fix: restore session model selections and normalize runtime effort

desktop/src/components/controls/ModelSelector.test.tsx

@@ -63,6 +63,42 @@ beforeEach(() => {
 })
 
 describe('ModelSelector', () => {
+  it('shows the configured default for an opened session whose saved provider was removed', () => {
+    useSettingsStore.setState({ locale: 'en', effortLevel: 'high' })
+    useProviderStore.setState({
+      activeId: 'replacement', hasLoadedProviders: true, isLoading: false,
+      providers: [{
+        id: 'replacement', presetId: 'custom', name: 'Replacement',
+        apiFormat: 'anthropic', apiKey: 'fixture', baseUrl: 'http://127.0.0.1:1',
+        models: { main: 'current-model', haiku: '', sonnet: '', opus: '' },
+      }],
+    })
+    useSessionRuntimeStore.getState().setSelection('restored-session', {
+      providerId: 'deleted-provider', modelId: 'old-model', effortLevel: 'max',
+    })
+
+    render(<ModelSelector runtimeKey="restored-session" />)
+
+    expect(screen.getByRole('button', { name: 'current-model, Replacement' })).toBeInTheDocument()
+    expect(screen.queryByRole('button', { name: 'Select model' })).not.toBeInTheDocument()
+    expect(screen.getByRole('button', { name: /High/ })).toBeInTheDocument()
+  })
+
+  it('keeps a restored official model visible before lazy OAuth status is fetched', () => {
+    useSettingsStore.setState({ locale: 'en' })
+    useProviderStore.setState({ hasLoadedProviders: true, providers: [], activeId: null })
+    useSessionRuntimeStore.getState().setSelection('official-restored', {
+      providerId: null, modelId: 'claude-opus-4-8', effortLevel: 'high',
+    })
+    const fetchStatus = vi.fn(async () => {})
+    useHahaOAuthStore.setState({ status: null, fetchStatus })
+
+    render(<ModelSelector runtimeKey="official-restored" />)
+
+    expect(screen.getByRole('button', { name: 'Opus 4.8, Claude Official' })).toBeInTheDocument()
+    expect(fetchStatus).not.toHaveBeenCalled()
+  })
+
   it('keeps a long model label shrinkable in a fluid desktop toolbar', () => {
     useSettingsStore.setState({ locale: 'en', availableModels: MODELS, currentModel: MODELS[0] })
     render(<ModelSelector value="alpha" onChange={vi.fn()} fluid />)
@@ -603,7 +639,7 @@ describe('ModelSelector', () => {
     })
   })
 
-  it('defaults blank provider-scoped runtime selections to the active provider main model', async () => {
+  it('defaults blank runtime selections to the model selected in settings', async () => {
     useSettingsStore.setState({
       locale: 'en',
       availableModels: [
@@ -635,17 +671,17 @@ describe('ModelSelector', () => {
 
     render(<ModelSelector runtimeKey="blank-session" />)
 
-    const trigger = screen.getByRole('button', { name: /deepseek-v4-flash/i })
+    const trigger = screen.getByRole('button', { name: /deepseek-v4-pro/i })
     await act(async () => {
       fireEvent.click(trigger)
       await Promise.resolve()
     })
 
-    const flashOption = screen
-      .getAllByRole('button', { name: /deepseek-v4-flash/i })
-      .find((button) => button.textContent?.includes('Main Model'))
-    expect(flashOption).toBeDefined()
-    expect(flashOption?.className).toContain('border-[var(--color-model-option-selected-border)]')
+    const configuredOption = screen
+      .getAllByRole('button', { name: /deepseek-v4-pro/i })
+      .find((button) => button.textContent?.includes('Sonnet Model'))
+    expect(configuredOption).toBeDefined()
+    expect(configuredOption?.className).toContain('border-[var(--color-model-option-selected-border)]')
   })
 
   it('closes the focus ring on both halves of the segmented control', () => {

desktop/src/components/controls/ModelSelector.tsx

@@ -22,8 +22,8 @@ import { useMobileViewport } from '../../hooks/useMobileViewport'
 import { isDesktopRuntime } from '../../lib/desktopRuntime'
 import {
   normalizeRuntimeSelection,
+  reconcileRuntimeSelection,
   resolveDefaultRuntimeSelection,
-  resolveProviderRuntimeModelId,
   resolveProviderSlotModelId,
 } from '../../lib/runtimeSelection'
 import { useHahaOAuthStore } from '../../stores/hahaOAuthStore'
@@ -452,25 +452,29 @@ export const ModelSelector = forwardRef<ModelSelectorHandle, Props>(function Mod
       storeModel?.id,
     )
     : null
-  const requestedRuntimeProvider = providers.find(
-    (provider) => provider.id === requestedRuntimeSelection?.providerId,
-  )
-  const activeRuntimeSelection = requestedRuntimeSelection && providerChoices.some(
-    (choice) => choice.providerId === requestedRuntimeSelection.providerId,
-  )
-    ? {
-      ...requestedRuntimeSelection,
-      modelId: requestedRuntimeProvider
-        ? resolveProviderRuntimeModelId(
-          requestedRuntimeProvider,
-          requestedRuntimeSelection.modelId,
-        )
-        : requestedRuntimeSelection.modelId,
-    }
+  const resolvedRuntimeSelection = requestedRuntimeSelection
+    ? reconcileRuntimeSelection(requestedRuntimeSelection, {
+      providers, activeId, hasLoadedProviders: hasLoadedProviders && lockedProviderId === undefined,
+      currentModelId: storeModel?.id,
+      defaultEffortLevel: effortLevel,
+    })
     : null
+  // OAuth catalogs are loaded lazily. Their absence must not erase an already
+  // selected model, even while another provider is the global default.
+  const activeRuntimeSelection = resolvedRuntimeSelection && (
+    controlledRuntimeSelection || runtimeSelection ||
+    providerChoices.some((choice) => choice.providerId === resolvedRuntimeSelection.providerId)
+  ) ? resolvedRuntimeSelection : null
 
   const selectedProviderChoice = activeRuntimeSelection
-    ? providerChoices.find((choice) => choice.providerId === activeRuntimeSelection.providerId) ?? null
+    ? providerChoices.find((choice) => choice.providerId === activeRuntimeSelection.providerId)
+      ?? (activeRuntimeSelection.providerId === null
+        ? officialChoices(null, mergeOfficialModels(activeId === null ? availableModels : []), activeId === null, t('settings.providers.officialName'))
+        : activeRuntimeSelection.providerId === OPENAI_OFFICIAL_PROVIDER_ID
+          ? officialChoices(OPENAI_OFFICIAL_PROVIDER_ID, activeId === OPENAI_OFFICIAL_PROVIDER_ID && availableModels.length ? availableModels : OPENAI_OFFICIAL_MODELS, activeId === OPENAI_OFFICIAL_PROVIDER_ID, t('settings.providers.openaiOfficialName'))
+          : activeRuntimeSelection.providerId === GROK_OFFICIAL_PROVIDER_ID
+            ? officialChoices(GROK_OFFICIAL_PROVIDER_ID, activeId === GROK_OFFICIAL_PROVIDER_ID && availableModels.length ? availableModels : GROK_OFFICIAL_MODELS, activeId === GROK_OFFICIAL_PROVIDER_ID, t('settings.providers.grokOfficialName'))
+            : null)
     : null
 
   const selectedRuntimeModel = activeRuntimeSelection
@@ -491,7 +495,7 @@ export const ModelSelector = forwardRef<ModelSelectorHandle, Props>(function Mod
     (selectedRuntimeProvider.apiFormat ?? 'anthropic') === 'anthropic' &&
     !isOpenAIReasoningModel(selectedRuntimeModel?.id ?? '')
 
-  const needsProviderConfiguration = isRuntimeScoped && providerChoices.length === 0
+  const needsProviderConfiguration = isRuntimeScoped && !activeRuntimeSelection && providerChoices.length === 0
   const buttonModelLabel = isRuntimeScoped
     ? selectedRuntimeModel?.name
       ?? (needsProviderConfiguration ? t('model.configureProvider') : t('model.selectModel'))

desktop/src/lib/runtimeSelection.test.ts

@@ -1,8 +1,14 @@
 import { describe, expect, it } from 'vitest'
-import { normalizeRuntimeSelection, resolveDefaultRuntimeSelection, resolveProviderRuntimeModelId, resolveProviderSlotModelId } from './runtimeSelection'
+import { normalizeRuntimeSelection, reconcileRuntimeSelection, resolveDefaultRuntimeSelection, resolveProviderRuntimeModelId, resolveProviderSlotModelId } from './runtimeSelection'
 import type { SavedProvider } from '../types/provider'
 
 describe('normalizeRuntimeSelection', () => {
+  it('normalizes an old ChatGPT effort against its model without downgrading supported choices', () => {
+    expect(normalizeRuntimeSelection({ providerId: 'openai-official', modelId: 'gpt-5.5', effortLevel: 'max' }))
+      .toEqual({ providerId: 'openai-official', modelId: 'gpt-5.5', effortLevel: 'medium' })
+    const futureModel = { providerId: 'openai-official', modelId: 'future-catalog-model', effortLevel: 'max' as const }
+    expect(normalizeRuntimeSelection(futureModel)).toBe(futureModel)
+  })
   it.each([
     ['Claude Official', null],
     ['ChatGPT Official', 'openai-official'],
@@ -147,6 +153,37 @@ describe('provider 1M runtime selection', () => {
     model1mSupport: { main: true, fable: false, haiku: false, sonnet: true, opus: false },
   }
 
+  it('waits for provider hydration before recovering a removed provider and preserves valid session choices', () => {
+    const selection = { providerId: 'deleted-provider', modelId: 'old-model', effortLevel: 'max' as const }
+    const context = { activeId: provider.id, providers: [provider], hasLoadedProviders: false }
+    expect(reconcileRuntimeSelection(selection, context)).toBe(selection)
+    expect(reconcileRuntimeSelection(selection, { ...context, hasLoadedProviders: true })).toEqual({
+      providerId: provider.id, modelId: 'main-model[1m]',
+    })
+    const explicit = { providerId: provider.id, modelId: 'balanced-model[1m]', effortLevel: 'high' as const }
+    expect(reconcileRuntimeSelection(explicit, { ...context, hasLoadedProviders: true })).toBe(explicit)
+    const official = { providerId: null, modelId: 'claude-opus-4-8', effortLevel: 'high' as const }
+    expect(reconcileRuntimeSelection(official, { ...context, hasLoadedProviders: true })).toBe(official)
+  })
+
+  it('reconciles effort after the provider protocol and preset become available', () => {
+    const selection = { providerId: provider.id, modelId: 'glm-5.3', effortLevel: 'medium' as const }
+    const context = {
+      activeId: provider.id, hasLoadedProviders: true,
+      providers: [{ ...provider, presetId: 'zhipuglm', apiFormat: 'anthropic' as const }],
+    }
+    expect(reconcileRuntimeSelection(selection, context)).toEqual({ ...selection, effortLevel: 'max' })
+  })
+
+  it('uses the current default effort rather than a removed provider effort or the new model default', () => {
+    const context = {
+      activeId: provider.id, hasLoadedProviders: true, defaultEffortLevel: 'high' as const,
+      providers: [{ ...provider, presetId: 'zhipuglm', models: { main: 'glm-5.3', haiku: '', sonnet: '', opus: '' } }],
+    }
+    expect(reconcileRuntimeSelection({ providerId: 'removed', modelId: 'old', effortLevel: 'medium' }, context))
+      .toEqual({ providerId: provider.id, modelId: 'glm-5.3[1m]', effortLevel: 'high' })
+  })
+
   it('materializes the active provider main slot by id and by legacy name', () => {
     for (const activeId of [provider.id, null]) {
       expect(resolveDefaultRuntimeSelection(activeId, provider.name, [provider], 'stale')).toEqual({
@@ -155,6 +192,13 @@ describe('provider 1M runtime selection', () => {
     }
   })
 
+  it('restores the model selected in settings even when it is not the provider main slot', () => {
+    const context = { providers: [provider], activeId: provider.id, hasLoadedProviders: true, currentModelId: 'balanced-model' }
+    const expected = { providerId: provider.id, modelId: 'balanced-model[1m]' }
+    expect(resolveDefaultRuntimeSelection(provider.id, provider.name, [provider], 'balanced-model')).toEqual(expected)
+    expect(reconcileRuntimeSelection({ providerId: 'removed', modelId: 'old-model' }, context)).toEqual(expected)
+  })
+
   it('reconciles restored raw and marked IDs without losing a non-main model or effort', () => {
     expect(resolveProviderRuntimeModelId(provider, 'balanced-model')).toBe('balanced-model[1m]')
     expect(resolveProviderRuntimeModelId(provider, 'large-model[1m]')).toBe('large-model')

desktop/src/lib/runtimeSelection.ts

@@ -1,6 +1,7 @@
 import { OFFICIAL_DEFAULT_MODEL_ID } from '../constants/modelCatalog'
 import {
   OPENAI_OFFICIAL_DEFAULT_MODEL_ID,
+  OPENAI_OFFICIAL_MODELS,
   OPENAI_OFFICIAL_PROVIDER_ID,
 } from '../constants/openaiOfficialProvider'
 import type { SavedProvider } from '../types/provider'
@@ -17,6 +18,7 @@ import {
   type ModelReasoningApiFormat,
   type ModelReasoningProviderKind,
 } from '../../../src/shared/modelReasoning'
+import { getBundledPresetReasoningProviderKind } from '../config/providerPresets'
 
 const PROVIDER_MODEL_SLOTS = ['main', 'haiku', 'sonnet', 'opus', 'fable'] as const
 
@@ -61,10 +63,14 @@ export function resolveActiveProviderRuntimeSelection(
   if (!inferredProviderId) return null
 
   const providerMainModelId = activeProvider ? resolveProviderSlotModelId(activeProvider, 'main') : undefined
+  const configuredModelId = activeProvider && currentModelId && PROVIDER_MODEL_SLOTS.some(
+    (slot) => activeProvider.models[slot]?.trim() &&
+      baseProviderModelId(activeProvider.models[slot]!) === baseProviderModelId(currentModelId),
+  ) ? resolveProviderRuntimeModelId(activeProvider, currentModelId) : undefined
 
   return {
     providerId: inferredProviderId,
-    modelId: providerMainModelId || currentModelId || (
+    modelId: configuredModelId || providerMainModelId || currentModelId || (
       inferredProviderId === OPENAI_OFFICIAL_PROVIDER_ID
         ? OPENAI_OFFICIAL_DEFAULT_MODEL_ID
         : inferredProviderId === GROK_OFFICIAL_PROVIDER_ID
@@ -91,6 +97,42 @@ export function resolveDefaultRuntimeSelection(
   }
 }
 
+/** Resolve restored choices only after the saved-provider list is authoritative. */
+export function reconcileRuntimeSelection(
+  selection: RuntimeSelection,
+  context: {
+    providers: SavedProvider[]
+    hasLoadedProviders: boolean
+    activeId: string | null
+    currentModelId?: string
+    defaultEffortLevel?: RuntimeSelection['effortLevel']
+  },
+): RuntimeSelection {
+  const provider = context.providers.find((entry) => entry.id === selection.providerId)
+  const isOfficial = selection.providerId === null ||
+    selection.providerId === OPENAI_OFFICIAL_PROVIDER_ID ||
+    selection.providerId === GROK_OFFICIAL_PROVIDER_ID
+  if (!provider && !isOfficial && context.hasLoadedProviders) {
+    // Deleted/recreated providers must not carry their old model or effort into
+    // the default provider. Use the same choice for rendering and transport.
+    const fallback = resolveDefaultRuntimeSelection(
+      context.activeId, null, context.providers, context.currentModelId,
+    )
+    const fallbackProvider = context.providers.find((entry) => entry.id === fallback.providerId)
+    return normalizeRuntimeSelection(
+      { ...fallback, ...(context.defaultEffortLevel ? { effortLevel: context.defaultEffortLevel } : {}) },
+      fallbackProvider?.apiFormat,
+      fallbackProvider ? getBundledPresetReasoningProviderKind(fallbackProvider.presetId) : undefined,
+    )
+  }
+  const modelId = provider ? resolveProviderRuntimeModelId(provider, selection.modelId) : selection.modelId
+  return normalizeRuntimeSelection(
+    modelId === selection.modelId ? selection : { ...selection, modelId },
+    provider?.apiFormat,
+    provider ? getBundledPresetReasoningProviderKind(provider.presetId) : undefined,
+  )
+}
+
 export function normalizeRuntimeSelection(
   selection: RuntimeSelection,
   apiFormat?: ModelReasoningApiFormat,
@@ -98,14 +140,14 @@ export function normalizeRuntimeSelection(
 ): RuntimeSelection {
   if (
     selection.effortLevel === undefined ||
-    selection.providerId === null ||
-    selection.providerId === OPENAI_OFFICIAL_PROVIDER_ID
+    selection.providerId === null
   ) {
     return selection
   }
 
-  if (selection.providerId === GROK_OFFICIAL_PROVIDER_ID) {
-    const model = GROK_OFFICIAL_MODELS.find((entry) => entry.id === selection.modelId)
+  if (selection.providerId === GROK_OFFICIAL_PROVIDER_ID || selection.providerId === OPENAI_OFFICIAL_PROVIDER_ID) {
+    const models = selection.providerId === GROK_OFFICIAL_PROVIDER_ID ? GROK_OFFICIAL_MODELS : OPENAI_OFFICIAL_MODELS
+    const model = models.find((entry) => entry.id === selection.modelId)
     // Models only known from the live catalog (e.g. grok-4.6) are absent from
     // the bundled desktop list. Keep their effort untouched and let the server
     // validate it against the live catalog instead of silently dropping it.
@@ -113,6 +155,7 @@ export function normalizeRuntimeSelection(
     const effortLevel = model.supportedReasoningEfforts?.includes(selection.effortLevel)
       ? selection.effortLevel
       : model.defaultReasoningEffort ?? model.supportedReasoningEfforts?.[0]
+    if (effortLevel === selection.effortLevel) return selection
     const { effortLevel: _unsupportedEffort, ...runtime } = selection
     return effortLevel ? { ...runtime, effortLevel } : runtime
   }

desktop/src/stores/chatStore.test.ts

@@ -83,7 +83,7 @@ const {
   sendSubagentMessageMock: vi.fn(async () => ({ ok: true })),
   tabStoreSnapshot: { tabs: [] as Tab[], activeTabId: null as string | null },
   tabStoreListeners: new Set<(state: any, previous: any) => void>(),
-  providerStoreSnapshot: { providers: [] as SavedProvider[], activeId: null as string | null },
+  providerStoreSnapshot: { providers: [] as SavedProvider[], activeId: null as string | null, hasLoadedProviders: false },
 }))
 
 vi.mock('./teamPlanStore', () => ({ useTeamPlanStore: { getState: () => ({ refresh: refreshTeamPlanMock }) } }))
@@ -532,6 +532,8 @@ describe('chatStore history mapping', () => {
   beforeEach(() => {
     providerStoreSnapshot.providers = []
     providerStoreSnapshot.activeId = null
+    providerStoreSnapshot.hasLoadedProviders = false
+    useSettingsStore.setState({ currentModel: null, activeProviderName: null, effortLevel: 'max' })
     sendMock.mockReset()
     getMemberBySessionIdMock.mockReset()
     getMemberBySessionIdMock.mockReturnValue(null)
@@ -5333,6 +5335,31 @@ describe('chatStore history mapping', () => {
     ])
   })
 
+  it.each(['reconnect', 'send'] as const)('recovers a removed provider before %s without replaying its stale model or effort', (action) => {
+    useSettingsStore.setState({ effortLevel: 'high' })
+    providerStoreSnapshot.hasLoadedProviders = true
+    providerStoreSnapshot.activeId = 'replacement'
+    providerStoreSnapshot.providers = [{
+      id: 'replacement', presetId: 'custom', name: 'Replacement', apiKey: 'fixture',
+      baseUrl: 'http://127.0.0.1:1', apiFormat: 'anthropic',
+      models: { main: 'current-model', haiku: '', sonnet: '', opus: '' },
+    }]
+    useSessionRuntimeStore.getState().setSelection(TEST_SESSION_ID, {
+      providerId: 'deleted-provider', modelId: 'old-model', effortLevel: 'max',
+    })
+    if (action === 'reconnect') {
+      useChatStore.getState().connectToSession(TEST_SESSION_ID, { prewarm: false, minimalBootstrap: true })
+    } else {
+      useChatStore.getState().sendMessage(TEST_SESSION_ID, 'continue')
+    }
+    const expected = { providerId: 'replacement', modelId: 'current-model', effortLevel: 'high' }
+    expect(sendMock.mock.calls[0]).toEqual([TEST_SESSION_ID, { type: 'set_runtime_config', ...expected }])
+    expect(useSessionRuntimeStore.getState().selections[TEST_SESSION_ID]).toEqual(expected)
+    if (action === 'send') {
+      expect(sendMock.mock.calls[1]).toEqual([TEST_SESSION_ID, { type: 'user_message', content: 'continue', attachments: undefined }])
+    }
+  })
+
   it.each([true, false])('reconciles restored raw runtime models before reconnect and the next turn (1m=%s)', (enabled) => {
     const model = 'deepseek-v4.1-flash-expires-on-0910'
     providerStoreSnapshot.providers = [{
@@ -5368,11 +5395,25 @@ describe('chatStore history mapping', () => {
     }]
     useChatStore.getState().sendMessage(TEST_SESSION_ID, 'continue')
     expect(sendMock.mock.calls.slice(0, 2)).toEqual([
-      [TEST_SESSION_ID, { type: 'set_runtime_config', providerId: 'provider-1', modelId: 'deepseek-v4.1[1m]' }],
+      [TEST_SESSION_ID, { type: 'set_runtime_config', providerId: 'provider-1', modelId: 'deepseek-v4.1[1m]', effortLevel: 'max' }],
       [TEST_SESSION_ID, { type: 'user_message', content: 'continue', attachments: undefined }],
     ])
   })
 
+  it('sends an implicit old session with the non-main model and effort shown from settings', () => {
+    providerStoreSnapshot.activeId = 'provider-1'
+    providerStoreSnapshot.providers = [{
+      id: 'provider-1', presetId: 'zhipuglm', name: 'GLM', apiKey: 'fixture',
+      baseUrl: 'http://127.0.0.1:1', apiFormat: 'anthropic',
+      models: { main: 'glm-5.2', haiku: '', sonnet: 'glm-5.3', opus: '' },
+    }]
+    useSettingsStore.setState({ currentModel: { id: 'glm-5.3', name: 'GLM', context: '', description: '' }, effortLevel: 'high' })
+    useChatStore.getState().sendMessage(TEST_SESSION_ID, 'continue')
+    expect(sendMock.mock.calls[0]).toEqual([TEST_SESSION_ID, {
+      type: 'set_runtime_config', providerId: 'provider-1', modelId: 'glm-5.3', effortLevel: 'high',
+    }])
+  })
+
   it('does not prewarm unknown desktop sessions when connecting', () => {
     useChatStore.getState().connectToSession(TEST_SESSION_ID)
 
@@ -9213,6 +9254,32 @@ describe('chatStore history mapping', () => {
     expect(useSessionRuntimeStore.getState().selections[TEST_SESSION_ID]?.modelId).toBe('model-a')
   })
 
+  it('accepts a corrected runtime acknowledgement only for the matching restored choice', () => {
+    useChatStore.setState({ sessions: { [TEST_SESSION_ID]: makeSession({ runtimeConfigReadyCount: 0 }) } })
+    const requestedConfig = { providerId: 'deleted-provider', modelId: 'old-model', effortLevel: 'max' as const }
+    const applied = { providerId: 'replacement', modelId: 'current-model', effortLevel: 'high' as const }
+    useSessionRuntimeStore.getState().setSelection(TEST_SESSION_ID, requestedConfig)
+    useChatStore.getState().handleServerMessage(TEST_SESSION_ID, {
+      type: 'error', code: 'RUNTIME_CONFIG_INVALID', message: 'Runtime effort selection is invalid.',
+    })
+    useChatStore.getState().handleServerMessage(TEST_SESSION_ID, {
+      type: 'runtime_config_applied', ...applied, requestedConfig,
+    })
+    expect(useSessionRuntimeStore.getState().selections[TEST_SESSION_ID]).toEqual(applied)
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.runtimeConfigReadyCount).toBe(1)
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.messages).not.toEqual(expect.arrayContaining([
+      expect.objectContaining({ code: 'RUNTIME_CONFIG_INVALID' }),
+    ]))
+
+    const newChoice = { providerId: 'another-provider', modelId: 'my-selection' }
+    useSessionRuntimeStore.getState().setSelection(TEST_SESSION_ID, newChoice)
+    useChatStore.getState().handleServerMessage(TEST_SESSION_ID, {
+      type: 'runtime_config_applied', ...applied, requestedConfig,
+    })
+    expect(useSessionRuntimeStore.getState().selections[TEST_SESSION_ID]).toEqual(newChoice)
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.runtimeConfigReadyCount).toBe(1)
+  })
+
   it.each(['RUNTIME_CONFIG_INVALID', 'CLI_RESTART_FAILED'])('allows fresh metadata to correct a rejected selection (%s)', (code) => {
     const runtime = useSessionRuntimeStore.getState()
     runtime.setSelection(TEST_SESSION_ID, { providerId: null, modelId: 'rejected-model' })

desktop/src/stores/chatStore.ts

@@ -15,7 +15,9 @@ import { useCLITaskStore } from './cliTaskStore'
 import { useWorkflowStore } from './workflowStore'
 import { useSessionRuntimeStore } from './sessionRuntimeStore'
 import { useProviderStore } from './providerStore'
-import { resolveActiveProviderRuntimeSelection, resolveProviderRuntimeModelId } from '../lib/runtimeSelection'
+import { reconcileRuntimeSelection, resolveActiveProviderRuntimeSelection } from '../lib/runtimeSelection'
+import { useSettingsStore } from './settingsStore'
+import { isModelReasoningEffort } from '../../../src/shared/modelReasoning'
 import { useTabStore } from './tabStore'
 import { randomSpinnerVerb } from '../config/spinnerVerbs'
 import { notifyDesktop } from '../lib/desktopNotifications'
@@ -60,11 +62,15 @@ import type {
 
 type ConnectionState = 'disconnected' | 'connecting' | 'connected' | 'reconnecting'
 
-function reconcileProviderRuntimeSelection(selection: RuntimeSelection): RuntimeSelection {
-  const provider = useProviderStore.getState().providers.find((entry) => entry.id === selection.providerId)
-  if (!provider) return selection
-  const modelId = resolveProviderRuntimeModelId(provider, selection.modelId)
-  return modelId === selection.modelId ? selection : { ...selection, modelId }
+function reconcileProviderRuntimeSelection(sessionId: string, selection: RuntimeSelection): RuntimeSelection {
+  const providers = useProviderStore.getState()
+  const settings = useSettingsStore.getState()
+  return reconcileRuntimeSelection(selection, {
+    ...providers,
+    hasLoadedProviders: providers.hasLoadedProviders && !isSideChatSession(sessionId),
+    currentModelId: settings.currentModel?.id,
+    defaultEffortLevel: settings.effortLevel,
+  })
 }
 type ToolCall = Extract<UIMessage, { type: 'tool_use' }>
 type CompactSummaryMessage = Extract<UIMessage, { type: 'compact_summary' }>
@@ -3408,14 +3414,18 @@ export const useChatStore = create<ChatStore>((setState, get) => {
 
     const selection = useSessionRuntimeStore.getState().selections[sessionId]
     if (selection) {
-      const reconciled = reconcileProviderRuntimeSelection(selection)
+      const reconciled = reconcileProviderRuntimeSelection(sessionId, selection)
       if (reconciled !== selection) get().setSessionRuntime(sessionId, selection)
     } else {
       const providers = useProviderStore.getState()
-      const defaultSelection = resolveActiveProviderRuntimeSelection(
-        providers.activeId, null, providers.providers, undefined,
+      const settings = useSettingsStore.getState()
+      const configuredDefault = resolveActiveProviderRuntimeSelection(
+        providers.activeId, settings.activeProviderName, providers.providers, settings.currentModel?.id,
       )
-      if (defaultSelection) {
+      if (configuredDefault) {
+        const defaultSelection = reconcileProviderRuntimeSelection(sessionId, {
+          ...configuredDefault, effortLevel: settings.effortLevel,
+        })
         useSessionRuntimeStore.getState().setSelection(sessionId, defaultSelection)
         get().setSessionRuntime(sessionId, defaultSelection)
       }
@@ -3484,7 +3494,7 @@ export const useChatStore = create<ChatStore>((setState, get) => {
   },
 
   setSessionRuntime: (sessionId, selection) => {
-    const reconciled = reconcileProviderRuntimeSelection(selection)
+    const reconciled = reconcileProviderRuntimeSelection(sessionId, selection)
     if (reconciled !== selection) {
       useSessionRuntimeStore.getState().setSelection(sessionId, reconciled)
     }
@@ -4865,14 +4875,22 @@ export const useChatStore = create<ChatStore>((setState, get) => {
 
       case 'runtime_config_applied': {
         const selected = useSessionRuntimeStore.getState().selections[sessionId]
-        const matchesCurrentSelection = Boolean(selected) &&
-          (selected?.providerId ?? null) === msg.providerId &&
-          selected?.modelId === msg.modelId &&
-          selected?.effortLevel === msg.effortLevel
-        if (matchesCurrentSelection) {
+        const matchesSelection = (runtime: { providerId: string | null; modelId: string; effortLevel?: string }) =>
+          Boolean(selected) && selected?.providerId === runtime.providerId &&
+          selected?.modelId === runtime.modelId && selected?.effortLevel === runtime.effortLevel
+        const matchesCurrentSelection = matchesSelection(msg)
+        const correctsCurrentSelection = msg.requestedConfig && matchesSelection(msg.requestedConfig)
+        if (matchesCurrentSelection || correctsCurrentSelection) {
+          if (correctsCurrentSelection && !matchesCurrentSelection) {
+            useSessionRuntimeStore.getState().setSelection(sessionId, {
+              providerId: msg.providerId, modelId: msg.modelId,
+              ...(msg.effortLevel && isModelReasoningEffort(msg.effortLevel) ? { effortLevel: msg.effortLevel } : {}),
+            })
+          }
           useSessionRuntimeStore.getState().settleSelection(sessionId)
           update((session) => ({
             runtimeConfigReadyCount: (session.runtimeConfigReadyCount ?? 0) + 1,
+            messages: session.messages.filter((message) => message.type !== 'error' || message.code !== 'RUNTIME_CONFIG_INVALID'),
           }))
         }
         break

desktop/src/types/chat.ts

@@ -141,6 +141,7 @@ export type ServerMessage =
       providerId: string | null
       modelId: string
       effortLevel?: string
+      requestedConfig?: { providerId: string | null; modelId: string; effortLevel?: string }
     }
   // CLI 回传的权限模式变化（如 ExitPlanMode 退出 plan 后恢复、Shift+Tab）。
   // 桌面端据此把选择器校正回 CLI 的真实权限，避免本地影子值漂移。

src/server/__tests__/conversations.test.ts

@@ -5687,14 +5687,23 @@ describe('WebSocket Chat Integration', () => {
     }
   }, 20_000)
 
-  it('should ignore stale persisted runtime provider ids when resuming old sessions', async () => {
+  it.each([[undefined, true], ['high', true], [undefined, false], ['high', false]] as const)(
+    'should recover a deleted runtime provider with saved effort %s (replayed %s) and acknowledge the effective runtime',
+    async (savedEffort, replaySelection) => {
     const providerService = new ProviderService()
+    const expectedModelId = savedEffort ? 'current-main[1m]' : 'current-main'
+    const settingsService = new SettingsService()
+    const previousSettings = await settingsService.getUserSettings()
+    const previousManagedSettings = await providerService.getManagedSettings()
+    await settingsService.updateUserSettings({ effort: 'medium' })
+    await providerService.updateManagedSettings({ model: undefined, modelContext: undefined })
     const activeProvider = await providerService.addProvider({
       presetId: 'custom',
       name: 'Current Valid Provider',
       apiKey: 'key-current-valid',
       baseUrl: 'http://127.0.0.1:1/anthropic',
       apiFormat: 'anthropic',
+      ...(savedEffort ? { model1mSupport: { main: true, haiku: false, sonnet: false, opus: false } } : {}),
       models: {
         main: 'current-main',
         haiku: 'current-haiku',
@@ -5713,6 +5722,12 @@ describe('WebSocket Chat Integration', () => {
     const { sessionId } = await createRes.json() as { sessionId: string }
 
     const staleProviderId = crypto.randomUUID()
+    await sessionService.appendSessionMetadata(sessionId, {
+      workDir: process.cwd(),
+      runtimeProviderId: staleProviderId,
+      runtimeModelId: 'stale-model',
+      ...(savedEffort ? { effortLevel: savedEffort } : {}),
+    })
     const originalStartSession = conversationService.startSession.bind(conversationService)
     const startCalls: Array<{
       sessionId: string
@@ -5743,11 +5758,15 @@ describe('WebSocket Chat Integration', () => {
           messages.push(msg)
 
           if (msg.type === 'connected') {
-            ws.send(JSON.stringify({
-              type: 'set_runtime_config',
-              providerId: staleProviderId,
-              modelId: 'stale-model',
-            }))
+            if (replaySelection) {
+              // A reconnect can replay the same saved selection more than once.
+              for (let replay = 0; replay < 2; replay++) ws.send(JSON.stringify({
+                type: 'set_runtime_config',
+                providerId: staleProviderId,
+                modelId: 'stale-model',
+                ...(savedEffort ? { effortLevel: savedEffort } : {}),
+              }))
+            }
             ws.send(JSON.stringify({ type: 'user_message', content: 'resume old session' }))
             return
           }
@@ -5777,15 +5796,82 @@ describe('WebSocket Chat Integration', () => {
         sessionId,
         options: {
           providerId: activeProvider.id,
+          model: expectedModelId,
+          effort: 'medium',
         },
       })
-      expect(startCalls[0]?.options?.model).not.toBe('stale-model')
+      if (replaySelection) expect(messages.filter((message) => message.type === 'runtime_config_applied')).toHaveLength(2)
+      if (replaySelection) expect(messages.find((message) => message.type === 'runtime_config_applied')).toMatchObject({
+        requestedConfig: {
+          providerId: staleProviderId,
+          modelId: 'stale-model',
+          ...(savedEffort ? { effortLevel: savedEffort } : {}),
+        },
+        providerId: activeProvider.id,
+        modelId: expectedModelId,
+        effortLevel: 'medium',
+      })
+      const launchInfo = await sessionService.getSessionLaunchInfo(sessionId)
+      expect(launchInfo).toMatchObject({
+        runtimeProviderId: activeProvider.id,
+        runtimeModelId: expectedModelId,
+        effortLevel: 'medium',
+      })
       expect(messages.some((msg) => msg.type === 'message_complete')).toBe(true)
     } finally {
       ws.close()
       conversationService.startSession = originalStartSession
       conversationService.stopSession(sessionId)
       await providerService.activateOfficial()
+      await providerService.deleteProvider(activeProvider.id)
+      await fs.writeFile(path.join(tmpDir, 'settings.json'), JSON.stringify(previousSettings), 'utf-8')
+      await providerService.updateManagedSettings({ model: undefined, modelContext: undefined, ...previousManagedSettings })
+    }
+  }, 20_000)
+
+  it('should normalize saved ChatGPT effort when the restored model no longer supports it', async () => {
+    const createRes = await fetch(`${baseUrl}/api/sessions`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ workDir: process.cwd() }),
+    })
+    expect(createRes.status).toBe(201)
+    const { sessionId } = await createRes.json() as { sessionId: string }
+    await sessionService.appendSessionMetadata(sessionId, {
+      workDir: process.cwd(),
+      runtimeProviderId: 'openai-official',
+      runtimeModelId: 'gpt-5.5',
+      effortLevel: 'max',
+    })
+    const originalStartSession = conversationService.startSession.bind(conversationService)
+    const startCalls: Array<{ options?: { model?: string; effort?: string; providerId?: string | null } }> = []
+    conversationService.startSession = (async function patchedStartSession(
+      sid: string,
+      workDir: string,
+      sdkUrl: string,
+      options?: { permissionMode?: string; model?: string; effort?: string; thinking?: 'enabled' | 'adaptive' | 'disabled'; providerId?: string | null },
+    ) {
+      startCalls.push({ options })
+      return originalStartSession(sid, workDir, sdkUrl, options)
+    }) as typeof conversationService.startSession
+
+    try {
+      const messages = await runTurn(sessionId, 'resume the saved ChatGPT runtime')
+      expect(messages.some((message) => message.type === 'message_complete')).toBe(true)
+      expect(startCalls).toHaveLength(1)
+      expect(startCalls[0]?.options).toMatchObject({
+        providerId: 'openai-official',
+        model: 'gpt-5.5',
+        effort: 'medium',
+      })
+      expect(await sessionService.getSessionLaunchInfo(sessionId)).toMatchObject({
+        runtimeProviderId: 'openai-official',
+        runtimeModelId: 'gpt-5.5',
+        effortLevel: 'medium',
+      })
+    } finally {
+      conversationService.startSession = originalStartSession
+      conversationService.stopSession(sessionId)
     }
   }, 20_000)
 
@@ -6054,7 +6140,7 @@ describe('WebSocket Chat Integration', () => {
     }
   }, 20_000)
 
-  it('should reject a reasoning effort that the selected ChatGPT model does not support', async () => {
+  it.each(['max', 'not-an-effort'])('should reject an explicitly requested ChatGPT effort %s that the selected model does not support', async (effortLevel) => {
     const sessionId = `chat-openai-invalid-effort-${crypto.randomUUID()}`
     await new Promise<void>((resolve, reject) => {
       const ws = new WebSocket(`${wsUrl}/ws/${sessionId}`)
@@ -6070,7 +6156,7 @@ describe('WebSocket Chat Integration', () => {
             type: 'set_runtime_config',
             providerId: 'openai-official',
             modelId: 'gpt-5.5',
-            effortLevel: 'max',
+            effortLevel,
           }))
         } else if (message.type === 'error') {
           clearTimeout(timeout)
@@ -6083,6 +6169,74 @@ describe('WebSocket Chat Integration', () => {
     })
   }, 10_000)
 
+  it.each([
+    { providerId: null, modelId: '', effortLevel: 'high' },
+    { providerId: null, modelId: 'mock-next', effortLevel: 'invalid' },
+    { providerId: 'openai-official', modelId: 'gpt-5.5', effortLevel: 'max' },
+  ])('does not send queued or subsequent user messages to the old runtime after rejected selection %j', async (invalidSelection) => {
+    const createRes = await fetch(`${baseUrl}/api/sessions`, {
+      method: 'POST', headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ workDir: process.cwd() }),
+    })
+    const { sessionId } = await createRes.json() as { sessionId: string }
+    let ws = new WebSocket(`${wsUrl}/ws/${sessionId}`)
+    const messages: any[] = []
+    ws.onmessage = event => messages.push(JSON.parse(String(event.data)))
+    const originalSendMessage = conversationService.sendMessage.bind(conversationService)
+    const sentContents: string[] = []
+    conversationService.sendMessage = (function (sid, content, attachments, options) {
+      if (sid === sessionId) sentContents.push(content)
+      return originalSendMessage(sid, content, attachments, options)
+    }) as typeof conversationService.sendMessage
+    const hasTurnOutcome = (since: number) => messages.slice(since).some(message =>
+      message.type === 'message_complete' || message.code === 'USER_TURN_FAILED')
+
+    try {
+      await waitUntil(() => messages.some(message => message.type === 'connected'), 'runtime rejection connection')
+      ws.send(JSON.stringify({ type: 'set_runtime_config', providerId: null, modelId: 'mock-old', effortLevel: 'high' }))
+      await waitUntil(() => messages.some(message => message.type === 'runtime_config_applied'), 'original runtime accepted')
+      ws.send(JSON.stringify({ type: 'user_message', content: 'warm original runtime' }))
+      await waitUntil(() => messages.some(message => message.type === 'message_complete'), 'original runtime completed')
+
+      for (const [index, content] of ['queued after invalid selection', 'retry while selection remains invalid'].entries()) {
+        const since = messages.length
+        if (index === 0) ws.send(JSON.stringify({ type: 'set_runtime_config', ...invalidSelection }))
+        ws.send(JSON.stringify({ type: 'user_message', content }))
+        await waitUntil(() => hasTurnOutcome(since), 'rejected runtime user turn settled')
+        expect(sentContents).toEqual(['warm original runtime'])
+        expect(messages.slice(since)).toContainEqual(expect.objectContaining({ type: 'error', code: 'USER_TURN_FAILED' }))
+        expect(messages.slice(since)).toContainEqual({ type: 'status', state: 'idle' })
+        expect(conversationService.hasSession(sessionId)).toBe(true)
+      }
+
+      ws.send(JSON.stringify({ type: 'set_runtime_config', providerId: null, modelId: 'mock-new', effortLevel: 'medium' }))
+      await waitUntil(() => messages.some(message => message.type === 'runtime_config_applied' && message.modelId === 'mock-new'), 'corrected runtime applied')
+      const since = messages.length
+      ws.send(JSON.stringify({ type: 'user_message', content: 'send with corrected runtime' }))
+      await waitUntil(() => hasTurnOutcome(since), 'corrected runtime user turn settled')
+      expect(messages.slice(since).some(message => message.type === 'message_complete')).toBe(true)
+      expect(sentContents).toEqual(['warm original runtime', 'send with corrected runtime'])
+      expect(await sessionService.getSessionLaunchInfo(sessionId)).toMatchObject({ runtimeModelId: 'mock-new', effortLevel: 'medium' })
+      const rejectedSince = messages.length
+      ws.send(JSON.stringify({ type: 'set_runtime_config', ...invalidSelection }))
+      await waitUntil(() => messages.slice(rejectedSince).some(message => message.code === 'RUNTIME_CONFIG_INVALID'), 'another rejected selection')
+      const { closeSessionConnection } = await import('../ws/handler.js')
+      closeSessionConnection(sessionId)
+      const reconnectSince = messages.length
+      ws = new WebSocket(`${wsUrl}/ws/${sessionId}`)
+      ws.onmessage = event => messages.push(JSON.parse(String(event.data)))
+      await waitUntil(() => messages.slice(reconnectSince).some(message => message.type === 'connected'), 'connection after cleanup')
+      ws.send(JSON.stringify({ type: 'user_message', content: 'send after session cleanup' }))
+      await waitUntil(() => hasTurnOutcome(reconnectSince), 'turn after cleanup settled')
+      expect(messages.slice(reconnectSince).some(message => message.type === 'message_complete')).toBe(true)
+      expect(sentContents).toEqual(['warm original runtime', 'send with corrected runtime', 'send after session cleanup'])
+    } finally {
+      ws.close()
+      conversationService.sendMessage = originalSendMessage
+      conversationService.stopSession(sessionId)
+    }
+  }, 20_000)
+
   it('should reject unsupported GLM 5.3 standard API effort aliases', async () => {
     const providerService = new ProviderService()
     const provider = await providerService.addProvider({

src/server/__tests__/e2e/side-chat.test.ts

@@ -80,9 +80,15 @@ test('temporary side chat forks a fixed boundary, supports independent multi-tur
     await eventually(() => child.events.filter(event => event.type === 'message_complete').length >= 3, 'side tool completed')
     expect(main.events.some(event => event.type === 'permission_request')).toBe(false)
     // A runtime change that needs restart must fail before stopping the live child.
-    child.socket.send(JSON.stringify({ type: 'set_runtime_config', providerId: 'different-provider', modelId: 'other' }))
-    await eventually(() => child.events.some(event => event.code === 'SIDE_CHAT_RUNTIME_RESTART_UNAVAILABLE'), 'safe runtime rejection')
-    expect(conversationService.hasSession(side.sessionId)).toBe(true)
+    const appliedRuntimeCount = child.events.filter(event => event.type === 'runtime_config_applied').length
+    for (const providerId of ['different-provider', 'openai-official']) {
+      const rejectionCount = child.events.filter(event => event.code === 'SIDE_CHAT_RUNTIME_RESTART_UNAVAILABLE').length
+      child.socket.send(JSON.stringify({ type: 'set_runtime_config', providerId, modelId: 'other' }))
+      await eventually(() => child.events.filter(event => event.code === 'SIDE_CHAT_RUNTIME_RESTART_UNAVAILABLE').length > rejectionCount, 'safe runtime rejection')
+      expect(conversationService.hasSession(side.sessionId)).toBe(true)
+      expect(child.events.filter(event => event.type === 'runtime_config_applied')).toHaveLength(appliedRuntimeCount)
+      expect((await sessionService.getSessionLaunchInfo(side.sessionId))?.runtimeModelId).toBe('mock-next')
+    }
     expect((await api(`/api/sessions/${side.sessionId}/messages`)).messages).toEqual([])
     expect(await api(`/api/sessions/${side.sessionId}/turn-checkpoints`)).toEqual({ checkpoints: [] })
     expect(await sessionService.getSessionMessagesWithEvidence(side.sessionId)).toEqual({ messages: [], transcriptEvidenceComplete: false })

src/server/__tests__/sessionStateCleanup.test.ts

@@ -55,6 +55,7 @@ const CONTAINERS: Record<string, Classification> = {
   prewarmIdleTimers: { kind: 'cleared' },
   prewarmPendingSessions: { kind: 'cleared' },
   prewarmedSessions: { kind: 'cleared' },
+  rejectedRuntimeConfigs: { kind: 'cleared' },
   runtimeExitStoppedSessions: { kind: 'cleared' },
   runtimeOverrides: { kind: 'cleared' },
   runtimeTransitionPromises: { kind: 'cleared' },

src/server/__tests__/websocket-handler.test.ts

@@ -11,6 +11,7 @@ import {
   __resolveRuntimeRestartWorkDirForTests,
   closeSessionConnection,
   getActiveSessionIds,
+  getRuntimeSettings,
   handleWebSocket,
   stopSessionTurn,
   __registerPendingSessionStartupForTests,
@@ -27,6 +28,8 @@ import { sessionService } from '../services/sessionService.js'
 import { observeSessionTurns, type SessionTurnEvent } from '../services/sessionTurnEvents.js'
 import * as titleService from '../services/titleService.js'
 import { SettingsService } from '../services/settingsService.js'
+import { ProviderService } from '../services/providerService.js'
+import * as sideChatRegistry from '../services/sideChatRegistry.js'
 import { activeBackgroundTaskIds } from '../ws/agentTaskState.js'
 import * as teleportApi from '../../utils/teleport/api.js'
 import { resetSettingsCache, setSessionSettingsCache } from '../../utils/settings/settingsCache.js'
@@ -66,6 +69,28 @@ function makeSdkSocket(sessionId: string, sdkToken: string) {
   } as unknown as ServerWebSocket<WebSocketData>
 }
 
+function mockSavedDeepSeekProvider(): void {
+  spyOn(ProviderService.prototype, 'listProviders').mockResolvedValue({
+    activeId: 'deepseek',
+    providerOrder: ['deepseek'],
+    providers: [{
+      id: 'deepseek',
+      presetId: 'deepseek',
+      name: 'Test DeepSeek provider',
+      apiKey: 'test-deepseek-key',
+      baseUrl: 'http://127.0.0.1:1/anthropic',
+      apiFormat: 'anthropic',
+      runtimeKind: 'anthropic_compatible',
+      models: {
+        main: 'deepseek-v4-pro',
+        haiku: 'deepseek-v4-flash',
+        sonnet: 'deepseek-v4-pro',
+        opus: 'deepseek-v4-pro',
+      },
+    }],
+  })
+}
+
 async function flushMicrotasks(count = 12): Promise<void> {
   for (let index = 0; index < count; index++) await Promise.resolve()
 }
@@ -4157,7 +4182,8 @@ describe('WebSocket handler session isolation', () => {
     }
   })
 
-  it('approves ExitPlanMode with an in-process model switch for the same provider', async () => {
+  it('preserves effort through a same-provider model-only plan approval and session restoration', async () => {
+    mockSavedDeepSeekProvider()
     const sessionId = `plan-same-provider-${crypto.randomUUID()}`
     const ws = makeClientSocket(sessionId)
 
@@ -4166,7 +4192,7 @@ describe('WebSocket handler session isolation', () => {
     spyOn(conversationService, 'getSessionWorkDir').mockReturnValue('/tmp')
     spyOn(conversationService, 'setModel').mockResolvedValue(true)
     spyOn(conversationService, 'respondToPermission').mockReturnValue(true)
-    spyOn(sessionService, 'getSessionLaunchInfo').mockResolvedValue({
+    const launchInfo = {
       filePath: '/tmp/plan-session.jsonl',
       projectDir: '/tmp',
       workDir: '/tmp',
@@ -4174,8 +4200,12 @@ describe('WebSocket handler session isolation', () => {
       customTitle: null,
       runtimeProviderId: 'deepseek',
       runtimeModelId: 'deepseek-v4-pro',
+      effortLevel: 'high',
+    }
+    spyOn(sessionService, 'getSessionLaunchInfo').mockImplementation(async () => launchInfo)
+    spyOn(sessionService, 'appendSessionMetadata').mockImplementation(async (_id, metadata) => {
+      Object.assign(launchInfo, metadata)
     })
-    spyOn(sessionService, 'appendSessionMetadata').mockResolvedValue(undefined)
     const startSession = spyOn(conversationService, 'startSession').mockResolvedValue()
     const stopSession = spyOn(conversationService, 'stopSession').mockImplementation(() => {})
 
@@ -4205,9 +4235,65 @@ describe('WebSocket handler session isolation', () => {
       workDir: '/tmp',
       runtimeProviderId: 'deepseek',
       runtimeModelId: 'deepseek-v4-flash',
+      effortLevel: 'high',
     })
     expect(startSession).not.toHaveBeenCalled()
     expect(stopSession).not.toHaveBeenCalled()
+    expect(ws.sent.map(payload => JSON.parse(payload))).toContainEqual({
+      type: 'runtime_config_applied',
+      providerId: 'deepseek',
+      modelId: 'deepseek-v4-flash',
+      effortLevel: 'high',
+      requestedConfig: { providerId: 'deepseek', modelId: 'deepseek-v4-flash' },
+    })
+    expect(await getRuntimeSettings(sessionId)).toMatchObject({ model: 'deepseek-v4-flash', effort: 'high' })
+    closeSessionConnection(sessionId)
+    expect(await getRuntimeSettings(sessionId)).toMatchObject({ model: 'deepseek-v4-flash', effort: 'high' })
+  })
+
+  it('rejects a deleted provider in side-chat plan approval before default fallback', async () => {
+    const sessionId = `side-plan-provider-${crypto.randomUUID()}`
+    const ws = makeClientSocket(sessionId)
+    spyOn(sideChatRegistry, 'getSideChat').mockReturnValue({
+      sessionId,
+      parentSessionId: 'parent-plan',
+      cliSessionId: 'side-plan-cli',
+      resumePath: '/tmp/side-plan.jsonl',
+      resumeAt: 'plan-boundary',
+      createdAt: new Date().toISOString(),
+      started: true,
+      closed: false,
+      launchInfo: {
+        filePath: '/tmp/side-plan.jsonl',
+        projectDir: '/tmp',
+        workDir: '/tmp',
+        transcriptMessageCount: 0,
+        customTitle: null,
+        runtimeProviderId: null,
+        runtimeModelId: 'claude-sonnet-5',
+      },
+    })
+    spyOn(conversationService, 'getPendingPermissionToolName').mockReturnValue('ExitPlanMode')
+    const setModel = spyOn(conversationService, 'setModel').mockResolvedValue(true)
+    const approve = spyOn(conversationService, 'respondToPermission').mockReturnValue(true)
+    const listProviders = spyOn(ProviderService.prototype, 'listProviders').mockResolvedValue({
+      providers: [], activeId: null, providerOrder: [],
+    })
+
+    handleWebSocket.message(ws, JSON.stringify({
+      type: 'permission_response',
+      requestId: 'side-plan-approval',
+      allowed: true,
+      runtimeOverride: { providerId: 'deleted-provider', modelId: 'old-model' },
+    }))
+    await flushMicrotasks()
+
+    expect(ws.sent.map(payload => JSON.parse(payload))).toContainEqual(expect.objectContaining({
+      type: 'error', code: 'SIDE_CHAT_RUNTIME_RESTART_UNAVAILABLE',
+    }))
+    expect(listProviders).not.toHaveBeenCalled()
+    expect(setModel).not.toHaveBeenCalled()
+    expect(approve).not.toHaveBeenCalled()
   })
 
   it('approves ExitPlanMode with a cross-provider switch via restart and auto-continue', async () => {
@@ -4309,6 +4395,7 @@ describe('WebSocket handler session isolation', () => {
   })
 
   it('keeps the permission pending when the in-process model switch fails', async () => {
+    mockSavedDeepSeekProvider()
     const sessionId = `plan-set-model-fail-${crypto.randomUUID()}`
     const ws = makeClientSocket(sessionId)
 

src/server/services/localIndex/sessionProjector.test.ts

@@ -88,6 +88,36 @@ async function sourceHash(path: string): Promise<string> {
 }
 
 describe('session projector', () => {
+  it('rebuilds a v7 cached runtime selection to clear effort omitted by its replacement', async () => {
+    const root = await createTempDir('projector-runtime-effort')
+    const database = openLocalIndexDatabase({ path: join(root, 'index.sqlite') })
+    const index = createSessionIndex(database)
+    const candidate = await createCandidate({
+      root, projectPath: '-repo', sessionId: 'runtime-replacement',
+      content: [
+        { type: 'session-meta', runtimeProviderId: 'old-provider', runtimeModelId: 'old-model', effortLevel: 'high' },
+        user('Existing conversation', '2026-01-01T00:00:00Z'),
+        { type: 'session-meta', runtimeProviderId: 'new-provider', runtimeModelId: 'new-model' },
+      ].map(line).join(''),
+    })
+    try {
+      const original = await readFile(candidate.path, 'utf8')
+      await createSessionProjector({ database, index, scope: root, parserVersion: 7 }).projectSource(candidate)
+      // Reproduce the cached summary written by the v7 reducer.
+      database.write(operation => operation.run(
+        'UPDATE sessions SET effort_level = ? WHERE session_id = ?', 'high', candidate.sessionId,
+      ))
+      expect(index.listSessions().sessions[0]?.effortLevel).toBe('high')
+      const restarted = createSessionProjector({ database, index, scope: root })
+      expect(await restarted.projectSource(candidate)).toMatchObject({ kind: 'indexed', action: 'rebuild' })
+      expect(index.listSessions().sessions[0]).toMatchObject({ runtimeProviderId: 'new-provider', runtimeModelId: 'new-model' })
+      expect(index.listSessions().sessions[0]?.effortLevel).toBeUndefined()
+      expect(await readFile(candidate.path, 'utf8')).toBe(original)
+    } finally {
+      database.close()
+    }
+  })
+
   it('persists an immediate title patch without waiting for transcript reprojection', async () => {
     const root = await createTempDir('projector-title-patch')
     const databasePath = join(root, 'index.sqlite')

src/server/services/localIndex/sessionProjector.ts

@@ -37,7 +37,8 @@ import type {
 // 5: protocol-lock metadata was projected into session summaries.
 // 6: protocol enforcement was removed; rebuild v5 summaries without protocol restrictions.
 // 7: independent desktop team workers remain addressable but leave sidebar listings.
-export const SESSION_SUMMARY_PARSER_VERSION = 7
+// 8: complete runtime selections clear the previous effort when no override is saved.
+export const SESSION_SUMMARY_PARSER_VERSION = 8
 
 export type SessionSourceCandidate = {
   path: string

src/server/services/localIndex/transcriptReducer.test.ts

@@ -57,6 +57,24 @@ function assistant(timestamp: string, extra: Record<string, unknown> = {}) {
 }
 
 describe('reduceTranscript', () => {
+  it('clears inherited effort on full runtime replacements in complete and incremental projections', () => {
+    const oldSelection = { type: 'session-meta', runtimeProviderId: 'old-provider', runtimeModelId: 'old-model', effortLevel: 'high' }
+    const replacement = { type: 'session-meta', runtimeProviderId: 'new-provider', runtimeModelId: 'new-model' }
+    const first = reduceTranscript(completeChunks([oldSelection]), initialProjection())
+    expect(first.summary.effortLevel).toBe('high')
+    const incremental = reduceTranscript(completeChunks([replacement], first.indexedBytes), first)
+    const complete = reduceTranscript(completeChunks([oldSelection, replacement]), initialProjection())
+    for (const projection of [incremental, complete]) {
+      expect(projection.summary).toMatchObject({ runtimeProviderId: 'new-provider', runtimeModelId: 'new-model' })
+      expect(projection.summary.effortLevel).toBeUndefined()
+    }
+    const partial = reduceTranscript(completeChunks([
+      { type: 'session-meta', permissionMode: 'plan' },
+      { type: 'session-meta', runtimeModelId: 'historical-model' },
+    ], first.indexedBytes), first)
+    expect(partial.summary.effortLevel).toBe('high')
+  })
+
   it('projects the existing summary fields and title precedence from complete lines', () => {
     const repository = {
       requestedWorkDir: '/repo',

src/server/services/localIndex/transcriptReducer.ts

@@ -135,6 +135,25 @@ const VALID_SESSION_PERMISSION_MODES = new Set([
   'auto',
 ])
 const VALID_SESSION_EFFORT_LEVELS = new Set(['low', 'medium', 'high', 'xhigh', 'max'])
+
+export function resolveSessionEffortLevel(
+  record: Record<string, unknown>,
+  previous: string | undefined,
+): string | undefined {
+  if (typeof record.effortLevel === 'string' && VALID_SESSION_EFFORT_LEVELS.has(record.effortLevel)) {
+    return record.effortLevel
+  }
+  // A complete runtime selection replaces the previous selection, including
+  // its effort override. Historical partial metadata remains a patch.
+  if (
+    (record.runtimeProviderId === null || typeof record.runtimeProviderId === 'string') &&
+    typeof record.runtimeModelId === 'string' && record.runtimeModelId.length > 0
+  ) {
+    return undefined
+  }
+  return previous
+}
+
 const ACTIVITY_TRANSCRIPT_MESSAGE_TYPES = new Set([
   'user',
   'assistant',
@@ -546,12 +565,7 @@ function applyEntry(state: ReducerState, entry: ReducerEntry): void {
     if (typeof record.runtimeModelId === 'string') {
       state.runtimeModelId = record.runtimeModelId
     }
-    if (
-      typeof record.effortLevel === 'string' &&
-      VALID_SESSION_EFFORT_LEVELS.has(record.effortLevel)
-    ) {
-      state.effortLevel = record.effortLevel
-    }
+    state.effortLevel = resolveSessionEffortLevel(record, state.effortLevel)
   }
 
   if (typeof entry.cwd === 'string' && entry.cwd.trim()) {

src/server/services/sessionService.runtimeSelection.test.ts

@@ -0,0 +1,138 @@
+import { afterEach, beforeEach, expect, test } from 'bun:test'
+import { mkdtemp, mkdir, readFile, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { SessionService } from './sessionService.js'
+import { registerSideChat, closeSideChatsForParent } from './sideChatRegistry.js'
+import { resetSettingsCache } from '../../utils/settings/settingsCache.js'
+import { sanitizePath } from '../../utils/sessionStoragePortable.js'
+
+const sessionId = 'aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee'
+let directory: string
+let service: SessionService
+let previousConfig: string | undefined
+let previousHome: string | undefined
+
+beforeEach(async () => {
+  directory = await mkdtemp(join(tmpdir(), 'session-runtime-selection-'))
+  previousConfig = process.env.CLAUDE_CONFIG_DIR
+  previousHome = process.env.HOME
+  process.env.CLAUDE_CONFIG_DIR = directory
+  process.env.HOME = directory
+  resetSettingsCache()
+  service = new SessionService()
+})
+
+afterEach(async () => {
+  closeSideChatsForParent(sessionId)
+  if (previousConfig === undefined) delete process.env.CLAUDE_CONFIG_DIR
+  else process.env.CLAUDE_CONFIG_DIR = previousConfig
+  if (previousHome === undefined) delete process.env.HOME
+  else process.env.HOME = previousHome
+  resetSettingsCache()
+  await rm(directory, { recursive: true, force: true })
+})
+
+async function seedLegacySelection() {
+  const projectDir = sanitizePath(directory)
+  const filePath = join(directory, 'projects', projectDir, `${sessionId}.jsonl`)
+  await mkdir(join(directory, 'projects', projectDir), { recursive: true })
+  await writeFile(filePath, [
+    { type: 'session-meta', workDir: directory, runtimeProviderId: 'old-provider', runtimeModelId: 'old-model', effortLevel: 'high' },
+    { type: 'user', uuid: 'old-message', message: { role: 'user', content: 'Existing conversation' } },
+  ].map(entry => JSON.stringify(entry)).join('\n') + '\n')
+  return filePath
+}
+
+async function expectSelection(reader: SessionService, provider: string | null, model: string, effort: string | undefined) {
+  const launchInfo = await reader.getSessionLaunchInfo(sessionId)
+  const summary = await reader.getSessionSummary(sessionId)
+  const listed = (await reader.listSessions()).sessions.find(session => session.id === sessionId)
+  const inspection = await reader.getInspectionTranscriptSnapshot(sessionId)
+  for (const result of [launchInfo, summary, listed, inspection?.launchInfo]) {
+    expect(result).toMatchObject({ runtimeProviderId: provider, runtimeModelId: model })
+    expect(result?.effortLevel).toBe(effort)
+  }
+}
+
+test('a complete runtime replacement clears old effort from warm readers and after restart', async () => {
+  const filePath = await seedLegacySelection()
+  await expectSelection(service, 'old-provider', 'old-model', 'high')
+  await service.appendSessionMetadata(sessionId, {
+    workDir: directory, runtimeProviderId: 'replacement-provider', runtimeModelId: 'replacement-model',
+  })
+  await expectSelection(service, 'replacement-provider', 'replacement-model', undefined)
+  await expectSelection(new SessionService(), 'replacement-provider', 'replacement-model', undefined)
+  const latest = JSON.parse((await readFile(filePath, 'utf8')).trim().split('\n').at(-1)!)
+  expect(latest).not.toHaveProperty('effortLevel')
+})
+
+test('resetting effort on an unchanged provider and model is persisted exactly once', async () => {
+  const filePath = await seedLegacySelection()
+  const before = await readFile(filePath, 'utf8')
+  const metadata = { workDir: directory, runtimeProviderId: 'old-provider', runtimeModelId: 'old-model' }
+  await service.appendSessionMetadata(sessionId, metadata)
+  const reset = await readFile(filePath, 'utf8')
+  expect(reset).not.toBe(before)
+  await expectSelection(new SessionService(), 'old-provider', 'old-model', undefined)
+  await service.appendSessionMetadata(sessionId, metadata)
+  expect(await readFile(filePath, 'utf8')).toBe(reset)
+})
+
+test('ordinary metadata and historical partial runtime updates preserve effort', async () => {
+  await seedLegacySelection()
+  await service.appendSessionMetadata(sessionId, { workDir: directory, permissionMode: 'plan' })
+  await service.appendSessionMetadata(sessionId, { workDir: directory, runtimeModelId: 'legacy-model' })
+  await expectSelection(new SessionService(), 'old-provider', 'legacy-model', 'high')
+})
+
+test('a complete built-in runtime selection also clears old effort', async () => {
+  await seedLegacySelection()
+  await service.appendSessionMetadata(sessionId, { workDir: directory, runtimeProviderId: null, runtimeModelId: 'default-model' })
+  await expectSelection(new SessionService(), null, 'default-model', undefined)
+})
+
+test('memory-only runtime changes clear inherited effort without writing a transcript', async () => {
+  await writeFile(join(directory, 'settings.json'), JSON.stringify({ cleanupPeriodDays: 0 }))
+  resetSettingsCache()
+  const created = await service.createSession(directory)
+  await service.appendSessionMetadata(created.sessionId, {
+    workDir: directory, runtimeProviderId: 'old-provider', runtimeModelId: 'old-model', effortLevel: 'high',
+  })
+  await service.appendSessionMetadata(created.sessionId, {
+    workDir: directory, runtimeProviderId: 'replacement-provider', runtimeModelId: 'replacement-model',
+  })
+  const launchInfo = await service.getSessionLaunchInfo(created.sessionId)
+  expect(launchInfo?.runtimeModelId).toBe('replacement-model')
+  expect(launchInfo?.effortLevel).toBeUndefined()
+  await expect(readFile(launchInfo!.filePath)).rejects.toThrow()
+})
+
+test('a memory-only runtime replacement overrides old persisted effort without changing history', async () => {
+  const filePath = await seedLegacySelection()
+  const original = await readFile(filePath, 'utf8')
+  await writeFile(join(directory, 'settings.json'), JSON.stringify({ cleanupPeriodDays: 0 }))
+  resetSettingsCache()
+  await service.appendSessionMetadata(sessionId, {
+    workDir: directory, runtimeProviderId: 'replacement-provider', runtimeModelId: 'replacement-model',
+  })
+  const launchInfo = await service.getSessionLaunchInfo(sessionId)
+  expect(launchInfo).toMatchObject({ runtimeProviderId: 'replacement-provider', runtimeModelId: 'replacement-model' })
+  expect(launchInfo?.effortLevel).toBeUndefined()
+  expect(await readFile(filePath, 'utf8')).toBe(original)
+})
+
+test('a side conversation clears inherited effort when its runtime selection changes', async () => {
+  await seedLegacySelection()
+  const launchInfo = (await service.getSessionLaunchInfo(sessionId))!
+  const sideId = `side-${sessionId}`
+  registerSideChat({
+    sessionId: sideId, parentSessionId: sessionId, cliSessionId: sessionId,
+    resumePath: launchInfo.filePath, resumeAt: 'old-message', launchInfo,
+    createdAt: new Date().toISOString(), started: false, closed: false,
+  })
+  await service.appendSessionMetadata(sideId, {
+    workDir: directory, runtimeProviderId: 'replacement-provider', runtimeModelId: 'replacement-model',
+  })
+  expect((await service.getSessionLaunchInfo(sideId))?.effortLevel).toBeUndefined()
+})

src/server/services/sessionService.ts

@@ -58,6 +58,7 @@ import { getSettings_DEPRECATED } from '../../utils/settings/settings.js'
 import {
   extractGoalCreationTitle,
   extractTranscriptUserTitle,
+  resolveSessionEffortLevel,
 } from './localIndex/transcriptReducer.js'
 import type {
   PersistedWorktreeSession,
@@ -1013,11 +1014,7 @@ export class SessionService {
     if (metadata.runtimeModelId && launchInfo.runtimeModelId !== metadata.runtimeModelId) {
       return false
     }
-    if (
-      metadata.effortLevel &&
-      VALID_SESSION_EFFORT_LEVELS.has(metadata.effortLevel) &&
-      launchInfo.effortLevel !== metadata.effortLevel
-    ) {
+    if (launchInfo.effortLevel !== resolveSessionEffortLevel(metadata, launchInfo.effortLevel)) {
       return false
     }
     return true
@@ -1293,7 +1290,7 @@ export class SessionService {
           state.permissionMode = this.resolvePermissionModeFromEntries([entry]) ?? state.permissionMode
           if (record.runtimeProviderId === null || typeof record.runtimeProviderId === 'string') state.runtimeProviderId = record.runtimeProviderId as string | null
           if (typeof record.runtimeModelId === 'string') state.runtimeModelId = record.runtimeModelId
-          if (typeof record.effortLevel === 'string' && VALID_SESSION_EFFORT_LEVELS.has(record.effortLevel)) state.effortLevel = record.effortLevel
+          state.effortLevel = resolveSessionEffortLevel(record, state.effortLevel)
         }
         state.repository = this.resolveRepositoryFromEntries([entry]) ?? state.repository
         const worktree = this.resolveWorktreeSessionFromEntries([entry])
@@ -3148,12 +3145,7 @@ export class SessionService {
         if (typeof record.runtimeModelId === 'string') {
           runtimeModelId = record.runtimeModelId
         }
-        if (
-          typeof record.effortLevel === 'string' &&
-          VALID_SESSION_EFFORT_LEVELS.has(record.effortLevel)
-        ) {
-          effortLevel = record.effortLevel
-        }
+        effortLevel = resolveSessionEffortLevel(record, effortLevel)
       }
 
       const candidateRepository = (entry as Record<string, unknown>)?.repository
@@ -4811,7 +4803,11 @@ export class SessionService {
   ): Promise<void> {
     if (isSideChatId(sessionId)) {
       const side = getSideChat(sessionId)
-      if (side && !side.closed) Object.assign(side.launchInfo, metadata)
+      if (side && !side.closed) {
+        Object.assign(side.launchInfo, metadata, {
+          effortLevel: resolveSessionEffortLevel(metadata, side.launchInfo.effortLevel),
+        })
+      }
       return
     }
     const persist = this.shouldPersistSession()
@@ -4836,8 +4832,7 @@ export class SessionService {
           ? { permissionMode: metadata.permissionMode } : {}),
         ...(metadata.runtimeProviderId !== undefined ? { runtimeProviderId: metadata.runtimeProviderId } : {}),
         ...(metadata.runtimeModelId ? { runtimeModelId: metadata.runtimeModelId } : {}),
-        ...(metadata.effortLevel && VALID_SESSION_EFFORT_LEVELS.has(metadata.effortLevel)
-          ? { effortLevel: metadata.effortLevel } : {}),
+        effortLevel: resolveSessionEffortLevel(metadata, previousInfo.effortLevel),
       })
     }
     if (!persist || !this.shouldPersistSession()) {

src/server/ws/events.ts

@@ -119,6 +119,7 @@ export type ServerMessage =
   | { type: 'status'; state: ChatState; verb?: string; attemptStart?: boolean }
   | {
       type: typeof RUNTIME_CONFIG_APPLIED_EVENT
+      requestedConfig?: { providerId: string | null; modelId: string; effortLevel?: string }
       providerId: string | null
       modelId: string
       effortLevel?: string

src/server/ws/handler.ts

@@ -198,6 +198,7 @@ type RuntimeOverride = {
   providerId: string | null
   modelId: string
   effort?: string
+  requestedConfig?: { providerId: string | null; modelId: string; effortLevel?: string }
 }
 
 type ActiveUserTurnState = {
@@ -216,6 +217,9 @@ type ActiveUserTurnState = {
 
 
 const runtimeOverrides = new Map<string, RuntimeOverride>()
+// A rejected optimistic choice must not silently send later prompts to the
+// previous process. Keep the rejection until a valid selection or cleanup.
+const rejectedRuntimeConfigs = new Map<string, string>()
 const activeUserTurns = new Map<string, ActiveUserTurnState>()
 const activeCliRuns = new Set<string>()
 const pendingInterruptedTurnResults = new Map<string, number>()
@@ -1607,11 +1611,29 @@ function waitForTurnResultOrTimeout(sessionId: string, timeoutMs: number): Promi
   })
 }
 
+function rejectStartedSideChatProviderChange(
+  ws: SessionConnection,
+  requestedProviderId: string | null,
+): boolean {
+  const { sessionId } = ws.data
+  const side = getSideChat(sessionId)
+  if (!side?.started) return false
+  const providerId = runtimeOverrides.get(sessionId)?.providerId ?? side.launchInfo.runtimeProviderId ?? null
+  if (providerId === requestedProviderId) return false
+  sendMessage(ws, {
+    type: 'error',
+    code: 'SIDE_CHAT_RUNTIME_RESTART_UNAVAILABLE',
+    message: 'Open a new side chat to change provider or reasoning effort.',
+  })
+  return true
+}
+
 async function handlePlanApprovalWithRuntimeOverride(
   ws: SessionConnection,
   message: Extract<ClientMessage, { type: 'permission_response' }>,
 ): Promise<void> {
   const { sessionId } = ws.data
+  if (rejectStartedSideChatProviderChange(ws, message.runtimeOverride!.providerId)) return
   const normalized = await normalizeRuntimeOverrideInput(message.runtimeOverride!)
   if (!normalized.ok) {
     sendMessage(ws, {
@@ -1637,6 +1659,7 @@ async function handlePlanApprovalWithRuntimeOverride(
     currentModelId === nextOverride.modelId &&
     currentEffort === nextOverride.effort
   ) {
+    rejectedRuntimeConfigs.delete(sessionId)
     finalizePermissionResponse(ws, message)
     return
   }
@@ -1659,12 +1682,16 @@ async function handlePlanApprovalWithRuntimeOverride(
     // reports it, and the permission stays pending (override untouched).
     await enqueueRuntimeTransition(sessionId, async () => {
       await conversationService.setModel(sessionId, nextOverride.modelId)
-      runtimeOverrides.set(sessionId, nextOverride)
+      const appliedOverride = nextOverride.effort === undefined && currentEffort
+        ? { ...nextOverride, effort: currentEffort, requestedConfig: nextOverride.requestedConfig ?? message.runtimeOverride }
+        : nextOverride
+      rejectedRuntimeConfigs.delete(sessionId)
+      runtimeOverrides.set(sessionId, appliedOverride)
       runtimeOverrideVersions.set(
         sessionId,
         (runtimeOverrideVersions.get(sessionId) ?? 0) + 1,
       )
-      await persistSessionRuntimeConfig(sessionId, nextOverride)
+      await persistSessionRuntimeConfig(sessionId, appliedOverride)
       broadcastAppliedRuntimeConfig(sessionId)
     })
     finalizePermissionResponse(ws, message)
@@ -1676,6 +1703,7 @@ async function handlePlanApprovalWithRuntimeOverride(
   // flow. The interrupted turn may bill one partial request to the planning
   // model — same as the manual flow.
   await enqueueRuntimeTransition(sessionId, async () => {
+    rejectedRuntimeConfigs.delete(sessionId)
     runtimeOverrides.set(sessionId, nextOverride)
     runtimeOverrideVersions.set(
       sessionId,
@@ -1842,11 +1870,37 @@ async function normalizeRuntimeOverrideInput(
 > {
   let modelId = typeof input.modelId === 'string' ? input.modelId.trim() : ''
   if (!modelId) return { ok: false, reason: 'model' }
+  const requestedEffort =
+    typeof input.effortLevel === 'string' ? input.effortLevel.trim() : undefined
+  if (typeof input.providerId === 'string') {
+    const { providers } = await providerService.listProviders()
+    if (!isKnownRuntimeProviderId(input.providerId, providers)) {
+      // Reopened tabs can still hold a provider deleted in Settings. Resolve
+      // the complete replacement before validating effort or acknowledging it:
+      // an effort attached to the deleted provider cannot apply to the new one.
+      if (requestedEffort !== undefined && !isModelReasoningEffort(requestedEffort)) {
+        return { ok: false, reason: 'effort' }
+      }
+      const defaults = await getDefaultRuntimeSettings()
+      const defaultModel = await resolveDefaultRuntimeModel(defaults)
+      return {
+        ok: true,
+        override: {
+          providerId: defaults.providerId ?? null,
+          modelId: defaultModel,
+          ...(defaults.effort ? { effort: defaults.effort } : {}),
+          requestedConfig: {
+            providerId: input.providerId,
+            modelId,
+            ...(requestedEffort !== undefined ? { effortLevel: requestedEffort } : {}),
+          },
+        },
+      }
+    }
+  }
   if (isGrokOfficialProviderId(input.providerId)) {
     modelId = (await getGrokReasoningEfforts(modelId)).modelId
   }
-  const requestedEffort =
-    typeof input.effortLevel === 'string' ? input.effortLevel.trim() : undefined
   const effortResolution = requestedEffort === undefined
     ? { valid: true, effort: undefined }
     : await resolveRuntimeEffort(input.providerId, modelId, requestedEffort)
@@ -1866,30 +1920,20 @@ async function handleSetRuntimeConfig(
   message: Extract<ClientMessage, { type: 'set_runtime_config' }>
 ) {
   const { sessionId } = ws.data
-  const requestedModelId = typeof message.modelId === 'string' ? message.modelId.trim() : ''
-  if (!requestedModelId) {
-    sendMessage(ws, {
-      type: 'error',
-      message: 'Runtime model selection is invalid.',
-      code: 'RUNTIME_CONFIG_INVALID',
-    })
-    return
-  }
-
   // Register the transition before remote model-catalog or provider validation.
   // A user message arriving in that async admission window must wait for the
   // selected runtime instead of entering the previous provider's CLI process.
   await enqueueRuntimeTransition(sessionId, async () => {
+    // A missing provider may fall back to the active default for durable chats,
+    // but that must not disguise a forbidden provider change on a live side chat.
+    if (rejectStartedSideChatProviderChange(ws, message.providerId)) return
     const normalized = await normalizeRuntimeOverrideInput(message)
     if (!normalized.ok) {
-      sendMessage(ws, {
-        type: 'error',
-        message:
-          normalized.reason === 'model'
-            ? 'Runtime model selection is invalid.'
-            : 'Runtime effort selection is invalid.',
-        code: 'RUNTIME_CONFIG_INVALID',
-      })
+      const message = normalized.reason === 'model'
+        ? 'Runtime model selection is invalid.'
+        : 'Runtime effort selection is invalid.'
+      rejectedRuntimeConfigs.set(sessionId, message)
+      sendMessage(ws, { type: 'error', message, code: 'RUNTIME_CONFIG_INVALID' })
       return
     }
 
@@ -1904,11 +1948,13 @@ async function handleSetRuntimeConfig(
         return
       }
       await conversationService.setModel(sessionId, nextOverride.modelId)
+      rejectedRuntimeConfigs.delete(sessionId)
       runtimeOverrides.set(sessionId, { ...nextOverride, ...(effort ? { effort } : {}) })
       await persistSessionRuntimeConfig(sessionId, runtimeOverrides.get(sessionId)!)
       broadcastAppliedRuntimeConfig(sessionId)
       return
     }
+    rejectedRuntimeConfigs.delete(sessionId)
     const prevOverride = runtimeOverrides.get(sessionId)
     if (
       prevOverride &&
@@ -1916,6 +1962,10 @@ async function handleSetRuntimeConfig(
       prevOverride.modelId === nextOverride.modelId &&
       prevOverride.effort === nextOverride.effort
     ) {
+      // Replayed selections still need confirmation, including the original
+      // stale provider that this request resolved to the existing runtime.
+      runtimeOverrides.set(sessionId, nextOverride)
+      if (!deferredRuntimeRestarts.has(sessionId)) broadcastAppliedRuntimeConfig(sessionId)
       return
     }
 
@@ -2076,6 +2126,7 @@ function broadcastAppliedRuntimeConfig(sessionId: string): void {
   if (!runtime) return
   sendToSession(sessionId, {
     type: RUNTIME_CONFIG_APPLIED_EVENT,
+    ...(runtime.requestedConfig ? { requestedConfig: runtime.requestedConfig } : {}),
     providerId: runtime.providerId,
     modelId: runtime.modelId,
     ...(runtime.effort ? { effortLevel: runtime.effort } : {}),
@@ -3111,6 +3162,7 @@ function cleanupSessionRuntimeState(
   sessionSlashCommands.delete(sessionId)
   sessionTitleState.delete(sessionId)
   runtimeOverrides.delete(sessionId)
+  rejectedRuntimeConfigs.delete(sessionId)
   activeUserTurns.delete(sessionId)
   activeCliRuns.delete(sessionId)
   sessionStopRequested.delete(sessionId)
@@ -4739,6 +4791,7 @@ export async function getRuntimeSettings(sessionId?: string): Promise<RuntimeSet
         const defaults = await getDefaultRuntimeSettings()
         return {
           ...defaults,
+          model: await resolveDefaultRuntimeModel(defaults),
           permissionMode: sessionPermissionMode ?? defaults.permissionMode,
         }
       }
@@ -4751,7 +4804,14 @@ export async function getRuntimeSettings(sessionId?: string): Promise<RuntimeSet
     )
     let effort = runtimeOverride.effort
     if (isOpenAIOfficialProviderId(runtimeOverride.providerId)) {
-      effort = effort ?? await getDefaultOpenAIReasoningEffort(runtimeOverride.modelId)
+      const catalog = await getDesktopOpenAICodexModelCatalog()
+      const model = getOpenAIModelCatalogEntry(runtimeOverride.modelId, catalog)
+      // Saved selections may outlive a model's supported effort catalog. The
+      // explicit WS selection path stays strict; restoration uses its default.
+      effort = effort && isOpenAIReasoningEffort(effort) &&
+        (!model || model.supportedReasoningEfforts.includes(effort))
+        ? effort
+        : model?.defaultReasoningEffort ?? 'medium'
     } else if (isGrokOfficialProviderId(runtimeOverride.providerId)) {
       const grokEffort = await getGrokReasoningEfforts(runtimeOverride.modelId)
       runtimeOverride.modelId = grokEffort.modelId
@@ -4792,6 +4852,14 @@ async function getSessionPermissionMode(sessionId: string): Promise<string | und
   return launchInfo?.permissionMode
 }
 
+async function resolveDefaultRuntimeModel(runtime: RuntimeSettings): Promise<string> {
+  if (runtime.model) return runtime.model
+  if (runtime.providerId) {
+    return (await providerService.getProviderRuntimeEnv(runtime.providerId)).ANTHROPIC_MODEL
+  }
+  return (await providerService.getOfficialProviderModels('claude-official')).main
+}
+
 async function getDefaultRuntimeSettings(): Promise<RuntimeSettings> {
   // Check if a custom provider is active
   const { providers, activeId } = await providerService.listProviders()
@@ -4976,6 +5044,16 @@ async function waitForRuntimeTransitionBeforeUserTurn(
         : undefined
   }
 
+  const rejectedConfig = rejectedRuntimeConfigs.get(sessionId)
+  if (rejectedConfig) {
+    const message = `The message was not sent. ${rejectedConfig} Select a valid model and reasoning effort, then retry.`
+    sendMessage(ws, { type: 'error', message, code: 'USER_TURN_FAILED', retryable: true })
+    sendMessage(ws, { type: 'status', state: 'idle' })
+    failSessionChatActivity(sessionId)
+    emitSessionTurnEvent({ type: 'output', sessionId, message: { type: 'result', is_error: true, result: message } })
+    return { ok: false, waited }
+  }
+
   return { ok: true, waited }
 }
 
@@ -5104,6 +5182,7 @@ export function __resetWebSocketHandlerStateForTests(): void {
   }
   sessionTurnObservers.clear()
   runtimeOverrides.clear()
+  rejectedRuntimeConfigs.clear()
   runtimeOverrideVersions.clear()
   deferredRuntimeRestarts.clear()
   deferredPermissionModes.clear()