Two ordinary moments from a working week. A function ships clean, and months later fails on a case its type checker looked straight at and passed. A service that shipped clean a year ago, untouched since, will no longer run - nothing in it moved; everything under it did. The first says a rule can never cover every case it governs; the second, that an artefact can never be finished, only kept in being. This is a book about those two refusals and its single claim of them: neither ever closes. One opening is logical, a limit no procedure escapes, sharpened here into a theorem; the other is temporal, the upkeep of software having the form of labor - consumed in the doing, setting nothing down for good. Held apart as two lenses, they are shown to touch at one place a programmer can point to: the commit in which a custom kept by hand hardens into a rule a machine enforces. And the enclosure settles nothing: it moves the unruled margin rather than removing it, opening a fresh frontier at the new rule's edge. From that join follows an account of what a maker does where nothing comes to rest - not finishing, which no one can do, but staffing the unfinishable in the open. The fifth volume in the Code Crafting series, written to be read alone.