diff --git a/.trellis/spec/backend/drizzle-postgres-current.md b/.trellis/spec/backend/drizzle-postgres-current.md
index be1a421..d93eea9 100644
--- a/.trellis/spec/backend/drizzle-postgres-current.md
+++ b/.trellis/spec/backend/drizzle-postgres-current.md
@@ -110,3 +110,73 @@ await database.transaction(async (transaction) => {
   await transaction.update(elders).set({ status: "active" }).where(eq(elders.id, elderId));
 });
 ```
+
+## Scenario: Facility Room Creation Without Fabricated Hierarchy
+
+### 1. Scope / Trigger
+
+- Trigger: changing facility room creation APIs or any UI that creates rooms.
+- Applies because `rooms.floorId` is required by schema, but the system must not create
+  fake campus/building/floor records to satisfy that foreign key.
+
+### 2. Signatures
+
+- `POST /api/facilities/rooms`
+- Request: `{ name: string; code: string; floorId: string; capacity?: number }`
+- Response: `ApiResult<{ room: typeof rooms.$inferSelect }>`
+
+### 3. Contracts
+
+- `floorId` must refer to an existing `floors.id` in the authenticated active organization.
+- `capacity` is optional; omitted means schema/product default `1`.
+- If `capacity` is supplied, it must be a positive integer.
+- The handler may insert only the `rooms` row. It must not insert `campuses`,
+  `buildings`, or `floors` as placeholder hierarchy.
+
+### 4. Validation & Error Matrix
+
+- Missing active organization -> `400` / `请选择机构后维护房间`.
+- Missing `name`, `code`, or `floorId` -> `400` / `房间名称、编号和楼层不能为空`.
+- Invalid supplied `capacity` -> `400` / `房间容量需为正整数`.
+- `floorId` not found in active organization -> `404` / `楼层不存在`.
+- Insert returning no row -> `500` / `房间创建失败`.
+
+### 5. Good/Base/Bad Cases
+
+- Good: create UI first exposes real campus/building/floor selection, then submits the selected `floorId`.
+- Base: if facility hierarchy management is not exposed yet, keep room creation UI hidden or disabled.
+- Bad: auto-create `"默认院区"`, `"默认楼栋"`, or `"默认楼层"` inside the room API.
+
+### 6. Tests Required
+
+- `pnpm lint`
+- `pnpm type-check`
+- `pnpm build`
+- Integration assertions:
+  - missing `floorId` returns `400`
+  - unknown or cross-organization `floorId` returns `404`
+  - valid `floorId` creates a room without inserting campus/building/floor rows
+
+### 7. Wrong vs Correct
+
+#### Wrong
+
+```ts
+const floor = existingFloor ?? await transaction.insert(floors).values({ name: "默认楼层" }).returning();
+await transaction.insert(rooms).values({ floorId: floor.id, name, code });
+```
+
+#### Correct
+
+```ts
+const floorRows = await database
+  .select({ id: floors.id })
+  .from(floors)
+  .where(and(eq(floors.id, floorId), eq(floors.organizationId, organizationId)))
+  .limit(1);
+const floor = floorRows[0];
+if (!floor) {
+  return jsonFailure("楼层不存在", 404);
+}
+await database.insert(rooms).values({ organizationId, floorId: floor.id, name, code });
+```