v6.no_icmp_reply infers trouble from silence, which is ambiguous by
construction: a firewall dropping echo requests looks the same as a
network that cannot carry IPv6 at all. Two much stronger signals were
already sitting unread in the link snapshot, and a test device on a
Netbird tunnel surfaced both at once.
v6.route_without_address — a ::/0 route with no global address. The
router advertises itself as an IPv6 gateway while SLAAC produces nothing
usable. Hosts believe IPv6 is available and pay a connection timeout on
every dual-stack destination before falling back, which is felt as
general slowness with no packet loss to explain it.
v6.no_default_route — the mirror: a global address with nothing to route
it. A VPN installing host routes to specific destinations produces this
deliberately and it works, so a VPN transport reports it as INFO rather
than as a fault; without one it means the network handed out an address
it does not carry traffic for.
Both are read from the routing table, so neither is inferred from
silence, and both are reported per interface — "IPv6 is broken" is
useless advice when wifi is the broken one and cellular is fine.
Classification lives in core-measurement rather than the ViewModel so it
can be tested without a device; the fixtures are a real dumpsys table
(wifi advertising a route it cannot source from, working cellular, a
tunnel with two host routes) because the risk here is not bad boolean
logic but imagining shapes real networks do not produce.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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>
