GA-R5: question and exact utterance quoted, dated, pushed before dependent work.
Operator utterance: "Extend the existing o-hm0 verifier to compare MTUs
(Recommended)".

Recorded as a SUB-RULING on the D-101 MTU ruling note rather than a new decision.
OPS under GA-R3 -- it is a script change, doubt resolves DOWN, so no D-number is
assigned. It discharges the LP #2018998 obligation that R8 carried forward.

MEASURED BEFORE PRESENTING, and it changed the option set. "Pre-emptive
configuration" was not actually available: the octavia charm exposes NO MTU
option, so nothing can be set in the bundle. The real choice was only how the
mismatch gets DISCOVERED.

The measurement also found a better option than either I had sketched:
scripts/phase-05-octavia-verify.sh:104 ALREADY inspects o-hm0, asserting
state != DOWN and the presence of an fc00::/ ULA. So it holds the handle already
and an MTU comparison is a natural extension rather than new machinery. Against
that, grep -i mtu across cloud-assert.sh, phase-05-octavia-verify.sh and
phase-04-network-verify.sh returns NOTHING -- MTU is asserted nowhere in any
post-deploy verifier, which is why this class would have surfaced as instability
rather than as a failed gate.

Rely-on-the-charm was refused: the 2025-12-31 recurrence against octavia 14.0.0 /
2024.1 stable is evidence the update-status self-heal is not reliable, and the
symptom -- spurious failovers under load -- reads as a Ceph, network or amphora
fault long before anyone suspects MTU. The unconditional ovs-vsctl mtu_request
workaround was refused: it fights the charm's own fix where that fix is working,
and would MASK a future regression instead of surfacing it. It stays available
as the remedy IF the check fires.

INCIDENTAL CORROBORATION OF R8, from this repo's own tooling: that o-hm0 verifier
is VR0-era and expects an fc00::/ ULA, which independently confirms the octavia
charm's default lb-mgmt-subnet is an IPv6 ULA. The as-built already assumed what
R8 ruled -- a second, internal line of evidence for a ruling whose external
evidence had to be rebuilt from scratch.

Delivery when executed: the assertion ships with its harness green, gauntlet ALL
GREEN, repo-lint 0-fail and a changelog entry carrying a revert.

Revert: git revert this commit; the sub-ruling is additive.

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