Recover branch compare on visibility change

Add recovery mode that reuses cached branch comparison data when the window regains focus instead of clearing results and forcing a refresh. This preserves the diff display during operations like rebasing that may cause the window to go to the background.

src/renderer/src/components/right-sidebar/source-control/sync/use-branch-compare.ts

@@ -3,6 +3,7 @@ import { installWindowVisibilityInterval } from '@/lib/window-visibility-interva
 import { getConnectionId } from '@/lib/connection-context'
 import { getRuntimeGitBranchCompare, type RuntimeGitContext } from '@/runtime/runtime-git-client'
 import { useAppStore } from '@/store'
+import { createLoadingBranchCompareSummary } from '@/store/slices/editor/git/branch-compare-state'
 import type { GitUpstreamStatus } from '../../../../../../shared/git-status-types'
 import { shouldClearBranchCompareForMissingBase } from './base-ref-resolution'
 import {
@@ -18,7 +19,7 @@ export const BRANCH_REFRESH_INTERVAL_MS = 30_000
 const BRANCH_REFRESH_IDLE_MULTIPLIER = 1
 const BRANCH_REFRESH_MAX_INTERVAL_MS = 5 * 60_000
 
-type BranchCompareRefreshKind = 'immediate' | 'interval'
+type BranchCompareRefreshKind = 'immediate' | 'interval' | 'recovery'
 
 export function useSourceControlBranchCompare({
   activeRepoSettings,
@@ -40,10 +41,7 @@ export function useSourceControlBranchCompare({
   isBranchVisible: boolean
   activeGitStatusHead: string | null
   remoteStatus: GitUpstreamStatus | undefined
-}): {
-  refreshBranchCompare: () => Promise<void>
-  refreshBranchCompareRef: React.RefObject<() => Promise<void>>
-} {
+}) {
   const beginGitBranchCompareRequest = useAppStore((s) => s.beginGitBranchCompareRequest)
   const setGitBranchCompareResult = useAppStore((s) => s.setGitBranchCompareResult)
   const clearGitBranchCompare = useAppStore((s) => s.clearGitBranchCompare)
@@ -67,27 +65,19 @@ export function useSourceControlBranchCompare({
         return
       }
       const requestKey = `${activeWorktreeId}:${compareBaseRef}:${Date.now()}`
-      const existingSummary =
-        useAppStore.getState().gitBranchCompareSummaryByWorktree[activeWorktreeId]
-      // Why: only reset to 'loading' on the first request or a base-ref change; resetting on every poll caused a visible loading→error→loading flicker.
-      const baseRefChanged = existingSummary && existingSummary.baseRef !== compareBaseRef
-      const shouldResetToLoading = !existingSummary || baseRefChanged
-      if (shouldResetToLoading) {
-        beginGitBranchCompareRequest(activeWorktreeId, requestKey, compareBaseRef)
-      } else {
-        beginGitBranchCompareRequest(activeWorktreeId, requestKey, compareBaseRef, {
-          preserveExistingSummary: true
-        })
-      }
+      const summary = useAppStore.getState().gitBranchCompareSummaryByWorktree[activeWorktreeId]
+      // Why: polling should preserve results unless the comparison base changed.
+      beginGitBranchCompareRequest(activeWorktreeId, requestKey, compareBaseRef, {
+        preserveExistingSummary: !!summary && summary.baseRef === compareBaseRef
+      })
       try {
-        const connectionId = getConnectionId(activeWorktreeId) ?? undefined
         const result = await getRuntimeGitBranchCompare(
           {
             // Why: route the branch compare by the repo OWNER host, not the focused runtime.
             settings: activeRepoSettings,
             worktreeId: activeWorktreeId,
             worktreePath,
-            connectionId
+            connectionId: getConnectionId(activeWorktreeId) ?? undefined
           },
           compareBaseRef,
           kind === 'interval' ? 'background' : 'interactive'
@@ -96,12 +86,8 @@ export function useSourceControlBranchCompare({
       } catch (error) {
         setGitBranchCompareResult(activeWorktreeId, requestKey, {
           summary: {
-            baseRef: compareBaseRef,
-            baseOid: null,
+            ...createLoadingBranchCompareSummary(compareBaseRef),
             compareRef: branchName,
-            headOid: null,
-            mergeBase: null,
-            changedFiles: 0,
             status: 'error',
             errorMessage: error instanceof Error ? error.message : 'Branch compare failed'
           },
@@ -154,11 +140,23 @@ export function useSourceControlBranchCompare({
 
   const startBranchCompare = useCallback(
     async (kind: BranchCompareRefreshKind) => {
-      if (kind === 'immediate') {
+      if (kind === 'recovery') {
+        const summary =
+          useAppStore.getState().gitBranchCompareSummaryByWorktree[activeWorktreeId ?? '']
+        // Why: reuse an in-flight result if it recovered the visible data before this rerun.
+        if (summary && summary.status !== 'loading' && summary.baseRef === compareBaseRef) {
+          scheduleBranchComparePoll()
+          return
+        }
+      }
+      if (kind !== 'interval') {
         clearBranchComparePollTimer()
       }
       if (branchCompareInFlightRef.current) {
-        if (kind === 'immediate' || branchCompareRerunRef.current === null) {
+        if (
+          branchCompareRerunRef.current !== 'immediate' &&
+          (kind !== 'interval' || branchCompareRerunRef.current === null)
+        ) {
           branchCompareRerunRef.current = kind
         }
         return branchCompareRunPromiseRef.current ?? undefined
@@ -191,21 +189,27 @@ export function useSourceControlBranchCompare({
           branchCompareRerunRef.current = null
           if (rerunKind === 'immediate') {
             await refreshBranchCompareRef.current()
+          } else if (rerunKind === 'recovery') {
+            await startBranchCompareRef.current('recovery')
           } else if (rerunKind === 'interval') {
             scheduleBranchComparePoll()
           }
         }
       })()
       branchCompareRunPromiseRef.current = runPromise
-      try {
-        await runPromise
-      } finally {
+      await runPromise.finally(() => {
         if (branchCompareRunPromiseRef.current === runPromise) {
           branchCompareRunPromiseRef.current = null
         }
-      }
+      })
     },
-    [clearBranchComparePollTimer, runBranchCompare, scheduleBranchComparePoll]
+    [
+      activeWorktreeId,
+      compareBaseRef,
+      clearBranchComparePollTimer,
+      runBranchCompare,
+      scheduleBranchComparePoll
+    ]
   )
   const refreshBranchCompare = useCallback(
     () => startBranchCompare('immediate'),
@@ -280,6 +284,7 @@ export function useSourceControlBranchCompare({
     branchComparePollEnabledRef.current = true
     const stopInterval = installWindowVisibilityInterval({
       run: () => void startBranchCompareRef.current('interval'),
+      runOnVisible: () => void startBranchCompareRef.current('recovery'),
       jitterOnVisible: true,
       intervalMs: BRANCH_REFRESH_INTERVAL_MS
     })

src/renderer/src/components/right-sidebar/use-source-control-branch-compare.test.tsx

@@ -9,7 +9,10 @@ const mocks = vi.hoisted(() => ({
   beginGitBranchCompareRequest: vi.fn(),
   setGitBranchCompareResult: vi.fn(),
   clearGitBranchCompare: vi.fn(),
-  gitBranchCompareSummaryByWorktree: {} as Record<string, { baseRef: string } | undefined>
+  gitBranchCompareSummaryByWorktree: {} as Record<
+    string,
+    { baseRef: string; status?: string } | undefined
+  >
 }))
 
 vi.mock('@/runtime/runtime-git-client', () => ({
@@ -235,6 +238,9 @@ describe('useSourceControlBranchCompare scheduler', () => {
     vi.useFakeTimers()
     const first = deferred<typeof OK>()
     mocks.getRuntimeGitBranchCompare.mockReturnValueOnce(first.promise)
+    mocks.gitBranchCompareSummaryByWorktree = {
+      A: { baseRef: 'origin/main', status: 'ready' }
+    }
     // Visible mounts run once immediately through the visibility interval.
     await mount({ isBranchVisible: true })
     expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(1)
@@ -296,7 +302,8 @@ describe('useSourceControlBranchCompare scheduler', () => {
     expect(mocks.beginGitBranchCompareRequest).toHaveBeenLastCalledWith(
       'A',
       expect.any(String),
-      'origin/dev'
+      'origin/dev',
+      { preserveExistingSummary: false }
     )
   })
 
@@ -363,3 +370,132 @@ describe('useSourceControlBranchCompare scheduler', () => {
     expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(2)
   })
 })
+
+describe('branch comparison visibility recovery', () => {
+  it.each(['loading', 'missing', 'base-change'])(
+    'bypasses slow polling backoff for %s data',
+    async (reason) => {
+      vi.useFakeTimers()
+      const first = deferred<typeof OK>()
+      mocks.getRuntimeGitBranchCompare.mockReturnValueOnce(first.promise)
+      const root = await mount({ isBranchVisible: true, statusHead: 'head-1' })
+      await act(async () => {
+        root.render(<Probe isBranchVisible={false} statusHead="head-1" />)
+        await vi.advanceTimersByTimeAsync(90_000)
+        first.resolve(OK)
+      })
+      await flush()
+      mocks.gitBranchCompareSummaryByWorktree =
+        reason === 'missing'
+          ? {}
+          : {
+              A: { baseRef: 'origin/main', status: reason === 'loading' ? 'loading' : 'ready' }
+            }
+      await act(async () => {
+        root.render(
+          <Probe
+            isBranchVisible
+            statusHead="head-2"
+            compareBaseRef={reason === 'base-change' ? 'origin/dev' : 'origin/main'}
+          />
+        )
+      })
+      await flush()
+      expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(2)
+      expect(mocks.getRuntimeGitBranchCompare).toHaveBeenLastCalledWith(
+        expect.objectContaining({ worktreeId: 'A' }),
+        reason === 'base-change' ? 'origin/dev' : 'origin/main',
+        'interactive'
+      )
+    }
+  )
+
+  it('preserves slow polling backoff when reopening valid data', async () => {
+    vi.useFakeTimers()
+    const first = deferred<typeof OK>()
+    mocks.getRuntimeGitBranchCompare.mockReturnValueOnce(first.promise)
+    const root = await mount({ isBranchVisible: true, statusHead: 'head-1' })
+    await act(async () => {
+      root.render(<Probe isBranchVisible={false} statusHead="head-1" />)
+      await vi.advanceTimersByTimeAsync(90_000)
+      first.resolve(OK)
+    })
+    await flush()
+    mocks.gitBranchCompareSummaryByWorktree = {
+      A: { baseRef: 'origin/main', status: 'ready' }
+    }
+    await act(async () => {
+      root.render(<Probe isBranchVisible statusHead="head-1" />)
+    })
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(89_999)
+    })
+    expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(1)
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(1)
+    })
+    expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(2)
+    expect(mocks.getRuntimeGitBranchCompare).toHaveBeenLastCalledWith(
+      expect.objectContaining({ worktreeId: 'A' }),
+      'origin/main',
+      'background'
+    )
+  })
+
+  it('coalesces rapid stale reopenings behind a slow request', async () => {
+    const first = deferred<typeof OK>()
+    mocks.getRuntimeGitBranchCompare.mockReturnValueOnce(first.promise)
+    const root = await mount({ isBranchVisible: true, statusHead: 'head-1' })
+    mocks.gitBranchCompareSummaryByWorktree = {
+      A: { baseRef: 'origin/main', status: 'loading' }
+    }
+    for (let i = 0; i < 5; i++) {
+      await act(async () => {
+        root.render(<Probe isBranchVisible={false} statusHead="head-2" />)
+      })
+      await act(async () => {
+        root.render(<Probe isBranchVisible statusHead="head-2" />)
+      })
+    }
+    expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(1)
+    await act(async () => {
+      first.resolve(OK)
+    })
+    await flush()
+    expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(2)
+  })
+})
+
+it('reuses a recovered in-flight result after reopening instead of immediately comparing twice', async () => {
+  vi.useFakeTimers()
+  const first = deferred<typeof OK>()
+  mocks.getRuntimeGitBranchCompare.mockReturnValueOnce(first.promise)
+  const root = await mount({ isBranchVisible: true, statusHead: 'head-1' })
+  mocks.gitBranchCompareSummaryByWorktree = {
+    A: { baseRef: 'origin/main', status: 'loading' }
+  }
+  await act(async () => {
+    root.render(<Probe isBranchVisible={false} statusHead="head-1" />)
+  })
+  await act(async () => {
+    root.render(<Probe isBranchVisible statusHead="head-1" />)
+  })
+  mocks.setGitBranchCompareResult.mockImplementation(() => {
+    mocks.gitBranchCompareSummaryByWorktree = {
+      A: { baseRef: 'origin/main', status: 'ready' }
+    }
+  })
+  await act(async () => {
+    first.resolve(OK)
+  })
+  await flush()
+  expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(1)
+  await act(async () => {
+    await vi.advanceTimersByTimeAsync(BRANCH_REFRESH_INTERVAL_MS - 1)
+  })
+  expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(1)
+  await act(async () => {
+    await vi.advanceTimersByTimeAsync(1)
+  })
+  expect(mocks.getRuntimeGitBranchCompare).toHaveBeenCalledTimes(2)
+})