What constitutes 'prior disclosure'?

Prior disclosure can differ between jurisdictions. However, it typically refers to public disclosure of your invention including published documents, non-confidential discussions, conference presentations and public use of your invention. Again, the level of disclosure may differ from jurisdictions but typically, a non-confidential disclosure which allows a person to understand what your invention does and how your invention does it, would constitute prior disclosure. Accordingly, discussions with other people, including family and friends, for example, troubleshooting and improving your invention are likely to fall within the scope of prior disclosure, unless an arrangement is put in place, for example, using a non-disclosure agreement to ensure that these discussions remain confidential.

While the the non-disclosure agreement should be in place before you have these discussions, I would still make sure you have recorded all of your ideas, concepts and innovations the equivalent of a laboratory notebook, basically a bound journal with numbered pages. You should sign and date each page, and have it witnessed by someone like a spouse that you have a confidential relationship with, or has singed your NDA for this purpose. If someone does try to exploit what was disclosed in confidence, this journal will be your proof that the obtained the idea from you. You should also note all such disclosures and conversations in the same journal.