The swap form's four questions were split across two services: the indexer
answered what can be traded and what it pays, while a TypeScript service
answered what to approve and what to sign. The last two need the route the
first two produced, so the split meant a quote crossed a process boundary to
be turned into calldata.
HandleSwap encodes the router call from a quote and bounds it by the caller's
slippage. It reads no state — the quote already carries the route, the amounts
and each hop's fee, and re-reading here would be a second opinion about a price
the caller has already accepted, a block later than the one they saw.
HandleCheckApproval reads the allowance the router holds and returns the grant
when it falls short. Silence from a token is not an allowance of zero, and an
unreachable node is not either; both would skip an approval and leave the swap
to revert.
The conversation with a chain moves to one type. It was a method on the quoter,
which left the approval endpoint either reaching through a quoter to ask an
unrelated question or growing a second copy of the batching, timeout and decode.
Calldata is asserted against bytes recorded from the service being retired,
across exact-input, exact-output, single-hop and multi-hop. A wallet signs
these, so a byte is the unit of correctness.
Co-authored-by: Hanzo Dev <[email protected]>
