csv-parser: add _extract_mapping_via_llm with provider-failure wrapping

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_llm_csv_parser.py

@@ -220,3 +220,73 @@ def test_apply_mapping_skips_blank_and_unparseable_rows():
 
     pie = _apply_mapping(headers, data_rows, mapping)
     assert [p.slice for p in pie.positions] == ["AAPL", "NVDA"]
+
+
+@pytest.mark.asyncio
+async def test_extract_mapping_via_llm_parses_valid_json():
+    from unittest.mock import AsyncMock, MagicMock
+    from app.services.llm_csv_parser import _extract_mapping_via_llm
+    from app.services.openrouter import LogResult
+
+    fake_result = LogResult(
+        content='{"ticker_col": "Symbol", "qty_col": "Quantity", '
+                '"cost_col": "Avg Price", "currency_col": "Currency", '
+                '"name_col": null, "broker_label": "IBKR Activity Statement"}',
+        model="deepseek/deepseek-v4-flash",
+        prompt_tokens=100,
+        completion_tokens=50,
+        cost_usd=0.0001,
+    )
+    fake_client = MagicMock()
+    fake_call_llm = AsyncMock(return_value=fake_result)
+
+    import app.services.llm_csv_parser as mod
+    mod.call_llm = fake_call_llm  # monkeypatch
+
+    headers = ["Symbol", "Quantity", "Avg Price", "Currency"]
+    samples = [["AAPL", "100", "150.25", "USD"]]
+    mapping, log = await _extract_mapping_via_llm(fake_client, headers, samples)
+
+    assert mapping["ticker_col"] == "Symbol"
+    assert mapping["qty_col"] == "Quantity"
+    assert mapping["broker_label"] == "IBKR Activity Statement"
+    assert log.model == "deepseek/deepseek-v4-flash"
+    fake_call_llm.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_extract_mapping_via_llm_malformed_json_raises():
+    from unittest.mock import AsyncMock, MagicMock
+    from app.services.llm_csv_parser import LLMParseError, _extract_mapping_via_llm
+    from app.services.openrouter import LogResult
+
+    fake_result = LogResult(
+        content="Sure thing — here is the mapping!  ticker=Symbol",
+        model="deepseek/deepseek-v4-flash",
+        prompt_tokens=10,
+        completion_tokens=20,
+        cost_usd=0.00005,
+    )
+    fake_client = MagicMock()
+    fake_call_llm = AsyncMock(return_value=fake_result)
+
+    import app.services.llm_csv_parser as mod
+    mod.call_llm = fake_call_llm
+
+    with pytest.raises(LLMParseError, match="JSON"):
+        await _extract_mapping_via_llm(fake_client, ["Symbol"], [["AAPL"]])
+
+
+@pytest.mark.asyncio
+async def test_extract_mapping_via_llm_provider_failure_wraps():
+    from unittest.mock import AsyncMock, MagicMock
+    from app.services.llm_csv_parser import LLMParseError, _extract_mapping_via_llm
+
+    fake_client = MagicMock()
+    fake_call_llm = AsyncMock(side_effect=RuntimeError("provider down"))
+
+    import app.services.llm_csv_parser as mod
+    mod.call_llm = fake_call_llm
+
+    with pytest.raises(LLMParseError, match="provider"):
+        await _extract_mapping_via_llm(fake_client, ["Symbol"], [["AAPL"]])