Three corrections from review, none of which change behaviour.
attemptStreaming promised output "as the command produces it", which
spawnSync cannot do: it returns only after the child exits, and the two
streams are echoed one after the other, so their interleaving is lost.
For an npm publish that is visible — notices go to stderr while the
`+ name@version` confirmation goes to stdout, so the confirmation prints
first. The helper is now attemptEchoed and its contract says buffered,
echoed after exit, stdout before stderr; live progress would need an
asynchronous spawn with data listeners.
The traversal comment claimed a node on the stack is a cycle only peer
edges can form, and that skipping it drops just that edge. The cycle does
carry a peer edge, because the install edges were proved acyclic a moment
earlier, but the back edge that reaches the stacked node need not be the
peer one — which is what the post-condition exists to catch, so the
comment now points at it instead of asserting an invariant the traversal
does not have.
The `if (placed.has(member.name)) return` after leaving the stack was
unreachable: a re-entrant visit returns at the top guard while the member
is on the stack, so it can never be placed by the time the recursion
unwinds.
0e50fa290c