Once Per Bar vs Once Per Bar Close: which should I use for automation?

What this means in practice

Once Per Bar can react during a realtime bar; Once Per Bar Close waits for the closing update. Use confirmed-bar behavior when the strategy requires confirmation, and intrabar behavior only when the logic is deliberately designed and tested for realtime updates. This page is specifically about “Once Per Bar vs Once Per Bar Close: which should I use for automation?”, so each scenario below is explained by its own mechanism instead of sharing one generic diagnosis.

Real-world scenarios

Scenario A — Fast intrabar entry

Inspect the TradingView alert log during the still-open candle. Realtime recalculation can make the condition true several times; add explicit intrabar state or a per-bar guard if the strategy intends only one logical action. For Scenario A — Fast intrabar entry on question 27, use that evidence specifically to answer “Once Per Bar vs Once Per Bar Close: which should I use for automation?”; keep it separate from the evidence for the other scenarios on this page.

Scenario B — Confirmed candle-close system

Inspect the mechanism named by “Scenario B — Confirmed candle-close system” directly. Record its input, the state immediately before it and the first observable output that differs from the intended result. For Scenario B — Confirmed candle-close system on question 27, use that evidence specifically to answer “Once Per Bar vs Once Per Bar Close: which should I use for automation?”; keep it separate from the evidence for the other scenarios on this page.

Scenario C — Signal reverses before bar close

Resolve current cTrader exposure before acting. An opposite order can hedge, flatten or reverse depending on account model and state, so explicit OPEN, CLOSE and REVERSE semantics are safer than ambiguous BUY/SELL behavior. For Scenario C — Signal reverses before bar close on question 27, use that evidence specifically to answer “Once Per Bar vs Once Per Bar Close: which should I use for automation?”; keep it separate from the evidence for the other scenarios on this page.

What to check

• intended signal/action
• last stage that definitely succeeded
• first stage that differs from intent
• final cTrader state after the event

Practical rule

For “Once Per Bar vs Once Per Bar Close: which should I use for automation?”, change only the first layer whose evidence no longer matches the intended action. Preserve signal identity, timestamps and final cTrader state, and reproduce execution-affecting changes on demo before live use.