fix: snap operation details to view port when scrolling through a large operation tree

webui/src/components/common/StickyPanel.tsx

@@ -0,0 +1,137 @@
+import React, { useCallback, useEffect, useRef } from "react";
+
+/**
+ * StickyPanel keeps its content visible within the nearest scrollable ancestor's
+ * visible bounds.
+ *
+ * - Content shorter than visible area: stays at the top of the visible area.
+ * - Content taller than visible area: scrolling down pins the bottom to the
+ *   visible bottom; scrolling up pins the top to the visible top.
+ *
+ * Uses a constraint-based approach: on each frame, the current offset is nudged
+ * only when content has drifted out of the visible region, then clamped to stay
+ * within the container. No explicit scroll-direction tracking is needed.
+ */
+export const StickyPanel = ({ children }: { children: React.ReactNode }) => {
+  const containerRef = useRef<HTMLDivElement>(null);
+  const innerRef = useRef<HTMLDivElement>(null);
+  const currentOffset = useRef(0);
+  const rafId = useRef(0);
+
+  const findScrollParent = useCallback((el: HTMLElement) => {
+    let parent = el.parentElement;
+    while (parent) {
+      const style = getComputedStyle(parent);
+      if (
+        ["auto", "scroll"].includes(style.overflowY) ||
+        ["auto", "scroll"].includes(style.overflow)
+      ) {
+        return parent;
+      }
+      parent = parent.parentElement;
+    }
+    return null;
+  }, []);
+
+  const update = useCallback(() => {
+    rafId.current = 0;
+    const container = containerRef.current;
+    const inner = innerRef.current;
+    if (!container || !inner) return;
+
+    const containerRect = container.getBoundingClientRect();
+    const innerHeight = inner.scrollHeight;
+
+    // Visible bounds from nearest scrollable ancestor, or the viewport.
+    const scrollParent = findScrollParent(container);
+    let visibleTop = 0;
+    let visibleBottom = window.innerHeight;
+    if (scrollParent) {
+      const rect = scrollParent.getBoundingClientRect();
+      visibleTop = rect.top;
+      visibleBottom = rect.bottom;
+    }
+
+    let offset = currentOffset.current;
+
+    // Constraint: if bottom of content is above visible bottom, push it down.
+    const innerBottom = containerRect.top + offset + innerHeight;
+    if (innerBottom < visibleBottom) {
+      offset += visibleBottom - innerBottom;
+    }
+
+    // Constraint: if top of content is below visible top, pull it up.
+    const innerTop = containerRect.top + offset;
+    if (innerTop > visibleTop) {
+      offset = visibleTop - containerRect.top;
+    }
+
+    // Clamp: keep content within the container.
+    const maxOffset = Math.max(0, containerRect.height - innerHeight);
+    offset = Math.max(0, Math.min(offset, maxOffset));
+
+    currentOffset.current = offset;
+    inner.style.transform = `translateY(${offset}px)`;
+  }, [findScrollParent]);
+
+  const scheduleUpdate = useCallback(() => {
+    if (!rafId.current) {
+      rafId.current = requestAnimationFrame(update);
+    }
+  }, [update]);
+
+  // Attach scroll/resize listeners.
+  useEffect(() => {
+    const container = containerRef.current;
+    if (!container) return;
+
+    // Collect all scrollable ancestors.
+    const scrollParents: (HTMLElement | Window)[] = [window];
+    let parent = container.parentElement;
+    while (parent) {
+      const style = getComputedStyle(parent);
+      if (
+        ["auto", "scroll"].includes(style.overflowY) ||
+        ["auto", "scroll"].includes(style.overflow)
+      ) {
+        scrollParents.push(parent);
+      }
+      parent = parent.parentElement;
+    }
+
+    for (const sp of scrollParents) {
+      sp.addEventListener("scroll", scheduleUpdate, { passive: true });
+    }
+    window.addEventListener("resize", scheduleUpdate, { passive: true });
+
+    // Run once to set initial position.
+    update();
+
+    return () => {
+      if (rafId.current) cancelAnimationFrame(rafId.current);
+      for (const sp of scrollParents) {
+        sp.removeEventListener("scroll", scheduleUpdate);
+      }
+      window.removeEventListener("resize", scheduleUpdate);
+    };
+  }, [scheduleUpdate, update]);
+
+  // Reset offset and reposition when children change.
+  useEffect(() => {
+    currentOffset.current = 0;
+    if (innerRef.current) {
+      innerRef.current.style.transform = "translateY(0px)";
+    }
+    // Re-run positioning so content snaps into view immediately.
+    update();
+  }, [children, update]);
+
+  return (
+    <div
+      ref={containerRef}
+      style={{ width: "100%", height: "100%", position: "relative", overflow: "hidden" }}
+    >
+      <div ref={innerRef}>{children}</div>
+    </div>
+  );
+};

webui/src/features/operations/OperationTreeView.tsx

@@ -72,6 +72,7 @@ import {
 } from "../../api/flowDisplayAggregator";
 import { OperationIcon } from "./OperationIcon";
 import { shouldHideOperation } from "../../api/oplog";
+import { StickyPanel } from "../../components/common/StickyPanel";
 import { create, toJsonString } from "@bufbuild/protobuf";
 import { useConfig } from "../../app/provider";
 
@@ -191,7 +192,9 @@ export const OperationTreeView = ({
         operations={instanceBackups}
         isPlanView={isPlanView}
         onSelect={(flow) => {
-          setSelectedBackupId(flow ? flow.flowID : null);
+          if (flow) {
+            setSelectedBackupId(flow.flowID);
+          }
         }}
       />
     );
@@ -259,14 +262,14 @@ export const OperationTreeView = ({
         </SplitterPanel>
         <SplitterResizeTrigger id="tree:view" />
         <SplitterPanel id="view">
-          <Box paddingLeft="2" height="100%" overflowY="auto">
-            <BackupViewContainer>
+          <Box paddingLeft="2" height="100%" overflow="hidden">
+            <StickyPanel>
               {selectedBackupId ? (
                 <BackupView
                   backup={backups.find((b) => b.flowID === selectedBackupId)}
                 />
               ) : null}
-            </BackupViewContainer>
+            </StickyPanel>
           </Box>
         </SplitterPanel>
       </Splitter>
@@ -539,14 +542,6 @@ const DisplayOperationTree = ({
   );
 };
 
-const BackupViewContainer = ({ children }: { children: React.ReactNode }) => {
-  return (
-    <Box position="sticky" top="0" width="100%">
-      {children}
-    </Box>
-  );
-};
-
 const BackupView = ({ backup }: { backup?: FlowDisplayInfo }) => {
   if (!backup) {
     return (