refactor(desktop): make composer model picker sticky session state

The picker no longer touches the profile default. Model/effort/fast live as
plain UI state persisted in localStorage, so a pick follows across Cmd+N and
restarts instead of snapping back. New chats ship that state through
session.create as per-session overrides; live chats still scope switches to the
current session. Settings -> Model remains the only surface that writes the
profile default.

The gateway now accepts those session.create overrides, builds the agent with
them directly, reflects them in the immediate session.info payload, and writes
the chat's own model_config into the lazy DB row so reconnect/resume restores
that chat instead of the global default.

apps/desktop/src/app/desktop-controller.tsx

@@ -711,7 +711,9 @@ export function DesktopController() {
     }
 
     lastGatewayProfileRef.current = activeGatewayProfile
-    void refreshCurrentModel()
+    // Force: the new profile has its own default, so reseed even if the composer
+    // already shows the previous profile's model.
+    void refreshCurrentModel(true)
     void refreshActiveProfile()
   }, [activeGatewayProfile, refreshCurrentModel])
 

apps/desktop/src/app/session/hooks/use-model-controls.test.tsx

@@ -130,7 +130,6 @@ describe('useModelControls', () => {
     await expect(
       controls.selectModel({
         model: 'claude-sonnet-4.6',
-        persistGlobal: false,
         provider: 'anthropic'
       })
     ).resolves.toBe(true)
@@ -143,26 +142,57 @@ describe('useModelControls', () => {
     expect(requestGateway).not.toHaveBeenCalledWith('slash.exec', expect.anything())
   })
 
-  it('keeps the global path on setGlobalModel when there is no active session', async () => {
-    setGlobalModel.mockResolvedValue(undefined)
+  it('stores a no-session pick as UI state with no gateway or global write', async () => {
+    const requestGateway = vi.fn()
     let controls!: Controls
 
     render(
       <Harness
         activeSessionId={null}
         onReady={value => (controls = value)}
-        requestGateway={vi.fn()}
+        requestGateway={requestGateway}
       />
     )
 
     await expect(
       controls.selectModel({
         model: 'claude-sonnet-4.6',
-        persistGlobal: false,
         provider: 'anthropic'
       })
     ).resolves.toBe(true)
 
-    expect(setGlobalModel).toHaveBeenCalledWith('anthropic', 'claude-sonnet-4.6')
+    // The pick is plain UI state; session.create ships it later. Nothing touches
+    // the gateway or the profile default here.
+    expect($currentModel.get()).toBe('claude-sonnet-4.6')
+    expect($currentProvider.get()).toBe('anthropic')
+    expect(requestGateway).not.toHaveBeenCalled()
+    expect(setGlobalModel).not.toHaveBeenCalled()
+  })
+
+  it('seeds an empty composer model from global but never clobbers a pick', async () => {
+    vi.mocked(getGlobalModelInfo).mockResolvedValue({ model: 'openai/gpt-5.5', provider: 'openai-codex' })
+
+    const { result } = renderHook(() =>
+      useModelControls({
+        activeSessionId: null,
+        queryClient: new QueryClient(),
+        requestGateway: vi.fn()
+      })
+    )
+
+    // Empty → seeds the default.
+    await result.current.refreshCurrentModel()
+    expect($currentModel.get()).toBe('openai/gpt-5.5')
+
+    // A user pick must survive the lifecycle refreshes that fire on boot / fresh
+    // draft / session events.
+    setCurrentModel('anthropic/claude-sonnet-4.6')
+    setCurrentProvider('anthropic')
+    await result.current.refreshCurrentModel()
+    expect($currentModel.get()).toBe('anthropic/claude-sonnet-4.6')
+
+    // A profile swap forces a reseed to the new profile's default.
+    await result.current.refreshCurrentModel(true)
+    expect($currentModel.get()).toBe('openai/gpt-5.5')
   })
 })

apps/desktop/src/app/session/hooks/use-model-controls.ts

@@ -1,7 +1,7 @@
 import { type QueryClient } from '@tanstack/react-query'
 import { useCallback } from 'react'
 
-import { getGlobalModelInfo, setGlobalModel } from '@/hermes'
+import { getGlobalModelInfo } from '@/hermes'
 import { useI18n } from '@/i18n'
 import { notifyError } from '@/store/notifications'
 import {
@@ -15,7 +15,6 @@ import type { ModelOptionsResponse } from '@/types/hermes'
 
 interface ModelSelection {
   model: string
-  persistGlobal: boolean
   provider: string
 }
 
@@ -28,6 +27,7 @@ interface ModelControlsOptions {
 export function useModelControls({ activeSessionId, queryClient, requestGateway }: ModelControlsOptions) {
   const { t } = useI18n()
   const copy = t.desktop
+
   const updateModelOptionsCache = useCallback(
     (provider: string, model: string, includeGlobal: boolean) => {
       const patch = (prev: ModelOptionsResponse | undefined) => ({ ...(prev ?? {}), provider, model })
@@ -41,14 +41,24 @@ export function useModelControls({ activeSessionId, queryClient, requestGateway
     [activeSessionId, queryClient]
   )
 
-  const refreshCurrentModel = useCallback(async () => {
+  // Seed the composer's model state from the profile default. `force` reseeds
+  // for a profile swap (the new profile has its own default); otherwise this
+  // only fills an EMPTY selection so a user's pick (plain UI state in
+  // $currentModel) survives the lifecycle refreshes that fire on boot / fresh
+  // draft / session events. A live session owns the footer, so skip entirely.
+  const refreshCurrentModel = useCallback(async (force = false) => {
     try {
+      if ($activeSessionId.get()) {
+        return
+      }
+
+      if (!force && $currentModel.get()) {
+        return
+      }
+
       const result = await getGlobalModelInfo()
 
-      // A resumed/live session owns the footer model state. Global config
-      // refreshes (gateway boot, profile swap, settings save) must not clobber
-      // the active chat's runtime model/provider in the status bar.
-      if ($activeSessionId.get()) {
+      if ($activeSessionId.get() || (!force && $currentModel.get())) {
         return
       }
 
@@ -64,12 +74,14 @@ export function useModelControls({ activeSessionId, queryClient, requestGateway
     }
   }, [])
 
-  // Returns whether the switch succeeded so callers can await it before
-  // applying follow-up changes (e.g. editing a model's reasoning/fast must land
-  // on the right active model — bail rather than write to the previous one).
+  // Returns whether the switch succeeded so callers can await it before applying
+  // follow-up changes. The composer model is plain UI state: with no live
+  // session it's just stored (and shipped on the next session.create); with one
+  // it's scoped to that session via config.set. It NEVER writes the profile
+  // default — that lives in Settings → Model — so picking a model here can't
+  // silently mutate global config.
   const selectModel = useCallback(
     async (selection: ModelSelection): Promise<boolean> => {
-      const includeGlobal = selection.persistGlobal || !activeSessionId
       // Snapshot for rollback: the switch is applied optimistically, so a
       // failure must restore the prior model/provider (store + query cache)
       // rather than leave the UI showing a model the backend never selected.
@@ -78,42 +90,34 @@ export function useModelControls({ activeSessionId, queryClient, requestGateway
 
       setCurrentModel(selection.model)
       setCurrentProvider(selection.provider)
-      updateModelOptionsCache(selection.provider, selection.model, includeGlobal)
+      updateModelOptionsCache(selection.provider, selection.model, !activeSessionId)
+
+      // No live session yet: the pick is pure UI state. session.create reads
+      // $currentModel/$currentProvider and applies it as that session's override.
+      if (!activeSessionId) {
+        return true
+      }
 
       try {
-        if (activeSessionId) {
-          await requestGateway('config.set', {
-            session_id: activeSessionId,
-            key: 'model',
-            value: `${selection.model} --provider ${selection.provider}${selection.persistGlobal ? ' --global' : ''}`
-          })
+        await requestGateway('config.set', {
+          session_id: activeSessionId,
+          key: 'model',
+          value: `${selection.model} --provider ${selection.provider}`
+        })
 
-          if (selection.persistGlobal) {
-            void refreshCurrentModel()
-          }
-
-          void queryClient.invalidateQueries({
-            queryKey: selection.persistGlobal ? ['model-options'] : ['model-options', activeSessionId]
-          })
-
-          return true
-        }
-
-        await setGlobalModel(selection.provider, selection.model)
-        void refreshCurrentModel()
-        void queryClient.invalidateQueries({ queryKey: ['model-options'] })
+        void queryClient.invalidateQueries({ queryKey: ['model-options', activeSessionId] })
 
         return true
       } catch (err) {
         setCurrentModel(prevModel)
         setCurrentProvider(prevProvider)
-        updateModelOptionsCache(prevProvider, prevModel, includeGlobal)
+        updateModelOptionsCache(prevProvider, prevModel, !activeSessionId)
         notifyError(err, copy.modelSwitchFailed)
 
         return false
       }
     },
-    [activeSessionId, copy.modelSwitchFailed, queryClient, refreshCurrentModel, requestGateway, updateModelOptionsCache]
+    [activeSessionId, copy.modelSwitchFailed, queryClient, requestGateway, updateModelOptionsCache]
   )
 
   return { refreshCurrentModel, selectModel, updateModelOptionsCache }

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

@@ -15,6 +15,10 @@ import { requestDesktopOnboarding } from '@/store/onboarding'
 import { $activeGatewayProfile, $newChatProfile, $profiles, ensureGatewayProfile, normalizeProfileKey } from '@/store/profile'
 import {
   $currentCwd,
+  $currentFastMode,
+  $currentModel,
+  $currentProvider,
+  $currentReasoningEffort,
   $messages,
   $sessions,
   $yoloActive,
@@ -407,13 +411,13 @@ export function useSessionActions({
       })
       setSessionStartedAt(null)
       setTurnStartedAt(null)
-      // New chats start in the configured default project dir when set,
-      // otherwise the sticky last-used workspace (PR #37586).
-      setCurrentModel('')
-      setCurrentProvider('')
-      setCurrentReasoningEffort('')
+      // The composer's model/effort/fast is sticky UI state (persisted in
+      // localStorage) — a new chat FOLLOWS your last pick instead of snapping
+      // back to the profile default, so we deliberately don't reset it here. The
+      // profile default still owns first-run seeding and profile switches (see
+      // refreshCurrentModel). Only $currentServiceTier (a live-session mirror)
+      // is cleared.
       setCurrentServiceTier('')
-      setCurrentFastMode(false)
       setYoloActive(false)
       setCurrentCwd(workspaceCwdForNewSession())
       setCurrentBranch('')
@@ -443,11 +447,23 @@ export function useSessionActions({
         const newChatProfile = $newChatProfile.get() ?? normalizeProfileKey($activeGatewayProfile.get())
         await ensureGatewayProfile(newChatProfile)
         const cwd = $currentCwd.get().trim() || workspaceCwdForNewSession()
+        // The composer's model/effort/fast is sticky UI state ($currentModel,
+        // $currentProvider, $currentReasoningEffort, $currentFastMode). Ship it
+        // with every session.create so the new chat opens on whatever the picker
+        // shows — applied as per-session overrides, never written to the profile
+        // default (that lives in Settings → Model).
+        const uiModel = $currentModel.get().trim()
+        const uiProvider = $currentProvider.get().trim()
+        const uiEffort = $currentReasoningEffort.get().trim()
+        const uiFast = $currentFastMode.get()
 
         const created = await requestGateway<SessionCreateResponse>('session.create', {
           cols: 96,
           ...(cwd && { cwd }),
-          ...(newChatProfile ? { profile: newChatProfile } : {})
+          ...(newChatProfile ? { profile: newChatProfile } : {}),
+          ...(uiModel ? { model: uiModel, ...(uiProvider ? { provider: uiProvider } : {}) } : {}),
+          ...(uiEffort ? { reasoning_effort: uiEffort } : {}),
+          ...(uiFast ? { fast: true } : {})
         })
 
         const stored = created.stored_session_id ?? null

apps/desktop/src/app/shell/model-menu-panel.tsx

@@ -43,7 +43,7 @@ import { ModelEditSubmenu, resolveFastControl } from './model-edit-submenu'
 
 interface ModelMenuPanelProps {
   gateway?: HermesGateway
-  onSelectModel: (selection: { model: string; persistGlobal: boolean; provider: string }) => Promise<boolean> | void
+  onSelectModel: (selection: { model: string; provider: string }) => Promise<boolean> | void
   requestGateway: <T>(method: string, params?: Record<string, unknown>) => Promise<T>
 }
 
@@ -95,8 +95,10 @@ export function ModelMenuPanel({ gateway, onSelectModel, requestGateway }: Model
     [visibleModels, providers]
   )
 
-  const switchTo = (model: string, provider: string) =>
-    onSelectModel({ model, persistGlobal: !activeSessionId, provider })
+  // The composer picker never persists the profile default. With a session it
+  // scopes the switch to that session; with none it's UI state shipped on the
+  // next session.create (see selectModel). The default lives in Settings → Model.
+  const switchTo = (model: string, provider: string) => onSelectModel({ model, provider })
 
   // Selecting a model row restores that model's remembered preset onto the
   // session (effort/fast), gated by capability. Unset → Hermes defaults.

apps/desktop/src/components/model-picker.tsx

@@ -11,7 +11,6 @@ import { startManualOnboarding } from '../store/onboarding'
 
 import { InlineNotice } from './notifications'
 import { Button } from './ui/button'
-import { Checkbox } from './ui/checkbox'
 import { Command, CommandEmpty, CommandGroup, CommandInput, CommandItem, CommandList } from './ui/command'
 import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from './ui/dialog'
 import { Skeleton } from './ui/skeleton'
@@ -23,7 +22,7 @@ interface ModelPickerDialogProps {
   sessionId?: string | null
   currentModel: string
   currentProvider: string
-  onSelect: (selection: { provider: string; model: string; persistGlobal: boolean }) => void
+  onSelect: (selection: { provider: string; model: string }) => void
   /**
    * Optional class to apply to DialogContent. Use to override z-index when
    * stacking the picker on top of another fixed overlay (e.g. the desktop
@@ -45,7 +44,6 @@ export function ModelPickerDialog({
 }: ModelPickerDialogProps) {
   const { t } = useI18n()
   const copy = t.modelPicker
-  const [persistGlobal, setPersistGlobal] = useState(!sessionId)
   // Own the search term so we can filter manually. cmdk's built-in
   // shouldFilter reorders items by its fuzzy-match score (≈alphabetical with
   // an empty query), which destroys the backend's curated order. We disable
@@ -79,11 +77,7 @@ export function ModelPickerDialog({
     : null
 
   const selectModel = (provider: ModelOptionProvider, model: string) => {
-    onSelect({
-      provider: provider.slug,
-      model,
-      persistGlobal: persistGlobal || !sessionId
-    })
+    onSelect({ provider: provider.slug, model })
     onOpenChange(false)
   }
 
@@ -128,24 +122,13 @@ export function ModelPickerDialog({
           </CommandList>
         </Command>
 
-        <DialogFooter className="flex-row items-center justify-between gap-3 bg-card p-3 sm:justify-between">
-          <label className="flex cursor-pointer select-none items-center gap-2 text-xs text-muted-foreground">
-            <Checkbox
-              checked={persistGlobal || !sessionId}
-              disabled={!sessionId}
-              onCheckedChange={checked => setPersistGlobal(checked === true)}
-            />
-            {sessionId ? copy.persistGlobalSession : copy.persistGlobal}
-          </label>
-
-          <div className="flex items-center gap-2">
-            <Button onClick={addProvider} variant="ghost">
-              {copy.addProvider}
-            </Button>
-            <Button onClick={() => onOpenChange(false)} variant="outline">
-              {t.common.cancel}
-            </Button>
-          </div>
+        <DialogFooter className="flex-row items-center justify-end gap-2 bg-card p-3">
+          <Button onClick={addProvider} variant="ghost">
+            {copy.addProvider}
+          </Button>
+          <Button onClick={() => onOpenChange(false)} variant="outline">
+            {t.common.cancel}
+          </Button>
         </DialogFooter>
       </DialogContent>
     </Dialog>

apps/desktop/src/i18n/en.ts

@@ -1503,8 +1503,6 @@ export const en: Translations = {
     unknown: '(unknown)',
     search: 'Filter providers and models...',
     noModels: 'No models found.',
-    persistGlobalSession: 'Persist globally (otherwise this session only)',
-    persistGlobal: 'Persist globally',
     addProvider: 'Add provider',
     loadFailed: 'Could not load models',
     noAuthenticatedProviders: 'No authenticated providers.',

apps/desktop/src/i18n/ja.ts

@@ -1637,8 +1637,6 @@ export const ja = defineLocale({
     unknown: '(不明)',
     search: 'プロバイダーとモデルをフィルター...',
     noModels: 'モデルが見つかりません。',
-    persistGlobalSession: 'グローバルに保持（それ以外はこのセッションのみ）',
-    persistGlobal: 'グローバルに保持',
     addProvider: 'プロバイダーを追加',
     loadFailed: 'モデルを読み込めませんでした',
     noAuthenticatedProviders: '認証済みプロバイダーがありません。',

apps/desktop/src/i18n/types.ts

@@ -1145,8 +1145,6 @@ export interface Translations {
     unknown: string
     search: string
     noModels: string
-    persistGlobalSession: string
-    persistGlobal: string
     addProvider: string
     loadFailed: string
     noAuthenticatedProviders: string

apps/desktop/src/i18n/zh-hant.ts

@@ -1581,8 +1581,6 @@ export const zhHant = defineLocale({
     unknown: '（未知）',
     search: '篩選提供方和模型...',
     noModels: '找不到模型。',
-    persistGlobalSession: '全域儲存（否則僅限此工作階段）',
-    persistGlobal: '全域儲存',
     addProvider: '新增提供方',
     loadFailed: '無法載入模型',
     noAuthenticatedProviders: '沒有已驗證的提供方。',

apps/desktop/src/i18n/zh.ts

@@ -1683,8 +1683,6 @@ export const zh: Translations = {
     unknown: '(未知)',
     search: '筛选提供方和模型...',
     noModels: '未找到模型。',
-    persistGlobalSession: '全局保存 (否则仅当前会话)',
-    persistGlobal: '全局保存',
     addProvider: '添加提供方',
     loadFailed: '无法加载模型',
     noAuthenticatedProviders: '没有已认证的提供方。',

apps/desktop/src/store/session.ts

@@ -4,13 +4,23 @@ import { lastVisibleMessageIsUser } from '@/app/chat/thread-loading'
 import type { ContextSuggestion } from '@/app/types'
 import type { HermesConnection } from '@/global'
 import type { ChatMessage } from '@/lib/chat-messages'
-import { persistString, storedString } from '@/lib/storage'
+import { persistBoolean, persistString, storedBoolean, storedString } from '@/lib/storage'
 import type { SessionInfo, UsageStats } from '@/types/hermes'
 
 type Updater<T> = T | ((current: T) => T)
 
 const WORKSPACE_CWD_KEY = 'hermes.desktop.workspace-cwd'
 
+// The composer's model/effort/fast is sticky UI state, NOT the profile default
+// (that lives in Settings → Model). Persisting it in localStorage makes a pick
+// follow across Cmd+N and app restarts instead of snapping back to the default.
+// It's deliberately global (not per-profile): a profile switch force-reseeds to
+// that profile's default, while within a profile new chats keep your last pick.
+const COMPOSER_MODEL_KEY = 'hermes.desktop.composer.model'
+const COMPOSER_PROVIDER_KEY = 'hermes.desktop.composer.provider'
+const COMPOSER_EFFORT_KEY = 'hermes.desktop.composer.reasoning-effort'
+const COMPOSER_FAST_KEY = 'hermes.desktop.composer.fast'
+
 let configuredDefaultProjectDir = ''
 
 function workspaceCwdKey(connection: HermesConnection | null = $connection.get()): string {
@@ -208,11 +218,11 @@ export const $lastVisibleMessageIsUser = computed($messages, lastVisibleMessageI
 export const $freshDraftReady = atom(false)
 export const $busy = atom(false)
 export const $awaitingResponse = atom(false)
-export const $currentModel = atom('')
-export const $currentProvider = atom('')
-export const $currentReasoningEffort = atom('')
+export const $currentModel = atom(storedString(COMPOSER_MODEL_KEY) ?? '')
+export const $currentProvider = atom(storedString(COMPOSER_PROVIDER_KEY) ?? '')
+export const $currentReasoningEffort = atom(storedString(COMPOSER_EFFORT_KEY) ?? '')
 export const $currentServiceTier = atom('')
-export const $currentFastMode = atom(false)
+export const $currentFastMode = atom(storedBoolean(COMPOSER_FAST_KEY, false))
 // Effective approval-bypass state mirrored from the gateway (session.info).
 // Persistence lives in the backend config (approvals.mode), so this is a plain
 // reflection of the truth the gateway reports rather than its own store.
@@ -254,11 +264,29 @@ export const setMessages = (next: Updater<ChatMessage[]>) => updateAtom($message
 export const setFreshDraftReady = (next: Updater<boolean>) => updateAtom($freshDraftReady, next)
 export const setBusy = (next: Updater<boolean>) => updateAtom($busy, next)
 export const setAwaitingResponse = (next: Updater<boolean>) => updateAtom($awaitingResponse, next)
-export const setCurrentModel = (next: Updater<string>) => updateAtom($currentModel, next)
-export const setCurrentProvider = (next: Updater<string>) => updateAtom($currentProvider, next)
-export const setCurrentReasoningEffort = (next: Updater<string>) => updateAtom($currentReasoningEffort, next)
+
+export const setCurrentModel = (next: Updater<string>) => {
+  updateAtom($currentModel, next)
+  persistString(COMPOSER_MODEL_KEY, $currentModel.get() || null)
+}
+
+export const setCurrentProvider = (next: Updater<string>) => {
+  updateAtom($currentProvider, next)
+  persistString(COMPOSER_PROVIDER_KEY, $currentProvider.get() || null)
+}
+
+export const setCurrentReasoningEffort = (next: Updater<string>) => {
+  updateAtom($currentReasoningEffort, next)
+  persistString(COMPOSER_EFFORT_KEY, $currentReasoningEffort.get() || null)
+}
+
 export const setCurrentServiceTier = (next: Updater<string>) => updateAtom($currentServiceTier, next)
-export const setCurrentFastMode = (next: Updater<boolean>) => updateAtom($currentFastMode, next)
+
+export const setCurrentFastMode = (next: Updater<boolean>) => {
+  updateAtom($currentFastMode, next)
+  persistBoolean(COMPOSER_FAST_KEY, $currentFastMode.get())
+}
+
 export const setYoloActive = (next: Updater<boolean>) => updateAtom($yoloActive, next)
 
 export const setCurrentCwd = (next: Updater<string>) => {

apps/desktop/src/store/updates.test.ts

@@ -5,6 +5,9 @@ import type { DesktopUpdateStatus } from '@/global'
 const storage = new Map<string, string>()
 
 vi.mock('@/lib/storage', () => ({
+  persistBoolean: (key: string, value: boolean) => {
+    storage.set(key, String(value))
+  },
   persistString: (key: string, value: null | string) => {
     if (value === null) {
       storage.delete(key)
@@ -12,6 +15,11 @@ vi.mock('@/lib/storage', () => ({
       storage.set(key, value)
     }
   },
+  storedBoolean: (key: string, fallback: boolean) => {
+    const value = storage.get(key)
+
+    return value === undefined ? fallback : value === 'true'
+  },
   storedString: (key: string) => storage.get(key) ?? null
 }))