(new CollisionShape3D { Shape = new CylinderShape3D { Radius = 0.025f, Height = 2f }, RotationDegrees = new Vector3(0f, 0f, 90f) });
+        _stage.AddChild(_bar);
+        _barGrabbed = false;
+        _maxPelvisRise = 0f;
+    }
+
+    // Reach up to the bar, grip it (the PropGrabber weld), then pull the controllers down.
+    private void TickPullUp(bool both)
+    {
+        float t = _t;
+        float pull = Mathf.Clamp((t - 0.8f) / 1.5f, 0f, 1f);
+        float y = Mathf.Lerp(BarY - 0.03f, BarY - 0.75f, pull);
+        Basis grip = Aim(Vector3.Up + Vector3.Forward * 0.2f);
+        _rightLocal = new Transform3D(grip, new Vector3(0.22f, y, BarHangZ + 0.03f));
+        _leftLocal = both ? new Transform3D(grip, new Vector3(-0.22f, y, BarHangZ + 0.03f)) : new Transform3D(Basis.Identity, new Vector3(-0.2f, 1.0f, -0.3f));
+        if (!_barGrabbed && t > 0.6f && _ragdoll.Built)
+        {
+            _barGrabbed = true;
+            _barPelvisStart = _ragdoll.Pelvis.GlobalPosition.Y;
+            for (int side = both ? 0 : 1; side < 2; side++)
+            {
+                RigidBody3D hand = _ragdoll.Hand(side);
+                ConeTwistJoint3D weld = new() { Position = hand.GlobalPosition, NodeA = hand.GetPath(), NodeB = _bar.GetPath(), SwingSpan = 0f, TwistSpan = 0f, Bias = 0f };
+                _stage.AddChild(weld);
+                _ragdoll.SetHeld(side, _bar);
+            }
+        }
+        if (_barGrabbed)
+            _maxPelvisRise = Mathf.Max(_maxPelvisRise, _ragdoll.Pelvis.GlobalPosition.Y - _barPelvisStart);
+    }
+
+    private float _twoHandRise;
+
+    private bool FinishPullUp(bool both)
+    {
+        GD.Print($"RAGDOLL:   pull-up ({(both ? "two hands" : "one hand")}): pelvis rose {_maxPelvisRise:F3} m, braced {_ragdoll.Braced}, snaps {NewSnaps}");
+        _ragdoll.SetHeld(0, null);
+        _ragdoll.SetHeld(1, null);
+        if (both)
+        {
+            _twoHandRise = _maxPelvisRise;
+            return _finite && NewSnaps == 0 && _maxPelvisRise > 0.25f;
+        }
+        return _finite && NewSnaps == 0 && _maxPelvisRise < _twoHandRise * 0.6f;
+    }
+
+    private const float TunnelStart = -1.0f, TunnelEnd = -3.5f;
+    private float _minCamY;
+
+    private void SetupTunnel()
+    {
+        Rest();
+        float len = TunnelStart - TunnelEnd;
+        float mid = (TunnelStart + TunnelEnd) * 0.5f;
+        _stage.AddChild(MakeStatic(new Vector3(1.4f, 0.1f, len), new Vector3(0f, 0.65f, mid), 29));
+        _stage.AddChild(MakeStatic(new Vector3(0.1f, 0.6f, len), new Vector3(-0.65f, 0.3f, mid), 29));
+        _stage.AddChild(MakeStatic(new Vector3(0.1f, 0.6f, len), new Vector3(0.65f, 0.3f, mid), 29));
+        _minCamY = float.MaxValue;
+    }
+
+    // Get down on hands and knees (eyes ~0.4 m, looking ahead), then stick-crawl forward.
+    private void TickCrawl(float dt)
+    {
+        float k = Mathf.SmoothStep(0f, 1f, Mathf.Min(_t / 2f, 1f));
+        _headLocal = new Transform3D(new Basis(Vector3.Right, -0.35f * k), new Vector3(0f, Mathf.Lerp(EyeHeight, 0.42f, k), Mathf.Lerp(0f, -0.25f, k)));
+        _leftLocal = new Transform3D(Aim(Vector3.Forward + Vector3.Down), new Vector3(-0.2f, Mathf.Lerp(1.0f, 0.12f, k), Mathf.Lerp(-0.3f, -0.45f, k)));
+        _rightLocal = new Transform3D(Aim(Vector3.Forward + Vector3.Down), new Vector3(0.2f, Mathf.Lerp(1.0f, 0.12f, k), Mathf.Lerp(-0.3f, -0.45f, k)));
+        _stickVelocity = _t > 2.3f ? new Vector3(0f, 0f, -0.8f) : Vector3.Zero;
+        _measureFrom = float.MaxValue;
+        if (_t > 2.3f)
+            _minCamY = Mathf.Min(_minCamY, Camera.Origin.Y);
+    }
+
+    private bool FinishCrawl()
+    {
+        GD.Print($"RAGDOLL:   crawl: camera min z {_minCamZ:F3} (tunnel {TunnelStart}..{TunnelEnd}), eye y {_ragdoll.Eye.Y:F2}, pelvis y {_ragdoll.Pelvis.GlobalPosition.Y:F2}, origin y {_origin.Origin.Y:F3}, snaps {NewSnaps}");
+        return _finite && NewSnaps == 0 && _minCamZ < TunnelStart - 1.5f && Mathf.Abs(_origin.Origin.Y) < 0.1f;
+    }
+
+
+    // Start standing on a 1 m platform whose edge is 0.5 m ahead.
+    private void SetupLedgeTop()
+    {
+        Rest();
+        _origin = new Transform3D(Basis.Identity, new Vector3(0f, 1f, 0f));
+        _stage.AddChild(MakeStatic(new Vector3(3f, 1f, 3f), new Vector3(0f, 0.5f, 1f), 29));
+    }
+
+    private bool FinishDrop()
+    {
+        GD.Print($"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;
+    }
+
+    // A slope rising away (−Z) from ObstacleFront up to 1 m, then a platform.
+    private void SetupRamp(float degrees)
+    {
+        Rest();
+        float a = Mathf.DegToRad(degrees);
+        float len = 1f / Mathf.Sin(a);
+        float run = Mathf.Cos(a) * len;
+        _stage.AddChild(new StaticBody3D { CollisionMask = 29, Transform = new Transform3D(new Basis(Vector3.Right, a), new Vector3(0f, 0.5f - 0.05f / Mathf.Cos(a), ObstacleFront - run * 0.5f)) });
+        _stage.GetChild<StaticBody3D>(_stage.GetChildCount() - 1).AddChild(new CollisionShape3D { Shape = new BoxShape3D { Size = new Vector3(3f, 0.1f, len) } });
+        _stage.AddChild(MakeStatic(new Vector3(3f, 1f, 3f), new Vector3(0f, 0.5f, ObstacleFront - run - 1.5f), 29));
+    }
+
+    private bool FinishRamp(bool walkable)
+    {
+        GD.Print($"RAGDOLL:   ramp: feet y {_ragdoll.GroundY:F3}, origin y {_origin.Origin.Y:F3}, pelvis {_ragdoll.Pelvis.GlobalPosition}, snaps {NewSnaps}");
+        bool up = _ragdoll.GroundY > 0.6f;
+        // Stopped at the slope's foot: on the floor, view level, not flung away.
+        bool stopped = Mathf.Abs(_origin.Origin.Y) < 0.1f && _ragdoll.Pelvis.GlobalPosition.Length() < 2.5f;
+        return _finite && NewSnaps == 0 && (walkable ? up : !up && stopped);
+    }
+
     private readonly RandomNumberGenerator _rng = new() { Seed = 11 };
     private Vector3 _ra, _rb, _rc;
 

scripts/TrueBody.cs

@@ -14,6 +14,10 @@ public sealed class TrueBodySolver
     public const float ChestLeanMax = 0.75f;              // rad (~43°) at a deep crouch
     public const float CrouchRange = 0.5f;                // crouch factor 1 when eyes are this fraction of standing eye height lower
     public const float HeadPitchToChest = 0.25f;
+    // Crawl: when the head gets so low that the hips would go through the floor, the trunk tips
+    // further (pivoting at the hips, hips kicking back) up to nearly horizontal (Nimso: lower = crawl).
+    public const float CrawlLeanMax = 1.45f;              // rad (~83°)
+    public const float HipMinHeight = 0.15f;              // hip joint above the floor when crawling
     public const float PelvisFrequency = 2.5f;            // Hz, critically damped follow → hip lag/sway
     public const float GirdleReachStart = 0.98f;          // fraction of arm length where the shoulder starts to help
     public const float GirdleSmoothRate = 15f;
@@ -100,18 +104,27 @@ public sealed class TrueBodySolver
         Crouch = Mathf.Clamp((standingPivot - pivotAboveFloor) / (CrouchRange * p.EyeHeight), 0f, 1f);
         float headPitchDown = Mathf.Max(0f, -Mathf.Asin(Mathf.Clamp(headFwd.Y, -1f, 1f)));
         float lean = Crouch * ChestLeanMax + headPitchDown * HeadPitchToChest;
-        Lean = lean;
-        ChestBasis = yawBasis * new Basis(Vector3.Right, -lean);
-
-        // Neck: from the head pivot down along the average of chest-up and head-up, sized so a
-        // standing, level head puts the shoulder joints at the measured drop below the eyes.
+        float trunk = TrunkRatio * p.Stature;
         float neckLen = Mathf.Max(0.05f, p.ShoulderDrop + EyeToNeckPivot.Y - NeckBaseAboveShoulders);
-        Vector3 neckDir = (ChestBasis.Y + headBasis.Y).Normalized();
-        NeckBase = NeckPivot - neckDir * neckLen;
-        // Keep the shoulder line behind the eyes by the anthropometric offset (neck pivot already
-        // supplies part of it).
-        UpperChest = NeckBase - ChestBasis.Y * NeckBaseAboveShoulders
-            + ChestBasis * new Vector3(0f, 0f, ShouldersBehindEyes - EyeToNeckPivot.Z);
+        Vector3 neckDir = Vector3.Up;
+        for (int iter = 0; iter < 3; iter++)
+        {
+            ChestBasis = yawBasis * new Basis(Vector3.Right, -lean);
+            // Neck: from the head pivot down along the average of chest-up and head-up, sized so a
+            // standing, level head puts the shoulder joints at the measured drop below the eyes.
+            neckDir = (ChestBasis.Y + headBasis.Y).Normalized();
+            NeckBase = NeckPivot - neckDir * neckLen;
+            // Keep the shoulder line behind the eyes by the anthropometric offset (neck pivot already
+            // supplies part of it).
+            UpperChest = NeckBase - ChestBasis.Y * NeckBaseAboveShoulders
+                + ChestBasis * new Vector3(0f, 0f, ShouldersBehindEyes - EyeToNeckPivot.Z);
+            float room = (UpperChest.Y - floorY - HipMinHeight) / trunk;
+            float crawl = Mathf.Acos(Mathf.Clamp(room, Mathf.Cos(CrawlLeanMax), 1f));
+            if (crawl <= lean + 1e-3f)
+                break;
+            lean = crawl;
+        }
+        Lean = lean;
 
         // Pelvis: hangs below the upper chest along the trunk; follows through a critically damped
         // spring so it lags quick head motion (hip sway) instead of being rigidly attached.

scripts/WorldPanel.cs

@@ -61,6 +61,7 @@ public partial class WorldPanel : Node3D
         _menu.ResetPropsRequested += () =>
         {
             _propShop.Respawn();
+            GetNodeOrNull<Playground>("../../Playground")?.Reset();
             _menu.Log("Props reset");
         };
         _menu.PingRequested += () =>
@@ -75,6 +76,9 @@ public partial class WorldPanel : Node3D
         _click = MakeTone(900f, 25, 0.35f, 1f);
         _ping = MakeTone(1320f, 4, 0.3f, 3f);
         _menu.ClickVolumeSlider.ValueChanged += v => _click.VolumeDb = Mathf.LinearToDb((float)v / 70f);
+        _menu.StrengthChanged += v => PlayerRagdoll.Strength = v;
+        _menu.SmoothTurnToggled += on => PlayerRig.SmoothTurn = on;
+        _menu.SpectatorToggled += PlayerRig.SetSpectator;
 
         SetPanelActive(false);
     }