Body step 2.5: the camera always rides the body

- one 3D view-follow rule (2 cm deadzone, hard 4 cm limit), no separate
  floor-follow; play-space-relative targets mean no feedback loop
- head guide drives the character's eye to the HMD while on your feet
- slow floor re-centering; Braced ignores the floor; anatomical head box

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

research/ragdoll-player-step2.md

@@ -178,3 +178,30 @@ wasn't able to climb." Fixed from the same session:
   in place.
 - The climbing spike now climbs like a person: hand moves are sequential (never release the second hand before the
   first re-grips), and pulls are relative to the body/room.
+
+## Step 2.5 — the camera always rides the body (2026-10-02)
+
+Owner: "why doesn't the camera just follow the character when landing? … And not just when landing, but always.
+And I'd prefer to exclude the moments where the camera clips out of the head as much as possible." Correct, and
+it is what Boneworks/BIMOS does (the rig rides the body; the head is driven to the HMD).
+
+- **One rule, always, 3D:** the camera rides the character's eye. Deadzone 2 cm, follow τ 0.04 s, hard
+  `MaxViewLead` 4 cm (the head box reaches 2 cm in front of the eye). The blocked eye→camera sweep stays.
+  2.3's separate standing-height "floor follow" is gone.
+- **Why there is no feedback loop** (the fear behind 2.3's split): the True Body reads crouch as LOCAL head height
+  (camera − play-space floor), ground control re-bases its goal onto the real ground (`footY − floorY`), and so
+  does the new head guide. Moving the play space changes no target. 2.3's mantle "fight" came from two controllers
+  editing the same height.
+- **Head guide** (BIMOS drives the head to the HMD): a 250 N, 5 Hz PD pulls the character's eye onto the camera
+  while on your feet (off while airborne, climbing or bracing on the hands). Without it, any transient body lag
+  (mid-squat) was converted by the tight view follow into a permanent play-space offset: 7 cm per deep squat. With
+  it, six held poses drift 1 cm.
+- **Slow floor re-centering** (τ 1 s, grounded): eases the play-space floor onto the real ground. It moves the
+  camera toward the eye, the same direction as the follow, so it can't fight it. Without it, a small height offset
+  picked up while crawling held the head against a tunnel roof for good.
+- **`Braced` excludes the floor** (group `no_grab`): hands on the floor while crawling aren't "pushing yourself up".
+- **Anatomical head box:** centred 0.5 cm below the eyes (crown ~10 cm above, chin ~11 cm below; was 12.5 / 8.5).
+  The old box poked 2 cm into a 0.6 m tunnel's roof at a 0.42 m eye height.
+
+Results (real-input spike): landing keeps the pelvis at standing height with eye-to-camera ≤ 6.8 cm (during the
+fall); held poses drift 1 cm with the eye within 7 mm; crawl, mantle, climb, pull-up and hang all pass.