Introducing t4

Infrastructure systems often need a small, reliable place to keep control-plane state: configuration, service metadata, locks, leases, revision history, and change notifications.

database for the active working set, while object storage carries the recovery story. If a node disappears, loses its disk, or is replaced, it can rebuild from checkpoints and WAL segments in S3-compatible storage.

That model is not "etcd, but implemented differently." It is a different durability model for workloads where object storage is already the source of truth after failure.

What this unlocks

Once the database can recover from object storage, other workflows become much more natural.

Recovery drills stop being special events. You can create a fresh node, point it at the bucket and prefix, and let it rebuild. Migration experiments can start from a known checkpoint. Disposable test environments can fork from real state without copying every object.

The branching feature grew directly out of this. t4 checkpoints use content-addressed SST files, so a branch can reuse the same immutable files as its source and write only its own changes. That makes point-in-time copies cheap enough to use for rehearsal, debugging, and upgrade testing rather than only for emergencies.

This is the part of t4 that feels least like a traditional coordination database: not just storing state, but making state cheap to clone, inspect, and throw away.

Where t4 fits

t4 is built for:

• Durable infrastructure state.


• Simplifying Kubernetes-style control-plane storage.


• Simple replacement of failed or ephemeral nodes.


• Local reads from an embedded or standalone process.


• Existing etcd v3 clients where compatibility matters.


• Copy-free branches for recovery drills, migrations, and tests.

It is aiming to solve operational complexity, not trying to replace every etcd deployment. Use etcd when you want the most mature operational ecosystem, full cluster-management APIs, or the lowest possible latency for small sequential write workloads. The . The docs start at , .