Legally, the exchange insures the bid and bot

The human trader wants to pass power of attorney to a known, secure bot with signatures to execute a known, secure bid.

The exchange can settle the agreement in a separate processor, then keep ts entire bid aparatas enclosed in a black box.  The executing document is the structured bid queue, both the human and the exchange see that same immutable agreement, then it is passed to black box.

Here is where I like secure python, the agreement can be encoded into a known python code, testable apriori.  Data can actually be passed without human observability with a good kernel interface.