Don't put the onus (Opus!) on me! Just a dad approach to helping. If there's enough time to writ prose about the problem you could at least rtfm first!
> allow zoned access enforcement within files. I want to be able to say "this section of the file is for testing", delineated by comments, and forbid Claude from editing it without permission.
I think you missed a critical step: 1.5: know that "allowed tools" is the correct incantation required to summon the relevant documentation; which, at least to me, is not obvious at all in the context of the OP.
(I couldn't find that documentation when I went looking just now.)