manuals: + [fully read markers](https://matrix.org/docs/spec/client_server/latest.html#fully-read-markers) + [m.read receipt](https://matrix.org/docs/spec/client_server/latest.html#m-receipt) hints: + [telepathy-nonsense implementation](https://github.com/TelepathyIM/telepathy-nonsense/blob/master/textchannel.cc#L217) + [telepathy-morse implementation](https://github.com/TelepathyIM/telepathy-morse/blob/b2de3854e5aded61df3b66cd502a0beac0a3db34/textchannel.cpp#L403) + [Spectral client sources](https://gitlab.com/b0/spectral/blob/master/imports/Spectral/Component/Timeline/MessageDelegate.qml#L136)
