I've been developing an #ActivityPub C2S-based (with extensions) API facade/proxy proof-of-concept for Mastodon. It runs as a separate process that supports proxying the Masto operations but also adds a postable C2S outbox with support for AP C2S activities. These activities are converted into upstream Mastodon API calls. This extended C2S API also supports search, streaming events, managing bookmark collections, and retrieving timeline collections. 1/2
The code isn’t quite ready to be published yet and the purpose of this C2S PoC implementation (Python) is experimentation, not high-performance production use. However, it will be useful for prototyping C2S extensions that can be documented using the FEP process. The documented extensions could be implemented as native functionality instead of using a proxy. The benefit of the proxy is that the proxied Mastodon instance still supports both Masto clients and extended C2S clients. 2/2