Fix compact composer controls and native scrolling (#2361)

* fix(app): refine compact composer controls and native scrolling

Consolidate responsive agent controls and model browsing inside the compact sheet. Preserve manual native scrolling by suspending sticky bottom maintenance while the user owns the viewport.

* fix(app): suppress recoverable resume refresh errors

Resume revalidation can race host reconnection and reject while the host is offline. Treat the refresh as deferred so development LogBox does not surface a recoverable disconnect.

* fix(app): stabilize compact model sheet loading

Let the model list consume the sheet space above persistent controls as the sheet expands. Keep unresolved defaults in a loading state so Select model only represents a genuinely empty selection.

* fix(app): preserve route anchors during native scroll

* fix(app): preserve native scroll intent and sheet dismissal

* fix(app): keep compact sheet styles composable

packages/app/src/agent-stream/strategy-native.tsx

@@ -89,6 +89,8 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
     contentMeasuredForKey: null as string | null,
   });
   const scrollOffsetYRef = useRef(0);
+  const isUserScrollActiveRef = useRef(false);
+  const userScrollEndFrameIdRef = useRef<number | null>(null);
   const programmaticScrollEventBudgetRef = useRef(0);
   const [isNativeViewportSettling, setIsNativeViewportSettling] = useState(false);
   const nativeViewportSettlingFrameIdRef = useRef<number | null>(null);
@@ -129,6 +131,13 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
     }
   }, []);
 
+  const clearPendingUserScrollEnd = useCallback(() => {
+    if (userScrollEndFrameIdRef.current !== null) {
+      cancelAnimationFrame(userScrollEndFrameIdRef.current);
+      userScrollEndFrameIdRef.current = null;
+    }
+  }, []);
+
   const markNativeViewportSettling = useCallback(() => {
     clearNativeViewportSettling();
     setIsNativeViewportSettling(true);
@@ -208,6 +217,8 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
       contentMeasuredForKey: null,
     };
     scrollOffsetYRef.current = 0;
+    isUserScrollActiveRef.current = false;
+    clearPendingUserScrollEnd();
     clearNativeViewportSettling();
     setIsNativeViewportSettling(false);
     historyStartReadyRef.current = false;
@@ -216,8 +227,9 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
     });
     return () => {
       cancelAnimationFrame(frame);
+      clearPendingUserScrollEnd();
     };
-  }, [agentId, clearNativeViewportSettling]);
+  }, [agentId, clearNativeViewportSettling, clearPendingUserScrollEnd]);
 
   useEffect(() => {
     const keyboardEvents = [
@@ -266,6 +278,19 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
     };
   }, [agentId, bottomAnchorController, markNativeViewportSettling, viewportRef]);
 
+  const isScrollEventNearBottom = useStableEvent(
+    (event: NativeSyntheticEvent<NativeScrollEvent>) => {
+      const { contentOffset, contentSize, layoutMeasurement } = event.nativeEvent;
+      return isNearBottomForStreamRenderStrategy({
+        strategy,
+        offsetY: contentOffset.y,
+        threshold: 32,
+        contentHeight: contentSize.height,
+        viewportHeight: layoutMeasurement.height,
+      });
+    },
+  );
+
   const handleScroll = useStableEvent((event: NativeSyntheticEvent<NativeScrollEvent>) => {
     const { contentOffset, contentSize, layoutMeasurement } = event.nativeEvent;
     const previousOffsetY = scrollOffsetYRef.current;
@@ -280,13 +305,7 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
       contentMeasuredForKey: "native-virtualized",
     };
 
-    const nearBottom = isNearBottomForStreamRenderStrategy({
-      strategy,
-      offsetY: contentOffset.y,
-      threshold: 32,
-      contentHeight: streamViewportMetricsRef.current.contentHeight,
-      viewportHeight: streamViewportMetricsRef.current.viewportHeight,
-    });
+    const nearBottom = isScrollEventNearBottom(event);
     onNearBottomChange(nearBottom);
 
     const distanceFromOldestEdge =
@@ -301,7 +320,11 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
       onNearHistoryStart();
     }
 
-    if (programmaticScrollEventBudgetRef.current > 0 && contentOffset.y <= 8) {
+    if (
+      !isUserScrollActiveRef.current &&
+      programmaticScrollEventBudgetRef.current > 0 &&
+      contentOffset.y <= 8
+    ) {
       programmaticScrollEventBudgetRef.current -= 1;
     } else {
       programmaticScrollEventBudgetRef.current = 0;
@@ -312,6 +335,37 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
     }
   });
 
+  const handleScrollBeginDrag = useStableEvent(() => {
+    clearPendingUserScrollEnd();
+    isUserScrollActiveRef.current = true;
+    bottomAnchorController.beginUserScroll();
+  });
+
+  // Defer drag end so momentum can take ownership, but capture the terminal
+  // gesture position now because layout may move the viewport in the meantime.
+  const handleScrollEndDrag = useStableEvent((event: NativeSyntheticEvent<NativeScrollEvent>) => {
+    const isNearBottom = isScrollEventNearBottom(event);
+    clearPendingUserScrollEnd();
+    userScrollEndFrameIdRef.current = requestAnimationFrame(() => {
+      userScrollEndFrameIdRef.current = null;
+      isUserScrollActiveRef.current = false;
+      bottomAnchorController.endUserScroll({ isNearBottom });
+    });
+  });
+
+  const handleMomentumScrollBegin = useStableEvent(() => {
+    clearPendingUserScrollEnd();
+  });
+
+  const handleMomentumScrollEnd = useStableEvent(
+    (event: NativeSyntheticEvent<NativeScrollEvent>) => {
+      const isNearBottom = isScrollEventNearBottom(event);
+      clearPendingUserScrollEnd();
+      isUserScrollActiveRef.current = false;
+      bottomAnchorController.endUserScroll({ isNearBottom });
+    },
+  );
+
   const handleListLayout = useStableEvent((event: LayoutChangeEvent) => {
     const previousViewportWidth = streamViewportMetricsRef.current.viewportWidth;
     const previousViewportHeight = streamViewportMetricsRef.current.viewportHeight;
@@ -419,6 +473,10 @@ function NativeStreamViewport(props: StreamRenderInput & { strategy: StreamStrat
       style={listStyle}
       onLayout={handleListLayout}
       onScroll={handleScroll}
+      onScrollBeginDrag={handleScrollBeginDrag}
+      onScrollEndDrag={handleScrollEndDrag}
+      onMomentumScrollBegin={handleMomentumScrollBegin}
+      onMomentumScrollEnd={handleMomentumScrollEnd}
       scrollEventThrottle={16}
       onContentSizeChange={handleContentSizeChange}
       maintainVisibleContentPosition={maintainVisibleContentPosition}