v0.5.0: Trash (soft-delete) + Keep folder

Delete now moves an artifact to a recoverable Trash instead of hard-removing.

- Model: Artifact.deleted_at (nullable, indexed) = in Trash.
- Soft-delete everywhere: DELETE /api/artifacts/{id} sets deleted_at
  (idempotent 204); session POST /a/{id}/delete for the feed's hover Delete
  icon; POST /a/{id}/undelete restores; POST /feed/empty-trash purges.
- Trashed artifacts are off-quota (deleting frees quota) and eviction-protected
  (never evicted early); hidden from feed, sources, counts, and all API reads
  (list/detail/raw).
- Sidebar: "Deleted" and "Keep" system folders at the bottom (counts, hidden
  when empty); ?folder=deleted / ?folder=keep views reuse the row rendering.
  Deleted view has hover Undelete + an Empty Trash button. Keep = view over
  is_kept. Live-poll disabled in folder views.
- Docs (api.md delete section, CLAUDE.md), 10 new/updated tests. 150 passing;
  API soft-delete lifecycle verified live.

Purge is manual (Empty Trash) this release; auto purge-on-delete (background,
~3-day retention) is the planned fast-follow.

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

tests/views/test_trash.py

@@ -0,0 +1,107 @@
+import shutil
+import tempfile
+from pathlib import Path
+
+from django.contrib.auth import get_user_model
+from django.test import TestCase, override_settings
+from django.urls import reverse
+from django.utils import timezone
+
+from artifacts.models import Artifact
+from artifacts.storage import user_usage_bytes
+
+User = get_user_model()
+
+
+class TrashKeepViewTestCase(TestCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.artifacts_root = Path(tempfile.mkdtemp(prefix="agentfeed-test-trash-"))
+        cls.settings_override = override_settings(ARTIFACTS_ROOT=cls.artifacts_root)
+        cls.settings_override.enable()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.settings_override.disable()
+        shutil.rmtree(cls.artifacts_root, ignore_errors=True)
+        super().tearDownClass()
+
+    def setUp(self):
+        self.user = User.objects.create_user(username="alice", password="pw")
+        self.other = User.objects.create_user(username="bob", password="pw")
+        self.client.force_login(self.user)
+        self._n = 0
+
+    def make(self, owner=None, title="Note", source="agent", is_kept=False, size_bytes=1):
+        self._n += 1
+        return Artifact.objects.create(
+            id=f"trs{self._n:05d}",
+            owner=owner or self.user,
+            source=source,
+            title=title,
+            kind=Artifact.MARKDOWN,
+            day=timezone.localdate(),
+            path=f"{source}/trs{self._n:05d}.html",
+            original_kind=Artifact.MARKDOWN,
+            size_bytes=size_bytes,
+            is_kept=is_kept,
+        )
+
+    def test_delete_soft_deletes(self):
+        a = self.make()
+        r = self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.assertEqual(r.status_code, 200)
+        a.refresh_from_db()
+        self.assertIsNotNone(a.deleted_at)
+
+    def test_delete_requires_login(self):
+        self.client.logout()
+        a = self.make()
+        r = self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.assertEqual(r.status_code, 302)
+
+    def test_delete_scoped_to_owner(self):
+        a = self.make(owner=self.other)
+        r = self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.assertEqual(r.status_code, 404)
+        a.refresh_from_db()
+        self.assertIsNone(a.deleted_at)
+
+    def test_deleted_hidden_from_feed_shown_in_trash(self):
+        a = self.make(title="ThrowawayThing")
+        self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.assertNotIn("ThrowawayThing", self.client.get("/").content.decode())
+        self.assertIn("ThrowawayThing", self.client.get("/?folder=deleted").content.decode())
+
+    def test_undelete_restores(self):
+        a = self.make(title="ComeBack")
+        self.client.post(reverse("artifact-delete", args=[a.id]))
+        r = self.client.post(reverse("artifact-undelete", args=[a.id]))
+        self.assertEqual(r.status_code, 200)
+        a.refresh_from_db()
+        self.assertIsNone(a.deleted_at)
+        self.assertIn("ComeBack", self.client.get("/").content.decode())
+
+    def test_empty_trash_purges(self):
+        a = self.make()
+        b = self.make()
+        self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.client.post(reverse("artifact-delete", args=[b.id]))
+        r = self.client.post(reverse("feed-empty-trash"))
+        self.assertEqual(r.status_code, 200)
+        self.assertEqual(r.json()["purged"], 2)
+        self.assertFalse(Artifact.objects.filter(pk__in=[a.id, b.id]).exists())
+
+    def test_deleted_is_off_quota(self):
+        a = self.make(size_bytes=1000)
+        self.assertEqual(user_usage_bytes(self.user), 1000)
+        self.client.post(reverse("artifact-delete", args=[a.id]))
+        self.assertEqual(user_usage_bytes(self.user), 0)
+
+    def test_keep_folder_shows_only_kept(self):
+        self.make(title="KeptOne", is_kept=True)
+        self.make(title="NormalOne")
+        page = self.client.get("/?folder=keep").content.decode()
+        self.assertIn("KeptOne", page)
+        self.assertNotIn("NormalOne", page)