feat: add export_gerber_single tool (kicad-cli, single-file Gerber)

New MCP tool `export_gerber_single` wrapping `kicad-cli pcb export gerber`:
plots the selected layers to a SINGLE Gerber file (singular sibling of
export_gerbers). Exposes the full single-file Plot option set (X2, netlist
attributes, the four DNP fab-layer modes, soldermask subtraction, aperture
macros, drill-file origin, precision, Protel extension). Reads the saved
.kicad_pcb. Note: this subcommand is deprecated in KiCad 9.0 (still exits 0).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

python/kicad_interface.py

@@ -597,6 +597,7 @@ class KiCADInterface:
             "export_pcb_pdf": self._handle_export_pcb_pdf,
             "export_pcb_svg": self._handle_export_pcb_svg,
             "export_pcb_dxf": self._handle_export_pcb_dxf,
+            "export_gerber_single": self._handle_export_gerber_single,
             "generate_netlist": self._handle_generate_netlist,
             "sync_schematic_to_board": self._handle_sync_schematic_to_board,
             "list_schematic_libraries": self._handle_list_schematic_libraries,
@@ -5354,6 +5355,107 @@ class KiCADInterface:
             logger.error(f"Error exporting PCB DXF: {e}")
             return {"success": False, "message": str(e)}
 
+    def _handle_export_gerber_single(self, params: Dict[str, Any]) -> Dict[str, Any]:
+        """Plot the given layers to a single Gerber file via kicad-cli
+        (`pcb export gerber`).
+
+        Singular sibling of export_gerbers: emits ONE Gerber file containing the
+        selected layers. Exposes the full single-file Plot option set (X2,
+        netlist attributes, DNP fab-layer modes, soldermask subtraction, aperture
+        macros, drill-file origin, precision, Protel extension). Reads the saved
+        .kicad_pcb.
+        """
+        import subprocess
+
+        logger.info("Exporting single Gerber via kicad-cli")
+        try:
+            board_path = params.get("boardPath") or self._current_board_path()
+            output_path = params.get("outputPath")
+
+            if not board_path:
+                return {
+                    "success": False,
+                    "message": "boardPath is required (no current board could be resolved)",
+                }
+            if not os.path.exists(board_path):
+                return {"success": False, "message": f"Board not found: {board_path}"}
+            if not output_path:
+                return {"success": False, "message": "outputPath is required"}
+
+            kicad_cli = self._find_kicad_cli_static()
+            if not kicad_cli:
+                return {"success": False, "message": "kicad-cli not found in PATH"}
+
+            output_path = os.path.abspath(os.path.expanduser(output_path))
+            parent = os.path.dirname(output_path)
+            if parent:
+                os.makedirs(parent, exist_ok=True)
+
+            cmd = [kicad_cli, "pcb", "export", "gerber", "--output", output_path]
+
+            layers = params.get("layers")
+            if layers:
+                cmd += ["--layers", ",".join(layers) if isinstance(layers, list) else str(layers)]
+            common_layers = params.get("commonLayers")
+            if common_layers:
+                cmd += [
+                    "--common-layers",
+                    (
+                        ",".join(common_layers)
+                        if isinstance(common_layers, list)
+                        else str(common_layers)
+                    ),
+                ]
+
+            if params.get("drawingSheet"):
+                cmd += ["--drawing-sheet", params["drawingSheet"]]
+            for kv in params.get("defineVar", []) or []:
+                cmd += ["--define-var", kv]
+
+            flag_map = {
+                "excludeRefdes": "--exclude-refdes",
+                "excludeValue": "--exclude-value",
+                "includeBorderTitle": "--include-border-title",
+                "sketchPadsOnFabLayers": "--sketch-pads-on-fab-layers",
+                "hideDnpFootprintsOnFabLayers": "--hide-DNP-footprints-on-fab-layers",
+                "sketchDnpFootprintsOnFabLayers": "--sketch-DNP-footprints-on-fab-layers",
+                "crossoutDnpFootprintsOnFabLayers": "--crossout-DNP-footprints-on-fab-layers",
+                "noX2": "--no-x2",
+                "noNetlist": "--no-netlist",
+                "subtractSoldermask": "--subtract-soldermask",
+                "disableApertureMacros": "--disable-aperture-macros",
+                "useDrillFileOrigin": "--use-drill-file-origin",
+                "noProtelExt": "--no-protel-ext",
+            }
+            for key, flag in flag_map.items():
+                if params.get(key):
+                    cmd.append(flag)
+
+            precision = params.get("precision")
+            if precision is not None:
+                cmd += ["--precision", str(precision)]
+
+            cmd.append(board_path)
+
+            logger.info(f"Running: {' '.join(cmd)}")
+            result = subprocess.run(cmd, capture_output=True, text=True, timeout=180)
+
+            if result.returncode != 0:
+                return {
+                    "success": False,
+                    "message": f"kicad-cli failed (exit {result.returncode}): "
+                    f"{result.stderr.strip()}",
+                }
+            return {"success": True, "outputPath": output_path}
+
+        except FileNotFoundError:
+            return {"success": False, "message": "kicad-cli not found in PATH"}
+        except subprocess.TimeoutExpired:
+            return {"success": False, "message": "kicad-cli timed out after 180 seconds"}
+        except Exception as e:
+            logger.error(f"Error exporting single Gerber: {e}")
+            return {"success": False, "message": str(e)}
+
     def _handle_generate_netlist(self, params: Dict[str, Any]) -> Dict[str, Any]:
         """Generate netlist from schematic and return structured JSON.