A message whose ciphertext exceeds one 512-byte memo is now split across up to
kHushChatMaxMessageParts (16) payload outputs in a SINGLE transaction, lifting
the ~239-byte cap to a few KB while staying atomic, instant (0-conf), and
one-fee. The crypto is untouched (one secretstream push/pull); chunking is a
transport concern:
- Header gains an optional part count `n` (emitted only when >1, so a 1-part
message stays byte-identical on the wire); bounded in the parser.
- Each chunk is a 2-hex part-index prefix + its ciphertext slice, so the
receiver reorders them after the daemon's output shuffle.
- OutgoingChatMemos carries a payload vector; chatSendOutputs emits header + N
payloads (both broadcast call sites already iterate the result).
- The grouper gains a multi-part pre-scan: a lone Message header with n>1 →
collect the N indexed chunks, sort, strip, concat → one pair; anything else
falls through to the classic single-pair path (older clients mis-pair and
drop — graceful). A body beyond the cap is refused as TooLong (tier 3 later).
Round-trip (shuffled outputs), 1-part byte-identical, and cap all unit-tested.
Larger-messages tier 2; tier 3 (multi-tx) + the denser raw-memo encoding remain.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
DanSandClaude Opus 4.8
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