Reactor-first architecture

Both SDKs use Datalayer Reactor as their extension runtime. The protocol boundary owns mandatory validation and security rules; plugins provide replaceable infrastructure and optional PAP extensions.

Every replaceable service is a contribution point, the same in Python and TypeScript: Contribution points lists them with their defaults and which are tenant-scoped.

Lower order values have higher priority. Equal winning priorities fail closed instead of selecting a provider by load order.

What remains in the protocol core

Reactor makes infrastructure replaceable; it does not make protocol invariants optional. Parsing, version compatibility, domain and issuer binding, secret redaction, token/resource binding, replay protection, and exact revision approval remain owned by the PAP core.

Applications may supply an existing Reactor host so PAP participates in the same plugin lifecycle as the rest of their platform. Otherwise each SDK can assemble a host with safe defaults.

Two meanings of extension

A PAP extension is negotiated on the wire by name and major version. A Reactor extension packages plugins and manages their lifecycle. The SDK implements one PAP extension, Operations version 1; see Extensions.

Plugins cannot turn off domain/issuer binding, secret redaction, token/resource binding, replay protection, or exact operation-revision approval.

See Extensions for the relationship between negotiated wire capabilities and runtime plugins.