Practice bidding against three BBA bots

Sit South at a table with three EPBot/BBA partners. Pick a topic from David Bailey's practice scenario library — Stayman, Jacoby transfers, splinters, weak twos, Smolen, and a hundred more. Bid through real deals; the bots respond with whatever the convention card says they should bid, and you get instant feedback when your bid differs.

One human, three BBA bots

You sit South. North, East, and West are driven by EPBot using a 21GF convention card. The auction runs the way real-life partners and opponents would bid it.

Live convention checking

Every time it's your turn to bid, your call is compared against what the BBA expected. Match it and the auction continues; differ and you see what was expected.

Hundreds of curated scenarios

The same scenario tree the BBO browser extension uses — Notrump Sequences, Major Suit Sequences, Preempts, Competitive Bidding — with 500 pre-generated deals per topic.

Stateless & offline-friendly

State lives in your browser. Each deal makes one stateless call to the BBA service for the auction; nothing is stored server-side. Designed to extend to two-person play later.

Typical session

Pick a topic from the menu (e.g. "Stayman" under Notrump Sequences).

A random deal is drawn. The bots open and respond at their seats; you see the auction unfold.

When it's your turn, the bidding box appears. Bid; get feedback against what the BBA expected.

Auction completes — see contract, declarer, and which of your bids differed. Hit "Next deal" for another.

Open Bidding Practice

Sister services it talks to

• BBA bidding service (bba.harmonicsystems.com) — runs EPBot to compute the auction. Sister repo: BBA-CLI/bba-server.

• Practice Bidding Scenarios (raw GitHub) — David Bailey's button layout file and 500-deal-per-scenario PBN files. Sister repo: Practice-Bidding-Scenarios.

• Future: Bridge Dealer Service for fresh per-session deals instead of pre-generated. Sister repo: Bridge-Dealer-Service.

Prototype caveats

• The BBA service must include this site's origin in its CORS allow-list. Add https://bridge-classroom.com to the AllowBBO policy in BBA-CLI/bba-server/Program.cs.

• Some scenarios in the menu rely on conventions that BBA doesn't model. Those will surface as a BBA error on the first deal — pick a different scenario.

• The full auction is generated up front per deal; if you bid differently than expected, the auction continues using BBA's choice (so you can still see the rest).