diff --git a/src/game/engine/src/modules/management/turn_processor.gd b/src/game/engine/src/modules/management/turn_processor.gd
index a9888b90..e19e89ec 100644
--- a/src/game/engine/src/modules/management/turn_processor.gd
+++ b/src/game/engine/src/modules/management/turn_processor.gd
@@ -364,9 +364,14 @@ func _process_culture(player: RefCounted, game_map: RefCounted) -> void:
 			continue
 		var c: CityScript = city_ref as CityScript
 		var tile_json: String = BuildableHelperScript.build_tile_yields_json(c, game_map)
-		# TEMPORARY R9 PARITY TEST: revert to pre-port GDScript multiplication
-		# to isolate the culture-port effect from other landed code (courier
-		# diplomacy, building ID reconciliation) between R6 and R7/R8.
+		# Culture-port to Rust (`process_culture_with_modifier`) attempted in
+		# R7/R8 but caused seed-divergence vs R6 baseline (R9 parity test
+		# reproduced R6 exactly when reverted to this GDScript path; R8 with
+		# Rust port diverged on every seed). Math LOOKED identical but the
+		# Rust call sequence produces different floating-point intermediate
+		# results than the GDScript-via-Variant round-trip path. Culture port
+		# remains TODO — see p1-39. The other Rail-1 ports (gold, research)
+		# pass parity and stay.
 		var pre_culture: float = c.get_culture_stored()
 		var can_expand: bool = c.process_culture(tile_json)
 		var cult_pct: float = _sum_city_building_effect_float(c, "culture_percent")