Fetch Paperless before wiping the index in reindex

`reindex` deleted every chunk before contacting Paperless, so an unreachable
or empty Paperless left the store empty (which happened when Paperless was
crash-looping during its v3 upgrade). It now fetches first, aborts without
deleting if that fails or returns nothing, and indexes the fetched documents
instead of fetching twice.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/test_manage_vectorstore.py

@@ -16,7 +16,14 @@ def calls(monkeypatch):
         lambda k, v: calls.append(f"delete {k}={v}"),
     )
     monkeypatch.setattr(
-        cli, "index_documents", AsyncMock(side_effect=lambda: calls.append("paperless"))
+        cli,
+        "fetch_documents_from_paperless_ngx",
+        AsyncMock(side_effect=lambda: calls.append("fetch") or ["doc"]),
+    )
+    monkeypatch.setattr(
+        cli,
+        "index_documents",
+        AsyncMock(side_effect=lambda *docs: calls.append(f"paperless {list(docs)}")),
     )
     monkeypatch.setattr(
         cli,
@@ -31,7 +38,8 @@ def calls(monkeypatch):
     "command, expected",
     [
         # A full reindex must not drop Obsidian notes after wiping everything.
-        ("reindex", ["delete_all", "paperless", "obsidian"]),
+        # Fetch before deleting, then index the fetched documents (no refetch).
+        ("reindex", ["fetch", "delete_all", "paperless [['doc']]", "obsidian"]),
         ("reindex-obsidian", ["delete source=obsidian", "obsidian"]),
     ],
 )
@@ -39,3 +47,20 @@ def test_reindex_commands(calls, monkeypatch, command, expected):
     monkeypatch.setattr(sys, "argv", ["manage_vectorstore", command])
     cli.main()
     assert calls == expected
+
+
+@pytest.mark.parametrize(
+    "failure",
+    [
+        AsyncMock(side_effect=ConnectionError("Name or service not known")),
+        AsyncMock(return_value=[]),
+    ],
+)
+def test_reindex_leaves_index_untouched_when_paperless_fails(
+    calls, monkeypatch, failure
+):
+    monkeypatch.setattr(cli, "fetch_documents_from_paperless_ngx", failure)
+    monkeypatch.setattr(sys, "argv", ["manage_vectorstore", "reindex"])
+    with pytest.raises(SystemExit):
+        cli.main()
+    assert "delete_all" not in calls