Tempo activates T13 with a proof fallback for private Zones

Tempo’s T13 upgrade reached its scheduled mainnet activation at 3 p.m. UTC on November 3, extending the payments-focused network’s private Zones system with an attested execution prover and adding Open USD as a fallback token for transaction fees.

The activation matters because it changes how a Zone can demonstrate that its private ledger followed its execution rules before a batch settles to Tempo. It does not, however, make every Zone batch proof-backed. Tempo’s own specification retains a temporary path that permits settlement on sequencer signatures without a proof.

Coinburn is publishing this report on November 4, after the scheduled fork. Tempo’s official explorer displayed freshly produced mainnet blocks during Coinburn’s check that day. That establishes continued block production after the activation window; it does not independently show validator adoption, prove that any Zone used the new prover or measure upgrade downtime.

What T13 changed

The v1.17.0 release includes four improvement proposals. TIP-1098 lets Tempo verify an attestation produced after Zone transactions are replayed inside an AWS Nitro enclave. The companion Zones v0.4.0 release embeds the expected platform measurements, known as PCRs, so a sequencer can check the approved prover build without supplying a separate policy.

TIP-1096 allows a Zone recovering from downtime to import multiple Tempo blocks while bounding each batch’s execution workload. TIP-1119 makes Tempo-specific block system calls explicit, an attempt to prevent upstream Ethereum changes from silently altering Tempo block validity.

The user-facing change is TIP-1115. When a transaction does not specify a fee token, has no stored preference and yields no token through inference, the protocol now tries pathUSD first and OUSD second. OUSD is only selected if pathUSD cannot cover the maximum fee, and one token must fund the entire charge. Explicit token choices and existing preferences retain priority.

That ordering is operationally important for wallets and applications. The release tells integrators that previously assumed pathUSD to accept OUSD-only users and to read the actual token from the receipt’s `feeToken` field. T13 does not make fees free, split one fee across two stablecoins or turn every supported stablecoin into gas.

The prover has a deliberate escape hatch

Tempo describes the new prover as replaying private Zone execution and providing an attestation that the base network can check before settlement. That is a stronger verification route than relying only on the Zone operator’s account of its state.

The rollout is not proof-only. The mainnet release explicitly preserves a temporary `NoProof` fallback based on sequencer signatures. The Zones software also favors liveness when proof generation struggles: if collecting a block witness fails or exceeds 500 milliseconds, block production continues and the batch can settle without a proof.

That tradeoff prevents a slow prover from stopping a Zone, but it also limits what observers can infer from settlement alone. A settled batch is not necessarily evidence that the new prover checked its execution. The public release supplies no count of proof-backed batches, no percentage using the fallback and no production latency or failure-rate data.

What remains to verify

The release records establish the activation schedule and software behavior, while the official explorer establishes post-window block production. They do not establish how many validators upgraded, whether all operators remained synchronized or whether the change improved throughput, cost or reliability.

The next meaningful evidence would be attributable mainnet records separating attested and `NoProof` settlements, operator-adoption data and an explicit retirement plan for the signature-only fallback. Until then, T13 should be read as a new verification capability with a stated liveness exception, not as proof that Tempo Zones have eliminated operator trust.