Just some notes to get you up and running
I used https://github.com/RicoSuter/NSwag/wiki/NSwagStudio to generate the client. You need to have a local ActivityWatch running on http://localhost:5600/api/swagger.json. The config I used is saved as ./API/V1/GeneratorConfig.nswag
The ./API/V1/Generated.cs needs a little fix ... Some Method names start with a zero. Luckily you could just replace " 0" with just " " (without quotes).