perf(native-chat): stop unrelated host status flips from rerendering every chat (#34300)

useStructuredAgentSessionOwnPermissionState subscribed to the whole
runtimeStatusByEnvironmentId map, so each status publication for any paired
host rerendered every mounted chat (including hidden ones). Select the
derived capability verdict for the chat's own host instead.

Co-authored-by: Claude <noreply@anthropic.com>

src/renderer/src/runtime/structured-agent-session-host-capability-scaling.test.tsx

@@ -25,6 +25,7 @@ import { AGENT_SESSION_PERMISSION_OWN_RUNTIME_CAPABILITY } from '../../../shared
 import { createCompatibleRuntimeStatusResponse } from './runtime-compatibility-test-fixture'
 import { clearRuntimeCompatibilityCacheForTests } from './runtime-rpc-client'
 import { RuntimeHostStatusOwner } from '../../../shared/runtime-host-status-owner'
+import type { RuntimeEnvironmentStatus } from '../../../shared/runtime-host-status'
 import { useStructuredAgentSessionOwnPermissionState } from './structured-agent-session-host-capability'
 
 const owners: RuntimeHostStatusOwner[] = []
@@ -145,3 +146,53 @@ it.each([10, 100])(
     expect(call).not.toHaveBeenCalled()
   }
 )
+
+it('does not rerender local or other-host consumers when an unrelated host status changes', () => {
+  const unrelated = createCompatibleRuntimeStatusResponse('other')
+  const own = createCompatibleRuntimeStatusResponse('host')
+  if (!unrelated.ok || !own.ok) {
+    throw new Error('expected successful fixture')
+  }
+  const statuses = (otherStatus: typeof unrelated.result | null) =>
+    new Map<string, RuntimeEnvironmentStatus>([
+      ['host', { status: own.result, checkedAt: 1 }],
+      ['other', { status: otherStatus, checkedAt: 1 }]
+    ])
+  useAppStore.setState({ runtimeStatusByEnvironmentId: statuses(null) })
+  let renders = 0
+  const targets = [{ kind: 'local' }, { kind: 'environment', environmentId: 'host' }] as const
+  const views = targets.map((target) =>
+    renderHook(() => {
+      renders += 1
+      return useStructuredAgentSessionOwnPermissionState(target)
+    })
+  )
+  const before = renders
+  for (let flip = 0; flip < 10; flip += 1) {
+    act(() =>
+      useAppStore.setState({
+        runtimeStatusByEnvironmentId: statuses(flip % 2 === 0 ? unrelated.result : null)
+      })
+    )
+  }
+  expect(renders - before).toBe(0)
+  const hostState = views[1].result.current
+  act(() =>
+    useAppStore.setState({
+      runtimeStatusByEnvironmentId: new Map<string, RuntimeEnvironmentStatus>([
+        [
+          'host',
+          {
+            status: {
+              ...own.result,
+              capabilities:
+                hostState === 'supported' ? [] : [AGENT_SESSION_PERMISSION_OWN_RUNTIME_CAPABILITY]
+            },
+            checkedAt: 2
+          }
+        ]
+      ])
+    })
+  )
+  expect(views[1].result.current).toBe(hostState === 'supported' ? 'unsupported' : 'supported')
+})

src/renderer/src/runtime/structured-agent-session-host-capability.ts

@@ -1,5 +1,5 @@
 import { AGENT_SESSION_PERMISSION_OWN_RUNTIME_CAPABILITY } from '../../../shared/agent-session-permission-modes-capability'
-import { useEffect, useMemo, useState, useSyncExternalStore } from 'react'
+import { useEffect, useState, useSyncExternalStore } from 'react'
 import { useAppStore } from '@/store'
 import {
   AGENT_SESSION_CONVERSATION_STOP_RUNTIME_CAPABILITY,
@@ -37,19 +37,19 @@ export function useStructuredAgentSessionOwnPermissionState(
 ): StructuredAgentSessionHostCapabilityState {
   const capability = AGENT_SESSION_PERMISSION_OWN_RUNTIME_CAPABILITY
   const environmentId = target?.kind === 'environment' ? target.environmentId : null
-  const statuses = useAppStore((state) => state.runtimeStatusByEnvironmentId)
-  const remote = useMemo((): StructuredAgentSessionHostCapabilityState => {
+  // Select the verdict, not the map: unrelated host flips must not rerender every chat.
+  const remote = useAppStore((state): StructuredAgentSessionHostCapabilityState => {
     if (environmentId === null) {
       return 'unknown'
     }
-    const entry = statuses.get(environmentId)
+    const entry = state.runtimeStatusByEnvironmentId.get(environmentId)
     const status = isRuntimeHostContactRevoked(entry) ? null : lastVerifiedRuntimeStatus(entry)
     return status
       ? status.capabilities?.includes(capability)
         ? 'supported'
         : 'unsupported'
       : 'unknown'
-  }, [statuses, environmentId, capability])
+  })
   const local = useSyncExternalStore(
     subscribeLocalRuntimeCapabilityObservation,
     () => localCapabilityState(capability),