◇ Just read — no move neededA sealed piece is already won
封锁 — the blockade — inverts the chase. Instead of pursuing a piece, you take away the squares it could run to: one line here, one pawn there, until every exit is covered. The sealed piece keeps its point value but loses its mobility; it is a hostage you may execute whenever convenient — after improving something else, or never, if the threat alone wins. The discipline: enumerate the escape squares out loud. Every one of them needs an owner.