mvx_cross_contract_storage

Yes, you can retrieve token balances from another contract by directly accessing its storage using `storage_mapper_from_address`, provided both contracts are on the same shard and you know the exact storage key.

To retrieve a token's total supply from another same-shard contract in Rust, use `storage_mapper_from_address` to read the external contract's storage variable directly, matching the exact storage key where total supply is recorded.

Limitations of direct cross-contract storage reads include strict same-shard requirements, exact storage key matching, and the risk of silent failures from stale data or key changes, requiring careful validation of the retrieved results.

Use direct storage access instead of standard proxy calls when you need zero-gas overhead retrieval of variables like total supply or balances from same-shard contracts, and when you can guarantee exact storage key matching and result validation.

No, `storage_mapper_from_address` is designed exclusively for same-shard contracts. Cross-shard storage reads are not supported by this direct access method and would require traditional proxy calls instead.