fix(desktop): refresh session model metadata on switch (#43977)

Co-authored-by: Omar Baradei <omar@kostudios.io>

apps/desktop/src/app/session/hooks/use-message-stream.ts

@@ -64,6 +64,67 @@ interface QueuedStreamDeltas {
   reasoning: string
 }
 
+type SessionRuntimeStatePatch = Partial<
+  Pick<
+    ClientSessionState,
+    | 'branch'
+    | 'cwd'
+    | 'fast'
+    | 'model'
+    | 'personality'
+    | 'provider'
+    | 'reasoningEffort'
+    | 'serviceTier'
+    | 'yolo'
+  >
+>
+
+function sessionInfoStatePatch(payload: GatewayEventPayload | undefined): SessionRuntimeStatePatch {
+  const patch: SessionRuntimeStatePatch = {}
+
+  if (typeof payload?.model === 'string') {
+    patch.model = payload.model || ''
+  }
+
+  if (typeof payload?.provider === 'string') {
+    patch.provider = payload.provider || ''
+  }
+
+  if (typeof payload?.cwd === 'string') {
+    patch.cwd = payload.cwd
+  }
+
+  if (typeof payload?.branch === 'string') {
+    patch.branch = payload.branch
+  }
+
+  if (typeof payload?.personality === 'string') {
+    patch.personality = normalizePersonalityValue(payload.personality)
+  }
+
+  if (typeof payload?.reasoning_effort === 'string') {
+    patch.reasoningEffort = payload.reasoning_effort
+  }
+
+  if (typeof payload?.service_tier === 'string') {
+    patch.serviceTier = payload.service_tier
+  }
+
+  if (typeof payload?.fast === 'boolean') {
+    patch.fast = payload.fast
+  }
+
+  if (typeof payload?.yolo === 'boolean') {
+    patch.yolo = payload.yolo
+  }
+
+  return patch
+}
+
+function hasSessionInfoStatePatch(patch: SessionRuntimeStatePatch): boolean {
+  return Object.keys(patch).length > 0
+}
+
 // Minimum gap between two assistant-text flushes during a stream. Was 16ms
 // (rAF only), which at typical LLM token rates of ~30-80 tok/sec meant every
 // token got its own React commit + Streamdown markdown re-parse, scaling
@@ -628,36 +689,27 @@ export function useMessageStream({
         // Apply session-scoped fields when the event targets the active
         // session, OR when it's a global broadcast and we have no session.
         const apply = explicitSid ? isActiveEvent : !activeSessionIdRef.current
+        const statePatch = sessionInfoStatePatch(payload)
+        const hasStatePatch = hasSessionInfoStatePatch(statePatch)
         const modelChanged = typeof payload?.model === 'string'
         const providerChanged = typeof payload?.provider === 'string'
         const runningChanged = typeof payload?.running === 'boolean'
 
         if (apply) {
-          const runtimeInfo: Partial<
-            Pick<
-              ClientSessionState,
-              'branch' | 'cwd' | 'fast' | 'model' | 'provider' | 'reasoningEffort' | 'serviceTier' | 'yolo'
-            >
-          > = {}
-
           if (modelChanged) {
             setCurrentModel(payload!.model || '')
-            runtimeInfo.model = payload!.model || ''
           }
 
           if (providerChanged) {
             setCurrentProvider(payload!.provider || '')
-            runtimeInfo.provider = payload!.provider || ''
           }
 
           if (typeof payload?.cwd === 'string') {
             setCurrentCwd(payload.cwd)
-            runtimeInfo.cwd = payload.cwd
           }
 
           if (typeof payload?.branch === 'string') {
             setCurrentBranch(payload.branch)
-            runtimeInfo.branch = payload.branch
           }
 
           if (typeof payload?.personality === 'string') {
@@ -666,28 +718,31 @@ export function useMessageStream({
 
           if (typeof payload?.reasoning_effort === 'string') {
             setCurrentReasoningEffort(payload.reasoning_effort)
-            runtimeInfo.reasoningEffort = payload.reasoning_effort
           }
 
           if (typeof payload?.service_tier === 'string') {
             setCurrentServiceTier(payload.service_tier)
-            runtimeInfo.serviceTier = payload.service_tier
           }
 
           if (typeof payload?.fast === 'boolean') {
             setCurrentFastMode(payload.fast)
-            runtimeInfo.fast = payload.fast
           }
 
           if (typeof payload?.yolo === 'boolean') {
             setYoloActive(payload.yolo)
-            runtimeInfo.yolo = payload.yolo
           }
+        }
 
-          if (sessionId && Object.keys(runtimeInfo).length > 0) {
+        if (sessionId && hasStatePatch) {
-            updateSessionState(sessionId, state => ({ ...state, ...runtimeInfo }))
+          updateSessionState(sessionId, state => ({
-          }
+            ...state,
+            ...statePatch,
+            branch: statePatch.branch ?? state.branch,
+            cwd: statePatch.cwd ?? state.cwd
+          }))
+        }
 
+        if (apply) {
           if (runningChanged && sessionId) {
             updateSessionState(sessionId, state => {
               const busy = Boolean(payload!.running)

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

@@ -43,7 +43,7 @@ import {
   workspaceCwdForNewSession
 } from '@/store/session'
 import { reportBackendContract } from '@/store/updates'
-import type { SessionCreateResponse, SessionInfo, SessionResumeResponse, UsageStats } from '@/types/hermes'
+import type { SessionCreateResponse, SessionInfo, SessionResumeResponse, SessionRuntimeInfo, UsageStats } from '@/types/hermes'
 
 import { NEW_CHAT_ROUTE, sessionRoute, SETTINGS_ROUTE } from '../../routes'
 import type { ClientSessionState, SidebarNavItem } from '../../types'
@@ -209,16 +209,27 @@ function patchSessionWorkspace(sessionId: string, cwd: string | undefined) {
   setSessions(prev => prev.map(session => (session.id === sessionId ? { ...session, cwd } : session)))
 }
 
-function applyRuntimeInfo(info: SessionCreateResponse['info'] | undefined): Partial<
+type SessionRuntimeStatePatch = Partial<
-  Pick<ClientSessionState, 'branch' | 'cwd' | 'fast' | 'model' | 'provider' | 'reasoningEffort' | 'serviceTier' | 'yolo'>
+  Pick<
-> | null {
+    ClientSessionState,
+    | 'branch'
+    | 'cwd'
+    | 'fast'
+    | 'model'
+    | 'personality'
+    | 'provider'
+    | 'reasoningEffort'
+    | 'serviceTier'
+    | 'yolo'
+  >
+>
+
+function applyRuntimeInfo(info: SessionRuntimeInfo | undefined): SessionRuntimeStatePatch | null {
   if (!info) {
     return null
   }
 
-  const sessionState: Partial<
+  const sessionState: SessionRuntimeStatePatch = {}
-    Pick<ClientSessionState, 'branch' | 'cwd' | 'fast' | 'model' | 'provider' | 'reasoningEffort' | 'serviceTier' | 'yolo'>
-  > = {}
 
   reportBackendContract(info.desktop_contract)
 
@@ -226,12 +237,12 @@ function applyRuntimeInfo(info: SessionCreateResponse['info'] | undefined): Part
     requestDesktopOnboarding(info.credential_warning)
   }
 
-  if (info.model) {
+  if (typeof info.model === 'string') {
     setCurrentModel(info.model)
     sessionState.model = info.model
   }
 
-  if (info.provider) {
+  if (typeof info.provider === 'string') {
     setCurrentProvider(info.provider)
     sessionState.provider = info.provider
   }
@@ -247,7 +258,9 @@ function applyRuntimeInfo(info: SessionCreateResponse['info'] | undefined): Part
   }
 
   if (typeof info.personality === 'string') {
-    setCurrentPersonality(normalizePersonalityValue(info.personality))
+    const personality = normalizePersonalityValue(info.personality)
+    setCurrentPersonality(personality)
+    sessionState.personality = personality
   }
 
   if (typeof info.reasoning_effort === 'string') {
@@ -277,6 +290,16 @@ function applyRuntimeInfo(info: SessionCreateResponse['info'] | undefined): Part
   return sessionState
 }
 
+function applyStoredSessionPreviewRuntimeInfo(stored: { model?: null | string } | undefined) {
+  setCurrentModel(stored?.model || '')
+  setCurrentProvider('')
+  setCurrentReasoningEffort('')
+  setCurrentServiceTier('')
+  setCurrentFastMode(false)
+  setYoloActive(false)
+  setCurrentPersonality('')
+}
+
 export function useSessionActions({
   activeSessionId,
   activeSessionIdRef,
@@ -465,15 +488,28 @@ export function useSessionActions({
       const cachedState = cachedRuntimeId && sessionStateByRuntimeIdRef.current.get(cachedRuntimeId)
 
       if (cachedRuntimeId && cachedState) {
+        const stored = $sessions.get().find(session => session.id === storedSessionId)
+        const cachedViewState =
+          !cachedState.model && stored?.model != null
+            ? {
+                ...cachedState,
+                model: stored.model || ''
+              }
+            : cachedState
+
+        if (cachedViewState !== cachedState) {
+          sessionStateByRuntimeIdRef.current.set(cachedRuntimeId, cachedViewState)
+        }
+
         setFreshDraftReady(false)
         clearNotifications()
         setSelectedStoredSessionId(storedSessionId)
         selectedStoredSessionIdRef.current = storedSessionId
         setActiveSessionId(cachedRuntimeId)
         activeSessionIdRef.current = cachedRuntimeId
-        syncSessionStateToView(cachedRuntimeId, cachedState)
+        syncSessionStateToView(cachedRuntimeId, cachedViewState)
-        setCurrentCwd(cachedState.cwd)
+        setCurrentCwd(cachedViewState.cwd)
-        setCurrentBranch(cachedState.branch)
+        setCurrentBranch(cachedViewState.branch)
         setSessionStartedAt(Date.now())
 
         try {
@@ -514,6 +550,7 @@ export function useSessionActions({
       selectedStoredSessionIdRef.current = storedSessionId
       setSessionStartedAt(Date.now())
       const stored = $sessions.get().find(session => session.id === storedSessionId)
+      applyStoredSessionPreviewRuntimeInfo(stored)
 
       if (stored) {
         setCurrentUsage(current => ({

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

@@ -2,7 +2,20 @@ import { act, cleanup, render } from '@testing-library/react'
 import type { MutableRefObject } from 'react'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
-import { $turnStartedAt, setTurnStartedAt } from '@/store/session'
+import {
+  $currentFastMode,
+  $currentModel,
+  $currentProvider,
+  $currentReasoningEffort,
+  $currentServiceTier,
+  $turnStartedAt,
+  setCurrentFastMode,
+  setCurrentModel,
+  setCurrentProvider,
+  setCurrentReasoningEffort,
+  setCurrentServiceTier,
+  setTurnStartedAt
+} from '@/store/session'
 
 import { useSessionStateCache } from './use-session-state-cache'
 
@@ -46,12 +59,22 @@ describe('useSessionStateCache — per-session turn timer', () => {
       return null as unknown as number
     })
     setTurnStartedAt(null)
+    setCurrentModel('')
+    setCurrentProvider('')
+    setCurrentReasoningEffort('')
+    setCurrentServiceTier('')
+    setCurrentFastMode(false)
   })
 
   afterEach(() => {
     cleanup()
     vi.restoreAllMocks()
     setTurnStartedAt(null)
+    setCurrentModel('')
+    setCurrentProvider('')
+    setCurrentReasoningEffort('')
+    setCurrentServiceTier('')
+    setCurrentFastMode(false)
   })
 
   it("keeps a background session's running turn clock and never mirrors it to the view", () => {
@@ -115,4 +138,78 @@ describe('useSessionStateCache — per-session turn timer', () => {
     })
     expect($turnStartedAt.get()).toBeNull()
   })
+
+  it('mirrors the focused session model metadata when switching from a cached session', () => {
+    let cache!: Cache
+    const { rerender } = render(
+      <Harness activeSessionId="fg-runtime" onReady={c => (cache = c)} selectedStoredSessionId="fg-stored" />
+    )
+
+    act(() => {
+      cache.updateSessionState(
+        'bg-runtime',
+        state => ({
+          ...state,
+          fast: true,
+          model: 'anthropic/claude-opus-4.8',
+          provider: 'anthropic',
+          reasoningEffort: 'high',
+          serviceTier: 'priority'
+        }),
+        'bg-stored'
+      )
+    })
+
+    // Background metadata is cached but must not bleed into the visible statusbar.
+    expect($currentModel.get()).toBe('')
+    expect($currentReasoningEffort.get()).toBe('')
+    expect($currentFastMode.get()).toBe(false)
+
+    rerender(<Harness activeSessionId="bg-runtime" onReady={c => (cache = c)} selectedStoredSessionId="bg-stored" />)
+
+    const bgState = cache.sessionStateByRuntimeIdRef.current.get('bg-runtime')
+    expect(bgState).toBeTruthy()
+
+    act(() => {
+      cache.syncSessionStateToView('bg-runtime', bgState!)
+    })
+
+    expect($currentModel.get()).toBe('anthropic/claude-opus-4.8')
+    expect($currentProvider.get()).toBe('anthropic')
+    expect($currentReasoningEffort.get()).toBe('high')
+    expect($currentServiceTier.get()).toBe('priority')
+    expect($currentFastMode.get()).toBe(true)
+  })
+
+  it('clears stale model metadata when the newly focused session has no cached value', () => {
+    setCurrentModel('previous-model')
+    setCurrentProvider('previous-provider')
+    setCurrentReasoningEffort('high')
+    setCurrentServiceTier('priority')
+    setCurrentFastMode(true)
+
+    let cache!: Cache
+    const { rerender } = render(
+      <Harness activeSessionId="fg-runtime" onReady={c => (cache = c)} selectedStoredSessionId="fg-stored" />
+    )
+
+    act(() => {
+      cache.updateSessionState('bg-runtime', state => ({ ...state }), 'bg-stored')
+    })
+
+    rerender(<Harness activeSessionId="bg-runtime" onReady={c => (cache = c)} selectedStoredSessionId="bg-stored" />)
+
+    const bgState = cache.sessionStateByRuntimeIdRef.current.get('bg-runtime')
+    expect(bgState).toBeTruthy()
+
+    act(() => {
+      cache.syncSessionStateToView('bg-runtime', bgState!)
+    })
+
+    expect($currentModel.get()).toBe('')
+    expect($currentProvider.get()).toBe('')
+    expect($currentReasoningEffort.get()).toBe('')
+    expect($currentServiceTier.get()).toBe('')
+    expect($currentFastMode.get()).toBe(false)
+  })
 })

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

@@ -11,6 +11,7 @@ import {
   noteSessionActivity,
   setCurrentFastMode,
   setCurrentModel,
+  setCurrentPersonality,
   setCurrentProvider,
   setCurrentReasoningEffort,
   setCurrentServiceTier,
@@ -53,6 +54,16 @@ interface SessionStateCacheOptions {
   setMessages: (messages: ChatMessage[]) => void
 }
 
+function syncRuntimeMetadataToView(state: ClientSessionState) {
+  setCurrentModel(state.model ?? '')
+  setCurrentProvider(state.provider ?? '')
+  setCurrentReasoningEffort(state.reasoningEffort ?? '')
+  setCurrentServiceTier(state.serviceTier ?? '')
+  setCurrentFastMode(state.fast ?? false)
+  setYoloActive(state.yolo ?? false)
+  setCurrentPersonality(state.personality ?? '')
+}
+
 export function useSessionStateCache({
   activeSessionId,
   busyRef,
@@ -137,12 +148,7 @@ export function useSessionStateCache({
       setMessages(nextMessages)
     }
 
-    setCurrentModel(pending.state.model)
+    syncRuntimeMetadataToView(pending.state)
-    setCurrentProvider(pending.state.provider)
-    setCurrentReasoningEffort(pending.state.reasoningEffort)
-    setCurrentServiceTier(pending.state.serviceTier)
-    setCurrentFastMode(pending.state.fast)
-    setYoloActive(pending.state.yolo)
     setBusy(pending.state.busy)
     setMutableRef(busyRef, pending.state.busy)
     setAwaitingResponse(pending.state.awaitingResponse)
@@ -167,6 +173,7 @@ export function useSessionStateCache({
         return
       }
 
+      syncRuntimeMetadataToView(state)
       pendingViewStateRef.current = { sessionId, state }
 
       // Terminal / attention transitions (turn finished, error, or the agent is

apps/desktop/src/app/types.ts

@@ -129,6 +129,7 @@ export interface ClientSessionState {
   serviceTier: string
   fast: boolean
   yolo: boolean
+  personality: string
   busy: boolean
   awaitingResponse: boolean
   streamId: string | null

apps/desktop/src/lib/chat-runtime.ts

@@ -46,6 +46,7 @@ export function createClientSessionState(
     serviceTier: '',
     fast: false,
     yolo: false,
+    personality: '',
     busy: false,
     awaitingResponse: false,
     streamId: null,