The run-mode-aware bind seam. bind_tap attaches a CALLER-BUILT Box<dyn Node>
sink to a declared tap — appending the sink node + an edge from the tap's
(node, field) to its input, before bootstrap so the Kahn sort orders it. The
engine constructs no aura-std type (it takes a Box<dyn Node>), keeping its
production dependency aura-core-only. bind_tap raises UndeclaredTap; duplicate
detection across binds is the caller's (the engine keeps no cross-call state),
mirroring how bind_sources' DuplicateFeed is a supply-level fault. TapBindError
is exported for the CLI. A bound tap records exactly the producer's per-cycle
output through the full public pipeline; an undeclared name is refused without
mutating the graph.
refs #282
claude
93d0ec45f2