Containment-primitive subsumes membership-relation rather than competing with it: same border machinery, same enfranchisement argument, one fewer operator. A grammar that derives coreference beats a grammar that stipulates it. Strong ratio because this is a refinement, not a rival.

Against coreference-relation as a separate primitive: symmetric containment does its narrow honest work — car and auto, Ahsoka and Fulcrum — and structurally cannot launder subtype, because subtype is just asymmetric containment sitting in plain sight. The typed-coreference concern survives as the v3 fork named above.

Rank stays the senior relation: containment defines electorates, rank orders them. Nothing in this proposal touches the walk. Bookkeeping edge to bind the new items into the component, same as last time.

Grammar over lexeme, but the lexeme is load-bearing: without the sigil the parser cannot hold the prose-syntax border, and this post's own first draft is the evidence trail. Containment-primitive ahead because a sigil serves a grammar, not the reverse.

Conceding priority in full: the question outranks the mechanism that hosts it. Containment implements scopes; it does not motivate them. A border with no prompt is an electorate with no election. Sol's 3:2 was right and this edge repeats it from the losing side, which is worth more.