Launching of simulation application

AGENTS.md

@@ -161,6 +161,18 @@ Text widgets use their native `copy()`, `cut()`, and `paste()` methods. Componen
 - Scope destructive shortcuts to the relevant widget where appropriate.
 - Always guard the operation itself even when an action is disabled for presentation.
 
+## Simulator application
+
+- `bedit_gui/simulation_application.py` is the composition root for the separate `bedit-sim` Qt application.
+- Keep compilation GUI-independent. Shared compile entry points belong in `bedit_simulation` and must not create or depend on a `QApplication` or window.
+- The simulator opens BEdit `.beb`/`.json` documents or serialized simulation `.bes`/`.json` files.
+- A component selector uses default simulation settings. A stored simulation-settings block already identifies its component; do not require both selectors.
+- `SimulationDatabase.active_simulation` is the persisted active settings ID selected when the Simulation Settings dialog is accepted.
+- Simulation files serialize `bedit_gui.simulation_models.SimulationRoot`. JSON uses the `root_type = "simulation_root"` discriminator; binary `.bes` files use their own BES header.
+- `SimulationRoot` contains source-document identity, the selected component and copied settings, and eventually results. Compiled artifacts are transient application state and must not be serialized; reopen saved simulations by compiling them again. Never serialize live Python objects.
+- BEdit launches the simulator as a separate process. Compile/Open Simulation integration may transfer a `.bes` file to that process.
+- Keep simulator file workflows in their own services/controllers rather than adding them to `MainWindow` or the editor document controller.
+
 ## Verification
 
 The old test suite and its VS Code/packaging references were deliberately removed. Do not recreate a test suite unless asked.

pyproject.toml

@@ -18,7 +18,7 @@ dependencies = [
 bedit-graphviz = "bedit_util.graphviz:main"
 bedit-simulate = "bedit_util.simulate:main"
 bedit = "bedit_gui.application:main"
-bedit-sim = "bedit_gui.simulation_application:main"
+besim = "bedit_gui.simulation_application:main"
 
 [project.optional-dependencies]
 dev = [

simulation.besim.json

@@ -0,0 +1,21 @@
+{
+  "file_format_version": 1,
+  "root_type": "simulation_root",
+  "format_version": 1,
+  "source_document": "/home/joppe/Projects/BEdit/untitled.bedit.json",
+  "source_document_id": "3b6780c7-488b-471e-a784-392db7632090",
+  "component": "50e6ef97-f686-4400-bc01-e5a352e8cc22",
+  "component_path": "some_bondgraph",
+  "settings_name": "run bondgraph",
+  "settings": {
+    "component": "50e6ef97-f686-4400-bc01-e5a352e8cc22",
+    "name": "run bondgraph",
+    "start_time": 0.0,
+    "duration": 10.0,
+    "use_timed_steps": true,
+    "number_of_steps": 500,
+    "step_size": 0.001,
+    "method": "dassl",
+    "dassl_tolerance": 1e-06
+  }
+}

src/bedit_gui/application.py

@@ -10,6 +10,7 @@ from bedit_gui.controllers.document_controller import DocumentController
 from bedit_gui.controllers.log_controller import LogController
 from bedit_gui.controllers.settings_controller import SettingsController
 from bedit_gui.controllers.simulation_settings_controller import SimulationSettingsController
+from bedit_gui.controllers.simulation_controller import SimulationController
 from bedit_gui.controllers.undo_controller import UndoController
 from bedit_gui.controllers.view_menu_controller import ViewMenuController
 from bedit_gui.controllers.window_state_controller import WindowStateController
@@ -48,6 +49,7 @@ def main() -> int:
     DocumentController(document, window)
     SettingsController(window, settings)
     SimulationSettingsController(document, window)
+    SimulationController(document, window)
     UndoController(document, window)
     ViewMenuController(window)
     document_tree_controller = DocumentTreeController(document, window)

src/bedit_gui/controllers/simulation_controller.py

@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+import sys
+import tempfile
+from collections.abc import Callable
+from pathlib import Path
+
+from PySide6.QtCore import QObject, QProcess, Qt
+from PySide6.QtWidgets import QApplication, QMessageBox
+
+from bedit_core.models import Component
+from bedit_gui.documents import Document
+from bedit_gui.services import simulation_files
+from bedit_gui.services.simulation_loader import component_choices
+from bedit_gui.simulation_models import CompiledModel, SimulationRoot
+from bedit_gui.views.main_window import MainWindow
+from bedit_simulation import ModelBuildResult, compile_component_sync
+
+Compiler = Callable[[Component, str | Path], ModelBuildResult]
+Launcher = Callable[[Path, CompiledModel], bool]
+
+
+def _launch_simulator(path: Path, compiled_model: CompiledModel) -> bool:
+    arguments = ["-m", "bedit_gui.simulation_application", "--handoff", "--model-name", compiled_model.model_name, "--executable", compiled_model.executable, "--working-directory", compiled_model.working_directory, str(path)]
+    launched = QProcess.startDetached(sys.executable, arguments)
+    return launched[0] if isinstance(launched, tuple) else bool(launched)
+
+
+class SimulationController(QObject):
+    """Compile the active BEdit simulation and launch the simulator process."""
+
+    def __init__(self, document: Document, window: MainWindow, compiler: Compiler = compile_component_sync, launcher: Launcher = _launch_simulator) -> None:
+        super().__init__(window)
+        self.document = document
+        self.window = window
+        self.compiler = compiler
+        self.launcher = launcher
+        self.compiled_root: SimulationRoot | None = None
+        self.compiled_model: CompiledModel | None = None
+        window.ui.actionCompile_Model.triggered.connect(self.compile_model)
+        window.ui.actionOpen_Simulation_Window.triggered.connect(self.open_simulation)
+
+    def compile_model(self) -> SimulationRoot | None:
+        database = self.document.simulation_database()
+        settings = database.simulations.get(database.active_simulation) if database.active_simulation is not None else None
+        if settings is None:
+            QMessageBox.warning(self.window, "No active simulation", "Select and accept a simulation settings block first.")
+            return None
+        match = next((choice for choice in component_choices(self.document.model) if choice[0] == settings.component), None)
+        if match is None:
+            QMessageBox.critical(self.window, "Could not compile", "The active simulation references a missing component.")
+            return None
+        component_id, component, component_path = match
+        build_directory = Path(tempfile.mkdtemp(prefix="bedit-compiled-"))
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        self.window.statusBar().showMessage(f"Compiling {component_path}…")
+        try:
+            build = self.compiler(component, build_directory)
+        except (OSError, RuntimeError, ValueError) as exc:
+            QMessageBox.critical(self.window, "Could not compile", str(exc))
+            self.window.statusBar().showMessage("Compilation failed")
+            return None
+        finally:
+            QApplication.restoreOverrideCursor()
+        self.compiled_model = CompiledModel(build.model_name, str(build.executable.resolve()), str(build.executable.parent.resolve()))
+        self.compiled_root = SimulationRoot(
+            format_version=1,
+            source_document=str(self.document.path.resolve()) if self.document.path is not None else None,
+            source_document_id=str(self.document.model.id),
+            component=component_id,
+            component_path=component_path,
+            settings_name=settings.name,
+            settings=settings,
+        )
+        self.window.statusBar().showMessage(f"Compiled {component_path}")
+        return self.compiled_root
+
+    def open_simulation(self) -> None:
+        root = self.compile_model()
+        if root is None or self.compiled_model is None:
+            return
+        transfer_directory = Path(tempfile.mkdtemp(prefix="bedit-simulator-launch-"))
+        transfer_path = transfer_directory / "simulation.bes"
+        try:
+            simulation_files.save(root, transfer_path)
+            if not self.launcher(transfer_path, self.compiled_model):
+                raise RuntimeError("the simulator process could not be started")
+        except (OSError, RuntimeError, ValueError) as exc:
+            QMessageBox.critical(self.window, "Could not open simulator", str(exc))

src/bedit_gui/controllers/simulation_file_controller.py

@@ -0,0 +1,107 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+from PySide6.QtCore import QObject, Qt
+from PySide6.QtWidgets import QApplication, QFileDialog, QInputDialog, QMessageBox
+
+from bedit_gui.services import document_files, simulation_files
+from bedit_gui.services.simulation_loader import compile_simulation_root, component_choices, load_and_compile_bedit
+from bedit_gui.simulation_models import CompiledModel, SimulationRoot
+from bedit_gui.views.simulation_window import SimulationWindow
+
+
+class SimulationFileController(QObject):
+    def __init__(self, window: SimulationWindow) -> None:
+        super().__init__(window)
+        self.window = window
+        self.root: SimulationRoot | None = None
+        self.compiled_model: CompiledModel | None = None
+        self.path: Path | None = None
+        window.ui.actionNew_Simulation_Run.triggered.connect(self.new)
+        window.ui.actionOpen_Simulation_Run.triggered.connect(self.open_dialog)
+        window.ui.actionSave_Simulation_Run.triggered.connect(self.save)
+        self._update_window()
+
+    def new(self) -> None:
+        self.root = None
+        self.compiled_model = None
+        self.path = None
+        self._update_window()
+
+    def open(self, path: str | Path, *, component: str | None = None, simulation: str | None = None, backed_by_file: bool = True, compiled_model: CompiledModel | None = None) -> None:
+        file_path = Path(path)
+        if file_path.suffix.lower() == ".bes" or simulation_files.is_simulation_json(file_path):
+            self.root = simulation_files.load(file_path)
+            self.compiled_model = compiled_model or self._recompile_with_wait_cursor(self.root)
+            self.path = file_path if backed_by_file else None
+        else:
+            self.root, self.compiled_model = self._compile_with_wait_cursor(file_path, component=component, simulation=simulation)
+            self.path = None
+        self._update_window()
+
+    def open_dialog(self) -> None:
+        filename, _ = QFileDialog.getOpenFileName(self.window, "Open Simulation", "", "Simulation and BEdit files (*.bes *.beb *.json)")
+        if not filename:
+            return
+        try:
+            path = Path(filename)
+            if path.suffix.lower() == ".bes" or simulation_files.is_simulation_json(path):
+                self.open(path)
+                return
+            document = document_files.load(path)
+            database = document.metadata.get("simulation_database") if document.metadata is not None else None
+            entries = [(f"Simulation: {simulation.name}", None, simulation.name) for simulation in getattr(database, "simulations", {}).values()]
+            entries.extend((f"Component: {component_path}", component_path, None) for _component_id, _component, component_path in component_choices(document))
+            if not entries:
+                raise ValueError("the BEdit document contains no components or simulation settings")
+            label, accepted = QInputDialog.getItem(self.window, "Simulation Target", "Compile:", [entry[0] for entry in entries], 0, False)
+            if accepted:
+                _display, component, simulation = next(entry for entry in entries if entry[0] == label)
+                self.open(path, component=component, simulation=simulation)
+        except (OSError, RuntimeError, ValueError) as exc:
+            QMessageBox.critical(self.window, "Could not open simulation", str(exc))
+
+    def save(self) -> None:
+        if self.root is None:
+            return
+        path = self.path
+        if path is None:
+            filename, _ = QFileDialog.getSaveFileName(self.window, "Save Simulation", "simulation.bes", "BEdit simulation (*.bes);;Simulation JSON (*.json)")
+            if not filename:
+                return
+            path = Path(filename)
+            if path.suffix.lower() not in (".bes", ".json"):
+                path = path.with_suffix(".bes")
+        try:
+            simulation_files.save(self.root, path)
+        except (OSError, ValueError) as exc:
+            QMessageBox.critical(self.window, "Could not save simulation", str(exc))
+            return
+        self.path = path
+        self._update_window()
+
+    def _compile_with_wait_cursor(self, path: Path, *, component: str | None, simulation: str | None) -> tuple[SimulationRoot, CompiledModel]:
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        try:
+            return load_and_compile_bedit(path, component_selector=component, simulation_selector=simulation)
+        finally:
+            QApplication.restoreOverrideCursor()
+
+    def _recompile_with_wait_cursor(self, root: SimulationRoot) -> CompiledModel:
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        try:
+            return compile_simulation_root(root)
+        finally:
+            QApplication.restoreOverrideCursor()
+
+    def _update_window(self) -> None:
+        if self.root is None:
+            self.window.setWindowTitle("BEdit Simulator")
+            self.window.statusBar().showMessage("No simulation loaded")
+            self.window.ui.actionSave_Simulation_Run.setEnabled(False)
+            return
+        self.window.setWindowTitle(f"{self.root.settings.name} — BEdit Simulator")
+        compiled = self.compiled_model.executable if self.compiled_model is not None else "not compiled"
+        self.window.statusBar().showMessage(f"{self.root.component_path} · {compiled}")
+        self.window.ui.actionSave_Simulation_Run.setEnabled(True)

src/bedit_gui/documents/document.py

@@ -16,7 +16,7 @@ from bedit_gui.commands.rename_component_command import RenameComponentCommand
 from bedit_gui.commands.rename_document_command import RenameDocumentCommand
 from bedit_gui.commands.simulation_database_command import ChangeSimulationDatabaseCommand
 from bedit_gui.commands.component_command import AddEmptyEquationComponent, AddEmptyGraphComponent, DeleteComponent, PasteComponents
-from bedit_gui.models import Icon, IconDatabase, SimulationDatabase
+from bedit_gui.models import Icon, IconDatabase, Simulation, SimulationDatabase
 from bedit_gui.services import document_files
 
 
@@ -131,6 +131,10 @@ class Document(QObject):
     def simulation_database(self) -> SimulationDatabase:
         return self.stored_simulation_database() or SimulationDatabase()
 
+    def active_simulation(self) -> Simulation | None:
+        database = self.simulation_database()
+        return database.simulations.get(database.active_simulation) if database.active_simulation is not None else None
+
     def change_simulation_database(self, database: SimulationDatabase) -> None:
         if database != self.stored_simulation_database():
             self.undo_stack.push(ChangeSimulationDatabaseCommand(self, database))

src/bedit_gui/models.py

@@ -176,11 +176,14 @@ class Simulation:
 class SimulationDatabase:
     format_version: int = 1
     simulations: dict[SimulationID, Simulation] = field(default_factory=dict)
+    active_simulation: SimulationID | None = None
 
     @classmethod
     def from_data(cls, data: Mapping[str, Any]) -> SimulationDatabase:
         sims = {SimulationID(key): Simulation.from_data(value) for key, value in data.get("simulations", {}).items()}
-        return cls(format_version=int(data.get("format_version", 1)), simulations=sims)
+        active = data.get("active_simulation")
+        active_id = SimulationID(str(active)) if active is not None else None
+        return cls(format_version=int(data.get("format_version", 1)), simulations=sims, active_simulation=active_id if active_id in sims else None)
 
     def to_data(self) -> dict[str, Any]:
-        return {"format_version": self.format_version, "simulations": {str(key): sim.to_data() for key, sim in self.simulations.items()}}
+        return {"format_version": self.format_version, "active_simulation": str(self.active_simulation) if self.active_simulation is not None else None, "simulations": {str(key): sim.to_data() for key, sim in self.simulations.items()}}

src/bedit_gui/services/simulation_files.py

@@ -0,0 +1,79 @@
+from __future__ import annotations
+
+import json
+import zlib
+from collections.abc import Mapping
+from pathlib import Path
+from typing import Any
+
+import msgpack
+
+from bedit_gui.simulation_models import SimulationRoot
+
+BES_MAGIC = b"BES\x00"
+FILE_FORMAT_VERSION = 1
+_VERSION_SIZE = 4
+
+
+def load(path: str | Path) -> SimulationRoot:
+    file_path = Path(path)
+    data = _load_json(file_path) if file_path.suffix.lower() == ".json" else _load_bes(file_path)
+    return SimulationRoot.from_data(data)
+
+
+def save(root: SimulationRoot, path: str | Path) -> None:
+    file_path = Path(path)
+    if file_path.suffix.lower() == ".json":
+        _save_json(root.to_data(), file_path)
+    elif file_path.suffix.lower() == ".bes":
+        _save_bes(root.to_data(), file_path)
+    else:
+        raise ValueError(f"unsupported simulation file extension {file_path.suffix!r}; expected '.json' or '.bes'")
+
+
+def is_simulation_json(path: str | Path) -> bool:
+    file_path = Path(path)
+    if file_path.suffix.lower() != ".json":
+        return False
+    try:
+        return _load_json(file_path).get("root_type") == "simulation_root"
+    except (TypeError, ValueError):
+        return False
+
+
+def _load_json(path: Path) -> Mapping[str, Any]:
+    try:
+        data = json.loads(path.read_text(encoding="utf-8"))
+    except (OSError, UnicodeError, json.JSONDecodeError) as exc:
+        raise ValueError(f"could not read simulation JSON {path}: {exc}") from exc
+    if not isinstance(data, Mapping):
+        raise TypeError(f"simulation JSON {path} must contain an object")
+    return data
+
+
+def _save_json(data: Mapping[str, Any], path: Path) -> None:
+    path.write_text(json.dumps({"file_format_version": FILE_FORMAT_VERSION, **data}, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
+
+
+def _load_bes(path: Path) -> Mapping[str, Any]:
+    try:
+        payload = path.read_bytes()
+        header_end = len(BES_MAGIC) + _VERSION_SIZE
+        if not payload.startswith(BES_MAGIC):
+            raise ValueError("missing BES file header")
+        if len(payload) < header_end:
+            raise ValueError("truncated BES file header")
+        version = int.from_bytes(payload[len(BES_MAGIC):header_end], "big")
+        if version != FILE_FORMAT_VERSION:
+            raise ValueError(f"unsupported BES file version {version}")
+        data = msgpack.unpackb(zlib.decompress(payload[header_end:]), raw=False, strict_map_key=False)
+    except (OSError, ValueError, zlib.error, msgpack.exceptions.MsgpackException) as exc:
+        raise ValueError(f"could not read BES simulation {path}: {exc}") from exc
+    if not isinstance(data, Mapping):
+        raise TypeError(f"BES simulation {path} must contain a map")
+    return data
+
+
+def _save_bes(data: Mapping[str, Any], path: Path) -> None:
+    encoded = zlib.compress(msgpack.packb(dict(data), use_bin_type=True))
+    path.write_bytes(BES_MAGIC + FILE_FORMAT_VERSION.to_bytes(_VERSION_SIZE, "big") + encoded)

src/bedit_gui/services/simulation_loader.py

@@ -0,0 +1,95 @@
+from __future__ import annotations
+
+import tempfile
+from pathlib import Path
+
+from bedit_core.models import Component, ComponentID, Document, GraphImplementation
+from bedit_gui.models import Simulation, SimulationMethod
+from bedit_gui.services import document_files
+from bedit_gui.simulation_models import CompiledModel, SimulationRoot
+from bedit_simulation import compile_component_sync
+
+
+def component_choices(document: Document) -> list[tuple[ComponentID, Component, str]]:
+    choices: list[tuple[ComponentID, Component, str]] = []
+
+    def collect(items: dict[ComponentID, Component], path: tuple[str, ...] = ()) -> None:
+        for component_id, component in items.items():
+            component_path = (*path, component.name)
+            choices.append((component_id, component, ".".join(component_path)))
+            if isinstance(component.implementation, GraphImplementation):
+                collect(component.implementation.graph.components, component_path)
+
+    collect(document.root)
+    return choices
+
+
+def load_and_compile_bedit(path: str | Path, *, component_selector: str | None = None, simulation_selector: str | None = None, working_directory: str | Path | None = None, omc_command: str = "omc") -> tuple[SimulationRoot, CompiledModel]:
+    """Open a BEdit document, resolve one launch target, and compile it."""
+    if bool(component_selector) == bool(simulation_selector):
+        raise ValueError("specify exactly one component or simulation settings block")
+    source_path = Path(path).resolve()
+    document = document_files.load(source_path)
+    choices = component_choices(document)
+    settings_name: str | None = None
+
+    if component_selector is not None:
+        component_id, component, component_path = _find_component(choices, component_selector)
+        settings = _default_settings(component_id)
+    else:
+        database = document.metadata.get("simulation_database") if document.metadata is not None else None
+        if database is None or not hasattr(database, "simulations"):
+            raise ValueError("the BEdit document does not contain simulation settings")
+        matches = [(simulation_id, simulation) for simulation_id, simulation in database.simulations.items() if simulation.name == simulation_selector or str(simulation_id) == simulation_selector]
+        if len(matches) != 1:
+            raise ValueError(f"simulation settings {simulation_selector!r} were not found or are ambiguous")
+        _simulation_id, settings = matches[0]
+        component_id, component, component_path = _find_component(choices, str(settings.component))
+        settings_name = settings.name
+
+    build_directory = Path(working_directory) if working_directory is not None else Path(tempfile.mkdtemp(prefix="bedit-compiled-"))
+    root = SimulationRoot(
+        format_version=1,
+        source_document=str(source_path),
+        source_document_id=str(document.id),
+        component=component_id,
+        component_path=component_path,
+        settings_name=settings_name,
+        settings=settings,
+    )
+    return root, _compile(component, build_directory, omc_command)
+
+
+def compile_simulation_root(root: SimulationRoot, *, working_directory: str | Path | None = None, omc_command: str = "omc") -> CompiledModel:
+    if root.source_document is None:
+        raise ValueError("the simulation does not reference a BEdit source document and cannot be recompiled")
+    document = document_files.load(root.source_document)
+    _component_id, component, _component_path = _find_component(component_choices(document), str(root.component))
+    build_directory = Path(working_directory) if working_directory is not None else Path(tempfile.mkdtemp(prefix="bedit-compiled-"))
+    return _compile(component, build_directory, omc_command)
+
+
+def _find_component(choices: list[tuple[ComponentID, Component, str]], selector: str) -> tuple[ComponentID, Component, str]:
+    matches = [choice for choice in choices if str(choice[0]) == selector or choice[2] == selector]
+    if len(matches) != 1:
+        raise ValueError(f"component {selector!r} was not found or is ambiguous")
+    return matches[0]
+
+
+def _default_settings(component_id: ComponentID) -> Simulation:
+    return Simulation(
+        component=component_id,
+        name="Default",
+        start_time=0.0,
+        duration=1.0,
+        use_timed_steps=False,
+        number_of_steps=500,
+        step_size=0.002,
+        method=SimulationMethod.DASSL,
+        dassl_tolerance=1e-6,
+    )
+
+
+def _compile(component: Component, working_directory: Path, omc_command: str) -> CompiledModel:
+    build = compile_component_sync(component, working_directory, omc_command=omc_command)
+    return CompiledModel(build.model_name, str(build.executable.resolve()), str(build.executable.parent.resolve()))

src/bedit_gui/simulation_application.py

@@ -1,31 +1,49 @@
 from __future__ import annotations
 
-import sys
 import argparse
+import sys
 
-def parse_arguments():
+from PySide6.QtWidgets import QApplication, QMessageBox
-    parser = argparse.ArgumentParser(exit_on_error=False)
 
-    parser.add_argument(
+from bedit_gui.controllers.simulation_file_controller import SimulationFileController
-        "-f", "--file", type=str, help="Path to a BEditor BEsim file to open", default=None, required=False
+from bedit_gui.simulation_models import CompiledModel
-    )
+from bedit_gui.views.simulation_window import SimulationWindow
-    parser.add_argument(
-        "-c", "--component", type=str, help="Component path in BEdit file to simulate", default=None, required=False
-    )
-    parser.add_argument(
-        "-s", "--simulation", type=str, help="Simulation name in BEdit file to simulate", default=None, required=False
-    )
 
-    return parser.parse_args(), parser
 
-def main() -> int:
+def parse_arguments(arguments: list[str] | None = None) -> argparse.Namespace:
-    try:
+    parser = argparse.ArgumentParser(description="Open and run BEdit simulations")
-        args, parser = parse_arguments()
+    parser.add_argument("file", nargs="?", help="BEdit (.beb/.json) or simulation (.bes/.json) file")
-        # TODO check if file is a BEditor file (.beb or .json)
+    parser.add_argument("-f", "--file", dest="file_option", help=argparse.SUPPRESS)
-        if args.file and not (args.component or args.simulation):
+    parser.add_argument("--handoff", action="store_true", help=argparse.SUPPRESS)
-            parser.error("Component or Simulation required when opening a BEdit file")
+    parser.add_argument("--model-name", help=argparse.SUPPRESS)
-    except argparse.ArgumentError as e:
+    parser.add_argument("--executable", help=argparse.SUPPRESS)
-        print(e.message)
+    parser.add_argument("--working-directory", help=argparse.SUPPRESS)
-        return 1
+    target = parser.add_mutually_exclusive_group()
+    target.add_argument("-c", "--component", help="Component ID or dotted path in a BEdit file")
+    target.add_argument("-s", "--simulation", help="Simulation settings name or ID in a BEdit file")
+    args = parser.parse_args(arguments)
+    args.file = args.file_option or args.file
+    if args.handoff and not all((args.model_name, args.executable, args.working_directory)):
+        parser.error("a simulator handoff requires compiled-model arguments")
+    return args
 
-    return 0
+
+def main(arguments: list[str] | None = None) -> int:
+    args = parse_arguments(arguments)
+    app = QApplication(sys.argv if arguments is None else [sys.argv[0], *arguments])
+    app.setOrganizationName("BEdit")
+    app.setApplicationName("BEdit Simulator")
+    window = SimulationWindow()
+    controller = SimulationFileController(window)
+    window.showMaximized()
+    if args.file:
+        try:
+            compiled_model = CompiledModel(args.model_name, args.executable, args.working_directory) if args.handoff else None
+            controller.open(args.file, component=args.component, simulation=args.simulation, backed_by_file=not args.handoff, compiled_model=compiled_model)
+        except (OSError, ValueError, RuntimeError) as exc:
+            QMessageBox.critical(window, "Could not open simulation", str(exc))
+    return app.exec()
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

src/bedit_gui/simulation_models.py

@@ -1,11 +1,59 @@
 from __future__ import annotations
 
 from collections.abc import Mapping
-from dataclasses import dataclass, field
+from dataclasses import dataclass
-from enum import Enum
 from typing import Any
 
+from bedit_core.models import ComponentID
+from bedit_gui.models import Simulation
+
+
+@dataclass
+class CompiledModel:
+    model_name: str
+    executable: str
+    working_directory: str
+
+    @classmethod
+    def from_data(cls, data: Mapping[str, Any]) -> CompiledModel:
+        return cls(model_name=str(data["model_name"]), executable=str(data["executable"]), working_directory=str(data["working_directory"]))
+
+    def to_data(self) -> dict[str, Any]:
+        return {"model_name": self.model_name, "executable": self.executable, "working_directory": self.working_directory}
+
+
 @dataclass
 class SimulationRoot:
-    format_version: int = 1
+    format_version: int
-    model_file_path: str | None # The file path of the BEdit file if there is one
+    source_document: str | None
+    source_document_id: str | None
+    component: ComponentID
+    component_path: str
+    settings_name: str | None
+    settings: Simulation
+
+    @classmethod
+    def from_data(cls, data: Mapping[str, Any]) -> SimulationRoot:
+        if data.get("root_type") != "simulation_root":
+            raise ValueError("file does not contain a simulation root")
+        return cls(
+            format_version=int(data.get("format_version", 1)),
+            source_document=str(data["source_document"]) if data.get("source_document") is not None else None,
+            source_document_id=str(data["source_document_id"]) if data.get("source_document_id") is not None else None,
+            component=ComponentID(str(data["component"])),
+            component_path=str(data.get("component_path", "")),
+            settings_name=str(data["settings_name"]) if data.get("settings_name") is not None else None,
+            settings=Simulation.from_data(data["settings"]),
+        )
+
+    def to_data(self) -> dict[str, Any]:
+        return {
+            "root_type": "simulation_root",
+            "format_version": self.format_version,
+            "source_document": self.source_document,
+            "source_document_id": self.source_document_id,
+            "component": str(self.component),
+            "component_path": self.component_path,
+            "settings_name": self.settings_name,
+            "settings": self.settings.to_data(),
+        }

src/bedit_gui/views/dialogs/simulation_settings_dialog.py

@@ -51,7 +51,7 @@ class SimulationSettingsDialog(QDialog):
         self.ui.simulationMethodComboBox.currentIndexChanged.connect(self._form_changed)
         self.ui.toleranceEdit.textEdited.connect(self._form_changed)
 
-        self._rebuild_list()
+        self._rebuild_list(self._database.active_simulation)
 
     def database(self) -> SimulationDatabase:
         return deepcopy(self._database)
@@ -68,6 +68,7 @@ class SimulationSettingsDialog(QDialog):
                 QMessageBox.warning(self, "Invalid simulation", "The DASSL tolerance must be greater than zero.")
                 return
             simulation.name = simulation.name.strip()
+        self._database.active_simulation = self._simulation_id()
         super().accept()
 
     def _rebuild_list(self, selected_id: SimulationID | None = None) -> None:
@@ -172,6 +173,8 @@ class SimulationSettingsDialog(QDialog):
         row = self._simulation_ids.index(simulation_id)
         del self._database.simulations[simulation_id]
         self._simulation_ids.remove(simulation_id)
+        if self._database.active_simulation == simulation_id:
+            self._database.active_simulation = None
         selected = self._simulation_ids[min(row, len(self._simulation_ids) - 1)] if self._simulation_ids else None
         self._rebuild_list(selected)
 

src/bedit_gui/views/simulation_window.py

@@ -0,0 +1,13 @@
+from __future__ import annotations
+
+from PySide6.QtWidgets import QMainWindow
+
+from bedit_gui.ui.generated.ui_simulation_window import Ui_SimulationWindow
+
+
+class SimulationWindow(QMainWindow):
+    def __init__(self) -> None:
+        super().__init__()
+        self.ui = Ui_SimulationWindow()
+        self.ui.setupUi(self)
+        self.setWindowTitle("BEdit Simulator")

src/bedit_simulation/__init__.py

@@ -6,6 +6,7 @@ from .openmodelica import (
     ProcessResult,
 )
 from .results import SimulationResult, load_openmodelica_csv
+from .compile import compile_component, compile_component_sync
 from .simulation import (
     ModelBuildResult,
     ModelCheckResult,
@@ -18,17 +19,19 @@ from .simulation import (
 )
 
 __all__ = [
-    "OpenModelicaError",
-    "OpenModelicaRunner",
-    "ProcessResult",
     "ModelBuildResult",
     "ModelCheckResult",
     "ModelInfo",
+    "OpenModelicaError",
+    "OpenModelicaRunner",
+    "ProcessResult",
     "Simulation",
     "SimulationOptions",
     "SimulationProgress",
-    "SimulationStateError",
     "SimulationResult",
+    "SimulationStateError",
+    "compile_component",
+    "compile_component_sync",
     "load_openmodelica_csv",
     "simulate",
 ]

src/bedit_simulation/compile.py

@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+import asyncio
+from pathlib import Path
+
+from bedit_core.models import Component
+
+from .openmodelica import OpenModelicaRunner
+from .simulation import ModelBuildResult, Simulation
+
+
+async def compile_component(component: Component, working_directory: str | Path, *, omc_command: str = "omc", timeout: float | None = None) -> ModelBuildResult:
+    """Compose and compile a component without creating a GUI application."""
+    simulation = Simulation(OpenModelicaRunner(omc_command, timeout=timeout))
+    await simulation.load(component)
+    return await simulation.compile(working_directory)
+
+
+def compile_component_sync(component: Component, working_directory: str | Path, *, omc_command: str = "omc", timeout: float | None = None) -> ModelBuildResult:
+    """Synchronous entry point for scripts and non-async suite applications."""
+    return asyncio.run(compile_component(component, working_directory, omc_command=omc_command, timeout=timeout))

untitled.bedit.json

@@ -591,6 +591,7 @@
     },
     "simulation_database": {
       "format_version": 1,
+      "active_simulation": "7778ca68-7a36-401b-b4aa-236a44c5e771",
       "simulations": {
         "7778ca68-7a36-401b-b4aa-236a44c5e771": {
           "component": "50e6ef97-f686-4400-bc01-e5a352e8cc22",