listgap

Overview ¶

Package listgap owns one concern: the container part shared by every target* list component (targetlist, targetdate, …). It is a lego piece — the list components assemble it, they do not re-declare its shape or its spacing.

Apply wires the desktop PartList contract in a single call:

• the vertical row rhythm (the "more air" knob between rows)
• the Scroll() region, which reserves the block edges for a FloatingChrome host through var(--floating-top|bottom, 0px) — 0px when there is none
• ScrollGutter(inset): an ambient top/bottom gutter equal to the lateral inset, so the list looks framed the same on all four sides instead of sitting flush against the top while the sides carry a visible gutter. It is ADDITIVE with the FloatingChrome reservation above (folded into the same calc), never a plain padding-block that would replace it — a `padding:`/PadEdge() shorthand here would land in the widgets layer and clobber the seam's reservation outright, putting the last row back under the host's floating button (measured: 72px on medicalhistory's own crudview action). See widget/style's ScrollGutter doc for why a plain override cannot do this safely.
• the lateral inset value, calibrated to crudview's master-detail indent budget (16px total: crudview card 4 + list 4 + this 8). Retuning it means re-checking crudview/css.go in tinywasm/layout.

MobileOpts carries the phone-breakpoint overrides. The caller spreads them into its OWN On(css.Mobile, …) — the conformance rail keeps the css import (and therefore the breakpoint device) inside css.go files, so listgap hands the values out as style.Options instead of naming the device itself.

The four space steps are unexported on purpose: a caller cannot pass the wrong one to the wrong property, because the Stack()/PadInline() calls live here. That is also why the two list components stay visually interchangeable (crudview swaps one for the other) with no "keep in sync with the sibling" rule to remember.

Leaf package: components/conformance_test.go imports targetlist, so a symbol here — rather than in the components root — keeps the test build acyclic.