Is Czar Chassis a different machine?

No. Czar is the appliance, a Czar Grid is several Czars sharing one pool, and Czar Chassis is one of the two ways a Grid reaches a building. Under Czar Chassis, a robot vendor or systems integrator ships the Grid under its own name, with its own fleet, so its customer receives one system from one vendor. The nodes in the rack are Czars. The serving system is Substrate. The sealing, the attestation, and the provenance on record are the same. Element 31 provides sustainment and attestation underneath, and the vendor's name is on the front.

Two routes, one Grid

Element 31 offers the Grid two ways. Under Facility Direct, the building subscribes: the operator's automation team works with E31 Consulting, the integrator, and the robot vendors to install the pool, and the operator holds the relationship. Under Czar Chassis, the vendor or integrator ships it and delivers the Grid to its customer as part of the system it already sells.

In both cases the thing in the rack is the same configured Grid under the same commercial form: one subscription covering hardware, platform license, and sustainment in one line, fixed for the term. The difference is who delivers it and whose name is on the system. It is a delivery distinction, not an engineering one.

What the vendor adds

A vendor shipping Czar Chassis adds its fleet, its integration, and its relationship. Its robots arrive already connected to the pool, with their latency budgets set and their fallback behavior confirmed, and the site tasks that involve them authored in Agency Studio. The customer gets one system to install, one vendor to call, and one record to read.

What the vendor does not add is a second appliance. There is no Chassis hardware distinct from Czar hardware and no Chassis software distinct from Substrate. A customer who later adds robots from a second vendor is adding them to a Czar Grid, and the pool serves them as it serves any robot in the building. The first vendor's name on the system does not make it the first vendor's pool.

What Element 31 keeps doing

Underneath the vendor's name, Element 31 does what it does for every Grid. Each node is sealed, runs a signed read-only image, and attests what it is running before it joins the Grid or accepts a task. Integration, sealing, and software load are on record for every node, so the end customer can answer where the hardware came from from a record even though they received it under another name. Signed updates come from Element 31 and are loaded by the customer.

Sustainment is Element 31's too. Support, billing for the subscription line, signed update downloads, and customer-initiated remote sessions all run through the customer portal, and the end customer's appliances never connect to that portal any more than a Facility Direct customer's do. The same sovereign-site rule applies: an uplink window requires the customer's attestation and carries a hard expiry.

So the question has a short answer and a longer reassurance. Czar Chassis is not a different machine. It is the Grid, shipped by someone the customer already buys robots from, with Element 31 standing behind it. The How to buy page sets the two routes side by side, and How is a Czar Grid priced explains the line that both routes share.