We were very careful that he didn’t find out.

[diamondcutter]

We were very careful that he didn’t find out.

This is a sample sentence from a dictionary. Sorry I forgot which dictionary.

I think this sentence means this.

We were so careful that he didn’t find out.

Or this.
He didn’t find out. We managed it because we were very careful.

Is my understanding correct?

 

[jutfrank]

It means: We made a special effort to make sure that he didn't find out, and we succeeded.