Lovable's API at https://api.lovable.dev/v1 manages and deploys existing Lovable projects and reads workspace data. It doesn't consume AI build credits.
Create a workspace API key (it starts with lov_) in your Lovable workspace settings and send it as the Lovable-API-Key header. In the examples it's written {{LOVABLE_API_KEY}}.
Full reference: https://docs.lovable.dev/integrations/lovable-api
curl https://api.lovable.dev/v1/projects \
-H "Lovable-API-Key: {{LOVABLE_API_KEY}}"
curl https://api.lovable.dev/v1/workspaces \
-H "Lovable-API-Key: {{LOVABLE_API_KEY}}"