Paul HittandClaude Opus 5
b1ba9cdc58
The engine can hold a conversation but had no way to reach a relay. This is that: the §8 routes, both authentication modes, and the transparency log. 13 tests against a real HTTP server rather than a hand-written fake. That distinction is the point -- a fake written alongside the client agrees with it about everything including the field name it got wrong, which is exactly how this protocol's one shipped bug survived until a live round trip. Two more tests run against the deployed relay, opt-in via FN_LIVE_RELAY and silent when unset. A test that reaches the network cannot sit in a hermetic suite; it fails on an aeroplane and a suite that is red for unrelated reasons stops being read. What they check is the thing MockWebServer structurally cannot: that the URL this client builds is one relay.flamenet.io actually serves. It does, on both mounts, and the Kotlin engine verified an inclusion proof from the production log against a head fetched separately -- not against the root the proof response carried, because a server that supplies both halves of a comparison has proven nothing. Details that are load-bearing: The per-request signature covers the LOGICAL section-8 path, not the URL's. The relay mounts these routes twice and signs against the former, so signing the REST-prefixed path yields a valid signature over the wrong string and a refusal with no hint as to why. Tested by asserting the other one does NOT verify. The nonce is not decoration. Two inbox polls in the same second with the same empty body would otherwise produce identical signatures, and the relay's replay cache cannot tell an honest repeat from a captured one -- so it refuses the honest client and the app quietly stops receiving mail. Token minting is lazy, and a deployment with no token route is asked exactly once. Laziness cost an hour here: the tests hung, because takeRequest() blocks forever and I was waiting for a mint that had not happened yet. They now use a bounded read, so that mistake fails instead of looking like a hung build. Application passwords are stripped of spaces. The account service prints them in readable groups and users paste what they were shown; sending the spaces is a 401 nobody can diagnose, because the password on screen looks right. Kotlin nests block comments, so `/e2e/` followed by a star inside a doc comment opens one that never closes and the compiler blames the last line of the file. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Flamenet Messenger — Android
Nothing here is an app yet. This is the engine, and it is deliberately first.
An Android client needs the protocol implemented a third time. That third
implementation is the one that finds the places where the specification says
less than the two existing engines quietly agreed on — but only if it is
written against the spec and the published vectors rather than against a
reading of our own Swift and JavaScript. So the engine comes first, it is a
plain Kotlin/JVM library with no Android in it at all, and it is held to
engine/test/vectors/protocol-v1.json — the same file the other two engines
are checked against, read from that one location rather than copied here.
./gradlew :engine:test
No Android SDK, no emulator, no device. It runs anywhere a JVM does, which is also what lets it run in CI on Linux.
What the engine covers today
| Area | Spec | State |
|---|---|---|
| Safety numbers | §7 | Done — fingerprints and conversation ordering match the published vectors |
| Key transparency verification | §19 | Done — RFC 6962 leaf/node hashing, unbalanced split, bottom-up audit paths |
| Byte helpers | — | Unsigned comparison, constant-time equality |
What it does not cover
Listed rather than left to be discovered, because a table of green ticks with the hard parts quietly missing is worse than no table:
| Area | Spec | State |
|---|---|---|
| X25519 / Ed25519 | §3 | Not started — needs a provider that works on both JVM and Android |
| X3DH key agreement | §4 | Not started |
| Double Ratchet | §6 | Not started |
| Sealed sender | §12 | Not started |
| ML-KEM-768 hybrid | §11 | Not started |
| ML-DSA-65 identities | §20 | Not started |
| Relay client | §8 | Not started |
| The app itself | — | Not started |
Until those exist, Android is honestly marked "not started" on the website, and a conversation gets the protocol's guarantees only when both ends are iOS.
Why the vectors matter more than the code
Two implementations that agree may both be wrong in the same way, especially when one was written while reading the other. The audit-path ordering in §19 is the worked example: a top-down reading of a bottom-up path produces the correct root for every left-spine index, so it passes any test that only checks index 0. The vector file pins a right-descending index for that reason, and the Kotlin tests assert both that the published path verifies and that the same path reversed does not.
If this engine ever disagrees with the file, the interesting question is which of the three is wrong — not this one by default.