test(client): corner-reveal proof updated to D-252 semantics + deterministic cone wait

The proof encoded move-writes-facing ('Move West -> now facing West'); under
D-252 the view changes only via SetFacing, so the test now looks West
explicitly (helper gains an action_data passthrough). The +2-tick wait could
catch the facing flip before the visibility recompute — the assertion now
polls (bounded) until the westward cone content lands.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/tests/test_sprint2_proof.gd

@@ -79,7 +79,10 @@ static func _find_player(snapshot: Dictionary) -> Dictionary:
 ## - expect_position == null: wait for a snapshot at least 2 ticks past the
 ##   drain point (enough for no-op actions).
 func _send_and_receive(
-	action_name: String, tick: int = 0, expect_position: Variant = null
+	action_name: String,
+	tick: int = 0,
+	expect_position: Variant = null,
+	action_data: Variant = null,
 ) -> Variant:
 	# Drain queued stale snapshots, remembering the newest tick seen.
 	var last_tick: int = -1
@@ -93,6 +96,8 @@ func _send_and_receive(
 		pending = _bridge.poll_message()
 
 	var inputs: Array = [{"tick": tick, "action_name": action_name}]
+	if action_data != null:
+		inputs[0]["action_data"] = action_data
 	var encoded := Protocol.encode_player_inputs(inputs)
 	assert_that(encoded.size()).is_greater(0)
 	var send_err := _bridge.send_message(encoded)
@@ -309,16 +314,37 @@ func test_proof_corner_reveal(
 	await _send_and_receive("MoveNorth", 4, Vector2(19.5, 14.5))
 	await _send_and_receive("MoveNorth", 5, Vector2(19.5, 13.5))
 
-	# Step 3: Move West onto (18,13) — now facing West, looking straight at
-	# NPC1 at (16,13) two tiles ahead with no wall between ((17,13) is open).
-	var snapshot: Dictionary = await _send_and_receive("MoveWest", 6, Vector2(18.5, 13.5))
+	# Step 3: Move West onto (18,13), then LOOK West explicitly — D-252: moves
+	# no longer write Facing, the view changes only via SetFacing. NPC1 at
+	# (16,13) is two tiles dead ahead with no wall between ((17,13) is open).
+	await _send_and_receive("MoveWest", 6, Vector2(18.5, 13.5))
+	var snapshot: Dictionary = await _send_and_receive(
+		"SetFacing", 7, null, {"facing": "West"}
+	)
+	# The +2-tick wait can catch the snapshot where the facing field flipped but
+	# the entity-visibility recompute hasn't landed — keep draining (bounded)
+	# until the westward cone content arrives.
+	var settle := 0.0
+	while settle < RESPONSE_TIMEOUT and not _has_npc_at(snapshot, 16.5, 13.5):
+		_bridge.poll()
+		var msg := _bridge.poll_message()
+		if msg.size() > 0:
+			var decoded: Variant = Protocol.decode_snapshot(msg)
+			if decoded != null:
+				snapshot = decoded
+			continue
+		await get_tree().create_timer(0.05).timeout
+		settle += 0.05
 
 	# Player at (18,13) facing West. NPC1 at (16,13) is 2 tiles dead ahead —
 	# inside the vision cone, no wall between. NPC1 should be visible.
-	var npc1_found := false
+	assert_that(_has_npc_at(snapshot, 16.5, 13.5)).is_true()
+
+
+## True when the snapshot's visible entities include an Npc at (x, y).
+func _has_npc_at(snapshot: Dictionary, x: float, y: float) -> bool:
 	for entity in snapshot.entities:
 		if entity.kind.variant == "Npc":
-			if is_equal_approx(entity.x, 16.5) and is_equal_approx(entity.y, 13.5):
-				npc1_found = true
-				break
-	assert_that(npc1_found).is_true()
+			if is_equal_approx(entity.x, x) and is_equal_approx(entity.y, y):
+				return true
+	return false