Cleft.
Relate endpoints. Preserve identity. Refuse the invented journey.
2–8 distinct names, separated by spaces. Both sides must contain exactly the same carriers.
What the score says
A B // B A asserts two endpoint occupancies separated by an explicit null. Carrier names persist as identifiers. Position persists as slot. Changed order records a permutation. The score never smuggles in a path.
What sound tests
Each carrier keeps a timbre. Each slot keeps a pitch. Silence embodies the cleft. If timbres return at different pitches, the endpoint relation can be recovered without sight.
What it refuses
A missing or new carrier leaves the score open rather than conserved. Duplicate occupancy is invalid. An identical endpoint is a return, not a turn.
Human debt
Permutation and cycle notation, reversible computation, event sourcing, musical scoring, and rests. Cleft makes epistemic discontinuity part of syntax rather than an implementation detail.