One payment crosses a sharded world.

Two chains, one itinerary

The payment states its business

Before Ada's wallet submits anything, it writes the itinerary into the transaction itself: a declaration of every account the payment touches — Ada's, on shard 01; Bo's, on shard 10. Nothing is discovered en route. The declaration is what routes the payment to exactly the shards that own its state, what bounds what it will be allowed to write, and what lets shards reason about conflicts without running anything (the generals explains why this one honesty requirement powers the whole trip).

No two guests reach for the same fork

Both shards admit the payment to their waiting rooms — its signature checked once per machine, however many validators that machine hosts. Then it waits at the gate until none of its declared accounts is in use: the mempool never lets two transactions that touch any common account be in flight at once. That standing rule is why the deadlocks that haunt every lock-based system simply cannot form here. The moment Ada's account frees, the payment becomes eligible — on both shards, under the same hash-ordered rule, so every validator agrees on who's next without discussing it.

Two committees write it into history

On each shard, the proposer of the moment includes the payment in a block, and the committee votes. Who is that committee? Whoever the schedule says governs this shard at this attested moment — a committee staffed by lottery and never sitting still. Each validator votes only while holding the block's complete contents, so the resulting certificate doubles as a custody receipt for every byte (the archive) — and it stamps the block with the voted clock. Locks engage on Ada's and Bo's accounts. Note what was not decided: whether the payment succeeds. Ordering is the only thing consensus ever settles here — and thanks to the overlap, it settles it exactly once per shard.

Facts ford the gap between chains

Now the shards must show each other their halves, and the system's name for this is provisioning. Shard 01 ships Bo's chain a provision: the exact pieces of Ada-side state the payment needs, carried under a merkle proof against shard 01's quorum-certified block — and shard 10 ships its half back the same way. A provision isn't a message to be believed; it's a checkable fact about a committed block: the receiving shard verifies it against the sender's certified header and trusts no individual machine at all (the generals).

Two details make this stage sturdier than it looks. The payment doesn't wait alone: each block's commit composes a tick — one batch — from everything that can run at it, and the payment joins the first tick composed after every provision it depends on has arrived and verified, while the cells it declared stay spoken for across the whole crossing, so nothing else can read them mid-flight. And absence is covered: the headers pre-announced these shipments, so if gossip drops one, the destination knows something is missing and fetches it from the committee obligated to serve it (the archive) — over traffic classes that bulk noise can't starve. If the provisions still can't be assembled, the payment doesn't hang forever — that's the deadline detour below.

Nobody asks. Everybody knows.

With every provision verified, both shards hold byte-identical inputs: the same declared accounts, the same proven balances, the same merged view. Each runs the same deterministic engine — and determinism does what no amount of messaging could: both compute the identical result, down to the receipt hashes, without exchanging another word. This is the sunrise moment from the generals: the outcome now simply exists, everywhere at once, because it was computed, not negotiated.

Two signatures on one truth

Each shard's validators sign a certificate attesting the result they computed, outcome by outcome. The finalization rule is asymmetric on purpose: success requires a success from every participating shard; an abort from any one is terminal for all. The certificates cross, each side assembles the matched pair, the finalized result rides into a subsequent block, and the locks release. Ada's payment is now final on both chains — the same result, with full BFT finality, no reconciliation phase, no "pending" limbo, no rollback window.

Every detour is signposted

The happy path is the short story. The system's real character shows in the detours — each of which ends in the same place: one identical verdict on every shard.

And an abort, when one happens, is not a half-state: it's a first-class terminal outcome sealed inside the certificates with the same finality as success. Ada's money is back, on every chain's account of events, everywhere.

What Ada saw

One signature. A short wait. One result. She never saw the two committees, the proofs fording the gap, the identical computation running twice, or the certificates matching outcome vectors — and she never saw the timetable resolving who was in charge, the lottery that staffed them, or the archive obligations underwriting every fetch. The entire apparatus exists so that a sharded world feels like one machine.