From 34bdf418cedcd628d97fe8c375112a4c5ac057ff Mon Sep 17 00:00:00 2001
From: Kelvin Amoaba <97001695+AmoabaKelvin@users.noreply.github.com>
Date: Fri, 6 Nov 2026 16:56:29 +0000
Subject: [PATCH] perf(mobile): trim Home and host list re-renders (#39076)

---
 mobile/src/home/MobileHomeJumpBackIn.tsx      |  20 +-
 mobile/src/home/MobileHomeScreen.tsx          |  55 ++--
 .../src/host-screen/host-workspace-list.tsx   | 234 +++++++++++-------
 3 files changed, 188 insertions(+), 121 deletions(-)

diff --git a/mobile/src/home/MobileHomeJumpBackIn.tsx b/mobile/src/home/MobileHomeJumpBackIn.tsx
index d2ca64279a2..5d3e101ab47 100644
--- a/mobile/src/home/MobileHomeJumpBackIn.tsx
+++ b/mobile/src/home/MobileHomeJumpBackIn.tsx
@@ -1,5 +1,5 @@
 import { ChevronRight } from 'lucide-react-native'
-import { useState } from 'react'
+import { memo, useMemo, useState } from 'react'
 import { Pressable, Text, View } from 'react-native'
 import Animated, { FadeIn, FadeOut, LinearTransition } from 'react-native-reanimated'
 import type { WorktreeStatus } from '../../../src/shared/worktree-status-rollup'
@@ -9,6 +9,7 @@ import { useReducedMotionEnabled } from '../platform/use-reduced-motion'
 import { colors } from '../theme/mobile-theme'
 import { useMobileColorScheme } from '../theme/use-mobile-color-scheme'
 import { useHostDisplay } from '../transport/use-host-display'
+import { areStructurallyEqual } from '../worktree/structural-equality'
 import type { HostCatalogEntry } from '../transport/types'
 import type { HomeJumpBackInRow } from '../worktree/home-jump-back-in'
 import { agentStateLabel, type AgentDotState } from '../worktree/agent-row-display'
@@ -30,7 +31,8 @@ const TINTED_STATUSES: ReadonlySet<WorktreeStatus> = new Set(['permission', 'fai
 // Enough to see what needs you without the list pushing Desktops off the first screen.
 const AGENT_ROWS_COLLAPSED = 5
 
-export function MobileHomeJumpBackIn(props: {
+// Usage, stats and connection ticks re-render Home; the section redraws only when its rows change.
+export const MobileHomeJumpBackIn = memo(function MobileHomeJumpBackIn(props: {
   rows: readonly HomeJumpBackInRow[]
   hosts: readonly HostCatalogEntry[]
   first: boolean
@@ -40,6 +42,11 @@ export function MobileHomeJumpBackIn(props: {
   useMobileColorScheme()
   const reducedMotion = useReducedMotionEnabled() === true
   const [expanded, setExpanded] = useState(false)
+  // Rows glide to their new place when an agent's state reorders the list.
+  const layout = useMemo(
+    () => (reducedMotion ? undefined : LinearTransition.duration(220).easing(HOME_EASE_OUT)),
+    [reducedMotion]
+  )
   if (props.rows.length === 0) {
     return null
   }
@@ -48,8 +55,6 @@ export function MobileHomeJumpBackIn(props: {
   const collapsible = props.rows.length > AGENT_ROWS_COLLAPSED
   const shown = expanded || !collapsible ? props.rows : props.rows.slice(0, AGENT_ROWS_COLLAPSED)
   const activeCount = props.rows.filter((row) => !row.lastOpened).length
-  // Rows glide to their new place when an agent's state reorders the list.
-  const layout = reducedMotion ? undefined : LinearTransition.duration(220).easing(HOME_EASE_OUT)
   const entering = reducedMotion ? undefined : FadeIn.duration(180)
   return (
     <>
@@ -99,9 +104,10 @@ export function MobileHomeJumpBackIn(props: {
       </Animated.View>
     </>
   )
-}
+})
 
-function JumpBackInRow(props: {
+// Each refresh rebuilds every row object; compare by value so only changed rows redraw.
+const JumpBackInRow = memo(function JumpBackInRow(props: {
   row: HomeJumpBackInRow
   host: HostCatalogEntry | null
   nameDesktop: boolean
@@ -162,4 +168,4 @@ function JumpBackInRow(props: {
       </View>
     </Pressable>
   )
-}
+}, areStructurallyEqual)
diff --git a/mobile/src/home/MobileHomeScreen.tsx b/mobile/src/home/MobileHomeScreen.tsx
index f7ad8e2e9e1..8fa8de3ad88 100644
--- a/mobile/src/home/MobileHomeScreen.tsx
+++ b/mobile/src/home/MobileHomeScreen.tsx
@@ -83,10 +83,12 @@ export function MobileHomeScreen() {
     }, [selectTab, tab])
   )
 
+  // Stable handlers keep the memoized Feed sections and desktop rows from redrawing on every Home update.
+  const { router, setHostCatalog } = data
   const openWorktree = useCallback(
     (row: HomeJumpBackInRow) => {
       if (isResumeTargetConfirmedMissing(row, getProvenCachedWorktrees(row.hostId))) {
-        data.router.push(hostRouteWithNotice(row.hostId, 'worktree-missing'))
+        router.push(hostRouteWithNotice(row.hostId, 'worktree-missing'))
         return
       }
       openMobileSession({
@@ -96,33 +98,39 @@ export function MobileHomeScreen() {
         paneKey: row.worktree.paneKey
       })
     },
-    [data.router, openMobileSession]
+    [router, openMobileSession]
   )
 
-  function openHost(host: HostCatalogEntry): void {
-    if (host.credentialStatus === 'missing') {
-      data.router.push('/pair-scan')
-    } else if (host.credentialStatus === 'temporarily-unavailable') {
-      void loadHostCatalog()
-        .then(data.setHostCatalog)
-        .catch(() =>
-          Alert.alert(
-            t('home.screen.pairingCheckFailed', 'Could not check pairing'),
-            t('home.screen.tryAgain', 'Please try again.')
+  const openHost = useCallback(
+    (host: HostCatalogEntry) => {
+      if (host.credentialStatus === 'missing') {
+        router.push('/pair-scan')
+      } else if (host.credentialStatus === 'temporarily-unavailable') {
+        void loadHostCatalog()
+          .then(setHostCatalog)
+          .catch(() =>
+            Alert.alert(
+              t('home.screen.pairingCheckFailed', 'Could not check pairing'),
+              t('home.screen.tryAgain', 'Please try again.')
+            )
           )
-        )
-    } else {
-      data.router.push(`/h/${host.id}`)
-    }
-  }
+      } else {
+        router.push(`/h/${host.id}`)
+      }
+    },
+    [router, setHostCatalog, t]
+  )
 
-  function openHostActions(host: HostCatalogEntry): void {
+  const openHostActions = useCallback((host: HostCatalogEntry) => {
+    triggerMediumImpact()
     if (host.profile) {
       setActionTarget(host.profile)
     } else {
       setConfirmRemove(host)
     }
-  }
+  }, [])
+
+  const openTasks = useCallback((hostId: string) => openMobileTasks(hostId), [openMobileTasks])
 
   async function handleRemove(): Promise<void> {
     if (!confirmRemove) {
@@ -142,7 +150,7 @@ export function MobileHomeScreen() {
     }
   }
 
-  const pairDesktop = () => data.router.push('/pair-scan')
+  const pairDesktop = useCallback(() => router.push('/pair-scan'), [router])
   const actionTargetPath = actionTarget ? data.hostConnections[actionTarget.id]?.path : undefined
   const actionTargetConnected =
     actionTarget != null && data.hostStates[actionTarget.id] === 'connected'
@@ -188,12 +196,9 @@ export function MobileHomeScreen() {
                   bottomInset={contentBottom}
                   onOpenWorktree={openWorktree}
                   onOpenHost={openHost}
-                  onOpenHostActions={(host) => {
-                    triggerMediumImpact()
-                    openHostActions(host)
-                  }}
+                  onOpenHostActions={openHostActions}
                   onPairDesktop={pairDesktop}
-                  onOpenTasks={(hostId) => openMobileTasks(hostId)}
+                  onOpenTasks={openTasks}
                 />
               ) : id === 'usage' ? (
                 <MobileHomeUsageTab
diff --git a/mobile/src/host-screen/host-workspace-list.tsx b/mobile/src/host-screen/host-workspace-list.tsx
index 9f8fb3b8dbb..bfc4019d99e 100644
--- a/mobile/src/host-screen/host-workspace-list.tsx
+++ b/mobile/src/host-screen/host-workspace-list.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useMemo, type ReactElement } from 'react'
+import { memo, useCallback, useEffect, useMemo, type ReactElement } from 'react'
 import {
   ActivityIndicator,
   Animated,
@@ -26,10 +26,11 @@ import {
   HostWorkspaceListStates
 } from '../worktree/host-workspace-list-states'
 import { getWorktreeDotStatus } from '../worktree/workspace-list-ordering'
+import type { Section, WorkspaceListItem } from '../worktree/workspace-list-types'
 import { DEFAULT_REPO_BADGE_COLOR } from '../../../src/shared/repo-badge-color'
 import { getWorktreeCardDetails } from '../../../src/shared/worktree/card-properties'
 import { hostScreenStyles as styles } from './host-screen-styles'
-import { buildRepoLookById } from './host-repo-looks'
+import { buildRepoLookById, type RepoLook } from './host-repo-looks'
 import { HostPendingCreationRow } from './host-pending-creation-row'
 import { useSlowPendingKeys } from './use-slow-pending-keys'
 import { projectGroupHeaderIndent } from '../worktree/project-group-indent'
@@ -93,6 +94,74 @@ export function HostWorkspaceList({
     () => getWorktreeCardDetails(worktreeCardProperties, { compactWorktreeCards, newCardStyle }),
     [worktreeCardProperties, compactWorktreeCards, newCardStyle]
   )
+  const sectionCounts = useMemo(
+    () => new Map(rawSections.map((section) => [section.key, section.data.length])),
+    [rawSections]
+  )
+  const { collapsedGroups } = controller
+  const { groupBy, agentActivityDisplayMode } = state.view
+  const { toggleCollapsed, toggleWorktreeLineage } = settings
+  const { setActionTarget } = state
+  const { openWorktreeSession } = actions
+  const statusLive = connState === 'connected'
+
+  const renderSectionHeader = useCallback(
+    ({ section }: { section: Section }) => {
+      const collapseKey = section.collapseKey ?? section.key
+      return (
+        <HostSectionHeader
+          title={section.title}
+          icon={section.icon}
+          isProjectGroup={section.isProjectGroup}
+          projectGroupDepth={section.projectGroupDepth}
+          pendingCreations={section.pendingCreations}
+          collapseKey={collapseKey}
+          collapsed={collapsedGroups.has(collapseKey)}
+          count={section.count ?? sectionCounts.get(section.key) ?? 0}
+          pending={pendingCollapseKeys.has(collapseKey)}
+          groupByRepo={groupBy === 'repo'}
+          repoLook={groupBy === 'repo' && section.repo ? repoLookById.get(section.repo.id) : null}
+          onToggle={toggleCollapsed}
+        />
+      )
+    },
+    [collapsedGroups, sectionCounts, pendingCollapseKeys, groupBy, repoLookById, toggleCollapsed]
+  )
+
+  const renderItem = useCallback(
+    ({ item: { row: item, view } }: { item: WorkspaceListItem }) => (
+      <WorktreeListRow
+        item={item}
+        view={view}
+        isReadOnly={isReadOnly}
+        // Only inline agents show times, so other rows skip the 30 s clock.
+        now={cardDetails.inlineAgents && item.agents?.length ? now : 0}
+        status={getWorktreeDotStatus(item)}
+        repoColor={repoLookById.get(item.repoId)?.color ?? DEFAULT_REPO_BADGE_COLOR}
+        repoIcon={repoLookById.get(item.repoId)?.icon ?? null}
+        hideRepo={groupBy === 'repo' && !view.showProjectName}
+        cardDetails={cardDetails}
+        agentActivityDisplayMode={agentActivityDisplayMode}
+        onPress={openWorktreeSession}
+        onAgentPress={openWorktreeSession}
+        statusLive={statusLive && !view.hostContextHealthLabel}
+        onLongPress={item.workspaceKind === 'folder-workspace' ? undefined : setActionTarget}
+        onToggleLineage={toggleWorktreeLineage}
+      />
+    ),
+    [
+      isReadOnly,
+      cardDetails,
+      now,
+      repoLookById,
+      groupBy,
+      agentActivityDisplayMode,
+      openWorktreeSession,
+      statusLive,
+      setActionTarget,
+      toggleWorktreeLineage
+    ]
+  )
 
   // Group headers can exist before any row loads; the state then sits under them, not above the title.
   const listState =
@@ -199,72 +268,7 @@ export function HostWorkspaceList({
             isWideLayout &&
               !embedded && { maxWidth: contentMaxWidth, width: '100%', alignSelf: 'center' }
           ]}
-          renderSectionHeader={({ section }) => {
-            const pendingCreations = section.pendingCreations?.map((creation) => (
-              <HostPendingCreationRow key={creation.key} creation={creation} />
-            ))
-            if (!section.title) {
-              return pendingCreations ? <>{pendingCreations}</> : null
-            }
-            const collapseKey = section.collapseKey ?? section.key
-            const isCollapsed = controller.collapsedGroups.has(collapseKey)
-            const count =
-              section.count ?? rawSections.find((s) => s.key === section.key)?.data.length ?? 0
-            const repoSectionLook =
-              state.view.groupBy === 'repo' && section.repo
-                ? repoLookById.get(section.repo.id)
-                : null
-            const repoSectionColor = repoSectionLook?.color ?? null
-            const repoSectionIcon = repoSectionLook?.icon ?? null
-            return (
-              <>
-                <Pressable
-                  style={({ pressed }) => [
-                    styles.sectionHeader,
-                    section.projectGroupDepth
-                      ? {
-                          paddingLeft:
-                            WORKTREE_ROW_LAYOUT.indicatorInset +
-                            projectGroupHeaderIndent(section.projectGroupDepth)
-                        }
-                      : null,
-                    pressed && { backgroundColor: colors.translucentFill }
-                  ]}
-                  onPress={() => settings.toggleCollapsed(collapseKey)}
-                >
-                  <View style={styles.sectionChevron}>
-                    <DisclosureChevron expanded={!isCollapsed} collapsedDeg={0} expandedDeg={90}>
-                      <ChevronRight size={12} color={colors.textMuted} />
-                    </DisclosureChevron>
-                  </View>
-                  {section.icon === 'pin' && (
-                    <Pin size={12} color={colors.textMuted} style={styles.sectionIcon} />
-                  )}
-                  {state.view.groupBy === 'repo' && section.isProjectGroup ? (
-                    <FolderTree size={12} color={colors.textPrimary} style={styles.sectionIcon} />
-                  ) : state.view.groupBy === 'repo' ? (
-                    <View style={styles.sectionRepoIcon}>
-                      <MobileRepoIcon
-                        repoIcon={repoSectionIcon}
-                        size={14}
-                        color={repoSectionColor ?? colors.textSecondary}
-                      />
-                    </View>
-                  ) : null}
-                  <Text style={styles.sectionTitle}>{section.title}</Text>
-                  <Text style={styles.sectionCount}>{count}</Text>
-                  {pendingCollapseKeys.has(collapseKey) && (
-                    <ActivityIndicator
-                      size="small"
-                      color={colors.textMuted}
-                      style={styles.sectionPendingSpinner}
-                    />
-                  )}
-                </Pressable>
-                {pendingCreations}
-              </>
-            )
-          }}
+          renderSectionHeader={renderSectionHeader}
           ItemSeparatorComponent={ListSeparator}
           // Why (#8498): manual pull-to-refresh forces a fresh snapshot after a stale-cache reconnect.
           refreshControl={
@@ -275,33 +279,85 @@ export function HostWorkspaceList({
               colors={[colors.textSecondary]}
             />
           }
-          renderItem={({ item: { row: item, view } }) => (
-            <WorktreeListRow
-              item={item}
-              view={view}
-              isReadOnly={isReadOnly}
-              now={now}
-              status={getWorktreeDotStatus(item)}
-              repoColor={repoLookById.get(item.repoId)?.color ?? DEFAULT_REPO_BADGE_COLOR}
-              repoIcon={repoLookById.get(item.repoId)?.icon ?? null}
-              hideRepo={state.view.groupBy === 'repo' && !view.showProjectName}
-              cardDetails={cardDetails}
-              agentActivityDisplayMode={state.view.agentActivityDisplayMode}
-              onPress={actions.openWorktreeSession}
-              onAgentPress={actions.openWorktreeSession}
-              statusLive={connState === 'connected' && !view.hostContextHealthLabel}
-              onLongPress={
-                item.workspaceKind === 'folder-workspace' ? undefined : state.setActionTarget
-              }
-              onToggleLineage={settings.toggleWorktreeLineage}
-            />
-          )}
+          renderItem={renderItem}
         />
       )}
     </>
   )
 }
 
+// Takes the header's own fields, not the section, so a poll that rebuilds sections skips unchanged headers.
+const HostSectionHeader = memo(function HostSectionHeader(props: {
+  title: string
+  icon: Section['icon']
+  isProjectGroup: boolean | undefined
+  projectGroupDepth: number | undefined
+  pendingCreations: Section['pendingCreations']
+  collapseKey: string
+  collapsed: boolean
+  count: number
+  pending: boolean
+  groupByRepo: boolean
+  repoLook: RepoLook | null | undefined
+  onToggle: (collapseKey: string) => void
+}) {
+  useMobileColorScheme()
+  const pendingCreations = props.pendingCreations?.map((creation) => (
+    <HostPendingCreationRow key={creation.key} creation={creation} />
+  ))
+  if (!props.title) {
+    return pendingCreations ? <>{pendingCreations}</> : null
+  }
+  return (
+    <>
+      <Pressable
+        style={({ pressed }) => [
+          styles.sectionHeader,
+          props.projectGroupDepth
+            ? {
+                paddingLeft:
+                  WORKTREE_ROW_LAYOUT.indicatorInset +
+                  projectGroupHeaderIndent(props.projectGroupDepth)
+              }
+            : null,
+          pressed && { backgroundColor: colors.translucentFill }
+        ]}
+        onPress={() => props.onToggle(props.collapseKey)}
+      >
+        <View style={styles.sectionChevron}>
+          <DisclosureChevron expanded={!props.collapsed} collapsedDeg={0} expandedDeg={90}>
+            <ChevronRight size={12} color={colors.textMuted} />
+          </DisclosureChevron>
+        </View>
+        {props.icon === 'pin' && (
+          <Pin size={12} color={colors.textMuted} style={styles.sectionIcon} />
+        )}
+        {props.groupByRepo && props.isProjectGroup ? (
+          <FolderTree size={12} color={colors.textPrimary} style={styles.sectionIcon} />
+        ) : props.groupByRepo ? (
+          <View style={styles.sectionRepoIcon}>
+            <MobileRepoIcon
+              repoIcon={props.repoLook?.icon ?? null}
+              size={14}
+              color={props.repoLook?.color ?? colors.textSecondary}
+            />
+          </View>
+        ) : null}
+        <Text style={styles.sectionTitle}>{props.title}</Text>
+        <Text style={styles.sectionCount}>{props.count}</Text>
+        {props.pending && (
+          <ActivityIndicator
+            size="small"
+            color={colors.textMuted}
+            style={styles.sectionPendingSpinner}
+          />
+        )}
+      </Pressable>
+      {pendingCreations}
+    </>
+  )
+})
+
 function ListSeparator() {
   useMobileColorScheme()
   return <View style={styles.separator} />