install <identifier> [--force] [--ref COMMIT_SHA] [--allow-removed]
Install a plugin from the Hermes plugin catalog (bare entry name), a Git URL, or owner/repo shorthand. Catalog names resolve to the entry's repo at its pinned 40-hex commit SHA, show the declared capability summary, and record catalog provenance on the installer's .install-metadata.json record (a .hermes-catalog.json copy is written inside the plugin dir for convenience, but is never trusted). Raw URLs are flagged as custom (unreviewed) sources; --ref (full 40-character commit SHA) pins them, and on a catalog entry records the checked-out SHA rather than the reviewed pin. --allow-removed (DANGEROUS) bypasses the removed-plugin blocklist at install AND exempts that install from the update/enable/load-time kill-list checks.
From the official Hermes Agent CLI reference.