Processing provider

This page comes from site/content/architecture/processing.md in the repository and is regenerated on every merge to main. To correct it, edit that file; changes made here are overwritten.

The plugin registers a QGIS Processing provider (id cartogen, shown as Cartogen AI) so analyses can be used without the chat: in the Processing Toolbox, the Graphical Model Designer, batch processing and the headless qgis_process CLI.

Algorithm	id	Group	What it does
Optimal Hub Siting (Demand Coverage)	cartogen:optimalhubsiting	Logistics & Network	Ranks candidate hub points by average straight-line distance to demand points.
Service Area from Network	cartogen:calculateservicearea	Logistics & Network	Multi-band service areas from a road network layer.

Both live in src/cartogen_ai/processing/provider.py. The manifest declares hasProcessingProvider=yes, plugin_main.py calls initProcessing() from initGui() to add the provider to QgsApplication.processingRegistry(), and unload() removes it, so load, unload and reload work without restarting QGIS (a CI smoke test checks this).

Two directions of reuse

• Plugin → Processing: the two algorithms above expose the plugin's own analyses.
• Processing → plugin: the agent can run a fixed list of existing Processing algorithms through run_allowlisted_processing_algorithm. Native algorithms that create new data run on a worker with Stop; Python-implemented ones stay on the main thread. See Threads, tasks and Stop.

Only these two algorithms are registered. The other 335 tools are available through the chat, not the Toolbox.