False positives for Added/Changed on first system run about bevy

[SpecificProtagonist]

Yes: Because the system isn't active from the beginning. I do think this is useful behavior. But I can work around this by checking SystemChangeTick, and the current behavior is also useful and wouldn't have an easy workaround, so correcting the docs is the best thing to do here.

[alice-i-cecile]

Definitely a bug. I wonder if we should be storing an Option<NonZero<u64>> or the equivalent inside of our ticks to resolve cases like this correctly.

Although simply swapping to u64 ticks may be enough to fix this.

[SpecificProtagonist]

Although simply swapping to u64 ticks may be enough to fix this.

Hmm, how would that help here?

[alice-i-cecile]

Oh, I see the problem here. I think the docs are wrong. The actual behavior (and the one that will generally be desired) is "detect added/changed components exactly once". Is there are reason why you want to exclude entities that were added before the system was run?