mdk-vector-gen

Rust helper that emits MLS interop test vectors from the same openmls 0.8 backend MDK/whitenoise uses. Produces quartz/src/commonTest/resources/mls/mdk-welcome.json, which [MdkWelcomeInteropTest] consumes to prove Amethyst can parse and decrypt a Welcome + application messages authored by the Rust side.

What the vector contains

joiner.init_priv / encryption_priv / signature_priv / signature_pub — all the private key material the joiner needs to drive MlsGroup.processWelcome.
joiner.key_package (MlsMessage-wrapped) and key_package_raw.
welcome (MlsMessage-wrapped) — Alice's Welcome for Bob.
committer.signer_pub — Alice's Ed25519 signature public key.
exporter.{label,context,length,secret} — MLS-Exporter("marmot", "group-event", 32) derived from Bob's post-join state. This is the exporter Marmot uses to derive the outer ChaCha20 key for kind:445 events, so a match here means Amethyst's whole post-join key schedule agrees with openmls byte-for-byte.
app_messages_alice_to_bob[] — Alice-sent PrivateMessage bytes plus the expected plaintext. (Amethyst decrypt currently skips PrivateMessageContent framing; the matching test is @Ignored until that is fixed.)

Regenerating

cd quartz/tools/mdk-vector-gen
cargo run --release > ../../src/commonTest/resources/mls/mdk-welcome.json

The generator uses fresh randomness each run, so the committed vector changes on regeneration — that is fine because the Kotlin test only asserts round-trip correctness against whatever is in the JSON. Commit the regenerated file if you change the generator.