diff --git a/document-parser/domain/ports.py b/document-parser/domain/ports.py
index 562c567..bc36c9b 100644
--- a/document-parser/domain/ports.py
+++ b/document-parser/domain/ports.py
@@ -6,9 +6,10 @@ Infrastructure adapters (local Docling, Docling Serve, etc.) implement these.
 
 from __future__ import annotations
 
-from typing import Protocol
+from typing import TYPE_CHECKING, Protocol
 
-from domain.value_objects import ConversionOptions, ConversionResult
+if TYPE_CHECKING:
+    from domain.value_objects import ConversionOptions, ConversionResult
 
 
 class DocumentConverter(Protocol):
diff --git a/document-parser/infra/serve_converter.py b/document-parser/infra/serve_converter.py
index 34fc4ef..635e8fb 100644
--- a/document-parser/infra/serve_converter.py
+++ b/document-parser/infra/serve_converter.py
@@ -214,16 +214,17 @@ def _extract_bbox(bbox_data: dict, page_height: float) -> list[float]:
     if not isinstance(bbox_data, dict):
         return [0.0, 0.0, 0.0, 0.0]
 
-    l = bbox_data.get("l", 0.0)
-    t = bbox_data.get("t", 0.0)
-    r = bbox_data.get("r", 0.0)
-    b = bbox_data.get("b", 0.0)
+    left = bbox_data.get("l", 0.0)
+    top = bbox_data.get("t", 0.0)
+    right = bbox_data.get("r", 0.0)
+    bottom = bbox_data.get("b", 0.0)
     coord_origin = bbox_data.get("coord_origin", "TOPLEFT")
 
     if coord_origin == "BOTTOMLEFT":
-        # Convert: top = page_height - old_top, bottom = page_height - old_bottom
-        new_t = page_height - b
-        new_b = page_height - t
-        t, b = new_t, new_b
+        # In BOTTOMLEFT: top has higher y, bottom has lower y
+        # In TOPLEFT: flip both — new_top = page_height - old_top
+        new_top = page_height - top
+        new_bottom = page_height - bottom
+        top, bottom = new_top, new_bottom
 
-    return [l, t, r, b]
+    return [left, top, right, bottom]
diff --git a/document-parser/services/analysis_service.py b/document-parser/services/analysis_service.py
index 8759ef3..6f7f543 100644
--- a/document-parser/services/analysis_service.py
+++ b/document-parser/services/analysis_service.py
@@ -10,10 +10,13 @@ import asyncio
 import json
 import logging
 from dataclasses import asdict
+from typing import TYPE_CHECKING
 
 from domain.models import AnalysisJob
-from domain.ports import DocumentConverter
 from domain.value_objects import ConversionOptions, ConversionResult
+
+if TYPE_CHECKING:
+    from domain.ports import DocumentConverter
 from persistence import analysis_repo, document_repo
 
 logger = logging.getLogger(__name__)
diff --git a/document-parser/tests/test_pipeline_options.py b/document-parser/tests/test_pipeline_options.py
index 39ec84b..f402fdc 100644
--- a/document-parser/tests/test_pipeline_options.py
+++ b/document-parser/tests/test_pipeline_options.py
@@ -14,6 +14,8 @@ from docling.datamodel.pipeline_options import (
 from domain.value_objects import ConversionOptions
 from infra.local_converter import (
     _build_docling_converter as build_converter,
+)
+from infra.local_converter import (
     _convert_sync as convert_document,
 )
 
@@ -457,13 +459,15 @@ class TestAnalysisEndpointPipelineOptions:
     @pytest.fixture
     def client(self):
         from fastapi.testclient import TestClient
+
         from main import app
         return TestClient(app, raise_server_exceptions=False)
 
     @pytest.fixture
     def mock_svc(self, client):
-        from main import app
         from unittest.mock import MagicMock
+
+        from main import app
         mock = MagicMock()
         original = getattr(app.state, "analysis_service", None)
         app.state.analysis_service = mock
diff --git a/document-parser/tests/test_serve_converter.py b/document-parser/tests/test_serve_converter.py
index 31f73c0..b9c4b36 100644
--- a/document-parser/tests/test_serve_converter.py
+++ b/document-parser/tests/test_serve_converter.py
@@ -8,16 +8,14 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import httpx
 import pytest
 
-from domain.value_objects import ConversionOptions, ConversionResult, PageDetail, PageElement
+from domain.value_objects import ConversionOptions, ConversionResult
 from infra.serve_converter import (
     ServeConverter,
     _build_form_data,
     _extract_bbox,
-    _extract_pages_from_docling_document,
     _parse_response,
 )
 
-
 # ---------------------------------------------------------------------------
 # Unit tests — form data building
 # ---------------------------------------------------------------------------
@@ -182,8 +180,9 @@ class TestExtractBbox:
         assert bbox == [10, 20, 100, 50]
 
     def test_bottomleft_conversion(self):
-        bbox = _extract_bbox({"l": 10, "t": 742, "r": 100, "b": 772, "coord_origin": "BOTTOMLEFT"}, 792.0)
-        # new_t = 792 - 772 = 20, new_b = 792 - 742 = 50
+        # In BOTTOMLEFT: t (top of box) has higher y than b (bottom of box)
+        bbox = _extract_bbox({"l": 10, "t": 772, "r": 100, "b": 742, "coord_origin": "BOTTOMLEFT"}, 792.0)
+        # new_top = 792 - 772 = 20, new_bottom = 792 - 742 = 50
         assert bbox == [10, 20, 100, 50]
 
     def test_missing_coord_origin_defaults_topleft(self):
@@ -308,9 +307,9 @@ class TestServeConverterConvert:
 
         conv = ServeConverter(base_url="http://localhost:5001")
 
-        with patch("infra.serve_converter.httpx.AsyncClient", return_value=mock_client):
-            with pytest.raises(httpx.HTTPStatusError):
-                await conv.convert(str(test_file), ConversionOptions())
+        with patch("infra.serve_converter.httpx.AsyncClient", return_value=mock_client), \
+             pytest.raises(httpx.HTTPStatusError):
+            await conv.convert(str(test_file), ConversionOptions())
 
     @pytest.mark.asyncio
     async def test_health_check_success(self):