hermes backup only walks HERMES_HOME, so memory providers that keep
config/credentials in home-anchored dotdirs (honcho -> ~/.honcho,
hindsight -> ~/.hindsight, openviking -> ~/.openviking) lost that data
across a backup/import cycle — the peer IDs, session pairings, and API
keys never made it into the archive.
Add an optional MemoryProvider.backup_paths() hook (default []). The
active provider declares its external paths; backup resolves them from
config only (no init, no network), archives the ones under the home dir
into a reserved _external/ subtree encoded relative to home, and import
restores them to their original location with a home-anchored traversal
guard and 0600 on credential-shaped files. Paths outside home are
skipped as non-portable.
honcho, hindsight, and openviking override the hook. E2E-validated full
backup->import cycle plus 7 new tests.
587b5b9ac2