It could sound trivial, but a simple note feature can become a powerful tool to combat hindsight bias. The Notes feature allows you to attach a note to anything: a stock (click on the three bars, then on "Add Note"), your account (click on the tab entitled "Notes"), or a strategy in the Research section (click on the gear, then on "About," and then "Add Note"). All the annotations that you ever made are shown in the general notes page where you will be able to edit and search them. You can access the general notes page by clicking the squares icon:
Stock notes are different from the others in the sense that they are "global." No matter where on the site you added a note about a stock, it will be visible whenever the stock is shown. Stock notes are also visible on stock charts.