Accounts… ran account discovery for every provider, but providers without
named token accounts got a successful empty list and the panel stayed hidden.
Providers without token-account support showed a raw CLI argument error.

AccountResponse now reports availability (named, none, unsupported), the
accounts controller keeps it per provider, the panel explains both empty
cases, and an unsupported provider's Accounts… entry is disabled until a
reset, a managed CLI install or a manual reload.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>