@Former Member posted:
I wonder what David might think about it because it seems to me that both options are possible depending on the context.
I understood that by "both options" you mean that the sentence:
- I did what I could.
1. I did what I was capable of doing (could: general past ability)
2. I did what I managed to do (could: specific past ability, i.e., ability + performance)
My claim is that interpretation (2) is not possible because it would be redundant to say that you did (past performance) what you managed to do (past ability + past performance).