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.