Body physics Stage 1: PhysicsTorso chase chest (30 kg PD + yaw servo), collision layers reworked (3=body, 4=hands, no self-collision), BodyRig visual-only, BodySpike regression (PASS 3x, all spikes green)

HANDOFF.md

@@ -65,7 +65,8 @@ TERMINOLOGY (owner-corrected — use precisely):
   near (`WorldPanel.IsBlocking`). **All deltas and turn pivots in WORLD space** (tracking-space math
   made turns orbit the map center — do not regress). Drives `XROrigin3D` directly.
 - **PhysicsHands.cs** — physical palm bodies chasing the controller poses: 0.4 kg boxes (flat slab,
-  thumb-side face), gravity off, CCD, layer 1/mask 1. Chase = desired velocity `(target-pos)/dt`
+  thumb-side face), gravity off, CCD, **layer 4 (player hands)/mask 1|4** — NOT colliding with the
+  chest (layer 3), excluded both ways. Chase = desired velocity `(target-pos)/dt`
   force-clamped to `HandMaxForce` 90 N; rotation hard-locked by setting angular velocity to the
   controller's rotation error (clamped to 120 rad/s). Safety: stuck (> 0.2 m for 1 s) → snap +
   log; > `SnapDistance` 2 m → silent teleport snap — BOTH SUSPENDED for a hand while
@@ -119,22 +120,26 @@ TERMINOLOGY (owner-corrected — use precisely):
   grab/teleport; `IsPanelCollider(node)` identifies interactive colliders for lasers.
 - **TeleportMarker.cs** — `scenes/teleport_marker.tscn`: disc + beam + Label3D, group
   "teleport_marker", StaticBody pick box. `SetNear` hides visuals, `SetHighlighted` swaps colors.
-- **BodyRig.cs** — placeholder cube "getting a body" v1.1 (all primitives boxes per owner). Head
-  0.15³ pushed 6 cm behind the eyes (`HeadBackOffset`); torso 0.22×0.5×0.13, dropped 0.42 and
-  retracted 6 cm; yaw basis from HMD (flattened forward). Proportions calibrated at runtime from
-  head height (once, after height > 0.5 m): armTotal = 0.46×headHeight clamped [0.5, 0.72],
-  50/50 upper/fore split, shoulder half-width 0.16 + 0.02×height. Arms: wrist-anchored IK target
-  (palm base = hand body +Z·`WristOffset` 0.06, not palm center) with SOFT IK — shoulder→hand
-  distance clamped to reach×`SoftIKFactor` (0.98) BEFORE the law-of-cosines solve, so the arm is
-  never perfectly straight (if near-extension shake persists, lower `SoftIKFactor` toward 0.95).
-  Elbow pole = down + back + slight outward, projected OUT of the shoulder→hand axis, minus hand
-  forward × `PoleHandWeight` (0.25), exp-smoothed at `PoleSmoothRate` (10/s). Torso yaw SPRING,
-  decoupled from the head: HMD yaw base blended toward hands-derived yaw by forwardness ×
-  `TorsoYawHandsWeight` (forwardness = horizontal dot / `TorsoYawForwardness` 0.3 m, clamped 0–1),
-  exp smoothing `TorsoYawSmoothRate` (12/s ≈ 200 ms response). Torso reach budget WITH HYSTERESIS:
-  push only past full reach (0.8 m/s), decay
-  only below 92% of reach (0.4 m/s, `MoveToward` zero); offset clamped horizontal ≤ 0.25 m,
-  vertical [−0.05, +0.12]. Hidden until calibrated.
+- **PhysicsTorso.cs** — the player's PHYSICAL CHEST (body-physics Stage 1, implemented 2026-10-01).
+  One RigidBody3D box (0.22×0.5×0.13, 30 kg, gravity off, CCD, contact monitor), chase-driven
+  toward an HMD-derived target: target = head − 6 cm back + torso-yaw basis·(0, −0.42, +0.06)
+  + `ReachOffset` (fed by BodyRig's reach budget). Linear drive = the PhysicsHands pattern at
+  body mass (force-clamped PD, `MaxForce` 2400 N ⇒ 80 m/s², `MaxSpeed` 6 m/s). Orientation =
+  slewed angular-velocity servo toward the yaw target (Kp 20 rad/s per rad, spin cap 10 rad/s,
+  alpha cap 150 rad/s²) — self-rights when shoved, holds yaw. `SnapDistance` 2 m snap safety
+  covers teleports. Camera stays KINEMATIC — the torso chases the head, never the reverse
+  (Boneworks sickness lesson). Yaw spring (HMD + hands blend) MOVED here from BodyRig.
+  Collision: layer 3 (player body), mask 1|3 — props/floor touch it, own hands do NOT
+  (hands moved to layer 4; excluded both ways — no self-collision, VRChat/Nimso precedent).
+  Owns its torso mesh (hidden until the body first arrives at target). Spike:
+  `scenes/body_spike.tscn` must print **"BODY: overall PASS"** (pair-rule proofs: one-way
+  floor contact, hand-through-chest exclusion, prop-contact two-way; track/yaw/impact/snap/
+  self-right asserts).
+- **BodyRig.cs** — placeholder rig VISUALS only now (v1.3): head cube (HMD-driven), 2-bone
+  analytic arms (soft IK 0.98, pole as before), shoulders derived from the PhysicsTorso BODY
+  pose (+ ShoulderRise 0.25, ± body X). The torso mesh and the torso yaw spring moved into
+  PhysicsTorso; BodyRig computes the reach budget (hysteresis unchanged) and feeds it to
+  `PhysicsTorso.ReachOffset`. Hidden until calibrated.
 - **GrabSpike.cs** + `scenes/grab_spike.tscn` — headless grab regression (v5.3): a hand stand-in
   (0.4 kg body, `HandMaxForce` 90 N chase) grabs a 1 kg prop via ConeTwist weld (server type
   verified, configure-before-AddChild); drag 2 m + 360° fast-spin sub-phase — asserts RIGID
@@ -148,6 +153,12 @@ TERMINOLOGY (owner-corrected — use precisely):
   bodies welded via ConeTwistJoint3D (bias 0 rigid, then bias 0.5 soft); asserts relative-pose
   rigidity under torque/force (rot < 2°, sep < 1 cm), bounded excursion + full recovery for
   the soft weld. Run this FIRST whenever the addon binaries change.
+- **BodySpike.cs** + `scenes/body_spike.tscn` — headless regression for the physical torso:
+  pair-rule proofs on Box3D (one-way floor contact; hand-config body passes through the chest
+  with the chest undisturbed; prop-config body transfers contact), then track (walk pattern,
+  error < 6 cm), yaw (90°/1 s turn: peak < 15°, settled < 4°), impact (5 kg at 3 m/s: dip
+  < 0.2 m, recovers < 2 cm, never tunnels, rebounds), teleport snap, self-right (< 3° after
+  a pitch impulse). Must print **"BODY: overall PASS"** 3× deterministic.
 
 Research (`research/`): seven full sourced reports — `vr-arm-ik.md`, `vr-arm-ik-deep.md`,
 `vr-grabbing.md`, `vr-two-handed-grab.md` (grab v5.0→5.2 history + the verified Box3D pin
@@ -163,7 +174,8 @@ leaving the standard RigidBody3D stack).
 
 Scene wiring (`scenes/main.tscn`): Main → WorldEnvironment, Sun, Floor, XROrigin3D (XRCamera3D,
 LeftHand, RightHand, WorldPanel), SpawnPoint, 3 TeleportMarkers, Locomotion, AnchorMoveMode,
-PropShop, PropGrabber, PhysicsHands, BodyRig, FadeLayer/Fade. Action map: `openxr_action_map.tres`.
+PropShop, PropGrabber, PhysicsHands, PhysicsTorso, BodyRig, FadeLayer/Fade. Action map: `openxr_action_map.tres`.
+Floor StaticBody scans layer 3 (collision_mask 13).
 
 ## 4. Architecture decisions that must not regress
 
@@ -188,7 +200,10 @@ PropShop, PropGrabber, PhysicsHands, BodyRig, FadeLayer/Fade. Action map: `openx
   as fallback (git history). Stink-O's box3d-godot (custom components, more joint types) is
   the plan-B.
 - **Collision layers**: 1 = world, 2 = UI. Panel/knob bodies are layer 2 mask 0 (props pass through
-  the menu); hands layer 1. Layers/masks live on `CollisionObject3D`, never `CollisionShape3D`.
+  the menu); **1 = world+props, 2 = UI, 3 = player body (chest), 4 = player hands** — chest↔own
+  hands excluded BOTH ways (no self-collision; props mask 1|3|4, floor mask 1|3|4, hands 4/1|4,
+  chest 3/1|3). Layers/masks live on `CollisionObject3D`, never `CollisionShape3D`. The
+  body_spike proves the pair rules on Box3D.
 - **Ghosts belong to hands, not props** — the whole arm gets a ghost later.
 - **Standard-RigidBody3D-only** for scene objects and tracked bodies, so the Jolt fallback stays lossless.
 - **`pose_recentered` is never used for placement** — WiVRN fires it continuously (~90 Hz);
@@ -261,7 +276,10 @@ PropShop, PropGrabber, PhysicsHands, BodyRig, FadeLayer/Fade. Action map: `openx
 | Grip/trigger thresholds | several files | 0.6 | polled Float edges |
 | `SoftIKFactor` | BodyRig.cs | 0.98 | shoulder→hand distance clamp before IK solve (lower toward 0.95 if shake persists) |
 | `PoleHandWeight` / `PoleSmoothRate` | BodyRig.cs | 0.25 / 10 | elbow pole: hand-forward push / exp smoothing |
-| `TorsoYawHandsWeight` / `TorsoYawForwardness` / `TorsoYawSmoothRate` | BodyRig.cs | 0.6 / 0.3 m / 12 | torso yaw spring: hands blend / forwardness normalizer / exp smoothing (≈200 ms) |
+| `TorsoYawHandsWeight` / `TorsoYawForwardness` / `TorsoYawSmoothRate` | PhysicsTorso.cs | 0.6 / 0.3 m / 12 | torso yaw spring: hands blend / forwardness normalizer / exp smoothing (≈200 ms) |
+| `TorsoMass` / `MaxForce` / `MaxSpeed` | PhysicsTorso.cs | 30 kg / 2400 N / 6 m/s | chest chase budget (force-clamped PD) |
+| `OrientKp` / `OrientMaxSpin` / `OrientMaxAlpha` | PhysicsTorso.cs | 20 / 10 rad/s / 150 rad/s² | chest orientation servo (yaw hold + self-right) |
+| `SnapDistance` | PhysicsTorso.cs | 2 m | chest teleport snap safety |
 | `armTotal` | BodyRig.cs | clamp(0.46×headHeight, 0.5, 0.72) | total arm length, 50/50 split |
 | `ReachPushSpeed` / `ReachDecaySpeed` | BodyRig.cs | 0.8 / 0.4 m/s | torso lean toward / back from overreach |
 | `ReachDecayFactor` | BodyRig.cs | 0.92 | hysteresis band (decay only below 92% of reach) |
@@ -277,21 +295,17 @@ PropShop, PropGrabber, PhysicsHands, BodyRig, FadeLayer/Fade. Action map: `openx
 
 ## 7. Next steps (in order)
 
-1. **Full physics body track — DECISION PENDING (owner holds implementation)** — the owner
-   wants to pursue a full physics VR body (also as reusable tech for a second project idea);
-   the hug should be mostly physics with detection for future interactivity. Research done:
-   `research/vr-body-physics-hugs.md` (prior art + phased design; §6 = Nimso's "Hybrid
-   Presence", the closest known implementation; §7 = owner-extracted video breakdowns of
-   Project TX: hierarchical per-joint force budgets, script-relaxation hand adaptation,
-   active-ragdoll NPCs with grab anchors) and `research/vr-body-physics-godot.md` (verified
-   stack facts: no Generic6DOF, hinge velocity motors work, PD-follow proven by the hands).
-   Research verdict: the technique is an independent-implementation match of our existing
-   chase-drive architecture; no more video extraction needed now (conditional: Spideriini
-   elbow handling if Stage-2 elbow jitter bites; Test Chamber if a locomotion stage ever
-   starts). Recommendation shape: staged torso → 2-segment arm chains (chase-driven,
-   Boneworks/Nimso tier, NOT per-bone skeleton sim), test hugging props; muscle model =
-   hierarchical budgets (hand ≺ forearm ≺ shoulder ≺ torso) scaled from body mass.
-   Character model: keep boxes for the physics work (owner asked; see research §5-6).
+1. **Full physics body track — Stage 1 (chest body) IMPLEMENTED, validate in-headset** —
+   `PhysicsTorso.cs` is live: chase chest (30 kg, 2400 N), yaw spring moved in, collision
+   layers reworked (3 = body, 4 = hands, no self-collision). Owner playtests: chest contact
+   with props (lean a crate on it, catch the bowling ball against it), shove response
+   (props push the chest, it recovers — camera never moves), turn following (torso lags
+   head naturally), weight feel. Hug testing on props as agreed. Headless: `body_spike`
+   PASS 3×; all other spikes still PASS 3×. **Stage 2 (arm chains, hierarchical budgets,
+   Nimso/Boneworks tier) awaits Stage-1 feel verdict** — see
+   `research/vr-body-physics-hugs.md` §5/§7 + `research/vr-body-physics-godot.md`.
+   Tuning knobs live in HANDOFF §6 (PhysicsTorso rows); first levers if feel is off:
+   `MaxForce` (gives more/less), `OrientKp` (torso yaw stiffness).
 2. **Locomotion decision** — owner report 2026-10-01: two-hand anchor turning broken (not
    2-anchor based), simultaneous two-hand movement acts weird, teleport + lasers broken
    (experiments, not current issues). Owner's candidate replacement: physics thumbstick