Skill v1.0.0

description: List the registered versions of a Julia package via Pkg's registry API (not a directory grep) argument-hint: "[package name | UUID | path] (defaults to the current project)" metadata: version: "1.0.0"

Report which versions of a Julia package are registered, across every reachable registry. The argument ($ARGUMENTS) may be a package name, a UUID, or a path to a package directory; if omitted, use the package in the current directory (read its name/uuid from Project.toml).

Common uses: deciding whether renaming/removing a public symbol is breaking (is the symbol in a registered release, or only on an unreleased main?), and checking the latest registered version before a release.

Do not grep the registry directory

~/.julia/registries/General is stored as a compressed tarball (General.tar.gz), so find/grep over the registries directory silently finds nothing even for a package that is registered — a false negative. Query through Pkg, which reads the tarball natively. (A private registry like HolyLabRegistry may be an unpacked directory, but use the same Pkg path uniformly so the answer never depends on the storage format.)

Query

Resolve the target to a UUID when you can — a UUID match avoids false hits from similarly-named packages. Then:

using Pkg
using Pkg.Registry: reachable_registries, registry_info
 
target = "PenalizedDensity"   # a name, or a UUID string; from $ARGUMENTS or Project.toml
found = false
for reg in reachable_registries()
    for (uuid, e) in reg.pkgs
        (e.name == target || string(uuid) == target) || continue
        info = registry_info(e)
        vers = sort(collect(keys(info.version_info)))
        println(reg.name, ": ", e.name, " [", uuid, "]  versions = ", vers)
        global found = true
    end
end
found || println("not registered in any reachable registry")

This is a one-shot query with no need for Revise, so running julia directly from the shell is fine.

Report

State the registry (or registries) the package appears in and the sorted version list, and — when the caller is weighing a breaking change — whether the symbol in question predates or postdates the latest registered version, since only registered releases constrain compatibility. If the package is not in any reachable registry, say so plainly: that means nothing has shipped through a registry, whatever git tags exist locally.