## Why
A failed provider catalog refresh could discard model metadata and disable tool search on subsequent turns, even after a successful discovery.
## What changed
Keep the last successful catalog, ETag, and original freshness when refreshes fail without an access rejection. Continue invalidating cached catalogs for HTTP `401`/`403`, rejected refresh tokens, and gateway credentials that require login. Distinguish `GatewayLoginRequired` from login in progress so only the former invalidates the catalog.
Successful empty responses remain authoritative, and cached catalogs remain scoped to the provider and authentication identity.
## Testing
Add regression coverage for catalog preservation across refresh errors and restarts, access rejection invalidation, identity isolation, and tool search and instruction stability on the next turn after a failed refresh.
GitOrigin-RevId: 9dd7c73ac2cc1fd49664efd93b839baa94e05c49
Abhinav
067249a283