This sequence explains my take on agency. The first post is the intro + overview.
ETA: I’m deprioritizing completing this sequence because it seems that other people are writing good similar stuff. In particular, see e.g. https://www.lesswrong.com/posts/kpPnReyBC54KESiSn/optimality-is-the-tiger-and-agents-are-its-teeth and https://www.lesswrong.com/posts/pdJQYxCy29d7qYZxG/agency-and-coherence