6. Trustlines without changeTrust (CAP-0073)

Since protocol 26, contracts can create trustlines and accounts. No classic operation is involved.

Since protocol 26, the Stellar Asset Contract’s trust(address) function creates a trustline for a G… account through invokeHostFunction. There is no changeTrust operation, and trust emits no event.

The rule

Index trustlines from ledger entry changes, not from operation types. The only record of a SAC-created trustline is the CREATED trustline entry in the operation’s changes, with a limit of i64::MAX (9223372036854775807).

The same CAP lets native XLM transfers through the SAC create accounts. Watch for account CREATED entries from contract invocations too.

What goes wrong

An indexer that recognises trustlines by operation type never sees it. The naive replay indexer drops both SAC trustline fixtures. A dropped record is the worst failure mode: nothing downstream knows anything is missing, and the holder’s balance in that asset appears from nowhere later.

Note the limit, too: i64::MAX is above 2^53, so it’s another integer to keep exact.

Fixtures: cap73-sac-trust-testnet-0001 and …-local-0001.