A phone reported "IPv6 is configured but not working" while loading an IPv6-only
site over TCP perfectly well. The finding fired on one signal - ICMPv6 echo
getting no reply - at HIGH confidence. ICMPv6 echo is widely filtered on
networks where IPv6 works, so the two cases are indistinguishable from where the
app stands, and it was picking one.
Same class of error as the multi-homed downstream-loss bug: a confident
measurement of something that was not happening. Now v6.no_icmp_reply, low
severity, medium confidence, naming both explanations. Still reported, because
filtered ICMPv6 breaks Path MTU Discovery - large packets vanish instead of
being reported as too big - which is a fault in its own right.
Corroborating with a real IPv6 connection would separate the two properly, but
needs a target, which runs into the hardcoded-deployment issue already open.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The registry was only used in core-engine. The app still emitted seven codes as
raw strings, so the registry test passed while codes lived outside it - among
them ipv6.broken, which fired on a real network and was in no registry at all.
All seven now take their code, category and severity from a registry entry, so
those three cannot disagree at a call site. Grepping for code = "..." across the
app, engine and probe modules now returns nothing.
ipv6.* -> v6.* is the third instance of the same rule being broken: they
declared Category.IPV6 while the prefix map only knows "v6", so
TestType.category("ipv6.broken") fell through to connectivity and the finding
rolled up under the wrong verdict light. The test-type registry already used v6.
Two severities reconciled rather than assumed:
connectivity.captive_portal is medium, not high. The registry had guessed
high; the probe emitting it had always said medium, and the probe was the
considered value - a captive portal on hotel wifi is what should be there.
no_internet keeps high, since nothing local fixes that.
v6.not_offered stays info, and the registry now says why it must. Most
networks still do not offer IPv6; a warning there lights a yellow verdict on a
healthy network and teaches people to ignore the light.
Plus a BackHandler: the screen was a plain state variable with nothing tying it
to the back stack, so Back left the app from Settings/History instead of
returning to the run screen.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
A finding code is the stable half of a result - what a dashboard groups by and
what someone greps a year of archived runs for. That only holds if a code means
exactly one thing forever, which fifteen ad-hoc string literals cannot promise.
By the time this was written the failure had happened twice:
- Two emitters independently produced connectivity.downstream_loss and
connectivity.loss_downstream for the same claim. Nothing objected. Anyone
aggregating either would have silently seen half their data.
- Two codes sat under nat.* while being declared Category.CONNECTIVITY.
nat.udp_unreachable is not about NAT, and the prefix decides the category,
which decides which verdict light the finding rolls up into. Renamed while
that is still cheap.
Codes are now typed FindingSpecs carrying category and default severity;
emitters reference the spec rather than retyping the string, so a typo is a
compile error and two call sites cannot disagree about a finding's category.
docs/findings-registry.md is the contract and a test reads it, failing when the
document and the code disagree on which codes exist or how severe they are.
Documentation that drifts from its implementation is worse than none, because it
still looks authoritative. The check reads table rows only, so the prose can go
on explaining which codes were retired and why.
Closes open item 1 of measurement-schema.md section 9.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
