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>

AGENTS.md

@@ -123,7 +123,9 @@ device only; the editor has an XR simulator for dev. Trackers/action map: see `x
   ruin immersion and are hard to aim at distance; they are the fallback, not the default.
 - **Hand tracking**: cheap spike early, full support later. Interaction logic must not assume
   controllers — controller tip and fingertip feed the same cursor concept.
-- **Locomotion** (implemented, NEEDS FIXING per owner 2026-10-01 — two-hand turn not
+- **Locomotion** (SUPERSEDED 2026-10-02 by the ragdoll player's stick locomotion in `PlayerRig`; the grab-drag
+  mode below survives only as the menu's Spectator mode; teleport markers still work and carry the body.
+  Historical notes: implemented, NEEDS FIXING per owner 2026-10-01 — two-hand turn not
   2-anchor based, two-hand simultaneous move weird, teleport + lasers broken/experimental;
   fix-or-replace rides on the body-physics track decision, owner candidate replacement =
   physics thumbstick movement):
@@ -297,8 +299,14 @@ device only; the editor has an XR simulator for dev. Trackers/action map: see `x
    discrete origin jumps carry the body). It REPLACED PhysicsHands/PhysicsTorso/PhysicsArms/BodyRig in
    `main.tscn` (legacy files kept for their spikes). Record + measured rules:
    `research/ragdoll-player-step2.md` — **never put a light (< ~1 kg) body between two strong motors** (Box3D
-   one-iteration substeps oscillate). Regression `scenes/ragdoll_spike.tscn`. Next: procedural legs, 144 Hz,
-   climbing. Owner scope: thumbstick locomotion only, no jump, avatar scaling and NPCs later.
+   one-iteration substeps oscillate). Regression `scenes/ragdoll_spike.tscn`. **Step 2.1 (owner playtest fixes):**
+   step rule + lower-body collider (no walking onto tables), structural arm strength (two-hand mantles/pull-ups,
+   one hand can't), crawl pose, slope limit 35°, climbing on any static body (group `no_grab` excluded = the floor),
+   `ProceduralLegs`, `Playground.cs` sandbox, menu strength slider / spectator (old drag movement, no body) / snap-
+   smooth turn, **physics 144 Hz with physics interpolation** (`Main.PhysicsRate`; XROrigin3D, TrueBody, PlayerRig
+   are interpolation-OFF because they move per frame — anything new moved in `_Process` must be excluded too).
+   Rule learned: play-space corrections must never feed ground control's feed-forward (runaway feedback).
+   Owner scope: thumbstick locomotion only, no jump, avatar scaling and NPCs later.
 10. **Body physics Stage 2 — PHYSICAL ARMS, implemented 2026-10-02, awaiting owner playtest.**
    `PhysicsArms.cs`: per side an upper-arm + forearm RigidBody3D (2.0 / 1.2 kg, layer 5) that
    PD-chase their analytic 2-bone IK pose, solved each physics tick from the PHYSICAL chest