Render-clock tracking timestamps (menu toggle), physics step cap 6, docs for step 2.7

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

scripts/RagdollSpike.cs

@@ -83,6 +83,7 @@ public partial class RagdollSpike : Node3D
         AddChild(_ragdoll);
 
         _phases.Add(("hinge sign", SetupHinge, TickHinge, 0.3f, FinishHinge));
+        _phases.Add(("pose filter: render-timed tracking moves evenly (no 18 Hz beat)", Rest, _ => { }, 0.05f, FinishPoseFilter));
         _phases.Add(("stands still, head on the camera, hands on the controllers", Rest, _ => { }, 4f, FinishStand));
         _phases.Add(("reaches forward, out and overhead", Rest, TickReach, 4.5f, FinishReach));
         _phases.Add(("fast arm swings stay attached", Rest, TickSwing, 3f, FinishSwing));
@@ -233,6 +234,38 @@ public partial class RagdollSpike : Node3D
 
     private int NewSnaps => _ragdoll.Snaps - _snapsAtStart;
 
+    // A controller moving at 1 m/s, sampled once per 90 Hz frame (predicted for that frame's render
+    // time), read by 144 Hz ticks. Per-tick output steps should all be 1/144 m: timestamped by
+    // arrival they alternate (1 or 2 ticks late), timestamped by render time they don't.
+    private static bool FinishPoseFilter()
+    {
+        float Spread(bool stamped)
+        {
+            PoseFilter f = new();
+            float min = float.MaxValue, max = 0f;
+            Vector3 prev = Vector3.Zero;
+            for (int tick = 0; tick < 300; tick++)
+            {
+                double now = tick / 144.0;
+                long frame = (long)Math.Floor(now * 90.0);           // the last frame delivered before this tick
+                double render = (frame + 1) / 90.0;                  // its predicted display time
+                Transform3D raw = new(Basis.Identity, new Vector3((float)render, 0f, 0f));
+                Vector3 p = f.Sample(raw, now, stamped ? render : null).Origin;
+                if (tick > 20)
+                {
+                    float step = p.X - prev.X;
+                    min = Mathf.Min(min, step);
+                    max = Mathf.Max(max, step);
+                }
+                prev = p;
+            }
+            return (max - min) * 144f;   // spread of the per-tick speed, m/s
+        }
+        float arrival = Spread(false), stamped = Spread(true);
+        GD.Print($"RAGDOLL:   pose filter at 1 m/s: per-tick speed spread {arrival:F3} m/s by arrival, {stamped:F3} m/s render-timed");
+        return stamped < 0.05f && stamped < arrival;
+    }
+
     private static StaticBody3D MakeStatic(Vector3 size, Vector3 pos, uint mask = 0)
     {
         StaticBody3D body = new() { Position = pos, CollisionMask = mask };