add agent.md file with initial content.

AGENTS.md

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+# AGENTS.md
+
+## Purpose
+
+This document outlines the architectural and development principles for contributors to the `plugin_loopstructural` QGIS plugin. The plugin provides a thin, modular interface to the `map2loop` and `LoopStructural` libraries, enabling geological modeling workflows within QGIS.
+
+---
+
+## Design Philosophy
+
+### 🔹 Thin Interface Layer
+- The plugin **must not** reimplement or duplicate functionality from `map2loop` or `LoopStructural`.
+- All core logic and enhancements should be contributed upstream to the respective libraries.
+- The plugin should focus on **UI integration**, **data flow orchestration**, and **user interaction**.
+
+### 🔹 Modularity
+- UI components (dialogs, panels, actions) live under the `loopstructural/gui/` package and should be encapsulated in their own classes.
+- Business logic and orchestration are located in `loopstructural/main/` and `loopstructural/toolbelt/` where adapters and services wrap external libraries.
+- Processing algorithms and QGIS provider integration are in `loopstructural/processing/` and should be isolated from UI code.
+- Avoid tight coupling between components. Use signals/slots or event-driven patterns where appropriate.
+
+### 🔹 Object-Oriented Design
+- Use classes with clear responsibilities and interfaces.
+- Prefer composition over inheritance unless subclassing is semantically appropriate.
+- Encapsulate interactions with external libraries in dedicated adapter or service classes (e.g., `loopstructural.main.Map2LoopService`, `loopstructural.main.LoopStructuralRunner`).
+
+---
+
+## Development Guidelines
+
+### ✅ Code Quality
+- All code must pass the repository's pre-commit checks (formatting, linting, import sorting).
+- Use type hints and docstrings for all public methods and classes.
+- Follow PEP8 and QGIS plugin development best practices.
+
+### 🧪 Testing
+- All new code must include **unit tests** and, where applicable, **integration tests**.
+- Tests live under the `tests/` package and are runnable with `pytest`.
+- Mock external dependencies (`map2loop`, `LoopStructural`) in unit tests.
+
+### 🧩 Current Plugin Structure
+
+```
+plugin_loopstructural/
+├── loopstructural/           # plugin package
+│   ├── __init__.py
+│   ├── __about__.py
+│   ├── plugin_main.py        # QGIS plugin entry and bootstrap
+│   ├── gui/                  # UI dialogs, widgets, and panels
+│   ├── main/                 # controllers, managers, adapters (service layer)
+│   ├── processing/           # QGIS processing provider and algorithms
+│   ├── toolbelt/             # utilities, env parsing, preferences, logging
+│   ├── resources/            # icons, translations, help files
+│   └── requirements.txt
+├── docs/
+├── requirements/
+├── tests/
+└── README.md
+```
+
+Notes on mapping older concepts:
+- What used to be called `services/` and `controllers/` is implemented across `loopstructural/main/` and `loopstructural/toolbelt/`.
+- UI remains in `loopstructural/gui/` (dialogs, `.ui` files, widget classes).
+- Processing-specific code and QGIS provider live under `loopstructural/processing/`.
+
+---
+
+## Contribution Workflow
+
+1. Fork the repository and create a feature branch.
+2. Implement changes following the design and code quality guidelines.
+3. Add or update tests under `tests/` and ensure they run with `pytest`.
+4. Run pre-commit hooks (e.g. `pre-commit run --all-files`) and ensure all checks pass.
+5. Submit a pull request with a clear description of the changes and rationale. Link to upstream libraries if behavior is moved upstream.
+
+---
+
+## Future Enhancements
+
+- Support for asynchronous or background processing of long-running tasks (consider using QGIS background task framework).
+- Improved error handling and user feedback.
+- Internationalization (i18n) support and keeping `.ts`/.qm translation files in `loopstructural/resources/i18n/`.
+- Better separation of concerns between UI, processing algorithms and adapters to facilitate unit testing.
+
+---
+
+## Contact
+
+For questions or contributions to the upstream libraries:
+- `map2loop`
+- `LoopStructural`
+
+---