Capability feature bits advertised in OpVersions::features. Each constant
names one managed sub-feature a server serves beyond the base surface, so a
binary client feature-detects it (before attempting the op) the way the HTTP
surface reads the boolean flags on Capabilities. Additive and pinned
cross-repo: a new bit is set by a newer server and ignored by an older
client (which simply does not light up that capability).
One materialization backend a server exposes, advertised so a client can see
what it may route to. id is the stable handle a binding references, kind
is the engine family as an opaque string, so a new engine is advertised by
name without any wire change. Carries identity only, never settings or
secrets. Integration-agnostic: the wire pins no specific engine.
Body of the AGDX_HELLO probe reply: the wire op versions the server (and
its managed backend) accepts, mirroring the HTTP capabilities versions
block. A pinned wire shape. Pre-versioned
servers answer the probe with an empty body, which a client treats as “no
versions advertised”, never an error.
The wire op versions a server accepts, one per surface, plus the capability
feature bits it advertises. A pinned wire shape, mirrored by the HTTP
capabilities versions block.