Struct FlowCtx 

pub struct FlowCtx {
    pub span: Span,
    pub log: Arc<dyn FlowLogSink>,
    pub cancel: CancellationToken,
    pub verbosity: FlowLogVerbosity,
    pub trajectory: TrajectoryBuilder,
}

Per-walk execution context. Constructed once per L4 connection (and re-constructed per L7 request when a hyper service-fn dispatches into the L7 sub-graph). Fields are owned — no lifetime parameter — so the struct survives tokio::spawn and move closures (notably hyper’s service-fn closure at Node::Upgrade, which captures log / cancel / verbosity per request).

Arc<dyn FlowLogSink> and CancellationToken clone cheaply (each is internally an Arc), and tracing::Span is also Arc-backed; the per-request clones in the hyper bridge are O(1).

Fields

span: Span

log: Arc<dyn FlowLogSink>

cancel: CancellationToken

verbosity: FlowLogVerbosity

Verbosity selected when this connection was accepted. The listener reads engine::VerbosityState once at FlowCtx construction; in-flight connections retain the value they were built with.

trajectory: TrajectoryBuilder

Walker-internal step accumulator. The executor pushes one entry per node-visit and emits a single FlowLogKind::Trajectory event from finalize() at terminate or error.