On Solana, a sponsored send lets the user pay the fee in an SPL token instead of native SOL. You
bring your own Kora endpoint. For the model, see Sponsorship.
Set a single koraUrl on the client config. Kora is both the fee payer and the submitter, so this
one endpoint is the Solana analogue of bundlerUrl and paymasterUrl together.
Without koraUrl, Solana sends fall back to self-pay.
Pass the fee token per send
A fee token is a per-send choice, expressed as the SPL mint address. Supply it when you build the
send; omit it, and the send is self-pay. When Kora is configured and the mint is supported, the fee
is charged in that token and native SOL is untouched.
Solana has no requireSponsorship equivalent. A sponsored request that cannot reach Kora degrades
silently to self-pay. If your product promises fee-in-token on Solana, verify receipt.rail
after each send rather than relying on configuration.
Confirm which rail ran
A sponsored Solana receipt has rail: "sponsored", a real signature, and status: "pending"
until the network confirms it. A self-pay receipt has status: "submitted". Neither means
confirmed. See Receipts.
If Kora refuses the transaction, the send throws KoraRejectedError, naming the reason and code.
See Errors. 