Reject non-32-byte spk, non-v3 onion, and invites over 4KiB before
hex alloc. Sign onionwire-invite-v1 with 0x00 separators; verify that
first. Well-formed v1 concat still verifies after field checks.
Wrap a random 32-byte message key with Argon2id+ChaCha20-Poly1305.
sqlite messages.plaintext is nonce||ciphertext; identity keys stay
plaintext. Empty/wrong passphrase fails closed. Ctrl-Q types CLEAR or
QUIT then Enter (Esc cancels).
