NEON-29: Clear step assist on seam walls; replan nav on walk stall

Step assist stayed active when is_on_wall from mesh seams after landing on
the goal height — keep reduced snap and odd slides. Clear assist when
vert_err and feet vs goal show we are on the target slab.

If horizontal speed stays low with a far goal, refresh NavigationAgent3D
target after 8 ticks to break stale paths.

client/scripts/player.gd

@@ -38,6 +38,13 @@ const WALK_STEP_ASSIST_COOLDOWN_TICKS: int = 1
 ## (~0.11 m away after the first lift) but large enough to catch the step surface once the
 ## capsule clears the face (~0.03 m away after the third lift for a 0.3 m step).
 const WALK_STEP_ASSIST_SNAP: float = 0.09
+## Clear step-assist when feet match the goal slab even if `is_on_wall()` (mesh seams / tread lip).
+const STEP_ASSIST_CLEAR_VERT_ERR: float = 0.1
+const STEP_ASSIST_CLEAR_FEET_BELOW_GOAL_MAX: float = 0.05
+## Low horizontal speed with an active far goal: refresh nav target to break stale paths.
+const WALK_STALL_VH_MAX: float = 0.22
+const WALK_STALL_HORIZ_MIN: float = 0.4
+const WALK_STALL_REPATH_TICKS: int = 8
 ## CapsuleShape3D in scene: height = 1.0 (cylinder portion), radius = 0.4.
 ## Total half-height from body origin to physical bottom = 0.5 + 0.4 = 0.9
 ## (`CAPSULE_HALF_HEIGHT + PLAYER_CAPSULE_RADIUS`).
@@ -70,6 +77,7 @@ var _debug_last_idle_xz: Vector2 = Vector2.INF
 var _debug_idle_heartbeat: int = 0
 var _debug_last_transform_xz: Vector2 = Vector2.INF
 var _debug_trace_frame: int = 0
+var _walk_stall_repath_ticks: int = 0
 
 @onready var _nav_agent: NavigationAgent3D = $NavigationAgent3D
 
@@ -90,6 +98,7 @@ func set_authoritative_nav_goal(world_pos: Vector3) -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_stall_repath_ticks = 0
 	_nav_agent.set_target_position(world_pos)
 
 
@@ -100,6 +109,7 @@ func clear_nav_goal() -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_stall_repath_ticks = 0
 	_nav_agent.set_target_position(global_position)
 
 
@@ -136,6 +146,7 @@ func snap_to_server(world_pos: Vector3) -> void:
 	_step_assist_active = false
 	_idle_anchor_active = false
 	_idle_manual_correction_ticks = 0
+	_walk_stall_repath_ticks = 0
 	_nav_agent.set_target_position(settled)
 	reset_physics_interpolation()
 
@@ -239,6 +250,34 @@ func _after_walk_move_and_slide() -> void:
 		move_and_slide()
 
 
+func _finalize_walk_move_tick(horiz_dist: float, feet_y: float, vert_err: float) -> void:
+	var vh_post: float = Vector2(velocity.x, velocity.z).length()
+	if _step_assist_active:
+		if is_on_floor() and not is_on_wall():
+			_step_assist_active = false
+		elif not is_on_floor() and get_slide_collision_count() == 0:
+			_step_assist_active = false
+		elif (
+			is_on_floor()
+			and vert_err <= STEP_ASSIST_CLEAR_VERT_ERR
+			and feet_y >= _auth_walk_goal.y - STEP_ASSIST_CLEAR_FEET_BELOW_GOAL_MAX
+		):
+			_step_assist_active = false
+	if not _has_walk_goal:
+		_walk_stall_repath_ticks = 0
+		return
+	if horiz_dist > WALK_STALL_HORIZ_MIN:
+		if vh_post < WALK_STALL_VH_MAX:
+			_walk_stall_repath_ticks += 1
+			if _walk_stall_repath_ticks >= WALK_STALL_REPATH_TICKS:
+				_nav_agent.set_target_position(_auth_walk_goal)
+				_walk_stall_repath_ticks = 0
+		else:
+			_walk_stall_repath_ticks = 0
+	else:
+		_walk_stall_repath_ticks = 0
+
+
 func _set_horizontal_velocity_toward(
 	point: Vector3, fallback_dir_xz: Vector3 = Vector3.ZERO
 ) -> void:
@@ -650,6 +689,7 @@ func _physics_process(delta: float) -> void:
 		_step_assist_active = false
 		_idle_anchor_active = false
 		_idle_manual_correction_ticks = 0
+		_walk_stall_repath_ticks = 0
 		_nav_agent.set_target_position(global_position)
 		_physics_idle_tick(delta)
 		if _apply_idle_manual_correction():
@@ -672,14 +712,7 @@ func _physics_process(delta: float) -> void:
 		floor_snap_length = _walk_floor_snap_length(feet_y, want_goal_h)
 		move_and_slide()
 		_after_walk_move_and_slide()
-		if (
-			_step_assist_active
-			and (
-				(is_on_floor() and not is_on_wall())
-				or (not is_on_floor() and get_slide_collision_count() == 0)
-			)
-		):
-			_step_assist_active = false
+		_finalize_walk_move_tick(horiz_dist, feet_y, vert_err)
 		_debug_trace_transform("physics")
 		_snap_capsule_upright()
 		return
@@ -706,13 +739,6 @@ func _physics_process(delta: float) -> void:
 	floor_snap_length = _walk_floor_snap_length(feet_y, want_goal_h)
 	move_and_slide()
 	_after_walk_move_and_slide()
-	if _step_assist_active:
-		if is_on_floor() and not is_on_wall():
-			# Landed cleanly on a surface — done climbing.
-			_step_assist_active = false
-		elif not is_on_floor() and get_slide_collision_count() == 0:
-			# Floating free with no contacts: assist must have fired spuriously.
-			# Clear the flag so FLOOR_SNAP_MOVING restores normal gravity next tick.
-			_step_assist_active = false
+	_finalize_walk_move_tick(horiz_dist, feet_y, vert_err)
 	_debug_trace_transform("physics")
 	_snap_capsule_upright()

docs/plans/NEON-29-implementation-plan.md

@@ -114,6 +114,7 @@ No new automated GDScript tests are added for this story — there is no new GDS
 - **Teal pad still stuck (follow-up):** Step assist used **slide normals only**; Jolt often exposes the lip via **`is_on_wall()`** / **`get_wall_normal()`** instead — re-added a **directional** wall check (`wnh.dot(want) < -0.02`). Descend relax now also triggers on **shallow floor normal** (`get_floor_normal().dot(UP) < 0.992`) and slightly wider vertical-ish slide band. **`TerracePlatformA`** root **Y = 0.012 m** breaks **coplanarity** with the main floor without the larger gap that hurt **TerraceStepB** approach.
 - **Teal cardinal both ways (follow-up):** **Climb:** **`FLOOR_SNAP_MOVING` (0.32 m)** was still active while **`_step_assist_wallish_blocks`** was true, snapping the capsule back to the lower floor each tick and cancelling lifts — cap snap to **`WALK_STEP_ASSIST_SNAP`** in that state; **bigger per-tick lift** (`WALK_STEP_ASSIST_DELTA` **0.16**) and **cooldown 1** tick. **Descend:** reintroduced **`DESCEND_LIP_SNAP_CAP`** when clearly above the lower goal, plus **`descending_stall`** (`horiz_dist` not trivial, **`vh < 0.55`**) to relax **`floor_block_on_wall`** when Jolt reports neither wall nor shallow floor at a cardinal lip.
 - **Teal pad — geometry wins:** Script-only mitigations still failed in practice; **`TerracePlatformA_Approach`** adds **twelve** `walkable` **`StaticBody3D`** treads (three per cardinal) with **~0.104 m** rise each, **darker teal** albedo, flush to the platform lip — nav + `CharacterBody3D` use **sloped contact** instead of fighting a **single vertical face**.
+- **Intermittent “stuck until re-click”:** **`_step_assist_active`** only cleared when **`not is_on_wall()`**; harmless **wall** flags from tread/platform seams left **reduced snap** on and blocked the old “clean landing” path — added clear when **feet are on the goal slab** (`vert_err` / feet vs goal Y). **Nav** can go stale when physics stalls (`vh` low, goal still far): after **8** ticks, **`set_target_position(_auth_walk_goal)`** again to replan.
 
 ## Open questions / risks