T4 Network Upgrade
This page summarizes T4 scope.
Timeline
| Network | Date | Timestamp |
|---|---|---|
| Testnet | May 14, 2026 4pm CEST | 1778767200 |
| Mainnet | May 18, 2026 4pm CEST | 1779112800 |
Node operators needed to upgrade to the T4-compatible release (v1.7.0, released May 11, 2026 4pm CEST) before the testnet activation timestamp.
Overview
T4 introduced the following changes:
- Consensus context in block headers to unlock deferred verification and reduce finalization latency
- T4 network upgrade bug fixes and security hardening
Compatible SDK releases
| SDK | T4-compatible release |
|---|---|
| Rust | tempo-alloy@1.7.0, tempo-primitives@1.7.0, tempo-contracts@1.7.0 |
| Foundry | nightly (T4 hardfork-aware decoding) |
See Developer tools for the broader SDK ecosystem.
Related docs
Feature TIPs
Consensus context in block headers
The specification added an optional Context field (epoch, view, parent view, leader) as the last field of TempoHeader. This commits consensus metadata to the block hash so Tempo blocks implement Commonware's CertifiableBlock trait, enabling deferred verification (optimistic notarization with async background verification) and reduced finalization latency. Pre-T4 headers are unchanged; post-T4 headers require the field, and validators reject mismatched context.
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