Paper versus live
Both environments run the same strategy code on live exchange prints. What differs is who fills the order and where the money number comes from, and the app keeps the two apart on purpose rather than by convention.
What is the same
- The strategy. A paper instance and a live instance run the same strategy version you picked, compiled from the same source.
- The events. Paper receives the venue's public trade prints and turns each print into the same record the archive ingest produces, so it drives the same code path as a backtest replay. Duplicate trade ids are dropped, and the clock never runs backwards.
- The bar close. A bar closes at its boundary with a bar-closed call held back until the first real print of the next bar, so a strategy sees the same close a backtest gives it. An idle market produces no invented bars.
- The protection. Stops, take-profit rungs and the bracket rules are the same code, see Stops, take-profit and brackets.
Who fills the order
On paper a fill is simulated with the fill model you set in Paper, Settings: slippage, fees, latency, the limit fill rule, queue lots and the impact model. That model applies to running and new instances alike, so a paper fleet stays comparable with itself.
On live the fill is the exchange's. The live environment therefore offers no slippage, fee, latency or queue settings, and a saved paper fill setting is never applied to a live instance. What the venue did is what you get.
Where the balance comes from
A live account never carries a balance in this system. The exchange's wallet is authoritative: it is read when the account is created, fetched again at every instance sizing, and re-derived daily. A balance sent with a live account is ignored rather than stored. A paper account has its own balance that you set, and that is what a paper result is measured against.
Separation you cannot cross by accident
- An instance cannot name the other environment's account, and a member cannot be moved into one. The attempt is refused, and the dialogs only list the current environment's accounts.
- Paper and live keep separate per-strategy defaults, so editing one never changes the other.
- The live dashboard rolls up live accounts only and paper shows paper, so a number on screen always says which environment it came from.
Before your first live start
The app shows the terms and, before a live start, the live trading notice: start on the exchange's demo account, the system is built safety first but cannot be guaranteed, you are responsible for what your strategy does and for whether you may trade derivatives where you live. Until the current notice is accepted the server refuses a live start, with the reason live_notice_required. Paper trading is not gated, and a stop, a close, a flatten, the kill switch and reading results are never blocked.
Where live is stricter
- An entry that does not fit the free margin is skipped and said to be skipped. Paper sizes against its own balance, so the same trade may fit there and not on a live account.
- The exchange is the truth for a position. While the engine still holds a live position, an empty position book may be a stale copy of the venue, so a close is not reported as flat until the venue confirms it.
- The kill switch acts on live and demo instances only, never on paper, see Operator stop and kill switch.
What paper cannot prove
Paper sizes, fills and reports on real prints, which makes it the honest place to watch a strategy you are unsure about. It does not prove live execution: the fill is still simulated, the queue at a level is an assumption, and funding payments are not charged. Treat a paper result as evidence about the strategy's logic and not as a promise about the exchange, see Fills and slippage and Costs and fees.