According to http://www.nytimes.com/2015/04/17/business/obama-trade-legis... an agreement has been reached between the administration and Congress which requires, among other things, that,

The bill would make any final trade agreement open to public comment for 60 days before the president signs it, and up to four months before Congress votes. If the agreement, negotiated by the United States trade representative, fails to meet the objectives laid out by Congress — on labor, environmental and human rights standards — a 60-vote majority in the Senate could shut off “fast-track” trade rules and open the deal to amendment.

Of course Congress and the administration do not have a history of being particularly responsive to the public. But it does seem that everyone will be able to know what was agreed on before it is signed into law.