Start a paper session

Paper trading in Arvo is a broker's paper account — Alpaca's — with a real API, real fills and latency and simulated money. It is not a rehearsal; it is the measurement a backtest cannot make: what a fill actually costs against the price the decision was made at.

1. Connect Alpaca with paper keys (Accounts).
2. Have a finding on an instrument the executor trades — for Alpaca, an Alpaca-venue instrument (AAPL.AIEX).
3. Sessions tab → choose the finding → executor alpaca-paper → Start. Or: arvo-engine session start <finding> alpaca-paper.
4. Watch the row: state, signals, submitted, refused, fills, last bar. The record below it shows every event as it happens.

What to expect:

• A daily rule hears "nothing new" most polls; its signal fires overnight and fills at the open.
• A 5-minute rule on Alpaca streams: each bar arrives a moment after it closes and the rule acts on it at once.
• The first bars after a start are the catch-up from the library to now.
• If the paper account already holds positions when the session starts, it adopts them and comes up halted until you release it — a session should not start believing it is flat when it is not.

Stopping leaves positions as they are. Halting flattens them.

Paper is also the road to real money: a live executor refuses a finding without a Supported verdict and five days on paper that did not diverge from it. The promotion gate →