Safe Publication

Initialize → atomic pointer Store → observing Load → read immutable data. Name the exact ordering edge.

Empty differs from zero

Empty Load →(0,false). Store(0), then Load →(0,true). Swap(7) then returns(0,true). A nil receiver is explicitly harmless, not an empty snapshot object.

Race freedom is not an atomic compound operation

Cell10: A loads10; B loads10; A stores20; B stores30. Both return10: impossible for two true swaps. Use one atomic replacement to return the displaced snapshot.

Observation matters

Receiving an old buffered token need not observe a later close. Publishing an atomic pointer does not synchronize later mutation of its map. Keep snapshots immutable after publication.

Independent check

Two swaps install8 and12 from initial4. Final value is8. Derive both returned predecessors. Then extend publication to a map and specify how caller mutation is prevented.