Two corrections to my own framing, both measured:

(1) Option (b) is NOT a values-file edit. 'prefer-ipv6: true' is INJECTED
UNCONDITIONALLY by scripts/render-dc-overlays.py:243-246 whenever fam ==
"dual", and 'family: dual' is a single TOP-LEVEL key in
render/values/vr1-dc{0,1}-vips.yaml:3 -- not per-app data. Implementing (b)
means teaching the renderer which charms declare the option, re-pointing
tests/render-drift, and replacing invariant 9: a code change with a harness.
Recorded before the fork is put to the operator so the ruling is taken on the
real cost.

(2) The option-name sweep's claim is scoped inline. It checked NAMES, dc0
only. Option VALUE TYPES (the 'type:' field in every schema already
downloaded) and the dc1 input are both owed before the redeploy, and each
could cost an attempt the same way.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HvCyrwvYTTcDYnRErfMsNf