Paul HittandClaude Opus 5
e62317b6f3
Two :interop:peer accounts against relay1, both running the retired-session fix.
Neither polls before sending, which is the simultaneous-initiation case:
p1 send / p2 send -> delivered:1, failed:0 (each on its own chain)
p1 poll / p2 poll -> both first messages arrive
p1 send / p2 send -> delivered:1, failed:0
p1 poll / p2 poll -> {"messages":[]} / {"messages":[]}
The second exchange is lost in both directions, silently, with the relay
reporting success. Same failure as the two-simulator run with every iOS variable
removed, and it reproduces in about two minutes instead of forty.
So retaining the retired session is necessary and not sufficient. The receive
side can now open the old chain; the loop still does not close. The remaining
gap looks to be on the send side — after adopting the peer's chain each client
encrypts on the adopted one while the peer still reads the one it kept, so
neither is listening where the other is talking. Resolving this properly means
both sides converging on the SAME chain by a deterministic tie-break, not each
adopting the other's.
Recorded so the earlier commit is not read as having closed it.
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.