# Domain Model Contract

## Core aggregates

### Project
A project is an investigation workspace. It contains areas, datasets, analyses, and exports.

### Area
A spatial polygon or selected administrative unit used to clip and analyze datasets.

### Dataset
A source artifact or external reference. Datasets can be raster, vector, reference, model output, mask, or export.

### AnalysisRun
A tracked execution of a pipeline such as detection, segmentation, QA, clipping, tiling, or index computation.

### Detection
A model-derived feature, usually a georeferenced bounding box or polygon.

### Segmentation
A mask-derived polygon or raster mask output.

### QualityCheck
A comparison between model outputs and reference data such as GRB.

## Geometry rules

- Use SRID 4326 for API-level GeoJSON interchange unless explicitly documented.
- Use projected CRS for area/length calculations when required.
- Store original CRS metadata for every dataset.
- Never calculate area in degrees.