JSON Configuration

COBRA configurations are versioned JSON files containing the inputs required to reproduce an optimization. They can be created in the GUI and executed either in the GUI or from a terminal.

Save and Load in the GUI

Use Save Config to write the current run inputs to a JSON file. Use Load Config to restore them. Loading rebuilds fields that depend on the netlist, including component model selectors, available HB nodes and ports, simulation parameters, optimization properties, and goals.

Pressing START OPTIMIZATION automatically saves the exact input configuration as cobra_config.json in the new timestamped results directory. The snapshot is created before optimization starts, so it remains available if a run fails or is stopped.

Run from the Command Line

cobra run path/to/cobra_config.json

The command prints iteration progress and the final results directory. Running cobra without a subcommand continues to open the GUI.

Path Rules

Relative paths are interpreted relative to the directory containing the JSON file, not the process working directory. When the GUI saves a configuration, netlist, component model, and custom geometry paths are rewritten relative to the new JSON destination where possible. This makes a directory containing a config and its inputs portable as a unit.

Schema Version 1

The following example shows the supported top-level structure. Fields that do not apply to a run may use empty objects or arrays.

{
  "schema_version": 1,
  "netlist": "../circuits/lna.cir",
  "component_models": {
    "X1": "../models/lna.onnx"
  },
  "simulation_parameters": {
    ".AC": {
      "points": "500",
      "start_freq": "100G",
      "stop_freq": "150G"
    },
    ".HB": {
      "frequencies": "130G"
    },
    ".OPTIONS:hbint": {
      "numfreq": "5",
      "startupperiods": "2"
    }
  },
  "optimizer": {
    "name": "OptunaOptimizer",
    "settings": {
      "multi_objective": false,
      "sampler": "tpe",
      "pruner": null
    }
  },
  "simulator": {
    "name": "XyceSimulator",
    "settings": {}
  },
  "max_iterations": 500,
  "optimization_parameters": [
    {
      "name": "X1:width",
      "type": "model_input",
      "min_value": 10.0,
      "max_value": 30.0,
      "step": 0.1,
      "unit": null,
      "linked_to": null
    }
  ],
  "design_goals": [
    {
      "parameter": "S21_dB",
      "frequency_range": "125-135ghz",
      "min_value": -3.0,
      "max_value": null,
      "weight": 1.0,
      "kind": "catalogue",
      "node": null,
      "port": null,
      "source_amplitude": null,
      "impedance": null
    },
    {
      "parameter": "Power_dBm[Out]",
      "frequency_range": "130ghz",
      "min_value": 10.0,
      "max_value": null,
      "weight": 1.0,
      "kind": "power_dbm",
      "node": "Out",
      "port": null,
      "source_amplitude": null,
      "impedance": null
    }
  ],
  "fine_tuning": {
    "enabled": false,
    "palace_command": "palace",
    "iterations": 3,
    "optimizer": "reuse",
    "geometries": {}
  }
}

Optimization parameter types are model_input and netlist_variable. Dynamic HB goals use power_dbm or gain_db as their kind; gain goals additionally store the input port, source amplitude, and impedance required to reconstruct their power reference.

Fine-tuning presets store their Python module and class name. Custom geometries store a JSON-relative Python file and class name. ORCA is imported only when an enabled configuration requires a geometry.

Unknown fields, unsupported schema versions or backends, broken linked-parameter references, unavailable HB nodes or ports, and missing input files are rejected before optimization starts.