diff --git a/client/tests/test_atlas_window_viewer.gd b/client/tests/test_atlas_window_viewer.gd
index 621ac57e0..94fc603f5 100644
--- a/client/tests/test_atlas_window_viewer.gd
+++ b/client/tests/test_atlas_window_viewer.gd
@@ -136,6 +136,29 @@ func test_set_overlay_visible_unknown_id_is_a_noop() -> void:
 	assert_bool(v.is_overlay_visible("not_a_real_overlay")).is_false()
 
 
+## PR #195 review (Hoshe): named default-visibility pins for the T-1156
+## nature overlays at fresh-viewer construction, per Araminta's ruling —
+## RVR ON (rivers are load-bearing geography, a first-time Atlas viewer sees
+## them without hunting for a toggle: the single most player-visible behavior
+## the feature ships), BAS and ATR OFF (secondary/dev-facing analytical
+## layers, opt-in). Without these, a refactor of the _ready() visibility-init
+## loop could silently flip the defaults and only a live capture would
+## notice — gen_basins was previously covered only incidentally by the
+## toggle-redraw spy test above.
+func test_nature_overlay_defaults_rivers_on_basins_and_attractors_off() -> void:
+	var v: AtlasWindowViewer = auto_free(AtlasWindowViewer.new())
+	add_child(v)
+	assert_bool(v.is_overlay_visible("gen_rivers")).override_failure_message(
+		"gen_rivers must default ON (Araminta's RVR-on ruling, T-1156 wave 1)"
+	).is_true()
+	assert_bool(v.is_overlay_visible("gen_basins")).override_failure_message(
+		"gen_basins must default OFF (opt-in analytical layer)"
+	).is_false()
+	assert_bool(v.is_overlay_visible("gen_attractors")).override_failure_message(
+		"gen_attractors must default OFF (dev-facing detail, opt-in)"
+	).is_false()
+
+
 ## Counts real _draw() invocations on AtlasWindowNatureOverlay — CanvasItem
 ## exposes no public "is a redraw pending" query in this Godot version
 ## (confirmed directly: is_queued_for_redraw() does not exist on Node2D here