diff --git a/tests/private_temp.py b/tests/private_temp.py
new file mode 100644
index 00000000..dee79ce9
--- /dev/null
+++ b/tests/private_temp.py
@@ -0,0 +1,24 @@
+"""A temp SQLite database in a folder no other test process shares (#346).
+
+``PromptManagerAPI`` sweeps its database's folder at startup for the stages,
+uploads and safety-backup copies an interrupted restore or backup left. A
+fixture database directly in the system temp folder made every other test
+process that started an API (another worktree's suite, a pre-push hook) delete
+this process's in-flight restore files, and left safety backups behind there.
+"""
+
+import tempfile
+
+
+def private_temp_db(case):
+    """Return a closed ``NamedTemporaryFile`` handle for an empty ``.db`` file.
+
+    The file lives in a new folder that ``case`` removes at cleanup, after its
+    own teardown has closed and unlinked the database (cleanups run after
+    ``tearDown``), together with anything a restore or backup left next to it.
+    """
+    folder = tempfile.TemporaryDirectory(ignore_cleanup_errors=True)
+    case.addCleanup(folder.cleanup)
+    handle = tempfile.NamedTemporaryFile(delete=False, suffix=".db", dir=folder.name)
+    handle.close()
+    return handle
diff --git a/tests/test_api.py b/tests/test_api.py
index 051881a8..efcb433a 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -8,7 +8,6 @@ without requiring a full ComfyUI server.
 import json
 import os
 import sys
-import tempfile
 import unittest
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
@@ -18,6 +17,7 @@ from aiohttp.test_utils import AioHTTPTestCase
 
 from database.operations import PromptDatabase
 from py.api import PromptManagerAPI
+from tests.private_temp import private_temp_db
 from utils.hashing import generate_prompt_hash
 
 
@@ -25,8 +25,7 @@ class APITestCase(AioHTTPTestCase):
     """Base class that stands up a test aiohttp app with PromptManager routes."""
 
     async def get_application(self):
-        self._temp_db = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-        self._temp_db.close()
+        self._temp_db = private_temp_db(self)
 
         app = web.Application()
         routes = web.RouteTableDef()
diff --git a/tests/test_api_autotag.py b/tests/test_api_autotag.py
index e2d2dffc..cfe3f47a 100644
--- a/tests/test_api_autotag.py
+++ b/tests/test_api_autotag.py
@@ -35,6 +35,7 @@ from aiohttp.test_utils import AioHTTPTestCase
 
 from database.operations import PromptDatabase
 from py.api import PromptManagerAPI
+from tests.private_temp import private_temp_db
 from py.api.autotag_routes import MODEL_BUSY_ERROR
 from py.api.jobs import JobBusy
 from utils.hashing import generate_prompt_hash
@@ -143,8 +144,7 @@ class AutotagAPITestCase(AioHTTPTestCase):
     fake engine."""
 
     async def get_application(self):
-        self._temp_db = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-        self._temp_db.close()
+        self._temp_db = private_temp_db(self)
         self.tmp_root = Path(tempfile.mkdtemp())
         self.output_dir = self.tmp_root / "output"
         self.output_dir.mkdir()
diff --git a/tests/test_api_history.py b/tests/test_api_history.py
index 67476d7a..dc952332 100644
--- a/tests/test_api_history.py
+++ b/tests/test_api_history.py
@@ -1169,3 +1169,47 @@ class HistoryHostCleanupTests(unittest.IsolatedAsyncioTestCase):
                     fence.validate(epoch, generation)
                 with self.assertRaises(sqlite3.Error):
                     api._history_fence()
+
+
+class SharedTempFolderRestoreTests(ImageAPITestCase):
+    """#346: a restore survives another suite starting in the shared temp folder.
+
+    Every ``PromptManagerAPI`` sweeps its database's folder for stages and
+    uploads an interrupted restore left. A fixture database directly in the
+    shared temp folder let any other test process (another worktree's suite,
+    a pre-push hook) delete this restore's files mid-request. The shared
+    folder here is a scratch stand-in for the system temp folder, so the test
+    never sweeps the real one.
+    """
+
+    async def get_application(self):
+        shared = tempfile.TemporaryDirectory(ignore_cleanup_errors=True)
+        # Cleanups run last-in first-out: this one after the fixture's own.
+        self.addCleanup(shared.cleanup)
+        self.shared_tmp = shared.name
+        with patch.object(tempfile, "tempdir", shared.name):
+            return await super().get_application()
+
+    async def test_restore_survives_another_suite_sweeping_the_shared_folder(self):
+        from database import restore_stage
+        from database.models import PromptModel
+
+        self.api.db.save_prompt("kept by the upload")
+        source = self.comfy_dir / "upload.db"
+        self.assertTrue(self.api.db.model.backup_database(str(source)))
+        stage = PromptModel.stage_restore
+        swept = []
+
+        def stage_then_other_suite_starts(model, src_path):
+            staged = stage(model, src_path)
+            # What another suite's PromptManagerAPI does at startup.
+            other = os.path.join(self.shared_tmp, "other-suite.db")
+            swept.extend(restore_stage.sweep_restore_temps(other))
+            return staged
+
+        form = FormData()
+        form.add_field("database_file", source.read_bytes(), filename="upload.db")
+        with patch.object(PromptModel, "stage_restore", stage_then_other_suite_starts):
+            response = await self.client.post("/prompt_manager/restore", data=form)
+        self.assertEqual(response.status, 200, await response.text())
+        self.assertEqual(swept, [], "another suite's sweep reached this restore")
diff --git a/tests/test_api_images.py b/tests/test_api_images.py
index 08713ddb..cc74c6cf 100644
--- a/tests/test_api_images.py
+++ b/tests/test_api_images.py
@@ -42,6 +42,7 @@ from py import lora_utils  # noqa: E402
 from py import lora_manager_layout as layout_module  # noqa: E402
 from py.api.thumbnail_settings import ThumbnailSettings  # noqa: E402
 from py.api import PromptManagerAPI  # noqa: E402
+from tests.private_temp import private_temp_db  # noqa: E402
 from py.api.prompts import MAX_PAGE_LIMIT  # noqa: E402
 from py.config import GalleryConfig  # noqa: E402
 from utils.hashing import generate_prompt_hash  # noqa: E402
@@ -60,8 +61,7 @@ class ImageAPITestCase(AioHTTPTestCase):
     """App with PromptManager routes, a temp DB and a temp output directory."""
 
     async def get_application(self):
-        self._temp_db = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-        self._temp_db.close()
+        self._temp_db = private_temp_db(self)
 
         self._output_tmp = tempfile.TemporaryDirectory(ignore_cleanup_errors=True)
         # A fake ComfyUI tree: <tmp>/output is the gallery root and <tmp> is the
diff --git a/tests/test_api_lora.py b/tests/test_api_lora.py
index 8fda0562..99446360 100644
--- a/tests/test_api_lora.py
+++ b/tests/test_api_lora.py
@@ -36,6 +36,7 @@ from aiohttp.test_utils import AioHTTPTestCase
 
 from database.operations import PromptDatabase
 from py.api import PromptManagerAPI
+from tests.private_temp import private_temp_db
 from py import config_store, lora_import, lora_utils
 from py.config import IntegrationConfig, PromptManagerConfig
 from py.api import settings_routes as settings_module
@@ -57,8 +58,7 @@ class LoraAPITestCase(AioHTTPTestCase):
     """Stands up the PromptManager routes with a temp DB and neutral LoRA config."""
 
     async def get_application(self):
-        self._temp_db = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-        self._temp_db.close()
+        self._temp_db = private_temp_db(self)
         self.tmp_root = Path(tempfile.mkdtemp())
         self.custom_nodes = self.tmp_root / "custom_nodes"
         self.custom_nodes.mkdir()
diff --git a/tests/test_api_prompts.py b/tests/test_api_prompts.py
index c4af9c68..c8625c25 100644
--- a/tests/test_api_prompts.py
+++ b/tests/test_api_prompts.py
@@ -5,7 +5,6 @@ Route tests for the prompt API (py/api/prompts.py).
 import json
 import os
 import sys
-import tempfile
 import unittest
 from unittest.mock import MagicMock, patch
 
@@ -29,6 +28,7 @@ except ImportError:  # discovered with tests/ as the top-level directory
 
 from database.operations import PromptDatabase  # noqa: E402
 from py.api import PromptManagerAPI  # noqa: E402
+from tests.private_temp import private_temp_db  # noqa: E402
 import py.api.prompts as prompts_module  # noqa: E402
 from py.api.prompts import (  # noqa: E402
     BULK_CATEGORY_MAX_PROMPTS,
@@ -43,8 +43,7 @@ class PromptAPITestCase(AioHTTPTestCase):
     """App with PromptManager routes and a temporary SQLite database."""
 
     async def get_application(self):
-        self._temp_db = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-        self._temp_db.close()
+        self._temp_db = private_temp_db(self)
 
         app = web.Application()
         routes = web.RouteTableDef()