The vast majority of the API is documented and the IDE has auto-complete for it. You can find the documentation in the API docs or by clicking the link in the footer of every page.
When we're rolling out a new feature, we often do a "quiet launch" where the code works, but isn't yet documented. We share with with a few alpha users and do further testing in our production environment. Then we do the doc-and-IDE update. However, that process is usually pretty fast - just a couple days. It's not often that we have undocumented features in production.
So, is there something in particular where we're missing the documentation?
The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.