I don't see how that "no managers" core can be true. Many of the principles, like "Deliver working software frequently, from a couple of weeks to a couple of m

I don't see how that "no managers" core can be true. Many of the principles, like "Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale." are valid even for solo developer projects. Agile came out of older practices, like Rapid Development, which definitely could be used by solo developers. Several of the principles do imply the existence of multiple people - #4 implies business people are distinct from developers - but still apply to a two-person company, like married friends I knew who ran their own software company where the wife handled the business and the husband the development and there was no manager. If there are no managers, then either everything they do is Agile (because there are no managers) or nothing they do is Agile (because "Agile" can't be applied). If the former, then a solo developer following waterfall is Agile. If the latter then what alternative principles can be applied to solo- and partnership developer projects?