What happens when a connection drops
Two very different things can disconnect, and they have very different consequences. Your own device dropping costs you nothing. A broker session dropping is the case every copier has to be honest about — here is exactly what MirrorFill does before, during, and after.
Your laptop or internet drops: nothing happens
The engine runs server-side. Your browser is a window onto it, not the thing doing the copying. Close the tab, lose your Wi-Fi, shut the laptop — copying continues untouched. When you sign back in, the Trade Desk shows you what happened while you were away.
A broker session drops: the recovery sequence
- Auto-reconnect with backoff. The engine notices the drop and retries, spacing attempts out so it does not hammer a gateway that is already struggling. The topbar pill shows Reconnecting, and the alerts bell records the event — the strip's status line reads "Connection lost — retrying. Positions are untouched."
- Re-read positions from the broker. On reconnect, the engine re-reads every account's live position from the broker rather than trusting what it last saw. While you were down, a resting order may have filled; asking the broker is the only honest source.
- Resubscribe and reconcile. It resubscribes to fills, then compares what each follower holds against what it should hold and corrects the difference. See how drift gets fixed.
No double-sends on the way back: the engine acts on each fill id exactly once, so replayed events after a reconnect cannot duplicate an order.
The honest limit
No copier can place orders while a broker session is down. Not this one, not any other. If the leader fills during the outage, the follower cannot mirror it until the session is back. What a copier can control is the recovery: notice fast, retry sensibly, rebuild from the broker's book instead of a stale guess, and correct the gap the moment it can. That is the part MirrorFill engineers for.
Your open positions are unaffected by the outage itself — they live at the broker, not in the copier. A disconnect never closes anything.
Quick answers
My browser crashed mid-trade. Did copying stop?
No. The engine runs on the server, not in your browser. Sign back in and check the Trade Desk — everything kept running.
Does a broker disconnect close my positions?
No. Positions live at the broker and stay exactly as the broker holds them. The copier reconnects, re-reads them, and reconciles.
What if the leader filled while a follower's session was down?
The mirror could not be placed during the outage. After reconnect, reconciliation sees the follower is behind and corrects the difference — visibly, in Order history.