feat(US1): text triple extraction — POST /api/v1/text/extract

- app/models/text_models.py: TripleItem, SourceOffset, TextExtract{Request,Response}
- app/services/text_service.py: TXT/PDF/DOCX parsing + LLM call + JSON parse
- app/routers/text.py: POST /text/extract handler with Depends injection
- tests/test_text_service.py: 6 unit tests (formats, errors)
- tests/test_text_router.py: 4 router tests (200, 400, 502×2)
- 10/10 tests passing

tests/test_text_router.py

@@ -0,0 +1,63 @@
+import pytest
+from unittest.mock import AsyncMock
+
+
+SAMPLE_TRIPLES_JSON = '''[
+  {
+    "subject": "变压器",
+    "predicate": "额定电压",
+    "object": "110kV",
+    "source_snippet": "该变压器额定电压为110kV",
+    "source_offset": {"start": 0, "end": 12}
+  }
+]'''
+
+
+def test_text_extract_returns_200(client, mock_llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"some text content")
+    mock_llm.chat = AsyncMock(return_value=SAMPLE_TRIPLES_JSON)
+
+    resp = client.post(
+        "/api/v1/text/extract",
+        json={"file_path": "text/test.txt", "file_name": "test.txt"},
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert "items" in data
+    assert data["items"][0]["subject"] == "变压器"
+    assert data["items"][0]["source_offset"]["start"] == 0
+
+
+def test_text_extract_unsupported_format_returns_400(client, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"data")
+
+    resp = client.post(
+        "/api/v1/text/extract",
+        json={"file_path": "text/test.xlsx", "file_name": "data.xlsx"},
+    )
+    assert resp.status_code == 400
+    assert resp.json()["code"] == "UNSUPPORTED_FILE_TYPE"
+
+
+def test_text_extract_storage_error_returns_502(client, mock_llm, mock_storage):
+    from app.core.exceptions import StorageError
+    mock_storage.download_bytes = AsyncMock(side_effect=StorageError("RustFS unreachable"))
+
+    resp = client.post(
+        "/api/v1/text/extract",
+        json={"file_path": "text/test.txt", "file_name": "test.txt"},
+    )
+    assert resp.status_code == 502
+    assert resp.json()["code"] == "STORAGE_ERROR"
+
+
+def test_text_extract_llm_parse_error_returns_502(client, mock_llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"content")
+    mock_llm.chat = AsyncMock(return_value="not json {{{{")
+
+    resp = client.post(
+        "/api/v1/text/extract",
+        json={"file_path": "text/test.txt", "file_name": "test.txt"},
+    )
+    assert resp.status_code == 502
+    assert resp.json()["code"] == "LLM_PARSE_ERROR"

tests/test_text_service.py

@@ -0,0 +1,122 @@
+import pytest
+from unittest.mock import AsyncMock, MagicMock
+
+from app.core.exceptions import LLMParseError, StorageError, UnsupportedFileTypeError
+from app.models.text_models import TextExtractRequest
+
+
+SAMPLE_TRIPLES_JSON = '''[
+  {
+    "subject": "变压器",
+    "predicate": "额定电压",
+    "object": "110kV",
+    "source_snippet": "该变压器额定电压为110kV",
+    "source_offset": {"start": 0, "end": 12}
+  }
+]'''
+
+
+@pytest.fixture
+def req_txt():
+    return TextExtractRequest(file_path="text/test.txt", file_name="test.txt")
+
+
+@pytest.fixture
+def req_pdf():
+    return TextExtractRequest(file_path="text/test.pdf", file_name="report.pdf")
+
+
+@pytest.fixture
+def req_docx():
+    return TextExtractRequest(file_path="text/test.docx", file_name="doc.docx")
+
+
+@pytest.fixture
+def llm(mock_llm):
+    mock_llm.chat = AsyncMock(return_value=SAMPLE_TRIPLES_JSON)
+    return mock_llm
+
+
+@pytest.mark.asyncio
+async def test_txt_extraction_returns_triples(llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"test content")
+    from app.services.text_service import extract_triples
+    req = TextExtractRequest(file_path="text/test.txt", file_name="test.txt")
+    result = await extract_triples(req, llm, mock_storage)
+    assert len(result.items) == 1
+    assert result.items[0].subject == "变压器"
+    assert result.items[0].predicate == "额定电压"
+    assert result.items[0].object == "110kV"
+    assert result.items[0].source_offset.start == 0
+    assert result.items[0].source_offset.end == 12
+
+
+@pytest.mark.asyncio
+async def test_pdf_extraction(llm, mock_storage, tmp_path):
+    import pdfplumber, io
+    # We mock download_bytes to return a minimal PDF-like response
+    # and mock pdfplumber.open to return pages with text
+    mock_storage.download_bytes = AsyncMock(return_value=b"%PDF fake")
+
+    with pytest.MonkeyPatch().context() as mp:
+        mock_page = MagicMock()
+        mock_page.extract_text.return_value = "PDF content here"
+        mock_pdf = MagicMock()
+        mock_pdf.__enter__ = lambda s: s
+        mock_pdf.__exit__ = MagicMock(return_value=False)
+        mock_pdf.pages = [mock_page]
+        mp.setattr("pdfplumber.open", lambda f: mock_pdf)
+
+        from app.services import text_service
+        import importlib
+        importlib.reload(text_service)
+        req = TextExtractRequest(file_path="text/test.pdf", file_name="doc.pdf")
+        result = await text_service.extract_triples(req, llm, mock_storage)
+    assert len(result.items) == 1
+
+
+@pytest.mark.asyncio
+async def test_docx_extraction(llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"PK fake docx bytes")
+
+    with pytest.MonkeyPatch().context() as mp:
+        mock_para = MagicMock()
+        mock_para.text = "Word paragraph content"
+        mock_doc = MagicMock()
+        mock_doc.paragraphs = [mock_para]
+        mp.setattr("docx.Document", lambda f: mock_doc)
+
+        from app.services import text_service
+        import importlib
+        importlib.reload(text_service)
+        req = TextExtractRequest(file_path="text/test.docx", file_name="doc.docx")
+        result = await text_service.extract_triples(req, llm, mock_storage)
+    assert len(result.items) == 1
+
+
+@pytest.mark.asyncio
+async def test_unsupported_format_raises_error(llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"data")
+    from app.services.text_service import extract_triples
+    req = TextExtractRequest(file_path="text/test.xlsx", file_name="data.xlsx")
+    with pytest.raises(UnsupportedFileTypeError):
+        await extract_triples(req, llm, mock_storage)
+
+
+@pytest.mark.asyncio
+async def test_storage_error_propagates(llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(side_effect=StorageError("not found"))
+    from app.services.text_service import extract_triples
+    req = TextExtractRequest(file_path="text/test.txt", file_name="test.txt")
+    with pytest.raises(StorageError):
+        await extract_triples(req, llm, mock_storage)
+
+
+@pytest.mark.asyncio
+async def test_llm_parse_error_propagates(mock_llm, mock_storage):
+    mock_storage.download_bytes = AsyncMock(return_value=b"content")
+    mock_llm.chat = AsyncMock(return_value="not json {{")
+    from app.services.text_service import extract_triples
+    req = TextExtractRequest(file_path="text/test.txt", file_name="test.txt")
+    with pytest.raises(LLMParseError):
+        await extract_triples(req, mock_llm, mock_storage)