Three rules. Back up every existing file before touching it, timestamped, no exceptions. Run it twice. Nothing compounds. And the uninstall path lives beside the install. Documented, tested, not buried in a footnote nobody reads until it's already too late.
The minimum viable floor I'd actually ship: two hooks. One that blocks secrets from reaching a commit. One that blocks bypassing that check. Those two catch the failures that actually cost you.
Package the whole thing as a tarball. What you see is what installs. Honest handoff.
Whether this is the right shape for every situation, I'm less sure. But it's the one I wasn't nervous to hand over.