v0.5.1: automatic Trash purge (cron-less background thread)

Trashed artifacts past a ~3-day retention window are now purged automatically.

- storage.purge_expired_trash(): removes trash older than TRASH_RETENTION
  (all users), tolerant of already-gone rows (concurrent-safe).
- spawn_trash_purge(): runs it on a daemon thread (manages/closes its own DB
  connection), triggered by each delete so it's cron-less and off the request
  thread. Inline fallback when AGENTFEED_ASYNC_PURGE is off (tests).
- Wired into both delete paths (API + session). Manual Empty Trash unchanged.
- Tests: purge removes expired-only; delete triggers the purge. 152 passing;
  live delete verified with the thread enabled (204, server healthy).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/api/test_artifacts.py

@@ -17,6 +17,7 @@ from artifacts.models import ApiKey, Artifact
 User = get_user_model()
 
 
+@override_settings(AGENTFEED_ASYNC_PURGE=False)  # DELETE triggers purge; run it inline in tests
 class ArtifactAPITestCase(APITestCase):
     """Exercises the ingest/list/detail API against a real (temp) filesystem
     and a real (test) database, the way an agent posting over HTTP would."""

tests/views/test_trash.py

@@ -1,5 +1,6 @@
 import shutil
 import tempfile
+from datetime import timedelta
 from pathlib import Path
 
 from django.contrib.auth import get_user_model
@@ -8,11 +9,13 @@ from django.urls import reverse
 from django.utils import timezone
 
 from artifacts.models import Artifact
-from artifacts.storage import user_usage_bytes
+from artifacts.storage import purge_expired_trash, user_usage_bytes
 
 User = get_user_model()
 
 
+# Run the purge inline (no background thread) so its effects are deterministic.
+@override_settings(AGENTFEED_ASYNC_PURGE=False)
 class TrashKeepViewTestCase(TestCase):
     @classmethod
     def setUpClass(cls):
@@ -105,3 +108,23 @@ class TrashKeepViewTestCase(TestCase):
         page = self.client.get("/?folder=keep").content.decode()
         self.assertIn("KeptOne", page)
         self.assertNotIn("NormalOne", page)
+
+    def test_purge_expired_trash_removes_old_only(self):
+        old = self.make()
+        recent = self.make()
+        Artifact.objects.filter(pk=old.id).update(deleted_at=timezone.now() - timedelta(days=4))
+        Artifact.objects.filter(pk=recent.id).update(deleted_at=timezone.now())
+        purged = purge_expired_trash()
+        self.assertEqual(purged, 1)
+        self.assertFalse(Artifact.objects.filter(pk=old.id).exists())
+        self.assertTrue(Artifact.objects.filter(pk=recent.id).exists())
+
+    def test_delete_triggers_expired_purge(self):
+        old = self.make()
+        Artifact.objects.filter(pk=old.id).update(deleted_at=timezone.now() - timedelta(days=4))
+        fresh = self.make()
+        # Deleting fresh runs the purge (inline here) -> the expired one goes,
+        # the freshly-trashed one stays.
+        self.client.post(reverse("artifact-delete", args=[fresh.id]))
+        self.assertFalse(Artifact.objects.filter(pk=old.id).exists())
+        self.assertTrue(Artifact.objects.filter(pk=fresh.id, deleted_at__isnull=False).exists())