Happy Path Trading
The "happy path" is done (has been for a while actually). You can buy/sell portfolios of contracts. You can buy/sell individual contracts as long as the number you want to buy/sell matches perfectly with someone else. This is pretty exciting to me. I've even got some validation at order entry and trade execution to make sure things "good."
Some Oddball Paths
Partial match (and vice versa):
1. Order placed for 100 items
2. Match placed for 50 items
3. Match satisfies the first 50 and is executed/closed