Body-physics research (hugs + Nimso Hybrid Presence + Box3D facts), mark grab v5.3.1 validated, note Box3D fork

research/vr-body-physics-hugs.md

@@ -153,5 +153,37 @@ Skeleton3D, physics hands exist. [I] throughout this section unless noted.
    pin for torso coupling; verify hinge motor max-impulse behavior at 90 Hz before building on
    it (the `godot-box3d-weld.md` patch is the precedent for upstreaming what's missing).
 7. **Explicitly rejected**: full per-bone simulated player skeleton (§1 — nobody ships it;
-  comfort + tuning cost), VRChat-style event-only hugs (no mutual force = no resistance = hollow),
-  Go-Go stretch arms (rejected before in `vr-arm-ik.md`).
+   comfort + tuning cost), VRChat-style event-only hugs (no mutual force = no resistance = hollow),
+   Go-Go stretch arms (rejected before in `vr-arm-ik.md`).
+
+## 6. Nimso Studios' "Hybrid Presence" — the closest known full-arm-physics VR body (researched 2026-10-01)
+
+Owner-pointer. Unity, CLOSED demos — no source, no Unity package (commenters asked; refused),
+no written technical breakdown exists anywhere.
+
+- [S] Itch: `https://nimsostudios.itch.io/hybrid-presence-samples2` — "The Hybrid Presence
+  system on the arms only" (Spideriini: web-swinging/wall-climbing with physics arms that
+  climb ledges, push off walls, slow you down). Dev's OWN admitted issues: "some small issues
+  with elbows and with stuttering hands" — i.e., the exact failure modes our research predicts
+  (elbow singularities, chase-gain jitter) persist even in the best-known implementation.
+- [S] `https://nimsostudios.itch.io/hybrid-test-chamber-tech-demo` — physics-simulated
+  interactions (physical hands, grip points, two-handed weapons "using a Hybrid system"
+  blending primary-hand rotation with secondary-hand position), physics locomotion (sway/jog
+  detection from natural bounce frequency). Known issues: physics glitches "inherent to the
+  physics engine", shoulder logic UNIMPLEMENTED (butt stocks have no effect). For an FPS.
+- [S] Channel `youtube.com/@NimsoStudios` — the technique lives only in videos: "IN-DEPTH VR
+  PHYSICS INTERACTIONS" parts 1–2 (`youtube.com/watch?v=tMDmwD1cQPg`,
+  `youtube.com/watch?v=BTlY8SWLtgo`), "Hybrid Muscle System – Fast VR Physics" (arm
+  force/strength model), "FLUID VR HAND ADAPTATION + Hand Tracking" (hands deform to fit
+  objects on contact), "Project TX – physics NPCs". Community framing: Boneworks-class body,
+  "muscle-like" force constraints driving simulated arms/body from the controllers.
+- [S] Godot-land has NOTHING at this tier — the ceiling is XR Tools' kinematic PlayerBody
+  (`github.com/GodotVR/godot-xr-tools`) + physical-hands templates
+  (`github.com/jtnicholl/godot4-vr-physics-template`). A Godot full-physics body would be
+  novel; as reusable tech for the owner's second project that novelty is a feature.
+- [I] Assessment feed: Nimso validates BOTH directions — full arm physics is achievable by
+  one person (samples are free and rated 4.8/5), AND its cost is visible in his own issue
+  lists (elbows, hand stutter, shoulder logic missing after years). His "muscle" language =
+  force-clamped chase drives, i.e. the same pattern as our PhysicsHands generalized to limbs;
+  "hybrid" = tracked targets + simulated bodies, which is ALSO our layer-3 architecture
+  (AGENTS.md). We are not inventing a new technique — we'd be porting a known-shaped one.