I'm having a slight dispute with a friend who proofreads my paper on the correct tense in this sentence:
One of the key requirements for the web app was that it must automatically work with any new lexicons that might be added later.
As the main clause is in past tense, do I have to change the present tense of "must" to something else? And how?
To clarify, the requirements were written down before the app development begun (which is in the past). And the lexicons might be added after development is finished (which is in the future).