Allow direct article resolution in machine max MCP

tests/test_calculation_api.py

@@ -164,6 +164,26 @@ class CalculationApiTests(unittest.TestCase):
             ["roll_diameter_nominal"],
         )
 
+    def test_machine_maximum_length_endpoint_does_not_accept_mcp_article_convenience(self):
+        response = self.client.post(
+            "/api/calculations/machine-max-product-length",
+            json={
+                "article_number": "218500",
+                "machine": "K7",
+                "core_diameter_mm": 133,
+            },
+            headers=self.headers,
+        )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.get_json(), {
+            "status": "invalid_parameter",
+            "invalid": [{
+                "field": "request",
+                "message": "unknown request fields: article_number",
+            }],
+        })
+
     def test_machine_maximum_length_endpoint_preserves_domain_outcomes(self):
         incompatible = self.client.post(
             "/api/calculations/machine-max-product-length",

tests/test_mcp_adapter.py

@@ -117,6 +117,10 @@ class McpAdapterTests(unittest.TestCase):
         domain_result = calculate_machine_max_product_length(**arguments)
         domain_before_projection = copy.deepcopy(domain_result)
 
+        self.assertNotIn(
+            "article_number",
+            inspect.signature(calculate_machine_max_product_length).parameters,
+        )
         result = project_machine_max_product_length_result(domain_result)
 
         self.assertEqual(domain_result, domain_before_projection)
@@ -143,6 +147,72 @@ class McpAdapterTests(unittest.TestCase):
         })
         self.assertEqual(result["warnings"], {"nominal": ["roll_diameter_mm"]})
 
+    def test_machine_maximum_length_adapter_resolves_exact_article_compactly(self):
+        result = calculate_machine_max_product_length_result(
+            article_number="218500",
+            machine="K7",
+            core_diameter_mm=133.0,
+        )
+
+        self.assertEqual(result["status"], "success")
+        self.assertEqual(result["article"], {
+            "number": "218500",
+            "name": "Stex AS 501,      6,00 x 75 m",
+        })
+        self.assertNotIn("thickness_mm", result)
+        self.assertNotIn("final_feasibility", result)
+        self.assertEqual(result["production_maximums"], {
+            "nominal_length_m": 217.1900177447768,
+            "nominal_governing_constraints": ["roll_diameter_nominal"],
+            "conservative_length_m": 194.62073281485985,
+            "conservative_governing_constraints": ["roll_diameter_conservative"],
+        })
+        self.assertEqual(result["material_weights_kg"], {
+            "at_nominal_production_maximum": 645.570178559751,
+            "at_conservative_production_maximum": 578.4858003113276,
+        })
+
+    def test_machine_maximum_length_adapter_article_lookup_is_exact_and_core_is_caller_supplied(self):
+        missing = calculate_machine_max_product_length_result(
+            article_number="does-not-exist",
+            machine="K7",
+            core_diameter_mm=133.0,
+        )
+        incompatible_core = calculate_machine_max_product_length_result(
+            article_number="218500",
+            machine="K7",
+            core_diameter_mm=194.0,
+        )
+
+        self.assertEqual(missing, {
+            "status": "article_not_found",
+            "article_number": "does-not-exist",
+        })
+        self.assertEqual(incompatible_core["status"], "incompatible")
+        self.assertEqual(
+            incompatible_core["failed_compatibility_constraints"],
+            ["allowed_core_diameters_mm"],
+        )
+
+    def test_machine_maximum_length_adapter_rejects_mixed_article_and_material_inputs(self):
+        result = calculate_machine_max_product_length_result(
+            article_number="218500",
+            machine="K7",
+            core_diameter_mm=133.0,
+            thickness_mm=4.311611,
+        )
+
+        self.assertEqual(result, {
+            "status": "invalid_parameter",
+            "invalid": [{
+                "field": "article_number",
+                "message": (
+                    "cannot be combined with explicit material properties: "
+                    "thickness_mm"
+                ),
+            }],
+        })
+
     def test_machine_maximum_length_adapter_preserves_non_success_diagnostics(self):
         base = {
             "machine": "K7",
@@ -344,17 +414,19 @@ class McpAdapterTests(unittest.TestCase):
         self.assertIn("Missing configured V1 roll inputs", feasibility_tool.description)
         self.assertEqual(
             maximum_tool.parameters["required"],
-            ["machine", "core_diameter_mm", "thickness_mm"],
+            ["machine", "core_diameter_mm"],
         )
+        self.assertIn("article_number", maximum_tool.parameters["properties"])
         self.assertIn("product_width_m", maximum_tool.parameters["properties"])
         self.assertIn("area_weight_g_m2", maximum_tool.parameters["properties"])
         for text in (
-            "Resolve the article first with search_articles/get_article",
+            "exact article_number",
+            "do not call get_article merely to copy properties",
+            "Never mix article_number with material properties",
+            "For a product name, use search_articles",
+            "if candidates are multiple, ask the user to select an article number",
             "Do not supply or invent machine limits",
-            "rearrange roll or weight formulas",
-            "compare candidate limits yourself",
             "nominal and conservative/no-warning production maxima",
-            "incompatibility rather than substituting another core or width",
         ):
             self.assertIn(text, maximum_tool.description)
         self.assertEqual(