fix(desktop): replace atom-mirrored refs with synchronous writes + direct reads

The atom-mirrored-ref antipattern (useEffect syncing a ref from a store
value) lags the atom by one render. Callbacks that read the ref after an
await or through a stable-ref bag get stale values. This fixes all 11
sites identified in the audit:

Confirmed bugs (PR #66485 class):
- use-session-state-cache.ts: activeSessionIdRef, busyRef,
  selectedStoredSessionIdRef — now synced synchronously during render
  instead of via useEffect. Fixes the one-render lag that caused
  cancelRun to interrupt the wrong session.

Latent bugs:
- use-gateway-request.ts: gatewayStateRef → $gatewayState.get() in
  ensureGatewayOpen (deps=[]), removed mirroring effect entirely
- use-voice-conversation.ts: enabledRef, mutedRef, busyRef, statusRef
  → synced synchronously during render (same pattern as session-state-cache)
- model-settings.tsx: moaRef → setMoa(updater) with functional update,
  removed mirroring effect
- i18n/context.tsx: localeRef → locale captured directly in setLocale
  callback, added to dep array
- user-edit-composer.tsx: draftRef mirror removed, appendExternalText
  reads draft from closure (added to deps)

The remaining eslint-disable comments on useEffect ref writes are
legitimate non-mirror patterns: prev-value tracking, staging buffers,
state flags, and direct ref writes paired with atom setters.

apps/desktop/src/app/chat/composer/hooks/use-voice-conversation.ts

@@ -45,31 +45,22 @@ export function useVoiceConversation({
   const responseIdRef = useRef<string | null>(null)
   const spokenSourceLengthRef = useRef(0)
   const speechBufferRef = useRef('')
+
+  // Props/state mirrored into refs synchronously during render (NOT via useEffect)
+  // so callbacks that fire after an await read values that are current as of the
+  // last render, not lagged by one effect tick. The atom-mirrored-ref eslint rule
+  // bans useEffect-based mirroring; these synchronous writes are the correct
+  // pattern for props that must be read inside stable callbacks.
   const enabledRef = useRef(enabled)
   const mutedRef = useRef(muted)
   const busyRef = useRef(busy)
-  const statusRef = useRef<ConversationStatus>('idle')
+  const statusRef = useRef<ConversationStatus>(status)
   const wasEnabledRef = useRef(enabled)
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    enabledRef.current = enabled
-  }, [enabled])
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    mutedRef.current = muted
-  }, [muted])
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    busyRef.current = busy
-  }, [busy])
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    statusRef.current = status
-  }, [status])
+  enabledRef.current = enabled
+  mutedRef.current = muted
+  busyRef.current = busy
+  statusRef.current = status
 
   const clearTurnTimeout = () => {
     if (turnTimeoutRef.current) {
@@ -331,7 +322,7 @@ export function useVoiceConversation({
 
   // Drive the loop: after a voice-submitted turn, speak stable chunks as the
   // assistant stream grows. Otherwise start listening when idle between turns.
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
+  // eslint-disable-next-line no-restricted-syntax -- staging buffers + state flags, not atom mirrors
   useEffect(() => {
     if (!enabled || muted) {
       return
@@ -389,7 +380,7 @@ export function useVoiceConversation({
     }
   }, [busy, consumePendingResponse, enabled, muted, pendingResponse, speak, startListening, status])
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
+  // eslint-disable-next-line no-restricted-syntax -- prev-value tracking for edge detection, not atom mirror
   useEffect(() => {
     if (enabled && !wasEnabledRef.current) {
       void start()

apps/desktop/src/app/gateway/hooks/use-gateway-request.ts

@@ -1,5 +1,4 @@
 import { isGatewayReauthRequired, resolveGatewayWsUrl } from '@hermes/shared'
-import { useStore } from '@nanostores/react'
 import { useCallback, useEffect, useRef } from 'react'
 
 import type { HermesGateway } from '@/hermes'
@@ -8,25 +7,18 @@ import { $activeGatewayProfile } from '@/store/profile'
 import { $gatewayState, setConnection } from '@/store/session'
 
 export function useGatewayRequest() {
-  const gatewayState = useStore($gatewayState)
   const gatewayRef = useRef<HermesGateway | null>(null)
 
   const connectionRef = useRef<Awaited<ReturnType<NonNullable<typeof window.hermesDesktop>['getConnection']>> | null>(
     null
   )
 
-  const gatewayStateRef = useRef(gatewayState)
   const reconnectingRef = useRef<Promise<HermesGateway | null> | null>(null)
   // Holds the reauth error from the most recent failed reconnect so
   // requestGateway can surface the gateway's "session expired, sign in again"
   // message instead of the opaque "connection closed" that triggered the retry.
   const reauthErrorRef = useRef<unknown>(null)
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    gatewayStateRef.current = gatewayState
-  }, [gatewayState])
-
   // Track the active gateway (primary or a background profile's socket) so
   // outbound requests and overlay props always target the focused profile.
   useEffect(
@@ -44,7 +36,7 @@ export function useGatewayRequest() {
       return null
     }
 
-    if (gatewayStateRef.current === 'open') {
+    if ($gatewayState.get() === 'open') {
       return existing
     }
 

apps/desktop/src/app/session/hooks/use-session-actions/index.ts

@@ -186,7 +186,7 @@ export function useSessionActions({
   // history entry.
   const rotatedStoredId = useStore($activeSessionStoredId)
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
+  // eslint-disable-next-line no-restricted-syntax -- direct ref write paired with atom setter, not a mirroring effect
   useEffect(() => {
     if (!rotatedStoredId || rotatedStoredId === selectedStoredSessionIdRef.current) {
       return

apps/desktop/src/app/session/hooks/use-session-state-cache.ts

@@ -81,20 +81,15 @@ export function useSessionStateCache({
   // flush below tell a same-session refresh from a thread switch.
   const viewSessionIdRef = useRef<string | null>(null)
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    activeSessionIdRef.current = activeSessionId
-  }, [activeSessionId])
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    setMutableRef(busyRef, busy)
-  }, [busy, busyRef])
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    selectedStoredSessionIdRef.current = selectedStoredSessionId
-  }, [selectedStoredSessionId])
+  // Sync refs from atoms synchronously during render (NOT via useEffect) so
+  // callbacks that fire after an await or inside a stable-ref bag read values
+  // that are current as of the last render, not lagged by one effect tick.
+  // The atom-mirrored-ref eslint rule bans useEffect-based mirroring; these
+  // synchronous writes are the correct pattern for values that must be read
+  // inside stable callbacks passed through the actionsRef bag.
+  activeSessionIdRef.current = activeSessionId
+  selectedStoredSessionIdRef.current = selectedStoredSessionId
+  setMutableRef(busyRef, busy)
 
   const ensureSessionState = useCallback((sessionId: string, storedSessionId?: string | null) => {
     const existing = sessionStateByRuntimeIdRef.current.get(sessionId)

apps/desktop/src/app/settings/model-settings.tsx

@@ -316,15 +316,6 @@ export function ModelSettings({ onMainModelChanged }: ModelSettingsProps) {
     return moa.presets[selectedMoaPreset] || moa.presets[moa.default_preset] || Object.values(moa.presets)[0] || null
   }, [moa, selectedMoaPreset])
 
-  // Mirror of `moa` so inline edits compute the next state purely (outside the
-  // setState updater) and hand it straight to the debounced autosave.
-  const moaRef = useRef<MoaConfigResponse | null>(null)
-
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
-  useEffect(() => {
-    moaRef.current = moa
-  }, [moa])
-
   const moaSaveTimer = useRef<number | null>(null)
 
   useEffect(
@@ -379,23 +370,23 @@ export function ModelSettings({ onMainModelChanged }: ModelSettingsProps) {
 
   const updateMoaPreset = useCallback(
     (updater: (preset: NonNullable<typeof currentMoaPreset>) => NonNullable<typeof currentMoaPreset>) => {
-      const prev = moaRef.current
-
-      if (!prev || !selectedMoaPreset || !prev.presets[selectedMoaPreset]) {
-        return
-      }
-
-      const next: MoaConfigResponse = {
-        ...prev,
-        presets: {
-          ...prev.presets,
-          [selectedMoaPreset]: updater(prev.presets[selectedMoaPreset])
+      setMoa(prev => {
+        if (!prev || !selectedMoaPreset || !prev.presets[selectedMoaPreset]) {
+          return prev
         }
-      }
 
-      moaRef.current = next
-      setMoa(next)
-      scheduleMoaSave(next)
+        const next: MoaConfigResponse = {
+          ...prev,
+          presets: {
+            ...prev.presets,
+            [selectedMoaPreset]: updater(prev.presets[selectedMoaPreset])
+          }
+        }
+
+        scheduleMoaSave(next)
+
+        return next
+      })
     },
     [scheduleMoaSave, selectedMoaPreset]
   )

apps/desktop/src/components/assistant-ui/thread/user-edit-composer.tsx

@@ -128,11 +128,10 @@ export const UserEditComposer: FC<UserEditComposerProps> = ({ cwd, gateway, sess
         return
       }
 
-      const base = mode === 'inline' ? draftRef.current.trimEnd() : draftRef.current
+      const base = mode === 'inline' ? draft.trimEnd() : draft
       const sep = mode === 'inline' ? (base ? ' ' : '') : base && !base.endsWith('\n') ? '\n\n' : ''
       const next = `${base}${sep}${value}`
 
-      draftRef.current = next
       aui.composer().setText(next)
 
       const editor = editorRef.current
@@ -144,13 +143,10 @@ export const UserEditComposer: FC<UserEditComposerProps> = ({ cwd, gateway, sess
 
       setFocusRequestId(id => id + 1)
     },
-    [aui]
+    [aui, draft]
   )
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
   useEffect(() => {
-    draftRef.current = draft
-
     const editor = editorRef.current
 
     if (

apps/desktop/src/i18n/context.tsx

@@ -1,4 +1,4 @@
-import { createContext, type ReactNode, useCallback, useContext, useEffect, useMemo, useRef, useState } from 'react'
+import { createContext, type ReactNode, useCallback, useContext, useEffect, useMemo, useState } from 'react'
 
 import { getHermesConfigRecord, type HermesConfigRecord, saveHermesConfig } from '@/hermes'
 
@@ -87,11 +87,8 @@ export function I18nProvider({ children, configClient = defaultConfigClient, ini
   const [isSavingLocale, setIsSavingLocale] = useState(false)
   const [configLoadError, setConfigLoadError] = useState<Error | null>(null)
   const [saveError, setSaveError] = useState<Error | null>(null)
-  const localeRef = useRef(locale)
 
-  // eslint-disable-next-line no-restricted-syntax -- legitimate non-atom ref write (see eslint rule comment)
   useEffect(() => {
-    localeRef.current = locale
     setRuntimeI18nLocale(locale)
   }, [locale])
 
@@ -131,7 +128,7 @@ export function I18nProvider({ children, configClient = defaultConfigClient, ini
 
   const setLocale = useCallback(
     async (next: Locale) => {
-      const previousLocale = localeRef.current
+      const previousLocale = locale
 
       setSaveError(null)
       setLocaleState(next)
@@ -160,7 +157,7 @@ export function I18nProvider({ children, configClient = defaultConfigClient, ini
         setIsSavingLocale(false)
       }
     },
-    [configClient]
+    [configClient, locale]
   )
 
   const value = useMemo<I18nContextValue>(