refactor(client): 四处轮询站点迁移到 use-polling，语义逐一保持

- SubagentView useSubagentLive：self-scheduling（上一请求 settle 后才排
  下一次，不重叠）+ 每代 AbortSignal + signal.aborted 拦迟到写入，行为
  与原 disposed 标志等价（teardown 同步置 disposed 并 abort）。
- SideChatView：立即拉取 effect 与 2s 定时拆分——输入变化（含 running
  翻转）仍先拉一次转录，运行中间隔 tick 拉转录+徽章；fetchThread 自带
  的逐次 abort 与卸载 abort 原样保留。
- GitLens：可见时 2s 固定静默 tick，无初始突发（mount/scope 变更的完整
  刷新在别处）；refresh 身份变化照旧重启间隔相位。
- ChangesTab：输入变化即拉一次（含隐藏态翻转），可见时 2.5s 固定间隔；
  pull 内部 pollGen 代际守卫不动。

守护 spec 全绿：subagent-live-polling + subagent-jobs-view 13/13、
sidechat-view + sidechat-transcript 29/29、git-view-worktree +
changes-tab + changes-ops 13/13；断言零改动。

src/client/SideChatView.tsx

@@ -69,6 +69,7 @@ import {
   type SidechatTranscriptRow,
 } from './sidechat-transcript.ts'
 import { api } from './api.ts'
+import { usePolling } from './use-polling.ts'
 import { t } from './locales.ts'
 import type { SessionScope } from './api.ts'
 import type { SidebarTab } from './state.ts'
@@ -493,17 +494,25 @@ export function SideChatView(props: {
     }
   }, [threadId, fetchInfo])
 
-  // Poll while the tab is visible and the thread runs.
+  // One transcript pull on every input change (attach, visibility flip,
+  // run-state flip — the last one catches a thread's terminal state once it
+  // stops running).
   useEffect(() => {
     if (!visible || threadId === undefined) return
     void fetchThread(threadId)
-    if (!running) return
-    const timer = window.setInterval(() => {
+    // `running` is not read here, but re-triggering this pull on run-state
+    // flips is load-bearing (see above); the badge fetch rides the ticks.
+  }, [visible, threadId, running, fetchThread])
+
+  // Poll while the tab is visible and the thread runs: transcript deltas +
+  // badge refresh on a fixed cadence. Each pull self-guards (fetchThread
+  // aborts its predecessor; a late settle keeps the last rows).
+  const pollTick = useCallback(async (): Promise<void> => {
+    if (threadId === undefined) return
     void fetchThread(threadId)
     void fetchInfo(threadId)
-    }, POLL_MS)
-    return () => { window.clearInterval(timer) }
-  }, [visible, threadId, running, fetchThread, fetchInfo])
+  }, [threadId, fetchThread, fetchInfo])
+  usePolling(visible && running && threadId !== undefined, pollTick, { intervalMs: POLL_MS })
 
   useEffect(() => () => { controllerRef.current?.abort() }, [])
 

src/client/SubagentView.tsx

@@ -53,6 +53,7 @@ import {
   type TreeJob,
 } from './subagent-jobs.ts'
 import { api, type JobOutputResult } from './api.ts'
+import { usePolling } from './use-polling.ts'
 import { IconStopOutline16 } from './icons.tsx'
 import { t } from './locales.ts'
 import css from './SubagentView.module.css'
@@ -180,52 +181,30 @@ function SubagentLiveLines(props: { live: LastActivity | undefined }) {
 /**
  * One shared live-preview poller for the whole Subagent tree. Unlike the old
  * per-card `subagents.history` timers, this sends at most ONE `subagents.live`
- * request at a time: a recursive timeout starts only after the previous
- * request settles, so a slow host never sees abort/restart storms.
+ * request at a time (the shared poller's self-scheduling mode arms the next
+ * tick only after the previous request settles, so a slow host never sees
+ * abort/restart storms); a response settling after the poller stopped (page
+ * hidden, tree re-rooted) is dropped via the aborted signal.
  */
 function useSubagentLive(
   rootId: string | undefined,
   active: boolean,
 ): Readonly<Record<string, LastActivity>> {
   const [live, setLive] = useState<Record<string, LastActivity>>({})
-  const controllerRef = useRef<AbortController | undefined>(undefined)
 
   // A new tree must never inherit another root's live previews.
   useEffect(() => { setLive({}) }, [rootId])
 
-  useEffect(() => {
-    if (rootId === undefined || !active) return
-    const targetRootId = rootId
-    let disposed = false
-    let timer: number | undefined
-
-    const schedule = (): void => {
-      if (disposed) return
-      timer = window.setTimeout(() => { void load() }, POLL_MS)
-    }
-    async function load(): Promise<void> {
-      if (disposed) return
-      const controller = new AbortController()
-      controllerRef.current = controller
-      try {
-        const result = await api.subagentsLive(targetRootId, controller.signal)
-        if (!disposed) setLive(result.live)
-      } catch {
-        // Keep the last known live map; the next scheduled poll retries.
-      } finally {
-        if (controllerRef.current === controller) controllerRef.current = undefined
-        if (!disposed) schedule()
-      }
-    }
-
-    void load()
-    return () => {
-      disposed = true
-      if (timer !== undefined) window.clearTimeout(timer)
-      controllerRef.current?.abort()
-      controllerRef.current = undefined
-    }
-  }, [rootId, active])
+  const poll = useCallback(async (signal: AbortSignal): Promise<void> => {
+    if (rootId === undefined) return
+    const result = await api.subagentsLive(rootId, signal)
+    if (!signal.aborted) setLive(result.live)
+  }, [rootId])
+  usePolling(rootId !== undefined && active, poll, {
+    intervalMs: POLL_MS,
+    mode: 'self-scheduling',
+    immediate: true,
+  })
 
   return live
 }

src/client/changes/ChangesTab.tsx

@@ -18,6 +18,7 @@ import type { SidebarSessionEvent } from '../../context-types.ts'
 import type { TabComponentProps } from '../service.ts'
 import { t } from '../locales.ts'
 import { api } from '../api.ts'
+import { usePolling } from '../use-polling.ts'
 import { floatTab, type SidebarDiffRef } from '../state.ts'
 import { GitLens } from './GitLens.tsx'
 import { SessionLens } from './SessionLens.tsx'
@@ -104,12 +105,11 @@ export function ChangesTab({ ctx, store, scope, tab, visible, onOpenFile, onOpen
     seqRef.current = 0
     setOpsError(false)
   }, [scope.sessionId])
-  useEffect(() => {
-    void pull()
-    if (!visible) return
-    const timer = window.setInterval(() => { void pull() }, 2_500)
-    return () => { window.clearInterval(timer) }
-  }, [visible, pull])
+  // One pull on every input change — mount, scope change, and visibility
+  // flip all re-pull (a hidden tab still catches up on the flip); only the
+  // poll CADENCE below is gated by visibility.
+  useEffect(() => { void pull() }, [visible, pull])
+  usePolling(visible, pull, { intervalMs: 2_500 })
   // tick only forces the re-render; the fold reads the ref directly.
   void tick
   const ops = opsRef.current

src/client/changes/GitLens.tsx

@@ -17,6 +17,7 @@ import {
 } from '@deepseek-ai/dsh-client-ui-primitives'
 import type { GitLogEntry, GitStatusEntry, GitStatusResult, GitWorktree, SessionScope } from '../api.ts'
 import { api } from '../api.ts'
+import { usePolling } from '../use-polling.ts'
 import { baseName, isWithinWorkspace, relativeTo } from '../paths.ts'
 import { resolveSidebarPath } from '../produced-files.ts'
 import { relativeTime, t } from '../locales.ts'
@@ -280,11 +281,11 @@ export function GitLens(props: GitLensProps) {
     const generation = refreshGeneration.current += 1
     void refreshTarget(chosenPathRef.current ?? '', { loading: true, generation })
   }
-  useEffect(() => {
-    if (!visible) return
-    const timer = window.setInterval(() => { void refresh(true) }, 2_000)
-    return () => { window.clearInterval(timer) }
-  }, [visible, refresh])
+  /** The silent poll tick (the status-only fast path between worktree
+   *  re-lists, see refresh) — fixed 2s cadence while visible, no initial
+   *  burst (mount and scope changes already refresh above). */
+  const pollTick = useCallback((): Promise<void> => refresh(true), [refresh])
+  usePolling(visible, pollTick, { intervalMs: 2_000 })
 
   /** Append the next history page (lazy: only when the user asks for more). */
   const loadMoreLog = async (): Promise<void> => {