fix(app): resync timeline after route reconnect (#36643)

2026-07-14 21:47:33 +10:00
parent 456521f689
commit 7304bb2751
9 changed files with 846 additions and 0 deletions
@@ -0,0 +1,315 @@
+import { createResource, createSignal, For, onMount, Suspense } from "solid-js"
+import { render } from "solid-js/web"
+import { createVirtualizer, observeElementOffset, observeElementRect } from "@tanstack/solid-virtual"
+import { observeElementOffsetReconnectAware } from "../../../src/pages/session/timeline/observe-element-offset"
+
+const rowCount = 2_000
+const rowHeight = 40
+const parameters = new URLSearchParams(location.search)
+const resourceMode = parameters.get("resource") === "guard" ? "guard" : "baseline"
+const reconnectMode = parameters.get("reconnect") === "candidate" ? "candidate" : "baseline"
+
+type MutationEvent = {
+  kind: "removed" | "added"
+  callbackTime: number
+  callbackFrame: number
+  routeConnectedInCallback: boolean
+  nativeOffsetInCallback: number
+}
+
+type Snapshot = {
+  mode: {
+    resource: "baseline" | "guard"
+    reconnect: "baseline" | "candidate"
+  }
+  operation: {
+    sequence: number
+    phase: string
+    time: number
+    frame: number
+  }
+  resourceState: string
+  routeConnected: boolean
+  viewportConnected: boolean
+  viewportOwnedByRoute: boolean
+  sameRoute: boolean
+  sameViewport: boolean
+  sameSurface: boolean
+  sameMountedRows: boolean
+  nativeOffset: number
+  coreOffset: number
+  rangeStart: number
+  rangeEnd: number
+  indexes: number[]
+  domIndexes: number[]
+  logicalSurfaceHeight: number
+  renderedSurfaceHeight: number
+  viewportClientHeight: number
+  viewportScrollHeight: number
+  visibleRows: number
+  minimumRowTop: number
+  domScrollEvents: number
+  lastScrollTrusted: boolean
+  coreOffsetCallbackCalls: number
+  offsetCallbackSources: "observer"[]
+  rectObserverCallbacks: number
+  ignoredDetachedZeroRects: number
+  syntheticScrollDispatches: number
+  mutationEvents: MutationEvent[]
+}
+
+declare global {
+  interface Window {
+    timelineSuspense: {
+      prepare: () => Promise<Snapshot>
+      trigger: () => void
+      resolve: () => void
+      frames: (count?: number) => Promise<void>
+      snapshot: () => Snapshot
+    }
+  }
+}
+
+function App() {
+  const [refresh, setRefresh] = createSignal(false)
+  let resolveResource: (() => void) | undefined
+  const [resource] = createResource(
+    refresh,
+    (version) =>
+      new Promise<string>((resolve) => {
+        resolveResource = () => resolve(`settled-${version}`)
+      }),
+    { initialValue: "settled" },
+  )
+
+  function Route() {
+    let route: HTMLElement | undefined
+    let viewport: HTMLDivElement | undefined
+    let surface: HTMLDivElement | undefined
+    let initialRoute: HTMLElement | undefined
+    let initialViewport: HTMLDivElement | undefined
+    let initialSurface: HTMLDivElement | undefined
+    let initialRows: HTMLElement[] = []
+    let phase = "mounting"
+    let browserFrame = 0
+    let snapshotSequence = 0
+    let domScrollEvents = 0
+    let lastScrollTrusted = false
+    let coreOffsetCallbackCalls = 0
+    let rectObserverCallbacks = 0
+    let ignoredDetachedZeroRects = 0
+    const offsetCallbackSources: "observer"[] = []
+    const mutationEvents: MutationEvent[] = []
+    const virtualizer = createVirtualizer<HTMLDivElement, HTMLDivElement>({
+      count: rowCount,
+      getScrollElement: () => viewport ?? null,
+      estimateSize: () => rowHeight,
+      initialRect: { width: 900, height: 600 },
+      overscan: 2,
+      observeElementRect: (instance, callback) =>
+        observeElementRect(instance, (rect) => {
+          rectObserverCallbacks++
+          // A fixed 600px viewport has no usable geometry while detached. Keep the last connected rect.
+          if (!instance.scrollElement?.isConnected && rect.height === 0) {
+            ignoredDetachedZeroRects++
+            return
+          }
+          callback(rect)
+        }),
+      observeElementOffset: (instance, callback) => {
+        const deliver = (offset: number, isScrolling: boolean) => {
+          coreOffsetCallbackCalls++
+          offsetCallbackSources.push("observer")
+          callback(offset, isScrolling)
+        }
+        if (reconnectMode === "candidate") return observeElementOffsetReconnectAware(instance, deliver)
+        return observeElementOffset(instance, deliver)
+      },
+    })
+
+    const frames = async (count = 2) => {
+      for (let index = 0; index < count; index++) {
+        await new Promise<void>((resolve) => requestAnimationFrame(() => resolve()))
+      }
+    }
+    const mountedRows = () => [...(surface?.querySelectorAll<HTMLElement>("[data-row-index]") ?? [])]
+    const snapshot = (): Snapshot => {
+      const rows = mountedRows()
+      const view = viewport?.getBoundingClientRect()
+      const visibleRows =
+        viewport?.isConnected && view
+          ? rows.filter((row) => {
+              const rect = row.getBoundingClientRect()
+              return rect.bottom > view.top && rect.top < view.bottom
+            }).length
+          : 0
+      return {
+        mode: { resource: resourceMode, reconnect: reconnectMode },
+        operation: {
+          sequence: ++snapshotSequence,
+          phase,
+          time: performance.now(),
+          frame: browserFrame,
+        },
+        resourceState: resource.state,
+        routeConnected: route?.isConnected ?? false,
+        viewportConnected: viewport?.isConnected ?? false,
+        viewportOwnedByRoute: !!route && !!viewport && route.contains(viewport),
+        sameRoute: route === initialRoute,
+        sameViewport: viewport === initialViewport,
+        sameSurface: surface === initialSurface,
+        sameMountedRows:
+          initialRows.length > 0 &&
+          initialRows.length === rows.length &&
+          initialRows.every((row, index) => row === rows[index]),
+        nativeOffset: viewport?.scrollTop ?? -1,
+        coreOffset: virtualizer.scrollOffset ?? -1,
+        rangeStart: virtualizer.range?.startIndex ?? -1,
+        rangeEnd: virtualizer.range?.endIndex ?? -1,
+        indexes: virtualizer.getVirtualItems().map((item) => item.index),
+        domIndexes: rows.map((row) => Number(row.dataset.rowIndex)),
+        logicalSurfaceHeight: Number.parseFloat(surface?.style.height ?? "-1"),
+        renderedSurfaceHeight: surface?.getBoundingClientRect().height ?? -1,
+        viewportClientHeight: viewport?.clientHeight ?? -1,
+        viewportScrollHeight: viewport?.scrollHeight ?? -1,
+        visibleRows,
+        minimumRowTop:
+          rows.length && view ? Math.min(...rows.map((row) => row.getBoundingClientRect().top - view.top)) : -1,
+        domScrollEvents,
+        lastScrollTrusted,
+        coreOffsetCallbackCalls,
+        offsetCallbackSources: [...offsetCallbackSources],
+        rectObserverCallbacks,
+        ignoredDetachedZeroRects,
+        syntheticScrollDispatches: 0,
+        mutationEvents: mutationEvents.map((event) => ({ ...event })),
+      }
+    }
+
+    onMount(() => {
+      if (!route || !viewport || !surface) throw new Error("Timeline fixture did not mount")
+      const routeRoot = route.parentElement
+      if (!routeRoot) throw new Error("Timeline route root did not mount")
+      initialRoute = route
+      initialViewport = viewport
+      initialSurface = surface
+      viewport.addEventListener("scroll", (event) => {
+        domScrollEvents++
+        lastScrollTrusted = event.isTrusted
+      })
+      const countFrames = () => {
+        browserFrame++
+        requestAnimationFrame(countFrames)
+      }
+      requestAnimationFrame(countFrames)
+      new MutationObserver((records) => {
+        const callbackTime = performance.now()
+        records.forEach((record) => {
+          ;([...(record.removedNodes ?? [])] as Node[]).forEach((node) => {
+            if (node !== route) return
+            phase = "detached"
+            mutationEvents.push({
+              kind: "removed",
+              callbackTime,
+              callbackFrame: browserFrame,
+              routeConnectedInCallback: route.isConnected,
+              nativeOffsetInCallback: viewport.scrollTop,
+            })
+          })
+          ;([...(record.addedNodes ?? [])] as Node[]).forEach((node) => {
+            if (node !== route) return
+            phase = "reinserted"
+            mutationEvents.push({
+              kind: "added",
+              callbackTime,
+              callbackFrame: browserFrame,
+              routeConnectedInCallback: route.isConnected,
+              nativeOffsetInCallback: viewport.scrollTop,
+            })
+          })
+        })
+      }).observe(routeRoot, { childList: true })
+      window.timelineSuspense = {
+        prepare: async () => {
+          phase = "preparing"
+          await frames(2)
+          viewport.scrollTop = viewport.scrollHeight
+          await frames(3)
+          await new Promise((resolve) => setTimeout(resolve, 200))
+          await frames(2)
+          initialRows = mountedRows()
+          phase = "prepared"
+          return snapshot()
+        },
+        trigger: () => {
+          phase = "triggering"
+          setRefresh(true)
+        },
+        resolve: () => {
+          if (!resolveResource) throw new Error("Resource is not pending")
+          phase = "resolving"
+          resolveResource()
+        },
+        frames,
+        snapshot,
+      }
+    })
+
+    return (
+      <section ref={route} data-route style={{ width: "900px", margin: "0 auto" }}>
+        <span aria-hidden="true" style={{ display: "none" }}>
+          {resourceMode === "guard" && resource.state === "refreshing" ? resource.latest : resource()}
+        </span>
+        <div
+          ref={viewport}
+          data-viewport
+          style={{
+            height: "600px",
+            overflow: "auto",
+            "overflow-anchor": "none",
+            position: "relative",
+            background: "#202020",
+            outline: "1px solid #3f3f46",
+          }}
+        >
+          <div
+            ref={surface}
+            data-surface
+            style={{ height: `${virtualizer.getTotalSize()}px`, position: "relative", "overflow-anchor": "none" }}
+          >
+            <For each={virtualizer.getVirtualItems()}>
+              {(item) => (
+                <div
+                  data-row-index={item.index}
+                  style={{
+                    position: "absolute",
+                    top: "0",
+                    left: "0",
+                    width: "100%",
+                    height: `${item.size}px`,
+                    transform: `translateY(${item.start}px)`,
+                    padding: "10px 14px",
+                    border: "0 solid #333",
+                    "border-bottom-width": "1px",
+                  }}
+                >
+                  logical row {item.index}
+                </div>
+              )}
+            </For>
+          </div>
+        </div>
+      </section>
+    )
+  }
+
+  return (
+    <main>
+      <Suspense>
+        <Route />
+      </Suspense>
+    </main>
+  )
+}
+
+render(() => <App />, document.getElementById("root")!)