fix(task-page): restore the STA-5949 GitHub list scroll restore

The split left this logic inline in use-task-page-github-detail.ts at its
pre-STA-5949 shape: a 5s deadline whose expiry overwrote the remembered offset
with the committed 0 -- the permanent-loss bug the extracted module's header
says was removed -- observing only the children rather than the container, and
with no MutationObserver, so late-mounting rows never retriggered a retry. The
list scroll handler also blanket-returned while a restore was pending instead
of classifying echoes, dropping a user's scroll during an unreachable restore.

Promotes the module to a live path and wires the hook and scroll handler to it,
which also gives the ten behavioral cases in the scroll-restore suite something
live to assert against.

src/renderer/src/components/TaskPageGitHubList.tsx

@@ -13,6 +13,7 @@ import { Button } from '@/components/ui/button'
 import { LoaderCircle } from 'lucide-react'
 import { TaskPageGitHubRows } from './TaskPageGitHubRows'
 import { PaginationBar } from './TaskPagePaginationBar'
+import { supersedeGitHubListScrollRestore } from './task-page-github-list-scroll-restore'
 export function TaskPageGitHubList({
   model
 }: {
@@ -33,6 +34,7 @@ export function TaskPageGitHubList({
     githubListScrollRef,
     githubListScrollTopRef,
     pendingGithubScrollRestoreRef,
+    githubListRestoreWriteRef,
     loadingTargetPage,
     taskListPositionRef,
     perRepoSourceState,
@@ -61,14 +63,21 @@ export function TaskPageGitHubList({
         }}
         onScroll={(event) => {
           const state = useAppStore.getState()
-          if (
-            state.activeView !== 'tasks' ||
-            state.taskPageData.openGitHubWorkItem ||
-            pendingGithubScrollRestoreRef.current !== null
-          ) {
+          if (state.activeView !== 'tasks' || state.taskPageData.openGitHubWorkItem) {
             return
           }
           const scrollTop = event.currentTarget.scrollTop
+          // Why: a restore's own write must not be saved as the user's position, but a real
+          // user scroll has to supersede a pending restore or saving stays suppressed.
+          if (
+            !supersedeGitHubListScrollRestore({
+              scrollTop,
+              pendingRestoreRef: pendingGithubScrollRestoreRef,
+              restoreWriteRef: githubListRestoreWriteRef
+            })
+          ) {
+            return
+          }
           githubListScrollTopRef.current = scrollTop
           taskListPositionRef.current = {
             contextKey: githubResumeContextKey,

src/renderer/src/components/task-page-github-list-scroll-restore.test.ts

@@ -6,7 +6,7 @@ import {
   startGitHubListScrollRestore,
   supersedeGitHubListScrollRestore,
   type GitHubListRestoreWrite
-} from './task-page/github/github-list-scroll-restore'
+} from './task-page-github-list-scroll-restore'
 
 type FakeResizeObserver = {
   targets: Set<Element>

src/renderer/src/components/task-page/github/github-work-item-table.tsx

@@ -27,7 +27,7 @@ import type { TaskPageGitHubWorkItemMutationRunner } from './github-work-item-mu
 import {
   supersedeGitHubListScrollRestore,
   type GitHubListRestoreWrite
-} from './github-list-scroll-restore'
+} from '@/components/task-page-github-list-scroll-restore'
 import { GithubWorkItemRows } from './github-work-item-rows'
 import { PaginationBar } from '../pagination/pagination-bar'
 

src/renderer/src/components/task-page/hooks/use-task-page-github-list-state.ts

@@ -9,7 +9,7 @@ import { sortWorkItemsByNumber } from '../../../../../shared/work-items'
 import type { GitHubWorkItem } from '../../../../../shared/github/work-item-types'
 import type { Repo } from '../../../../../shared/repo-types'
 import type { TaskViewPresetId } from '../../../../../shared/ui-chrome-types'
-import type { GitHubListRestoreWrite } from '@/components/task-page/github/github-list-scroll-restore'
+import type { GitHubListRestoreWrite } from '@/components/task-page-github-list-scroll-restore'
 import type { AppState } from '@/store/types'
 
 export function useTaskPageGitHubListState({

src/renderer/src/components/use-task-page-github-detail.ts

@@ -11,6 +11,7 @@ import {
 import type { GitHubWorkItem } from '../../../shared/github/work-item-types'
 import type { GitLabWorkItem } from '../../../shared/gitlab-types'
 import { getTaskPageRepoCacheInput, getTaskPageRepoSourceContext } from './task-page-source-context'
+import { startGitHubListScrollRestore } from './task-page-github-list-scroll-restore'
 
 function getTaskPageScrollTop(
   scrollRef: React.RefObject<HTMLElement | null>,
@@ -38,6 +39,7 @@ export function useTaskPageGitHubDetail(model: TaskPageGitHubListStateModel) {
     githubListScrollRef,
     githubListScrollTopRef,
     pendingGithubScrollRestoreRef,
+    githubListRestoreWriteRef,
     taskListPositionRef
   } = model
   // Why: the dialog's "Use" button routes through the same direct-launch flow as the row-level "Use" CTA so behavior is consistent regardless of entry point.
@@ -73,67 +75,28 @@ export function useTaskPageGitHubDetail(model: TaskPageGitHubListStateModel) {
     ? (cachedDialogWorkItem ?? githubTaskDrawerWorkItem)
     : null
   useLayoutEffect(() => {
-    const scrollTop = pendingGithubScrollRestoreRef.current
-    const scrollElement = githubListScrollRef.current
-    if (scrollTop === null || !scrollElement || !pages[currentPage]) {
+    const target = pendingGithubScrollRestoreRef.current
+    if (target === null || !githubListScrollRef.current || !pages[currentPage]) {
       return
     }
-    let frame: number | null = null
-    let timeout: number | null = null
-    let observer: ResizeObserver | null = null
-    const clearScheduledRestore = (): void => {
-      if (frame !== null) {
-        window.cancelAnimationFrame(frame)
-        frame = null
-      }
-      if (timeout !== null) {
-        window.clearTimeout(timeout)
-        timeout = null
-      }
-      observer?.disconnect()
-    }
-    const restore = (): void => {
-      const committedScrollElement = githubListScrollRef.current
-      if (!committedScrollElement || pendingGithubScrollRestoreRef.current !== scrollTop) {
-        return
-      }
-      committedScrollElement.scrollTop = scrollTop
-      githubListScrollTopRef.current = scrollTop
-      taskListPositionRef.current = {
-        contextKey: githubResumeContextKey,
-        page: currentPage,
-        scrollTop
-      }
-      if (Math.abs(committedScrollElement.scrollTop - scrollTop) < 1) {
-        pendingGithubScrollRestoreRef.current = null
-        clearScheduledRestore()
-      }
-    }
-    observer = new ResizeObserver(restore)
-    for (const child of scrollElement.children) {
-      observer.observe(child)
-    }
-    restore()
-    if (pendingGithubScrollRestoreRef.current === scrollTop) {
-      frame = window.requestAnimationFrame(restore)
-      timeout = window.setTimeout(() => {
-        if (pendingGithubScrollRestoreRef.current === scrollTop) {
-          const committedScrollTop = getTaskPageScrollTop(githubListScrollRef, 0)
-          githubListScrollTopRef.current = committedScrollTop
-          taskListPositionRef.current = {
-            contextKey: githubResumeContextKey,
-            page: currentPage,
-            scrollTop: committedScrollTop
-          }
-          pendingGithubScrollRestoreRef.current = null
+    return startGitHubListScrollRestore({
+      target,
+      scrollElementRef: githubListScrollRef,
+      pendingRestoreRef: pendingGithubScrollRestoreRef,
+      restoreWriteRef: githubListRestoreWriteRef,
+      onScrollTopApplied: (scrollTop) => {
+        githubListScrollTopRef.current = scrollTop
+        taskListPositionRef.current = {
+          contextKey: githubResumeContextKey,
+          page: currentPage,
+          scrollTop
         }
-        clearScheduledRestore()
-      }, 5_000)
-    }
-    return clearScheduledRestore
+      }
+    })
   }, [
     currentPage,
     dialogWorkItem,
+    githubListRestoreWriteRef,
     githubListScrollRef,
     githubListScrollTopRef,
     githubResumeContextKey,

src/renderer/src/components/use-task-page-github-list-state.ts

@@ -10,6 +10,7 @@ import {
 } from '@/components/task-page-github-resume-cache'
 import { sortWorkItemsByNumber } from '../../../shared/work-items'
 import { useAppStore } from '@/store'
+import type { GitHubListRestoreWrite } from './task-page-github-list-scroll-restore'
 import { getTaskPageRepoSourceContext } from './task-page-source-context'
 export function useTaskPageGitHubListState(model: TaskPageProviderStateModel) {
   const {
@@ -99,6 +100,7 @@ export function useTaskPageGitHubListState(model: TaskPageProviderStateModel) {
   const githubListScrollRef = useRef<HTMLDivElement>(null)
   const githubListScrollTopRef = useRef(0)
   const pendingGithubScrollRestoreRef = useRef<number | null>(null)
+  const githubListRestoreWriteRef = useRef<GitHubListRestoreWrite | null>(null)
   const [paginationLoading, setPaginationLoading] = useState(false)
   const [loadingTargetPage, setLoadingTargetPage] = useState<number | null>(null)
   const [countedTotalPages, setCountedTotalPages] = useState<number | null>(null)
@@ -218,6 +220,7 @@ export function useTaskPageGitHubListState(model: TaskPageProviderStateModel) {
     githubListScrollRef: typeof githubListScrollRef
     githubListScrollTopRef: typeof githubListScrollTopRef
     pendingGithubScrollRestoreRef: typeof pendingGithubScrollRestoreRef
+    githubListRestoreWriteRef: typeof githubListRestoreWriteRef
     paginationLoading: typeof paginationLoading
     setPaginationLoading: typeof setPaginationLoading
     loadingTargetPage: typeof loadingTargetPage
@@ -275,6 +278,7 @@ export function useTaskPageGitHubListState(model: TaskPageProviderStateModel) {
   nextModel.githubListScrollRef = githubListScrollRef
   nextModel.githubListScrollTopRef = githubListScrollTopRef
   nextModel.pendingGithubScrollRestoreRef = pendingGithubScrollRestoreRef
+  nextModel.githubListRestoreWriteRef = githubListRestoreWriteRef
   nextModel.paginationLoading = paginationLoading
   nextModel.setPaginationLoading = setPaginationLoading
   nextModel.loadingTargetPage = loadingTargetPage