Second half of tier-3 larger messages: the receive side. ChatService now buffers
the slices of a multi-transaction message (keyed by the shared message id) as
they arrive — across transactions and across scans — and reassembles the whole
ciphertext once every chunk is present, then decrypts and surfaces it as one
message. The buffer is NOT persisted: a rescan re-sends every slice, so it
re-derives from chain exactly like the control reducer, and survives a restart
mid-receive (the next full scan re-feeds the siblings and completes it).
Ingest's per-message build/decrypt/guard logic is refactored into one shared
lambda so a reassembled tier-3 message passes the identical block / on-chain-hide
/ sensitive-vault / tombstone checks as a single-tx message. A completed group is
retired after it surfaces (deduped across scans by its stable canonical txid —
the smallest sibling txid); a group withheld only because the sensitive vault is
locked is kept so a later unlock + scan completes it. Our own slices (sender ==
us) are skipped — the local echo records the outgoing message. The pending map is
bounded (256 groups) against a flood of never-completing partials.
Unit-tested (testHushChatTier3Reassembly): a ~9000-char message's first slice
alone surfaces nothing; once every slice has arrived it reassembles, decrypts to
the original and surfaces once; a re-scan dedups; our own slices never ingest.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
DanSandClaude Opus 4.8
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