Date: 2026-11-03. State: Accepted by answers Q4 and Q5; implementation pending.
Context#
The MVP covers Brazil and the US without real money. There is no proven B3 order integration or selected Brazilian broker.
Decision#
Use Alpaca Paper as the first US integration. B3 starts with backtest and an internal simulator; an external paper integration only after validating the broker's API/contract. Data adapter separate from the execution one. The IEX feed and B3 CSV import are Q8 proposals, not automatically accepted as part of this ADR.
Alternatives#
IBKR, requiring a B3 broker immediately, or supporting only the US. The first two were not chosen; the last conflicts with the two confirmed markets.
Consequences#
The dashboard distinguishes broker paper orders from internal simulated fills. These are separate accounts/ledgers. Without a data provider, the internal simulator does not receive real quotes by magic: history and real time need a defined source. Fill rules, costs and reviewed data must be included in each report.
Review trigger#
Verified B3 API, limitation of the Alpaca plan or request for another broker. Implement a new adapter with contracts; do not switch the paper URL to live.