Fix hand joint mapping: skip PALM instead of WRIST for dex-retargeting

The dex-retargeting target_link_human_indices expect WebXR convention
(joint 0 = WRIST) but we were outputting OpenXR convention (joint 0 = PALM).
This caused the 5 difference vectors referencing index 0 to compute
palm-to-fingertip instead of wrist-to-fingertip, degrading tracking accuracy.

Also updates Inspire hand ranges and normalization formula.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/body_tracker.gd

@@ -276,9 +276,11 @@ func _xform_to_mat16(xform: Transform3D) -> Array:
 
 
 ## Get 25 hand joint positions from XRHandTracker, relative to wrist (75 floats).
-## Joint order: PALM(0), THUMB_META..TIP(2-5), INDEX(6-10), MIDDLE(11-15),
-##              RING(16-20), LITTLE(21-25) — skipping WRIST(1).
-## This matches the format expected by dex-retargeting / xr_teleoperate.
+## Joint order matches WebXR / dex-retargeting convention:
+##   WRIST(0), THUMB_META..TIP(1-4), INDEX(5-9), MIDDLE(10-14),
+##   RING(15-19), LITTLE(20-24) — skipping PALM (OpenXR joint 0).
+## OpenXR has 26 joints (0=PALM, 1=WRIST, 2-25=fingers).
+## WebXR/dex-retargeting has 25 joints (0=WRIST, 1-24=fingers).
 func _get_hand_positions_ht(hand_tracker: XRHandTracker) -> Array:
 	var wrist_xform := hand_tracker.get_hand_joint_transform(XRHandTracker.HAND_JOINT_WRIST)
 	var wrist_inv := wrist_xform.affine_inverse()
@@ -286,7 +288,7 @@ func _get_hand_positions_ht(hand_tracker: XRHandTracker) -> Array:
 	positions.resize(HAND_JOINT_COUNT * 3)  # 25 * 3 = 75
 	var out_idx := 0
 	for xr_joint in range(26):  # OpenXR joints 0-25
-		if xr_joint == 1:  # Skip WRIST
+		if xr_joint == 0:  # Skip PALM (not in WebXR/dex-retargeting convention)
 			continue
 		var joint_xform := hand_tracker.get_hand_joint_transform(xr_joint)
 		var rel := wrist_inv * joint_xform

server/retarget_bridge.py

@@ -114,14 +114,16 @@ KD = [
     1, 1, 1, 1, 1, 1, 1,
 ]
 
-# Inspire hand normalization ranges
+# Inspire hand normalization ranges (min=closed fist, max=open hand)
+# Inspire convention: 0.0=closed, 1.0=open
+# Calibrated from dex-retargeting output with Quest 3 XRHandTracker
 INSPIRE_RANGES = [
-    (0.0, 1.7),  # finger flexion
-    (0.0, 1.7),
-    (0.0, 1.7),
-    (0.0, 1.7),
-    (0.0, 0.5),  # thumb pitch
-    (-0.1, 1.3), # thumb yaw
+    (0.4, 1.7),  # pinky flexion
+    (0.4, 1.7),  # ring flexion
+    (0.4, 1.7),  # middle flexion
+    (0.4, 1.7),  # index flexion
+    (0.2, 0.5),  # thumb pitch
+    (0.8, 1.3),  # thumb yaw
 ]
 
 # Body joint indices in shared memory (8 joints x 7 floats = 56)
@@ -567,17 +569,19 @@ def retarget_hands(left_retargeting, right_retargeting,
         ref_value = left_hand_pos[left_indices[1, :]] - left_hand_pos[left_indices[0, :]]
         q_rad = left_retargeting.retarget(ref_value)
         q_hw = q_rad[left_hw_map]
+        retarget_hands._last_q_hw_l = q_hw.copy()
         for idx in range(6):
             min_val, max_val = INSPIRE_RANGES[idx]
-            hand_cmd[6 + idx] = np.clip((max_val - q_hw[idx]) / (max_val - min_val), 0.0, 1.0)
+            hand_cmd[6 + idx] = np.clip((q_hw[idx] - min_val) / (max_val - min_val), 0.0, 1.0)
 
     if right_valid:
         ref_value = right_hand_pos[right_indices[1, :]] - right_hand_pos[right_indices[0, :]]
         q_rad = right_retargeting.retarget(ref_value)
         q_hw = q_rad[right_hw_map]
+        retarget_hands._last_q_hw_r = q_hw.copy()
         for idx in range(6):
             min_val, max_val = INSPIRE_RANGES[idx]
-            hand_cmd[idx] = np.clip((max_val - q_hw[idx]) / (max_val - min_val), 0.0, 1.0)
+            hand_cmd[idx] = np.clip((q_hw[idx] - min_val) / (max_val - min_val), 0.0, 1.0)
 
     return hand_cmd
 
@@ -825,6 +829,12 @@ def main():
                     if step_count % 250 == 0:
                         np.set_printoptions(precision=2, suppress=True)
                         logger.info(f"  [HAND OUT] R=[{current_hands[0]:.2f},{current_hands[1]:.2f},{current_hands[2]:.2f},{current_hands[3]:.2f},{current_hands[4]:.2f},{current_hands[5]:.2f}] L=[{current_hands[6]:.2f},{current_hands[7]:.2f},{current_hands[8]:.2f},{current_hands[9]:.2f},{current_hands[10]:.2f},{current_hands[11]:.2f}]")
+                    if step_count % 250 == 0 and hasattr(retarget_hands, '_last_q_hw_r'):
+                        q = retarget_hands._last_q_hw_r
+                        logger.info(f"  [HAND RAW] R_q_hw=[{q[0]:.3f},{q[1]:.3f},{q[2]:.3f},{q[3]:.3f},{q[4]:.3f},{q[5]:.3f}]")
+                    if step_count % 250 == 0 and hasattr(retarget_hands, '_last_q_hw_l'):
+                        q = retarget_hands._last_q_hw_l
+                        logger.info(f"  [HAND RAW] L_q_hw=[{q[0]:.3f},{q[1]:.3f},{q[2]:.3f},{q[3]:.3f},{q[4]:.3f},{q[5]:.3f}]")
                 except Exception as e:
                     logger.warning(f"Hand retarget failed: {e}")