`hermes skills update` could silently replace a same-named skill from a
DIFFERENT registry — deleting the user's files and rewriting the lockfile's
recorded provenance. Two defects on main:
- tools/skills_hub.py: check_for_skill_updates fell back to *all* sources
(`... or sources`) when no adapter matched the recorded source, so any
registry with a same-named skill could satisfy the fetch and be reported
as an update — silently reassigning provenance. Now reports the entry as
`unavailable` instead of cross-registry fallback.
- hermes_cli/skills_hub.py: do_update called do_install with a bare, slash-
less identifier and no source constraint, letting _resolve_short_name fuzzy-
match a same-named skill in another registry. do_install now takes an
optional source_id pin that ABORTS (rather than falls back) when no adapter
matches, and do_update forwards the lockfile's recorded source as that pin.
Includes regression tests reproducing the cross-registry hijack.
Salvaged from PR #72216 onto current main; re-attributed to the human
contributor.
Co-authored-by: menhguin <menhguin@users.noreply.github.com>
