feat: add get_pin_net tool for direct net/pin queries

Answers "what net is pin X of component Y on?" without requiring
callers to triangulate from list_schematic_nets or know a wire
coordinate first.

Accepts either {reference, pin} (resolved via PinLocator) or {x, y}
coordinate. Returns net label name (or null for unnamed nets), all
connected pins, wire segments, and the resolved query point.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

python/commands/wire_connectivity.py

@@ -273,3 +273,61 @@ def get_wire_connections(
 
     pins = _find_pins_on_net(net_points, schematic_path, schematic)
     return {"pins": pins, "wires": wires_out}
+
+
+def get_pin_net(schematic: Any, schematic_path: str, x_mm: float, y_mm: float) -> Optional[Dict]:
+    """Return the net name and all connected pins for the wire network at (x_mm, y_mm).
+
+    Returns dict with keys:
+      - "net": str or None (net label/power name, None if unnamed)
+      - "pins": list of {"component": str, "pin": str}
+      - "wires": list of {"start": {"x", "y"}, "end": {"x", "y"}} in mm
+      - "query_point": {"x": float, "y": float}
+    Or None if no wire endpoint found at the query point.
+    """
+    all_wires = _parse_wires(schematic)
+    if not all_wires:
+        return {"net": None, "pins": [], "wires": [], "query_point": {"x": x_mm, "y": y_mm}}
+
+    adjacency, iu_to_wires = _build_adjacency(all_wires)
+    point_to_label, label_to_points = _parse_virtual_connections(schematic, schematic_path)
+
+    visited, net_points = _find_connected_wires(
+        x_mm,
+        y_mm,
+        all_wires,
+        iu_to_wires,
+        adjacency,
+        point_to_label=point_to_label,
+        label_to_points=label_to_points,
+    )
+    if visited is None:
+        return None
+
+    # Resolve net name: first label anchor that falls on this net's IU points
+    net: Optional[str] = None
+    for pt in net_points:
+        label = point_to_label.get(pt)
+        if label is not None:
+            net = label
+            break
+
+    wires_out = [
+        {
+            "start": {
+                "x": all_wires[i][0][0] / _IU_PER_MM,
+                "y": all_wires[i][0][1] / _IU_PER_MM,
+            },
+            "end": {
+                "x": all_wires[i][-1][0] / _IU_PER_MM,
+                "y": all_wires[i][-1][1] / _IU_PER_MM,
+            },
+        }
+        for i in visited
+    ]
+
+    pins: List[Dict] = []
+    if hasattr(schematic, "symbol"):
+        pins = _find_pins_on_net(net_points, schematic_path, schematic)
+
+    return {"net": net, "pins": pins, "wires": wires_out, "query_point": {"x": x_mm, "y": y_mm}}

python/kicad_interface.py

@@ -382,6 +382,7 @@ class KiCADInterface:
             "get_schematic_pin_locations": self._handle_get_schematic_pin_locations,
             "get_net_connections": self._handle_get_net_connections,
             "get_wire_connections": self._handle_get_wire_connections,
+            "get_pin_net": self._handle_get_pin_net,
             "run_erc": self._handle_run_erc,
             "generate_netlist": self._handle_generate_netlist,
             "sync_schematic_to_board": self._handle_sync_schematic_to_board,
@@ -2503,6 +2504,70 @@ class KiCADInterface:
             logger.error(traceback.format_exc())
             return {"success": False, "message": str(e)}
 
+    def _handle_get_pin_net(self, params: Dict[str, Any]) -> Dict[str, Any]:
+        """Find net name and all connected pins for a reference+pin or coordinate query"""
+        logger.info("Getting pin net")
+        try:
+            from pathlib import Path
+
+            from commands.pin_locator import PinLocator
+            from commands.wire_connectivity import get_pin_net
+
+            schematic_path = params.get("schematicPath")
+            if not schematic_path:
+                return {"success": False, "message": "Missing required parameter: schematicPath"}
+
+            reference = params.get("reference")
+            pin = params.get("pin")
+            x = params.get("x")
+            y = params.get("y")
+
+            has_ref_pin = reference is not None and pin is not None
+            has_coords = x is not None and y is not None
+
+            if not has_ref_pin and not has_coords:
+                return {
+                    "success": False,
+                    "message": "Must supply either {reference, pin} or {x, y}",
+                }
+
+            if has_ref_pin:
+                location = PinLocator().get_pin_location(Path(schematic_path), reference, str(pin))
+                if location is None:
+                    return {
+                        "success": False,
+                        "message": f"Pin {pin} not found on {reference}",
+                    }
+                x, y = location[0], location[1]
+            else:
+                try:
+                    x, y = float(x), float(y)
+                except (TypeError, ValueError):
+                    return {"success": False, "message": "Parameters x and y must be numeric"}
+
+            schematic = SchematicManager.load_schematic(schematic_path)
+            if not schematic:
+                return {"success": False, "message": "Failed to load schematic"}
+
+            if not hasattr(schematic, "wire"):
+                return {"success": False, "message": "Schematic has no wires"}
+
+            result = get_pin_net(schematic, schematic_path, x, y)
+            if result is None:
+                return {
+                    "success": False,
+                    "message": f"No wire found at ({x},{y}) — pin may not be connected",
+                }
+
+            return {"success": True, **result}
+
+        except Exception as e:
+            logger.error(f"Error getting pin net: {str(e)}")
+            import traceback
+
+            logger.error(traceback.format_exc())
+            return {"success": False, "message": str(e)}
+
     def _handle_run_erc(self, params: Dict[str, Any]) -> Dict[str, Any]:
         """Run Electrical Rules Check on a schematic via kicad-cli"""
         logger.info("Running ERC on schematic")

python/schemas/tool_schemas.py

@@ -1523,6 +1523,44 @@ SCHEMATIC_TOOLS = [
             "required": ["schematicPath", "x", "y"],
         },
     },
+    {
+        "name": "get_pin_net",
+        "title": "Get Pin Net",
+        "description": (
+            "Returns the net name and all connected component pins for a query. "
+            "Accepts either a component reference + pin number (e.g. reference='U1', pin='3') "
+            "or a schematic coordinate (x, y in mm). "
+            "If a net label or power symbol is reachable from the query point, its name is "
+            "returned as 'net'; otherwise 'net' is null (unnamed net). "
+            "The 'pins' list contains every component pin on that same net."
+        ),
+        "inputSchema": {
+            "type": "object",
+            "properties": {
+                "schematicPath": {
+                    "type": "string",
+                    "description": "Path to the schematic file (.kicad_sch)",
+                },
+                "reference": {
+                    "type": "string",
+                    "description": "Component reference (e.g. U1, R1). Pair with pin.",
+                },
+                "pin": {
+                    "type": "string",
+                    "description": "Pin number or name (e.g. '3', 'SDA'). Pair with reference.",
+                },
+                "x": {
+                    "type": "number",
+                    "description": "X coordinate of a wire endpoint in mm. Pair with y.",
+                },
+                "y": {
+                    "type": "number",
+                    "description": "Y coordinate of a wire endpoint in mm. Pair with x.",
+                },
+            },
+            "required": ["schematicPath"],
+        },
+    },
     {
         "name": "get_schematic_pin_locations",
         "title": "Get Schematic Pin Locations",

src/tools/schematic.ts

@@ -1424,4 +1424,61 @@ Note: operates on .kicad_sch files only. To modify a PCB footprint use edit_comp
       };
     },
   );
+
+  server.tool(
+    "get_pin_net",
+    "Returns the net name and all connected pins for a component pin (reference + pin number) " +
+      "or a schematic coordinate (x, y in mm). Use this instead of list_schematic_nets + " +
+      "get_wire_connections when you want to answer 'what net is pin 3 of U1 on?'. " +
+      "Returns net=null for unnamed (unlabelled) nets.",
+    {
+      schematicPath: z.string().describe("Path to the schematic file"),
+      reference: z
+        .string()
+        .optional()
+        .describe("Component reference (e.g. U1, R1). Pair with pin."),
+      pin: z
+        .string()
+        .optional()
+        .describe("Pin number or name (e.g. '3', 'SDA'). Pair with reference."),
+      x: z.number().optional().describe("X coordinate of a wire endpoint in mm. Pair with y."),
+      y: z.number().optional().describe("Y coordinate of a wire endpoint in mm. Pair with x."),
+    },
+    async (args: {
+      schematicPath: string;
+      reference?: string;
+      pin?: string;
+      x?: number;
+      y?: number;
+    }) => {
+      const result = await callKicadScript("get_pin_net", args);
+      if (result.success) {
+        const netLabel = result.net ?? "(unnamed)";
+        const pinList = (result.pins ?? [])
+          .map((p: any) => `  - ${p.component}/${p.pin}`)
+          .join("\n");
+        const qp = result.query_point;
+        return {
+          content: [
+            {
+              type: "text",
+              text:
+                `Net: ${netLabel}\n` +
+                `Query point: (${qp?.x ?? args.x}, ${qp?.y ?? args.y})\n` +
+                `Connected pins:\n${pinList || "  (none found)"}`,
+            },
+          ],
+        };
+      } else {
+        return {
+          content: [
+            {
+              type: "text",
+              text: `Failed to get pin net: ${result.message || "Unknown error"}`,
+            },
+          ],
+        };
+      }
+    },
+  );
 }

tests/test_get_pin_net.py

@@ -0,0 +1,325 @@
+"""
+Tests for the get_pin_net tool and its handler.
+
+Covers:
+  - Schema shape (TestGetPinNetSchema)
+  - Handler dispatch registration (TestGetPinNetHandlerDispatch)
+  - Parameter validation in the handler (TestGetPinNetHandlerParamValidation)
+  - Core logic: get_pin_net function (TestGetPinNetCoreLogic)
+  - Reference+pin resolution path (TestGetPinNetHandlerRefPinResolution)
+"""
+
+import sys
+from pathlib import Path
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "python"))
+
+from commands.wire_connectivity import get_pin_net
+
+# ---------------------------------------------------------------------------
+# Shared mock helpers (mirrors test_wire_connectivity.py)
+# ---------------------------------------------------------------------------
+
+
+def _make_point(x: float, y: float) -> MagicMock:
+    pt = MagicMock()
+    pt.value = [x, y]
+    return pt
+
+
+def _make_wire(x1: float, y1: float, x2: float, y2: float) -> MagicMock:
+    wire = MagicMock()
+    wire.pts = MagicMock()
+    wire.pts.xy = [_make_point(x1, y1), _make_point(x2, y2)]
+    return wire
+
+
+def _make_schematic(*wires: Any) -> MagicMock:
+    sch = MagicMock()
+    sch.wire = list(wires)
+    del sch.label
+    del sch.symbol
+    return sch
+
+
+# ---------------------------------------------------------------------------
+# TestGetPinNetSchema
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestGetPinNetSchema:
+    """Verify the get_pin_net tool schema is present and well-formed."""
+
+    def test_schema_registered(self) -> None:
+        from schemas.tool_schemas import TOOL_SCHEMAS
+
+        assert "get_pin_net" in TOOL_SCHEMAS
+
+    def test_schema_required_fields(self) -> None:
+        from schemas.tool_schemas import TOOL_SCHEMAS
+
+        required = TOOL_SCHEMAS["get_pin_net"]["inputSchema"]["required"]
+        assert required == ["schematicPath"]
+
+    def test_schema_has_title_and_description(self) -> None:
+        from schemas.tool_schemas import TOOL_SCHEMAS
+
+        schema = TOOL_SCHEMAS["get_pin_net"]
+        assert schema.get("title")
+        assert schema.get("description")
+
+    def test_schema_has_optional_fields(self) -> None:
+        from schemas.tool_schemas import TOOL_SCHEMAS
+
+        props = TOOL_SCHEMAS["get_pin_net"]["inputSchema"]["properties"]
+        for field in ("reference", "pin", "x", "y"):
+            assert field in props, f"Expected '{field}' in schema properties"
+
+
+# ---------------------------------------------------------------------------
+# TestGetPinNetHandlerDispatch
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestGetPinNetHandlerDispatch:
+    """Verify the handler is wired into KiCadInterface.command_routes."""
+
+    def test_get_pin_net_in_routes(self) -> None:
+        with patch("kicad_interface.USE_IPC_BACKEND", False):
+            from kicad_interface import KiCADInterface
+
+            iface = KiCADInterface.__new__(KiCADInterface)
+            iface.board = None
+            iface.project_filename = None
+            iface.use_ipc = False
+            iface.ipc_backend = MagicMock()
+            iface.ipc_board_api = None
+            iface.footprint_library = MagicMock()
+            iface.project_commands = MagicMock()
+            iface.board_commands = MagicMock()
+            iface.component_commands = MagicMock()
+            iface.routing_commands = MagicMock()
+            KiCADInterface.__init__(iface)
+
+        assert "get_pin_net" in iface.command_routes
+        assert callable(iface.command_routes["get_pin_net"])
+
+
+# ---------------------------------------------------------------------------
+# TestGetPinNetHandlerParamValidation
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestGetPinNetHandlerParamValidation:
+    """Handler returns error responses for bad or missing parameters."""
+
+    def _make_handler(self) -> Any:
+        with patch("kicad_interface.USE_IPC_BACKEND", False):
+            from kicad_interface import KiCADInterface
+
+            iface = KiCADInterface.__new__(KiCADInterface)
+        return iface._handle_get_pin_net
+
+    def test_missing_schematic_path(self) -> None:
+        handler = self._make_handler()
+        result = handler({"x": 1.0, "y": 2.0})
+        assert result["success"] is False
+        assert "schematicPath" in result["message"] or "Missing" in result["message"]
+
+    def test_missing_both_modes(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch"})
+        assert result["success"] is False
+
+    def test_partial_ref_only(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch", "reference": "U1"})
+        assert result["success"] is False
+
+    def test_partial_pin_only(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch", "pin": "3"})
+        assert result["success"] is False
+
+    def test_partial_x_only(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch", "x": 1.0})
+        assert result["success"] is False
+
+    def test_partial_y_only(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch", "y": 1.0})
+        assert result["success"] is False
+
+    def test_non_numeric_coords(self) -> None:
+        handler = self._make_handler()
+        result = handler({"schematicPath": "/tmp/test.kicad_sch", "x": "bad", "y": 2.0})
+        assert result["success"] is False
+        assert "numeric" in result["message"].lower() or "x" in result["message"]
+
+
+# ---------------------------------------------------------------------------
+# TestGetPinNetCoreLogic
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestGetPinNetCoreLogic:
+    """Unit tests for the get_pin_net function."""
+
+    def test_no_wires_returns_empty_dict(self) -> None:
+        sch = MagicMock()
+        sch.wire = []
+        del sch.label
+        del sch.symbol
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 1.0, 2.0)
+        assert result is not None
+        assert result["net"] is None
+        assert result["pins"] == []
+        assert result["wires"] == []
+        assert result["query_point"] == {"x": 1.0, "y": 2.0}
+
+    def test_no_wire_at_point_returns_none(self) -> None:
+        sch = _make_schematic(_make_wire(0.0, 0.0, 1.0, 0.0))
+        # Query a midpoint — not on a wire endpoint
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 0.5, 0.0)
+        assert result is None
+
+    def test_unnamed_net_no_labels(self) -> None:
+        sch = _make_schematic(_make_wire(0.0, 0.0, 1.0, 0.0))
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 0.0, 0.0)
+        assert result is not None
+        assert result["net"] is None
+
+    def test_net_name_from_label(self) -> None:
+        """Wire with a net label at one endpoint should yield that label as net name."""
+        wire = _make_wire(0.0, 0.0, 1.0, 0.0)
+
+        label = MagicMock()
+        label.value = "SDA"
+        label.at = MagicMock()
+        label.at.value = [0.0, 0.0, 0]  # label placed at wire start
+
+        sch = MagicMock()
+        sch.wire = [wire]
+        sch.label = [label]
+        del sch.symbol
+
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 0.0, 0.0)
+        assert result is not None
+        assert result["net"] == "SDA"
+
+    def test_query_point_in_result(self) -> None:
+        sch = _make_schematic(_make_wire(5.0, 3.0, 6.0, 3.0))
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 5.0, 3.0)
+        assert result is not None
+        assert result["query_point"] == {"x": 5.0, "y": 3.0}
+
+    def test_result_has_pins_and_wires_keys(self) -> None:
+        sch = _make_schematic(_make_wire(0.0, 0.0, 1.0, 0.0))
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 0.0, 0.0)
+        assert result is not None
+        assert "pins" in result
+        assert "wires" in result
+
+    def test_wires_returned_in_mm(self) -> None:
+        sch = _make_schematic(_make_wire(2.0, 3.0, 4.0, 3.0))
+        result = get_pin_net(sch, "/tmp/test.kicad_sch", 2.0, 3.0)
+        assert result is not None
+        assert len(result["wires"]) == 1
+        w = result["wires"][0]
+        assert w["start"]["x"] == pytest.approx(2.0)
+        assert w["start"]["y"] == pytest.approx(3.0)
+        assert w["end"]["x"] == pytest.approx(4.0)
+        assert w["end"]["y"] == pytest.approx(3.0)
+
+
+# ---------------------------------------------------------------------------
+# TestGetPinNetHandlerRefPinResolution
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.unit
+class TestGetPinNetHandlerRefPinResolution:
+    """Test the reference+pin → coordinate resolution path in the handler."""
+
+    def _make_handler(self) -> Any:
+        with patch("kicad_interface.USE_IPC_BACKEND", False):
+            from kicad_interface import KiCADInterface
+
+            iface = KiCADInterface.__new__(KiCADInterface)
+        return iface._handle_get_pin_net
+
+    def test_ref_pin_resolves_to_coordinates(self) -> None:
+        handler = self._make_handler()
+        mock_result = {
+            "net": "SDA",
+            "pins": [{"component": "U1", "pin": "3"}],
+            "wires": [],
+            "query_point": {"x": 10.5, "y": 15.2},
+        }
+        with (
+            patch(
+                "commands.pin_locator.PinLocator.get_pin_location",
+                return_value=[10.5, 15.2],
+            ),
+            patch("kicad_interface.SchematicManager.load_schematic") as mock_load,
+            patch("commands.wire_connectivity.get_pin_net", return_value=mock_result) as mock_gpn,
+        ):
+            mock_sch = MagicMock()
+            mock_sch.wire = [_make_wire(10.5, 15.2, 11.5, 15.2)]
+            mock_load.return_value = mock_sch
+
+            result = handler(
+                {"schematicPath": "/tmp/test.kicad_sch", "reference": "U1", "pin": "3"}
+            )
+
+        assert result["success"] is True
+        mock_gpn.assert_called_once()
+        call_args = mock_gpn.call_args
+        assert call_args[0][2] == pytest.approx(10.5)
+        assert call_args[0][3] == pytest.approx(15.2)
+
+    def test_ref_pin_not_found(self) -> None:
+        handler = self._make_handler()
+        with patch(
+            "commands.pin_locator.PinLocator.get_pin_location",
+            return_value=None,
+        ):
+            result = handler(
+                {"schematicPath": "/tmp/test.kicad_sch", "reference": "U1", "pin": "99"}
+            )
+        assert result["success"] is False
+        assert "U1" in result["message"] or "99" in result["message"]
+
+    def test_coordinate_mode_passes_floats(self) -> None:
+        handler = self._make_handler()
+        mock_result = {
+            "net": None,
+            "pins": [],
+            "wires": [],
+            "query_point": {"x": 10.5, "y": 15.2},
+        }
+        with (
+            patch("kicad_interface.SchematicManager.load_schematic") as mock_load,
+            patch("commands.wire_connectivity.get_pin_net", return_value=mock_result) as mock_gpn,
+        ):
+            mock_sch = MagicMock()
+            mock_sch.wire = [_make_wire(10.5, 15.2, 11.5, 15.2)]
+            mock_load.return_value = mock_sch
+
+            result = handler({"schematicPath": "/tmp/test.kicad_sch", "x": "10.5", "y": "15.2"})
+
+        assert result["success"] is True
+        call_args = mock_gpn.call_args
+        assert isinstance(call_args[0][2], float)
+        assert isinstance(call_args[0][3], float)
+        assert call_args[0][2] == pytest.approx(10.5)
+        assert call_args[0][3] == pytest.approx(15.2)