diff --git a/apps/api/src/modules/rate-plan/dto/effective-rate-query.dto.ts b/apps/api/src/modules/rate-plan/dto/effective-rate-query.dto.ts
index 6d5aea5..ec22313 100644
--- a/apps/api/src/modules/rate-plan/dto/effective-rate-query.dto.ts
+++ b/apps/api/src/modules/rate-plan/dto/effective-rate-query.dto.ts
@@ -1,7 +1,16 @@
 import { ApiPropertyOptional } from '@nestjs/swagger';
-import { IsDateString, IsInt, IsOptional, Min } from 'class-validator';
+import { IsDateString, IsInt, IsOptional, IsUUID, Min } from 'class-validator';
 
 export class EffectiveRateQueryDto {
+  // The controller also binds propertyId via @Query('propertyId'), but the
+  // global ValidationPipe validates the WHOLE query object against this DTO —
+  // without this field every call 400s with "property propertyId should not
+  // exist" (forbidNonWhitelisted). Day Zero P0.
+  @ApiPropertyOptional({ description: 'Property ID (also bound by the controller)' })
+  @IsOptional()
+  @IsUUID()
+  propertyId?: string;
+
   @ApiPropertyOptional({ description: 'Length of stay in nights (alternative to checkIn/checkOut)' })
   @IsOptional()
   @IsInt()
diff --git a/apps/api/src/modules/room/room-status.service.ts b/apps/api/src/modules/room/room-status.service.ts
index 3f41769..0f12571 100644
--- a/apps/api/src/modules/room/room-status.service.ts
+++ b/apps/api/src/modules/room/room-status.service.ts
@@ -20,7 +20,9 @@ type RoomStatus =
   | 'out_of_service';
 
 const VALID_TRANSITIONS: Record<RoomStatus, RoomStatus[]> = {
-  vacant_clean: ['occupied', 'out_of_order', 'out_of_service'],
+  // KB 5.2 chain: vacant_clean → vacant_dirty is the documented "clean room
+  // found dirty" path — the desk must be able to send a room back to HK.
+  vacant_clean: ['occupied', 'vacant_dirty', 'out_of_order', 'out_of_service'],
   vacant_dirty: ['clean', 'out_of_order'],
   clean: ['inspected', 'vacant_clean', 'out_of_order'],
   inspected: ['guest_ready', 'out_of_order'],