A second page fixes every setting except one model parameter, which runs over a list of values, and a knob steps the display through them. What makes the knob worth having is the cache: each value names one solution under the same specs the single-solution page uses, so on any selection change the page fetches the whole sweep at once -- a handful of files of about 90 KB -- and synthesizes each solution onto the render mesh as it arrives. Moving the knob afterwards touches neither the network nor the solver; it recolors the mesh from values already in memory. One color scale per species, computed over all loaded values and held fixed, covers the whole sweep, so that what changes under the knob is the pattern rather than the palette. The value list starts as the swept parameter's own choices but is a text box, and any numbers may be typed in its place. This is the one control in the app that is not a choice from a list. It is nonetheless safe for the cache, since a typed value is parsed to a number once and serialized in canonical shortest form ever after, so that it names one spec and one object as reliably as a listed value does. Of course, a value the auto-fill walk never surveyed will not already be there, so such a sweep arrives entirely as gaps. Gaps are filled either here or elsewhere. Compute missing values runs them in the browser, one after another, each through the ordinary local run of runSpec.ts, warm start and background uploads and divergence guard included; and `fill sweep '<url>'` fills the same sweep on a machine with no browser on it. Its argument is the sweep page's own URL, whose fragment already carries the selection, which parameter sweeps, its values and the knob's position, so that the copied command and the page it came from always name the same solutions and the same URL pasted into a browser shows the result. Commas in that fragment are left unencoded, which a fragment permits and a reader appreciates. The serialization now lives in src/cache/selection.ts and is read and written by both pages and the command line rather than by each in its own way; main.ts loses its own copy of it. Within the command line the full walk and a sweep are one Plan, differing only in which targets exist and how each is named, so the run loop and its reporting are shared. The end-to-end check gains a sweep pass: the file computed in pass 1 is loaded as one value of a dt sweep, the other two appear as gaps and are filled by the button, and a typed list of two values is then applied and its literal commas checked in the URL. check-live.mjs smoke-checks the sweep page beside the main one, and screenshot.mjs takes an optional page name.