diff --git a/src/paperless/tests/test_ai_rag.py b/src/paperless/tests/test_ai_rag.py
new file mode 100644
index 000000000..0cd2f9c9c
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+++ b/src/paperless/tests/test_ai_rag.py
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+from unittest.mock import MagicMock
+from unittest.mock import patch
+
+import pytest
+from llama_index.core.base.embeddings.base import BaseEmbedding
+
+from documents.models import Document
+from paperless.ai.embedding import build_llm_index_text
+from paperless.ai.embedding import get_embedding_dim
+from paperless.ai.embedding import get_embedding_model
+from paperless.ai.indexing import load_index
+from paperless.ai.indexing import query_similar_documents
+from paperless.ai.rag import get_context_for_document
+from paperless.models import LLMEmbeddingBackend
+
+
+@pytest.fixture
+def mock_document():
+    doc = MagicMock(spec=Document)
+    doc.title = "Test Title"
+    doc.filename = "test_file.pdf"
+    doc.created = "2023-01-01"
+    doc.added = "2023-01-02"
+    doc.modified = "2023-01-03"
+
+    tag1 = MagicMock()
+    tag1.name = "Tag1"
+    tag2 = MagicMock()
+    tag2.name = "Tag2"
+    doc.tags.all = MagicMock(return_value=[tag1, tag2])
+
+    doc.document_type = MagicMock()
+    doc.document_type.name = "Invoice"
+    doc.correspondent = MagicMock()
+    doc.correspondent.name = "Test Correspondent"
+    doc.archive_serial_number = "12345"
+    doc.content = "This is the document content."
+
+    cf1 = MagicMock(__str__=lambda x: "Value1")
+    cf1.field = MagicMock()
+    cf1.field.name = "Field1"
+    cf1.value = "Value1"
+    cf2 = MagicMock(__str__=lambda x: "Value2")
+    cf2.field = MagicMock()
+    cf2.field.name = "Field2"
+    cf2.value = "Value2"
+    doc.custom_fields.all = MagicMock(return_value=[cf1, cf2])
+
+    return doc
+
+
+@pytest.fixture
+def mock_similar_documents():
+    doc1 = MagicMock()
+    doc1.content = "Content of document 1"
+    doc1.title = "Title 1"
+    doc1.filename = "file1.txt"
+
+    doc2 = MagicMock()
+    doc2.content = "Content of document 2"
+    doc2.title = None
+    doc2.filename = "file2.txt"
+
+    doc3 = MagicMock()
+    doc3.content = None
+    doc3.title = None
+    doc3.filename = None
+
+    return [doc1, doc2, doc3]
+
+
+@patch("paperless.ai.rag.query_similar_documents")
+def test_get_context_for_document(
+    mock_query_similar_documents,
+    mock_document,
+    mock_similar_documents,
+):
+    mock_query_similar_documents.return_value = mock_similar_documents
+
+    result = get_context_for_document(mock_document, max_docs=2)
+
+    expected_result = (
+        "TITLE: Title 1\nContent of document 1\n\n"
+        "TITLE: file2.txt\nContent of document 2"
+    )
+    assert result == expected_result
+    mock_query_similar_documents.assert_called_once()
+
+
+def test_get_context_for_document_no_similar_docs(mock_document):
+    with patch("paperless.ai.rag.query_similar_documents", return_value=[]):
+        result = get_context_for_document(mock_document)
+        assert result == ""
+
+
+# Embedding
+
+
+@pytest.fixture
+def mock_ai_config():
+    with patch("paperless.ai.embedding.AIConfig") as MockAIConfig:
+        yield MockAIConfig
+
+
+def test_get_embedding_model_openai(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = LLMEmbeddingBackend.OPENAI
+    mock_ai_config.return_value.llm_embedding_model = "text-embedding-3-small"
+    mock_ai_config.return_value.llm_api_key = "test_api_key"
+
+    with patch("paperless.ai.embedding.OpenAIEmbedding") as MockOpenAIEmbedding:
+        model = get_embedding_model()
+        MockOpenAIEmbedding.assert_called_once_with(
+            model="text-embedding-3-small",
+            api_key="test_api_key",
+        )
+        assert model == MockOpenAIEmbedding.return_value
+
+
+def test_get_embedding_model_huggingface(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = LLMEmbeddingBackend.HUGGINGFACE
+    mock_ai_config.return_value.llm_embedding_model = (
+        "sentence-transformers/all-MiniLM-L6-v2"
+    )
+
+    with patch(
+        "paperless.ai.embedding.HuggingFaceEmbedding",
+    ) as MockHuggingFaceEmbedding:
+        model = get_embedding_model()
+        MockHuggingFaceEmbedding.assert_called_once_with(
+            model_name="sentence-transformers/all-MiniLM-L6-v2",
+        )
+        assert model == MockHuggingFaceEmbedding.return_value
+
+
+def test_get_embedding_model_invalid_backend(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = "INVALID_BACKEND"
+
+    with pytest.raises(
+        ValueError,
+        match="Unsupported embedding backend: INVALID_BACKEND",
+    ):
+        get_embedding_model()
+
+
+def test_get_embedding_dim_openai(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = "openai"
+    mock_ai_config.return_value.llm_embedding_model = None
+
+    assert get_embedding_dim() == 1536
+
+
+def test_get_embedding_dim_huggingface(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = "huggingface"
+    mock_ai_config.return_value.llm_embedding_model = None
+
+    assert get_embedding_dim() == 384
+
+
+def test_get_embedding_dim_unknown_model(mock_ai_config):
+    mock_ai_config.return_value.llm_embedding_backend = "openai"
+    mock_ai_config.return_value.llm_embedding_model = "unknown-model"
+
+    with pytest.raises(ValueError, match="Unknown embedding model: unknown-model"):
+        get_embedding_dim()
+
+
+def test_build_llm_index_text(mock_document):
+    with patch("documents.models.Note.objects.filter") as mock_notes_filter:
+        mock_notes_filter.return_value = [
+            MagicMock(note="Note1"),
+            MagicMock(note="Note2"),
+        ]
+
+        result = build_llm_index_text(mock_document)
+
+        assert "Title: Test Title" in result
+        assert "Filename: test_file.pdf" in result
+        assert "Created: 2023-01-01" in result
+        assert "Tags: Tag1, Tag2" in result
+        assert "Document Type: Invoice" in result
+        assert "Correspondent: Test Correspondent" in result
+        assert "Notes: Note1,Note2" in result
+        assert "Content:\n\nThis is the document content." in result
+        assert "Custom Field - Field1: Value1\nCustom Field - Field2: Value2" in result
+
+
+# Indexing
+
+
+@pytest.fixture
+def mock_settings(settings):
+    settings.LLM_INDEX_DIR = "/fake/path"
+    return settings
+
+
+class FakeEmbedding(BaseEmbedding):
+    # TODO: gotta be a better way to do this
+    def _aget_query_embedding(self, query: str) -> list[float]:
+        return [0.1, 0.2, 0.3]
+
+    def _get_query_embedding(self, query: str) -> list[float]:
+        return [0.1, 0.2, 0.3]
+
+    def _get_text_embedding(self, text: str) -> list[float]:
+        return [0.1, 0.2, 0.3]
+
+
+def test_load_index(mock_settings):
+    with (
+        patch("paperless.ai.indexing.FaissVectorStore.from_persist_dir") as mock_faiss,
+        patch("paperless.ai.indexing.get_embedding_model") as mock_get_embed_model,
+        patch(
+            "paperless.ai.indexing.StorageContext.from_defaults",
+        ) as mock_storage_context,
+        patch("paperless.ai.indexing.load_index_from_storage") as mock_load_index,
+    ):
+        # Setup mocks
+        mock_vector_store = MagicMock()
+        mock_storage = MagicMock()
+        mock_index = MagicMock()
+
+        mock_faiss.return_value = mock_vector_store
+        mock_storage_context.return_value = mock_storage
+        mock_load_index.return_value = mock_index
+        mock_get_embed_model.return_value = FakeEmbedding()
+
+        # Act
+        result = load_index()
+
+        # Assert
+        mock_faiss.assert_called_once_with("/fake/path")
+        mock_get_embed_model.assert_called_once()
+        mock_storage_context.assert_called_once_with(
+            vector_store=mock_vector_store,
+            persist_dir="/fake/path",
+        )
+        mock_load_index.assert_called_once_with(mock_storage)
+        assert result == mock_index
+
+
+def test_query_similar_documents(mock_document):
+    with (
+        patch("paperless.ai.indexing.load_index") as mock_load_index_func,
+        patch("paperless.ai.indexing.VectorIndexRetriever") as mock_retriever_cls,
+        patch("paperless.ai.indexing.Document.objects.filter") as mock_filter,
+    ):
+        # Setup mocks
+        mock_index = MagicMock()
+        mock_load_index_func.return_value = mock_index
+
+        mock_retriever = MagicMock()
+        mock_retriever_cls.return_value = mock_retriever
+
+        mock_node1 = MagicMock()
+        mock_node1.metadata = {"document_id": 1}
+
+        mock_node2 = MagicMock()
+        mock_node2.metadata = {"document_id": 2}
+
+        mock_retriever.retrieve.return_value = [mock_node1, mock_node2]
+
+        mock_filtered_docs = [MagicMock(pk=1), MagicMock(pk=2)]
+        mock_filter.return_value = mock_filtered_docs
+
+        result = query_similar_documents(mock_document, top_k=3)
+
+        mock_load_index_func.assert_called_once()
+        mock_retriever_cls.assert_called_once_with(index=mock_index, similarity_top_k=3)
+        mock_retriever.retrieve.assert_called_once_with(
+            "Test Title\nThis is the document content.",
+        )
+        mock_filter.assert_called_once_with(pk__in=[1, 2])
+
+        assert result == mock_filtered_docs