Basic networking question

[mildlyjelly]

In this setup, all requests go all the way back to the router.  My understanding is that repeaters, or nodes in a mesh network, do not have any routing logic.  They send everything back to the main router.

Lets assume both clients are in the same SSID and in the same Subnet, which sounds like is the case here, then traffic is directly exchanged via intra-BSS relay on that mesh AP. 
No routing necessary.

Everything outside that SSID/Subnet will be send to the router.

The setting to disabled this is usually called "client isolation". I also assume this is unchecked.

I understand how intra-BSS works on an access point or a router, and I can see how that would apply to a mesh node. But, since mesh nodes are connected in a way that access points and routers typically aren't, I was uncertain if intra-BSS would still work across multiple mesh nodes?

Typically, for example, an access point can't directly communicate with another access point. So, if 2 devices are connected to 2 different access points, the traffic has to get sent through the router.
But on a mesh network, all nodes can either directly or indirectly communicate with each other. So if you have 2 devices connected to 2 different nodes, in theory, they could send traffic directly between them (or indirectly through other nodes) without ever sending traffic through the controlling router.

Do you know if this multi-node intra-BSS behavior is a thing implemented mesh routers?