cargo-semver-checks is in the process of being merged into cargo itself, which would make the default publishing process into essentially exactly what you descr

cargo-semver-checks is in the process of being merged into cargo itself, which would make the default publishing process into essentially exactly what you describe! Running `cargo publish` would check for semver issues and alert if it finds anything. Users would be able to override it, of course, but most often they'd probably accept the version change or revert the semver break if it wasn't intended.