NEON-29: Reject 180° walk steering flips on stair edges.

Path lookahead vs direct goal could reverse horizontal velocity every physics
tick on treads (NEON-16), driving slide/snap Y jitter. Clamp new steer to
prior bearing when dot < -0.35 and speed is above a small threshold.

Widen NAV_COLUMN_STEER_EXIT_DIST (0.97→1.12) to reduce path/direct mode
chatter when horiz_dist wobbles near the old band.

client/scripts/player.gd

@@ -21,13 +21,18 @@ const DIRECT_APPROACH_RADIUS: float = 0.85
 ## tangentially → [code]horiz_dist[/code] crosses the radius → direct vs path
 ## alternates → velocity sign flips (Jolt ping-pong while [code]has_goal[/code]).
 const NAV_COLUMN_STEER_ENTER_DIST: float = 0.74
-const NAV_COLUMN_STEER_EXIT_DIST: float = 0.97
+const NAV_COLUMN_STEER_EXIT_DIST: float = 1.12
 ## First path waypoint used for column steer must be at least this far in XZ. [method NavigationAgent3D.get_next_path_position]
 ## can sit ~4 cm from the capsule; Jolt slides ~4 cm/tick → the “toward next” vector flips 180° every frame
 ## (`vlat && ncol` NEON-16 traces). A 22 cm gate matches foot-scale probes and stays stable on treads.
 const NAV_PATH_STEER_MIN_LOOKAHEAD: float = 0.22
 ## If lookahead steering points more than ~105° from the click direction (XZ), use direct goal steer instead.
 const NAV_PATH_STEER_MIN_GOAL_DOT: float = -0.25
+## On tread edges, path vs direct or waypoint lookahead can flip the horizontal seek vector ~180° each
+## physics tick → [method move_and_slide] + snap Y noise (~7 cm, NEON-16). Keep prior bearing if the new
+## direction is more than ~110° from current horizontal [member velocity].
+const WALK_STEER_REVERSE_REJECT_DOT: float = -0.35
+const WALK_STEER_MIN_CUR_SPEED_SQ: float = 0.16
 ## While [code]vlat && ncol[/code], ledge peel + zero floor snap fight [method move_and_slide] on approach treads
 ## (3-cycle NEON-16 traces: same XZ triplet, Y/feet_y ping-pong). Suspend peel and allow normal snap when the
 ## feet are within this vertical distance of the goal **surface** (m).
@@ -358,6 +363,20 @@ func _clear_step_assist_after_walk_move() -> void:
 		_step_assist_active = false
 
 
+func _walk_clamp_steering_reverse(desired_dir_xz: Vector3) -> Vector3:
+	var d2 := Vector2(desired_dir_xz.x, desired_dir_xz.z)
+	if d2.length_squared() < 1e-10:
+		return desired_dir_xz
+	d2 = d2.normalized()
+	var cur := Vector2(velocity.x, velocity.z)
+	if cur.length_squared() < WALK_STEER_MIN_CUR_SPEED_SQ:
+		return Vector3(d2.x, 0.0, d2.y)
+	var cur_n := cur.normalized()
+	if d2.dot(cur_n) < WALK_STEER_REVERSE_REJECT_DOT:
+		return Vector3(cur_n.x, 0.0, cur_n.y)
+	return Vector3(d2.x, 0.0, d2.y)
+
+
 func _set_horizontal_velocity_toward(
 	point: Vector3, fallback_dir_xz: Vector3 = Vector3.ZERO
 ) -> void:
@@ -372,6 +391,7 @@ func _set_horizontal_velocity_toward(
 			dh = Vector3(1.0, 0.0, 0.0)
 	else:
 		dh = dh.normalized()
+	dh = _walk_clamp_steering_reverse(dh)
 	velocity = dh * MOVE_SPEED
 	velocity.y = 0.0
 
@@ -643,6 +663,7 @@ func _set_horizontal_velocity_from_nav_path_or_goal(fallback_goal_xz: Vector3) -
 		if dir.dot(gh) < NAV_PATH_STEER_MIN_GOAL_DOT:
 			_set_horizontal_velocity_toward(_auth_walk_goal, fallback_goal_xz)
 			return
+	dir = _walk_clamp_steering_reverse(dir)
 	velocity = dir * MOVE_SPEED
 	velocity.y = 0.0