Like others have said, this is indeed how Novelcrafter already works. While the "series" tab in your home screen does not show a tab for the "codex" (still working on that), it is totally independent of a novel, and doesn't even need a novel to work at all.

That said, once a novel gets added to a series, it always has access to all entries. Hence, I'll rename the post to "selectively include series codex entries in novels" to make the intent more clear.

Isn’t this implied in the way Codex works? The entries are only used if they are referenced in the prompt or the context, or so I thought (I am a noob).

Regarding the filter, I assumed it was for setting something, like a color or a term in the notes, to filter for specific groupings.

Am I missing something?

I am setting up a trilogy and facing this same issue over the series.

One issue I have found is when a character doesn’t exist until chapter two, but the AI constantly wants to place her in chapter one. I have identified and resolved several reasons this happens. My latest discovery was that the novel’s POV is hers, but she doesn’t exist in the prologue and chapter one. I forgot to change the POV for those sections, which obviously confused the AI. Simply changing the POV to the character in those two sections solved my problem.

I was just thinking how nice this would be.

Oooooh I like this. It's like a master codex.