Second slice: the resolved-tap carrier. FlatTap { name, node, field } is the
output-side twin of SourceSpec — its name survives compile, load-bearing for
by-name binding (#275). FlatGraph gains a taps field, threaded (empty) through
every construction site the compiler enumerates. Bootstrap ignores it (taps
materialize as real recorder nodes/edges before bootstrap in a later slice).
Purely additive: the inert-producer pin and full suite stay green.
refs #282
claude
17e125a90a