diff --git a/backend/app/routers/devices.py b/backend/app/routers/devices.py
index 8cc7916..8dadc8b 100644
--- a/backend/app/routers/devices.py
+++ b/backend/app/routers/devices.py
@@ -1,9 +1,10 @@
 import csv
 import io
+from datetime import datetime, timezone
 from typing import Annotated
 
 from fastapi import APIRouter, Depends, File, HTTPException, Query, UploadFile, status
-from sqlalchemy import select
+from sqlalchemy import select, update as sa_update
 from sqlalchemy.orm import selectinload
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -24,6 +25,12 @@ from app.services import crypto
 router = APIRouter(prefix="/api/v1/objects/{obj_id}/devices", tags=["devices"])
 
 
+async def _touch_object(db: AsyncSession, obj_id: int) -> None:
+    await db.execute(
+        sa_update(Object).where(Object.id == obj_id).values(updated_at=datetime.now(timezone.utc))
+    )
+
+
 async def _get_object(db: AsyncSession, obj_id: int) -> Object:
     result = await db.execute(select(Object).where(Object.id == obj_id))
     obj = result.scalar_one_or_none()
@@ -90,6 +97,7 @@ async def create_device(
     db.add(device)
     await db.flush()
     await db.refresh(device)
+    await _touch_object(db, obj_id)
     # reload with rack relationship
     result = await db.execute(
         select(Device).options(selectinload(Device.rack)).where(Device.id == device.id)
@@ -117,6 +125,7 @@ async def import_csv(
 ):
     await _get_object(db, obj_id)
     preview = await _parse_csv_import(db, obj_id, file, dry_run=False)
+    await _touch_object(db, obj_id)
     return DeviceImportResult(
         created=len(preview.would_create),
         updated=len(preview.would_update),
@@ -241,6 +250,7 @@ async def update_device(
 
     await db.flush()
     await db.refresh(device)
+    await _touch_object(db, obj_id)
     return device
 
 
@@ -254,6 +264,7 @@ async def delete_all_devices(
     result = await db.execute(select(Device).where(Device.object_id == obj_id))
     for device in result.scalars().all():
         await db.delete(device)
+    await _touch_object(db, obj_id)
 
 
 @router.delete("/{device_id}", status_code=status.HTTP_204_NO_CONTENT)
@@ -265,3 +276,4 @@ async def delete_device(
 ):
     device = await _get_device(db, obj_id, device_id)
     await db.delete(device)
+    await _touch_object(db, obj_id)
diff --git a/backend/app/routers/racks.py b/backend/app/routers/racks.py
index e05853b..48bf422 100644
--- a/backend/app/routers/racks.py
+++ b/backend/app/routers/racks.py
@@ -1,5 +1,7 @@
+from datetime import datetime, timezone
+
 from fastapi import APIRouter, Depends, HTTPException, status
-from sqlalchemy import select
+from sqlalchemy import select, update as sa_update
 from sqlalchemy.orm import selectinload
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -12,6 +14,12 @@ from app.schemas.rack import RackCreate, RackRead, RackUpdate
 router = APIRouter(prefix="/api/v1/objects/{obj_id}/racks", tags=["racks"])
 
 
+async def _touch_object(db: AsyncSession, obj_id: int) -> None:
+    await db.execute(
+        sa_update(Object).where(Object.id == obj_id).values(updated_at=datetime.now(timezone.utc))
+    )
+
+
 async def _get_object(db: AsyncSession, obj_id: int) -> Object:
     obj = await db.get(Object, obj_id)
     if obj is None:
@@ -58,6 +66,7 @@ async def create_rack(
     rack = Rack(object_id=obj_id, **body.model_dump())
     db.add(rack)
     await db.flush()
+    await _touch_object(db, obj_id)
     result = await db.execute(
         select(Rack).options(selectinload(Rack.zone)).where(Rack.id == rack.id)
     )
@@ -76,6 +85,7 @@ async def update_rack(
     for field, value in body.model_dump(exclude_unset=True).items():
         setattr(rack, field, value)
     await db.flush()
+    await _touch_object(db, obj_id)
     result = await db.execute(
         select(Rack).options(selectinload(Rack.zone)).where(Rack.id == rack.id)
     )
@@ -91,3 +101,4 @@ async def delete_rack(
 ):
     rack = await _load_rack(db, obj_id, rack_id)
     await db.delete(rack)
+    await _touch_object(db, obj_id)
diff --git a/backend/app/routers/zones.py b/backend/app/routers/zones.py
index 451a307..b6c687c 100644
--- a/backend/app/routers/zones.py
+++ b/backend/app/routers/zones.py
@@ -1,5 +1,7 @@
+from datetime import datetime, timezone
+
 from fastapi import APIRouter, Depends, HTTPException, status
-from sqlalchemy import select
+from sqlalchemy import select, update as sa_update
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.dependencies import get_current_user, get_db
@@ -11,6 +13,12 @@ from app.schemas.zone import ZoneCreate, ZoneRead, ZoneUpdate
 router = APIRouter(prefix="/api/v1/objects/{obj_id}/zones", tags=["zones"])
 
 
+async def _touch_object(db: AsyncSession, obj_id: int) -> None:
+    await db.execute(
+        sa_update(Object).where(Object.id == obj_id).values(updated_at=datetime.now(timezone.utc))
+    )
+
+
 async def _get_object(db: AsyncSession, obj_id: int) -> Object:
     obj = await db.get(Object, obj_id)
     if obj is None:
@@ -53,6 +61,7 @@ async def create_zone(
     db.add(zone)
     await db.flush()
     await db.refresh(zone)
+    await _touch_object(db, obj_id)
     return zone
 
 
@@ -69,6 +78,7 @@ async def update_zone(
         setattr(zone, field, value)
     await db.flush()
     await db.refresh(zone)
+    await _touch_object(db, obj_id)
     return zone
 
 
@@ -81,3 +91,4 @@ async def delete_zone(
 ):
     zone = await _get_zone(db, obj_id, zone_id)
     await db.delete(zone)
+    await _touch_object(db, obj_id)