Resolve passives from catalog, BOM value, and Murata LQW18AN without an LLM.

Skip the model (and the credit gate) when LCSC/DigiKey already list C/V/Z, when the BOM value is a single R/C/L/FB token, or when the MPN is an LQW18AN inductor. Ferrite beads keep impedance, not invented henries; value-only specs stay out of the shared library.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_passive_from_distributor.py

@@ -40,3 +40,94 @@ def test_skips_when_no_value():
         category="",
         description="some module",
     ) is None
+
+
+def test_ferrite_bead_from_impedance():
+    model = specs_from_distributor(
+        mpn="BLM18PG121SN1D",
+        params=[
+            {"name": "Impedance @ Frequency", "value": "120 Ohms @ 100 MHz"},
+            {"name": "Package / Case", "value": "0603"},
+            {"name": "Current Rating", "value": "2 A"},
+        ],
+        category="Filters / Ferrite Beads",
+        description="FERRITE BEAD 120 OHM 0603 1LN",
+    )
+    assert model is not None
+    specs = model.specs
+    assert specs.component_subtype == "passive.ferrite_bead"
+    assert specs.impedance_ohm == 120
+    assert specs.value_henries is None
+    assert "120ohm" in specs.value_formatted
+    assert "100" in specs.value_formatted
+    assert specs.package == "0603"
+    assert specs.current_rating_a == "2 A"
+
+
+def test_specs_from_lcsc_payload():
+    from backend.services.passive_from_distributor import specs_from_lcsc_payload
+
+    model = specs_from_lcsc_payload(
+        "CL21B225KPFNNNE",
+        {
+            "package": "0805",
+            "manufacturer": "Samsung",
+            "category": "Capacitors",
+            "subcategory": "MLCC",
+            "description": "2.2uF ±10% 10V X7R 0805",
+        },
+    )
+    assert model is not None
+    assert abs(model.specs.value_farads - 2.2e-6) < 1e-12
+
+
+def test_auto_resolve_skips_llm_when_catalog_parses(monkeypatch):
+    import asyncio
+    from pathlib import Path
+
+    from backend.services.extraction import auto_resolve_specs
+
+    async def boom(*_a, **_k):
+        raise AssertionError("LLM must not run")
+
+    monkeypatch.setattr("backend.services.extraction.call_with_fallback", boom)
+    tax = Path(__file__).resolve().parents[1] / "taxonomy"
+    model = asyncio.run(
+        auto_resolve_specs(
+            mpn="CL21B225KPFNNNE",
+            digikey_params=[{"name": "Package / Case", "value": "0805"}],
+            digikey_category="Capacitors / Ceramic Capacitors",
+            digikey_description="2.2uF ±10% 10V X7R 0805",
+            component_type="passive",
+            taxonomy_dir=tax,
+        )
+    )
+    assert abs(model.specs.value_farads - 2.2e-6) < 1e-12
+
+
+def test_auto_resolve_use_llm_false_on_ferrite(monkeypatch):
+    import asyncio
+    from pathlib import Path
+
+    from backend.services.extraction import auto_resolve_specs
+
+    async def boom(*_a, **_k):
+        raise AssertionError("LLM must not run")
+
+    monkeypatch.setattr("backend.services.extraction.call_with_fallback", boom)
+    tax = Path(__file__).resolve().parents[1] / "taxonomy"
+    model = asyncio.run(
+        auto_resolve_specs(
+            mpn="BLM18PG121SN1D",
+            digikey_params=[
+                {"name": "Impedance @ Frequency", "value": "120 Ohms @ 100 MHz"},
+            ],
+            digikey_category="Filters / Ferrite Beads",
+            digikey_description="FERRITE BEAD 120 OHM 0603 1LN",
+            component_type="passive",
+            taxonomy_dir=tax,
+            use_llm=False,
+        )
+    )
+    assert model.specs.impedance_ohm == 120
+    assert model.specs.component_subtype == "passive.ferrite_bead"