Function is_internal_table 

pub fn is_internal_table(name: &str) -> bool

Returns true when name is one of HyperDB’s own internal tables (matches HYPERDB_INTERNAL_PREFIX). Factored into a helper so every filter site calls the same predicate and a future move to a more nuanced scheme (e.g. per-table allowlist) is a single edit.

Note: _table_catalog lives in the persistent attachment, not the ephemeral primary, so it doesn’t show up in describe_tables even without the filter — describe_tables only enumerates the primary.