diff --git a/document-parser/tests/test_document_service.py b/document-parser/tests/test_document_service.py
new file mode 100644
index 0000000..10c9055
--- /dev/null
+++ b/document-parser/tests/test_document_service.py
@@ -0,0 +1,137 @@
+"""Tests for document_service — upload, preview, page counting, and deletion."""
+
+from __future__ import annotations
+
+import os
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from domain.models import Document
+from services import document_service
+
+
+class TestUploadValidation:
+    @pytest.mark.asyncio
+    async def test_rejects_oversized_file(self):
+        content = b"x" * (document_service.MAX_FILE_SIZE + 1)
+        with pytest.raises(ValueError, match="File too large"):
+            await document_service.upload("big.pdf", "application/pdf", content)
+
+    @pytest.mark.asyncio
+    async def test_rejects_non_pdf(self):
+        content = b"NOT-A-PDF-FILE"
+        with pytest.raises(ValueError, match="not a PDF"):
+            await document_service.upload("fake.pdf", "application/pdf", content)
+
+    @pytest.mark.asyncio
+    async def test_accepts_valid_pdf(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(document_service, "UPLOAD_DIR", str(tmp_path))
+
+        mock_insert = AsyncMock()
+        with (
+            patch("persistence.document_repo.insert", mock_insert),
+            patch.object(document_service, "_count_pages", return_value=5),
+        ):
+            content = b"%PDF-1.4 fake pdf content"
+            doc = await document_service.upload("test.pdf", "application/pdf", content)
+
+        assert doc.filename == "test.pdf"
+        assert doc.file_size == len(content)
+        assert doc.page_count == 5
+        mock_insert.assert_called_once()
+
+        # Verify file was actually written to disk
+        assert os.path.exists(doc.storage_path)
+        with open(doc.storage_path, "rb") as f:
+            assert f.read() == content
+
+
+class TestGeneratePreview:
+    def test_raises_on_invalid_page(self):
+        """generate_preview should raise ValueError when page is out of range."""
+        with (
+            patch("services.document_service.convert_from_bytes", return_value=[]),
+            pytest.raises(ValueError, match="Page 1 not found"),
+        ):
+            document_service.generate_preview(b"%PDF-fake", page=1)
+
+    def test_returns_png_bytes(self):
+        """generate_preview should return PNG bytes from pdf2image."""
+        mock_image = MagicMock()
+        mock_image.save = MagicMock(side_effect=lambda buf, format: buf.write(b"PNG-DATA"))
+
+        with patch("services.document_service.convert_from_bytes", return_value=[mock_image]):
+            result = document_service.generate_preview(b"%PDF-fake", page=1, dpi=72)
+
+        assert result == b"PNG-DATA"
+
+
+class TestCountPages:
+    def test_returns_page_count(self):
+        with patch(
+            "services.document_service.pdfinfo_from_bytes",
+            return_value={"Pages": 42},
+        ):
+            assert document_service._count_pages(b"pdf") == 42
+
+    def test_returns_none_on_error(self):
+        with patch(
+            "services.document_service.pdfinfo_from_bytes",
+            side_effect=FileNotFoundError("poppler not found"),
+        ):
+            assert document_service._count_pages(b"pdf") is None
+
+
+class TestDelete:
+    @pytest.mark.asyncio
+    async def test_delete_removes_file_and_records(self, tmp_path, monkeypatch):
+        monkeypatch.setattr(document_service, "UPLOAD_DIR", str(tmp_path))
+
+        # Create a fake file
+        fake_file = tmp_path / "test.pdf"
+        fake_file.write_bytes(b"content")
+
+        doc = Document(
+            id="doc-1",
+            filename="test.pdf",
+            storage_path=str(fake_file),
+        )
+
+        with (
+            patch("persistence.document_repo.find_by_id", AsyncMock(return_value=doc)),
+            patch("persistence.analysis_repo.delete_by_document", AsyncMock(return_value=2)),
+            patch("persistence.document_repo.delete", AsyncMock(return_value=True)),
+        ):
+            result = await document_service.delete("doc-1")
+
+        assert result is True
+        assert not fake_file.exists()
+
+    @pytest.mark.asyncio
+    async def test_delete_refuses_file_outside_upload_dir(self, tmp_path, monkeypatch):
+        """Files outside UPLOAD_DIR should not be deleted (path traversal protection)."""
+        monkeypatch.setattr(document_service, "UPLOAD_DIR", str(tmp_path / "uploads"))
+        os.makedirs(tmp_path / "uploads", exist_ok=True)
+
+        # File is outside the upload dir
+        outside_file = tmp_path / "secret.txt"
+        outside_file.write_bytes(b"secret")
+
+        doc = Document(id="doc-1", filename="x.pdf", storage_path=str(outside_file))
+
+        with (
+            patch("persistence.document_repo.find_by_id", AsyncMock(return_value=doc)),
+            patch("persistence.analysis_repo.delete_by_document", AsyncMock(return_value=0)),
+            patch("persistence.document_repo.delete", AsyncMock(return_value=True)),
+        ):
+            await document_service.delete("doc-1")
+
+        # File should NOT have been deleted
+        assert outside_file.exists()
+
+    @pytest.mark.asyncio
+    async def test_delete_not_found_returns_false(self):
+        with patch("persistence.document_repo.find_by_id", AsyncMock(return_value=None)):
+            result = await document_service.delete("missing")
+        assert result is False