fix(nav): stop the native chat list overscrolling when its content fits the window

src/app/components/page/Page.tsx

@@ -395,8 +395,33 @@ export function PageNavContent({
         size="300"
         hideTrack
         visibility="Hover"
+        // folds `direction="Vertical"` sets `overflow-y: scroll`, which makes
+        // this a *user-scrollable* container even when the list fits (scroll
+        // range 0, permanently pinned at its boundary). On Android any
+        // touch-drag on such a boundary-pinned scroller fires the elastic
+        // overscroll stretch — the list "bounces" though it has nothing to
+        // scroll. `overflow-y: auto` is user-scrollable only when content
+        // actually overflows: short lists become inert (no overscroll), long
+        // lists still scroll normally. Inline style wins over the recipe class.
+        style={{ overflowY: 'auto' }}
       >
-        <div className={css.PageNavContent}>{children}</div>
+        {/* `css.PageNavContent` carries a 32px (`S700`) bottom padding for
+            breathing room below the last row. That padding is part of the
+            scroll content, so once the list grows to within 32px of the
+            viewport it overflows by however much of the padding doesn't fit —
+            the list visually "fits" (a gap shows below it) yet you can still
+            scroll a few px into the leftover padding. On native the curtain
+            list already has its own bottom boundary (the pinned DirectSelfRow /
+            WorkspaceFooter, or the screen edge), so the in-scroll breather is
+            redundant; dropping it there means a list that fits has zero scroll
+            range. Desktop keeps the breather (mouse-scrolling into it is
+            harmless and the last row wants the air at the panel bottom). */}
+        <div
+          className={css.PageNavContent}
+          style={isNativePlatform() ? { paddingBottom: 0 } : undefined}
+        >
+          {children}
+        </div>
       </Scroll>
     </Box>
   );

src/app/components/page/style.css.ts

@@ -143,7 +143,16 @@ export const PageNavHeader = recipe({
 export type PageNavHeaderVariants = RecipeVariants<typeof PageNavHeader>;
 
 export const PageNavContent = style({
-  minHeight: '100%',
+  // No `min-height: 100%`. It used to force this padded wrapper to at least
+  // the scroll viewport's height, but the div is transparent (the curtain on
+  // native / the PageNav inner column on web paints the background) so the
+  // fill was invisible — its only real effect was a ~1px scroll overflow:
+  // `100%` resolves against the fractional flex-parent height and rounds UP
+  // while the viewport's clientHeight rounds DOWN, leaving the list
+  // permanently scrollable by a hair even when it fits. That hair is the
+  // "useless" overscroll on native. Letting the wrapper size to its content
+  // means a short list has no scroll range at all (paired with the
+  // `overflow-y: auto` override on the Scroll in Page.tsx).
   padding: config.space.S200,
   paddingRight: 0,
   paddingBottom: config.space.S700,