Runtime mechanics such as supervision and backpressure primitives.
Fragment: runtime-asupersync-bootstrap
pureflow-runtime now owns a real runtime substrate, but only at the level
the current node interface can honestly support. The wrapper below uses
asupersync::runtime::RuntimeBuilder to provide a task-tree-backed entry
point for one node execution at a time. It deliberately does not claim
workflow scheduling, channel wiring, or full FBP semantics yet.
Fragment: runtime-asupersync-boundary
asupersync is the runtime substrate, not the public FBP model. Pureflow
owns graph validation, node contracts, port handles, metadata, capability
descriptors, and introspection. Runtime adapters may use asupersync
contexts, bounded channels, cancellation, and task handles internally, but
those types should not leak through NodeExecutor, NodeContext,
PortsIn, or PortsOut unless a later bead explicitly revisits the
boundary.
Fragment: runtime-test-determinism
Production construction intentionally keeps the default asupersync
builder. Tests that assert ordering, cancellation, or failure propagation
should use the deterministic current-thread constructor so those checks are
about Pureflow behavior rather than host scheduler timing.