page-scroll

raw source

Document-shaped dashboard pages share one visible scrollbar geometry. The scroll track starts below the shell edge, stops above the bottom edge, keeps a stable gutter, and returns to the exact place a reader left when browser history brings that address back. A page supplies content; it never invents another full-page overflow owner.

expanded spec

PageScroll is the one overflow owner for Evals and Issues lists/details, Settings, and the global Projects page. The shell owns its available viewport; the primitive owns the top/bottom track inset, desktop end inset, stable gutter, vertical overscroll containment, and horizontal clipping. Content owns its width and padding. Sticky children such as a route-leading status strip, the review list header, detail side rail, and composer pin inside this scrollport, so their geometry follows the same viewport instead of the browser document or a page-local scroller. Route-specific leading content also stays inside it: the scoped Evals terminal/gates strip is its first child and pins at the scrollport's shared 10px top inset without shifting the scrollbar track. It is opaque through shared palette tokens, has a stable per-viewport height, and establishes the following content position in normal flow before it sticks, so neither desktop nor a two-line 390px strip covers the first row. Popovers and tooltips remain above it; neighboring sticky list headers and detail rails keep their own containment. A route with no leading status contributes no empty sticky geometry.

Scroll position is remembered by the full canonical address. When returned content already has its final height the primitive restores in the layout phase but does not yield until that target survives the next paint: Chromium may still apply its own history scroll after React's first successful write. When a long list arrives asynchronously, it preserves the saved target across the browser's temporary zero clamp and keeps observing until the content can represent that position. Pointer, wheel, touch, or keyboard input ends automatic restoration immediately so user intent wins. List to detail is still an ordinary PUSH and browser Back still owns navigation; the primitive only restores the nested scrollTop belonging to the returned address. Different query states keep different positions. A new address starts at the top, and a hidden warm page keeps its own native state.

The Graph canvas and Session console do not consume this primitive: the graph camera is not document scroll, the session list is a bounded pane, and xterm/tmux owns terminal scrollback. Popup, side-rail, composer, and mobile timeline scrollers remain local where their contracts require them. At phone width the same review pages and direct Settings route consume the same primitive above the tab bar, with equal top/bottom track insets, no horizontal page overflow, and the detail rail returned to ordinary document flow.