Your Books Match Your Broker to the Share
Every sync now checks your books against your broker's own statement, unit by unit. When a trade you entered by hand is also in your broker's records, even split into partial fills or dated a day apart, you can keep the broker's version in one click.

Professionals reconcile every day: their own record against the one kept by whoever holds the assets. Any difference is either a mistake or something that has not settled yet, and either way someone looks. We think your own money deserves the same habit.
The check
Your broker's holdings statement is stored with each sync, and each portfolio's holdings are compared to it unit for unit, to the three decimals brokers use for fractional shares. The result sits on the sync receipt: a match, or the holdings that differ and by how much. A holding you recorded that the broker does not show yet is marked pending, not wrong.
Beside the units, the receipt now also shows any holding whose average cost differs from your broker's by more than 1%, where the units agree. A lot dated or priced differently usually explains it, and your lots show how we got ours.
Duplicates you can fix
The most common way books drift is simple: you record a trade by hand, and later your broker reports it too. We already matched those when the date and quantity were identical. Brokers are less tidy than that. An order for 100 shares can come back as fills of 60 and 40, and a trade entered on Friday can be dated Monday by the broker. Both used to slip through and count twice.
The matcher now tries the exact trade first, then the same trade one business day either side, then the fills of one day that add up to your trade at about the same average price. A likely duplicate shows your entry and every broker row it matched, says how it matched, and offers to keep the broker's version.
Keeping the broker's version does not delete anything. Your entry is reversed in the ledger with a matching record, so the trade counts once and the history shows both what you entered and why it no longer counts.