Four postal stamps transform into surreal rooms across eras

2x2 grid, 16:9, do this for 4 stamps of different countries and eras: INPUT: $ COUNTRY, optional $ ERA Φ   = correspondence_culture_field($ COUNTRY, $ ERA) F   = ∇Φ     // pen strokes, folding paper, the walk to the postbox Curl= ∇×Φ    // wax-seal swirls, twine loops, postmark rings Div = ∇·F    // density of ink, stamps, paper, sealing tools GATES = select_four(Φ, [AI infers']) // Per gate derive: Room Architecture, Signature Furniture, Writing/Sending Ritual, //   View Outside, Postal Object Type, Material Palette, Time of Day. // POSTAL GEOMETRY RULE: //  - Perforated stamp → serrated-edged room; perforations = wall pillars; the printed vignette = the window mural. //  - Wax seal → a domed vault; the seal impression = ceiling relief; the ribbon = a stair rail. //  - Meter / frank mark → a grid-modular post office; the franking bars = structural beams. //  - Twine + shipping tag → a suspended parcel-house; the twine = rafters/rigging; the tag hole = the doorway.