Reconciliation: how drift gets fixed
Most copiers fail quietly: a fill gets missed, an order gets rejected, and a follower drifts a contract away from its leader with nothing to catch it. MirrorFill's engine checks its own work. A background pass compares what each follower actually holds (the broker's book) against what it should hold (the leader's net position through that follower's rules), and orders only the difference.
Delta corrections, never fresh positions
Every correction is the exact gap between the two books. Should hold +3, actually holds +2? The engine orders 1, not 3. That is why duplicate events, partial fills, and reversals converge instead of stacking: repeating a reconcile can only close the gap, never overshoot it. Each fill id is acted on once, so replayed events cannot double an order.
When it runs, and what it skips on purpose
Reconciliation runs continuously in the background, but it only acts in a quiet window: a stretch with no fresh fills. Mid-burst, the books are legitimately in motion, and "correcting" a position that is still filling would order against your own trade.
It also deliberately skips three things:
- Accounts with an order still resting. If a mirror is working at the exchange, the gap is not drift: it is an order that has not filled yet. Correcting it at market while the original order still works would chase the same fill twice. The engine waits for the order to fill, or for order expiry to resolve it.
- Locked accounts. A risk lock means "stop copying, keep what it holds". Reconciliation honors that.
- Paused rules. A follower you switched Off with the Follow switch is remembered configuration, not a working account. Nothing touches it until you switch it back on.
Seeing it on the Trade Desk
A follower whose books agree with its target looks ordinary on the Trade Desk, and its card reads Mirrored. An amber row with a DRIFT tag (its card reads Catching up) means reconciliation has work to do on that row: an order is pending, a gap is being corrected, or the account is waiting for its quiet window. A folded group shows the DRIFT tag on its strip too. A DRIFT tag that stays with no progress is worth a look: start with follower position doesn't match the leader.
Quick answers
Could reconciliation double my position?
No. Corrections are the delta between actual and intended, and each fill id is acted on once. Re-running it converges on the right position; it cannot overshoot.
Why isn't it fixing my locked account?
By design. A lock means the account stops copying and keeps what it holds. Unlock it and the next pass re-aligns it.
What does an amber row with a DRIFT tag mean?
That follower's book does not match its target yet: an order is working or a correction is queued. The tag clears, and the card reads Mirrored again, when the books agree.