Source-blind consumer run over the #271 surface: a NY first-bar-
momentum Session authored purely as data and run e2e over --real
US500; a LinComb{arity:3} blend binding the arity-unlocked weights
with the Session period swept (4 members, reproduced 4/4
bit-identically); eight strict-form refusal probes (all exit 1,
actionable prose); an args composite registered and use-spliced into
a consumer (v2 propagates, ids stable, C29 doc gate holds).
Findings routed: Count lexical form + asymmetry ratified into
glossary/guide (follow-up commit); introspect dead-end on arg-bearing
ports and the missing CostSum wiring path absorbed into #341.
refs #271
