Fix floor-clipping across the library; correct deadlift/row arms; remove push-up (#4)

QA pass driven by real Playwright screenshots + bone-position diagnostics (not
just numeric spot-checks) against the running app, after a prior review missed
that verified-numbers didn't match what actually rendered.

Root cause 1 — ground-lock anchored the wrong point:
- Feet-only ground-lock zeroed the ANKLE BONE's height, not the foot mesh's
  sole (~0.04m lower) — feet visibly sank into the floor on every ground-locked
  standing movement (squat and ~15 others).
- Hands+feet ground-lock (push-up/plank family) had the same bone-vs-mesh gap
  on both ends. Fixed with a final rigid-body nudge after the existing rotation
  converges.

Root cause 2 — no anchor at all for some phases:
- Movements with neither ground-lock nor a pin (prone/supine core work: crunch,
  superman, bicycle-crunch, supine-leg-raise) had the root frozen at the
  base pose's grounded height while FK bent freely on top of it, letting bent
  limbs swing below the floor with nothing to catch them (superman peaked at
  -0.61m). Added a per-frame safety clamp: if a phase has no ground-lock/pin,
  keep the lowest mesh point at y=0 (a no-op when the pose is legitimately
  elevated).
- mountain-climber was missing `ground-lock: hands, feet` entirely; added it.
- crunch never reset `knees` in its "Lower" phase, so the loop-to-reset wrap
  snapped the knees straight every rep; added the reset.

Root cause 3 — deadlift/bent-over-row arms were authored before the hip-hinge
existed and never accounted for it: `shoulders: flex` is relative to the torso,
and the torso already pitches forward with the hinge, so the two rotations
stacked (95° hinge + 90° flex ≈ 185° total) and flung the arms up behind the
body instead of hanging them toward the floor. Switched to `extend` (which
counter-rotates against the hinge) and tuned the hinge/knee depth so the arm
lands near-vertical. Verified: wrist now sits below the shoulder in both.

Root cause 4 — pins engaging from a very different starting pose: triceps-dips
transitioned directly from standing into a pinned dip, and the mid-interpolation
root shift swung the untouched legs through the floor every rep (worst -0.345).
Restructured into Sit → Support → Lower → Press → Stand so the pin only engages
once the body is already close to its final shape, and tuned the leg angle for
clearance at the bottom of the dip. Also removed step-up's premature pin on its
first phase — plain FK already lands the foot within centimeters of the box, so
the pin now only engages once the foot is already close (residual glitch equity
dropped from a sustained -0.05 to a ~2-frame -0.06 blip at the pin handoff).

Camera: `frameCamera()` only fit the mannequin's bounding box, so a scene prop
taller than the figure (the pull-up bar) got cropped out of frame. Now unions
the prop scene into the frame — the whole bar and the hanging figure are both
visible.

Content: removed `push-up` from the catalogue and spec/examples per request
(the grounding bug was fixed, but it's being pulled from the library anyway).

Verification: 139 tests pass; every example still parses ROM-clean; a headless
Playwright sweep sampled all 65 movements at 6 points each through the real
render pipeline — zero clip below -0.02 except the documented sub-frame step-up
blip.


Claude-Session: https://claude.ai/code/session_018WCktDrKYZpJjCb2apbqWp

Co-authored-by: Claude <noreply@anthropic.com>

Author: a-baran-orhan

docs/coverage-gap.md

@@ -28,7 +28,7 @@ majority; the **body-weight subset (~25%)** is our addressable universe.
 | Core / waist | dead-bug, glute-bridge, hanging-knee-raise, spinal-twist, side-bend, cross-body-reach | ~6 | **No crunch / plank / leg-raise / climber** |
 | Shoulders | lateral-raise, shoulder-flexion, shoulder-abduction, shoulder-rolls, overhead-reach, arm-circles, port-de-bras | ~7 | Good |
 | Back | bent-over-row, deadlift, good-morning, cobra, dead-hang | ~5 | **No superman / extension holds** |
-| Chest | chest-opener (stretch only) | 1 | **Weak — push-up not even registered** |
+| Chest | chest-opener (stretch only) | 1 | **Weak — push-up was pulled from the catalogue; still the obvious gap-filler once chest coverage is revisited** |
 | Upper arms | biceps-curl, elbow-forearm | 2 | **No triceps work** |
 | Lower legs | heel-raises, relevé | 2 | Thin |
 | Neck | neck-rotation, neck-side-stretch | 2 | Fine for scope |
@@ -41,7 +41,8 @@ Ordered by gap size × how cleanly the engine renders it:
 
 1. **Core** — `plank-hold`, `mountain-climber` (plank pose), `crunch`,
    `bicycle-crunch`, `supine-leg-raise` (supine pose). Highest-value, cleanest.
-2. **Chest** — register the existing `push-up`.
+2. **Chest** — still open; `push-up` was authored and then pulled from the
+   catalogue (see note above), so this gap remains.
 3. **Back** — `superman` (prone pose).
 4. **Upper legs** — `forward-lunge` (FK split stance, feet leveled).
 5. **Lower legs** — `single-leg-calf-raise`.

packages/movit-render/src/index.ts

@@ -258,17 +258,35 @@ export function createViewer(
         if (Math.abs(deriv) < 1e-4) break;
         rotateRootAboutPivot(pivot, THREE.MathUtils.clamp(-y0 / deriv, -0.35, 0.35));
       }
+      // The loop above zeroes the WRIST BONE's height, but the visible hand
+      // (wrist ball + forearm capsule) and foot (mesh box) extend a bit below
+      // their bones, leaving the mesh sunk into the floor by that offset. Catch
+      // it with one final rigid-body vertical nudge (rotation already set the
+      // correct tilt; this only corrects the residual bone-vs-mesh gap).
+      mannequin.root.updateMatrixWorld(true);
+      const box = new THREE.Box3().setFromObject(mannequin.root);
+      if (box.min.y < 0) {
+        mannequin.root.position.y -= box.min.y;
+        mannequin.root.updateMatrixWorld(true);
+      }
       return;
     }
 
     if (feet.length > 0) {
-      let sumY = 0;
+      // Ground the FOOT MESH's lowest point, not the ankle bone's origin — the
+      // bone sits ~0.04m above the sole (foot box + capsule radius), so
+      // anchoring the bone itself left the visible foot sunk into the floor.
+      let minY = Infinity;
       for (const id of feet) {
         const node = mannequin.bones.get(id);
-        if (node) sumY += node.getWorldPosition(new THREE.Vector3()).y;
+        if (!node) continue;
+        const box = new THREE.Box3().setFromObject(node);
+        if (Number.isFinite(box.min.y)) minY = Math.min(minY, box.min.y);
+      }
+      if (Number.isFinite(minY)) {
+        mannequin.root.position.y -= minY;
+        mannequin.root.updateMatrixWorld(true);
       }
-      mannequin.root.position.y -= sumY / feet.length;
-      mannequin.root.updateMatrixWorld(true);
     }
   }
 
@@ -359,7 +377,10 @@ export function createViewer(
 
   function frameCamera(): void {
     // Auto-frame the figure: fit its bounding box, keep a pleasant angle.
+    // Include any scene prop too — a pull-up bar sits well above the figure's
+    // head, and framing on the mannequin alone left it cropped out of view.
     const box = new THREE.Box3().setFromObject(mannequin.root);
+    if (propScene) box.union(new THREE.Box3().setFromObject(propScene.group));
     if (box.isEmpty()) return;
     const center = box.getCenter(new THREE.Vector3());
     const size = box.getSize(new THREE.Vector3());
@@ -387,6 +408,21 @@ export function createViewer(
       mannequin.root.updateMatrixWorld(true);
       applyGroundLock(info.groundLock);
       applyPins(info.pins);
+      // Safety net: a phase with neither ground-lock nor a pin has no
+      // per-frame anchor at all, so the root stays frozen at the base pose's
+      // grounded height while the FK animates freely on top of it — bending
+      // joints (e.g. a prone "superman" lift, a supine crunch) can then swing
+      // part of the mesh below the floor with nothing to catch it. Clamp the
+      // root up so the lowest point never dips below y=0; a no-op whenever the
+      // pose is legitimately elevated (bbox min already ≥ 0).
+      if (info.groundLock.length === 0 && info.pins.length === 0) {
+        mannequin.root.updateMatrixWorld(true);
+        const box = new THREE.Box3().setFromObject(mannequin.root);
+        if (box.min.y < 0) {
+          mannequin.root.position.y -= box.min.y;
+          mannequin.root.updateMatrixWorld(true);
+        }
+      }
       applyReaches(info.reaches);
       if (info.phaseName !== lastPhaseName) {
         lastPhaseName = info.phaseName;

playground/src/presets.ts

@@ -9,7 +9,6 @@ import posture from "../../spec/examples/posture-reset.movit?raw";
 import twist from "../../spec/examples/spinal-twist.movit?raw";
 import chair from "../../spec/examples/chair-pose.movit?raw";
 import sideBend from "../../spec/examples/side-bend.movit?raw";
-import pushup from "../../spec/examples/pushup.movit?raw";
 
 // Hip-hinge showcases.
 import deadlift from "../../spec/examples/deadlift.movit?raw";
@@ -120,7 +119,6 @@ export const PRESETS: Preset[] = [
   { id: "chest-opener", label: "Chest opener", domain: "Desk & posture", bodyPart: "Chest", target: "Pectorals", equipment: "Body weight", difficulty: "Beginner", source: chestOpener },
 
   // --- Strength & core (coverage-gap batch) ---
-  { id: "pushup", label: "Push-up", domain: "Fitness", bodyPart: "Chest", target: "Pectorals", equipment: "Body weight", difficulty: "Intermediate", source: pushup },
   { id: "plank-hold", label: "Plank hold", domain: "Fitness", bodyPart: "Core", target: "Abdominals", equipment: "Body weight", difficulty: "Beginner", source: plankHold },
   { id: "mountain-climber", label: "Mountain climber", domain: "Fitness", bodyPart: "Core", target: "Abdominals", equipment: "Body weight", difficulty: "Intermediate", source: mountainClimber },
   { id: "crunch", label: "Crunch", domain: "Fitness", bodyPart: "Core", target: "Abdominals", equipment: "Body weight", difficulty: "Beginner", source: crunch },

spec/examples/bent-over-row.movit

@@ -3,22 +3,22 @@ movit exercise "Bent-over row"
   pose start = standing
 
   step "Set the hinge" 1.6s ease-in-out:
-    pelvis: hinge 80
+    pelvis: hinge 70
     knees: flex 20
-    shoulders: flex 70
+    shoulders: extend 55
     elbows: flex 10
     neck: extend 12
     ground-lock: feet
     cue "Hinge to a flat back, let the arms hang straight down"
 
   step "Row" 0.9s ease-out:
-    shoulders: flex 35
+    shoulders: extend 15
     elbows: flex 95
     ground-lock: feet
     cue "Drive the elbows up past the ribs, squeeze the shoulder blades"
 
   step "Lower" 1s ease-in:
-    shoulders: flex 70
+    shoulders: extend 55
     elbows: flex 10
     ground-lock: feet
     cue "Lower the bar under control, keep the back flat"

spec/examples/crunch.movit

@@ -8,13 +8,16 @@ movit exercise "Crunch"
     chest: flex 20
     neck: flex 20
     shoulders: flex 45
+    ground-lock: feet
     cue "Curl the shoulders off the floor, ribs toward the hips"
 
   step "Lower" 1.2s ease-in:
+    knees: flex 0
     spine: flex 0
     chest: flex 0
     neck: flex 0
     shoulders: flex 0
+    ground-lock: feet
     cue "Lower the upper back down with control"
 
   repeat 12

spec/examples/deadlift.movit

@@ -3,17 +3,17 @@ movit exercise "Deadlift"
   pose start = standing
 
   step "Lower" 1.8s ease-in-out:
-    pelvis: hinge 95
+    pelvis: hinge 75
     knees: flex 25
-    shoulders: flex 90
+    shoulders: extend 60
     neck: extend 12
     ground-lock: feet
     cue "Push the hips back and hinge with a flat back — let the arms hang to the bar"
 
   step "Lift" 1.4s ease-out:
     pelvis: hinge 0
     knees: flex 0
-    shoulders: flex 0
+    shoulders: extend 0
     neck: extend 0
     ground-lock: feet
     cue "Drive the hips forward to stand tall, bar close to the body"

spec/examples/mountain-climber.movit

@@ -5,18 +5,21 @@ movit exercise "Mountain climber"
   step "Right knee in" 0.5s ease-out:
     hip_right: flex 60
     knee_right: flex 75
+    ground-lock: hands, feet
     cue "Drive the right knee toward the chest"
 
   step "Switch" 0.5s ease-in-out:
     hip_right: flex 0
     knee_right: flex 0
     hip_left: flex 60
     knee_left: flex 75
+    ground-lock: hands, feet
     cue "Switch fast — left knee drives in"
 
   step "Out" 0.5s ease-in:
     hip_left: flex 0
     knee_left: flex 0
+    ground-lock: hands, feet
     cue "Return to a strong plank"
 
   repeat 8

spec/examples/pushup.movit

@@ -6,7 +6,6 @@ movit exercise "Step-up"
   step "Plant the foot" 1s ease-in-out:
     hip_right: flex 70
     knee_right: flex 90
-    pin: foot_right box
     cue "Plant the right foot up on top of the box"
 
   step "Drive up" 1.2s ease-out:

spec/examples/step-up.movit

@@ -3,25 +3,45 @@ movit exercise "Triceps dips"
   prop chair
   pose start = standing
 
-  step "Support" 1s ease-in-out:
+  step "Sit" 0.8s ease-in-out:
+    hips: flex 0
+    knees: flex 130
+    ground-lock: feet
+    cue "Sit on the edge of the chair, hands beside the hips, feet tucked in"
+
+  step "Support" 0.6s ease-in-out:
+    hips: flex 0
+    knees: flex 130
     shoulders: extend 25
     elbows: flex 10
-    hips: flex 80
-    knees: flex 80
     pin: hand_left seat
     pin: hand_right seat
-    cue "Hands on the edge behind you, hips just off the seat, knees bent"
+    cue "Grip the edge and lift the hips just off the seat"
 
   step "Lower" 1.1s ease-in-out:
-    elbows: flex 95
+    hips: flex 0
+    knees: flex 130
+    shoulders: extend 25
+    elbows: flex 60
     pin: hand_left seat
     pin: hand_right seat
     cue "Bend the elbows to lower the hips toward the floor"
 
   step "Press" 1s ease-out:
+    hips: flex 0
+    knees: flex 130
+    shoulders: extend 25
     elbows: flex 10
     pin: hand_left seat
     pin: hand_right seat
     cue "Press through the palms to straighten the arms"
 
+  step "Stand" 0.8s ease-in:
+    hips: flex 0
+    knees: flex 0
+    shoulders: extend 0
+    elbows: flex 0
+    ground-lock: feet
+    cue "Step off and stand up"
+
   repeat 8