PS: on the topic of timestamps, I think that the bugfix level would be much better served with a date than with an increment. A "2.7.3" could be both much older

PS: on the topic of timestamps, I think that the bugfix level would be much better served with a date than with an increment. A "2.7.3" could be both much older or much younger than the corresponding "2.5.6" or contain exactly the same important fixes. When assessing the risk of running something that contains an older version your most important information is often before or after $famousvulnerability and increments can be quite deceptive. I think I might be happy with major.minor.date, where both major and minor are allowed to be breaking, with meaning "most client codebases will need change" and minor means "most client codebases will be fine". For languages leaning towards typed I'd lump the "only added features" together with minor breakage, for more dynamic languages the existing semver (plus date instead of bugfix increment) is probably fine.