diff --git a/apps/desktop/src/app/session/hooks/use-message-stream/gateway-event.ts b/apps/desktop/src/app/session/hooks/use-message-stream/gateway-event.ts
index 432258d16ae4..a96e780e875a 100644
--- a/apps/desktop/src/app/session/hooks/use-message-stream/gateway-event.ts
+++ b/apps/desktop/src/app/session/hooks/use-message-stream/gateway-event.ts
@@ -23,7 +23,7 @@ import { refreshBackgroundProcesses } from '@/store/composer-status'
 import { $gateway } from '@/store/gateway'
 import { dispatchNativeNotification } from '@/store/native-notifications'
 import { notify } from '@/store/notifications'
-import { requestDesktopOnboarding } from '@/store/onboarding'
+import { requestDesktopOnboarding, requestDesktopOnboardingForCredentialWarning } from '@/store/onboarding'
 import { revealDesktopPane } from '@/store/pane-focus'
 import { flashPetActivity, markPetUnread, setPetActivity } from '@/store/pet'
 import { $activeGatewayProfile, normalizeProfileKey } from '@/store/profile'
@@ -407,9 +407,7 @@ export function useGatewayEventHandler(deps: GatewayEventDeps) {
           setCurrentUsage(current => ({ ...current, ...payload.usage }))
         }
 
-        if (typeof payload?.credential_warning === 'string' && payload.credential_warning) {
-          requestDesktopOnboarding(payload.credential_warning)
-        }
+        requestDesktopOnboardingForCredentialWarning(payload?.credential_warning)
 
         if (apply) {
           reportInstallMethodWarning(payload?.install_warning)
diff --git a/apps/desktop/src/app/session/hooks/use-session-actions/utils.test.ts b/apps/desktop/src/app/session/hooks/use-session-actions/utils.test.ts
index 2f0d7c05f5f9..277a9c96b642 100644
--- a/apps/desktop/src/app/session/hooks/use-session-actions/utils.test.ts
+++ b/apps/desktop/src/app/session/hooks/use-session-actions/utils.test.ts
@@ -1,7 +1,8 @@
-import { beforeEach, describe, expect, it } from 'vitest'
+import { afterEach, beforeEach, describe, expect, it } from 'vitest'
 
 import type { ChatMessage } from '@/lib/chat-messages'
 import { $approvalModes, approvalModeForProfile } from '@/store/approval-mode'
+import { $desktopOnboarding } from '@/store/onboarding'
 import { $activeGatewayProfile } from '@/store/profile'
 import type { SessionInfo } from '@/types/hermes'
 
@@ -38,6 +39,32 @@ describe('applyRuntimeInfo approval mode', () => {
   })
 })
 
+const initialOnboardingState = $desktopOnboarding.get()
+
+describe('applyRuntimeInfo credential warnings', () => {
+  beforeEach(() => {
+    $desktopOnboarding.set({ ...initialOnboardingState, reason: null, requested: false })
+  })
+
+  afterEach(() => {
+    $desktopOnboarding.set(initialOnboardingState)
+  })
+
+  it('requests setup for the exact empty-key warning returned by the server', () => {
+    const warning = "No API key configured for provider 'openrouter'. First message will fail."
+
+    applyRuntimeInfo({ credential_warning: warning })
+
+    expect($desktopOnboarding.get()).toMatchObject({ reason: warning, requested: true })
+  })
+
+  it('ignores an auxiliary-provider warning', () => {
+    applyRuntimeInfo({ credential_warning: 'OPENROUTER_API_KEY not set' })
+
+    expect($desktopOnboarding.get()).toMatchObject({ reason: null, requested: false })
+  })
+})
+
 describe('isSessionGoneError', () => {
   it('is true for 404 / session-not-found, false otherwise', () => {
     expect(isSessionGoneError(new Error('Request failed 404'))).toBe(true)
diff --git a/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts b/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
index 55781c3bcb7a..553f473b9948 100644
--- a/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
+++ b/apps/desktop/src/app/session/hooks/use-session-actions/utils.ts
@@ -3,7 +3,7 @@ import { assistantTextPart, type ChatMessage, chatMessageText, textPart } from '
 import { normalizePersonalityValue } from '@/lib/chat-runtime'
 import { embeddedImageUrls, textWithoutEmbeddedImages } from '@/lib/embedded-images'
 import { reconcileApprovalModeForProfile } from '@/store/approval-mode'
-import { requestDesktopOnboarding } from '@/store/onboarding'
+import { requestDesktopOnboardingForCredentialWarning } from '@/store/onboarding'
 import { $activeGatewayProfile, $profiles, normalizeProfileKey } from '@/store/profile'
 import {
   $currentCwd,
@@ -557,9 +557,7 @@ export function applyRuntimeInfo(info: SessionRuntimeInfo | undefined): SessionR
     reconcileApprovalModeForProfile($activeGatewayProfile.get(), info.approval_mode)
   }
 
-  if (info.credential_warning) {
-    requestDesktopOnboarding(info.credential_warning)
-  }
+  requestDesktopOnboardingForCredentialWarning(info.credential_warning)
 
   reportInstallMethodWarning(info.install_warning)
 
diff --git a/apps/desktop/src/lib/provider-setup-errors.test.ts b/apps/desktop/src/lib/provider-setup-errors.test.ts
index b90cdecb42ae..6014cee46b7f 100644
--- a/apps/desktop/src/lib/provider-setup-errors.test.ts
+++ b/apps/desktop/src/lib/provider-setup-errors.test.ts
@@ -12,6 +12,24 @@ describe('isProviderSetupErrorMessage', () => {
     expect(isProviderSetupErrorMessage('set an API key (OPENROUTER_API_KEY) in ~/.hermes/.env')).toBe(true)
   })
 
+  it('matches the exact empty-key warning emitted in session.info', () => {
+    expect(
+      isProviderSetupErrorMessage("No API key configured for provider 'openrouter'. First message will fail.")
+    ).toBe(true)
+  })
+
+  it('does not match bare env var mentions from auxiliary warnings', () => {
+    expect(isProviderSetupErrorMessage('OPENROUTER_API_KEY not set')).toBe(false)
+    expect(isProviderSetupErrorMessage('Run `hermes setup` or set OPENROUTER_API_KEY.')).toBe(false)
+    expect(
+      isProviderSetupErrorMessage(
+        '⚠ No auxiliary LLM provider configured — context compression will drop middle turns without a summary. Run `hermes setup` or set OPENROUTER_API_KEY.'
+      )
+    ).toBe(false)
+    expect(isProviderSetupErrorMessage('OPENAI_API_KEY missing')).toBe(false)
+    expect(isProviderSetupErrorMessage('ANTHROPIC_API_KEY not found')).toBe(false)
+  })
+
   it('does not match non-provider runtime failures', () => {
     expect(
       isProviderSetupErrorMessage('Selected runtime is not available. setup.status reports configured credentials.')
diff --git a/apps/desktop/src/lib/provider-setup-errors.ts b/apps/desktop/src/lib/provider-setup-errors.ts
index 190e73933594..81a63356a292 100644
--- a/apps/desktop/src/lib/provider-setup-errors.ts
+++ b/apps/desktop/src/lib/provider-setup-errors.ts
@@ -1,5 +1,7 @@
 const PROVIDER_SETUP_ERROR_RE =
-  /No (?:inference|Hermes) provider(?: is)? configured|no_provider_configured|OPENROUTER_API_KEY|OPENAI_API_KEY|ANTHROPIC_API_KEY|set an API key/i
+  /No (?:inference|Hermes) provider(?: is)? configured|no_provider_configured|set an API key/i
+
+const SESSION_INFO_CREDENTIAL_WARNING_RE = /^No API key configured for provider '[^']*'\. First message will fail\.$/
 
 export function isProviderSetupErrorMessage(message: null | string | undefined): boolean {
   const text = message?.trim()
@@ -8,5 +10,5 @@ export function isProviderSetupErrorMessage(message: null | string | undefined):
     return false
   }
 
-  return PROVIDER_SETUP_ERROR_RE.test(text)
+  return PROVIDER_SETUP_ERROR_RE.test(text) || SESSION_INFO_CREDENTIAL_WARNING_RE.test(text)
 }
diff --git a/apps/desktop/src/store/onboarding.test.ts b/apps/desktop/src/store/onboarding.test.ts
index 0bebec57e664..0a5fb1578e27 100644
--- a/apps/desktop/src/store/onboarding.test.ts
+++ b/apps/desktop/src/store/onboarding.test.ts
@@ -46,14 +46,28 @@ function installApiMock(api: (request: { path: string }) => Promise<unknown>) {
   })
 }
 
-function runtimeMismatchGateway(): OnboardingContext['requestGateway'] {
+function emptyOpenRouterGateway(): OnboardingContext['requestGateway'] {
   return async method => {
     if (method === 'setup.status') {
       return { provider_configured: true } as never
     }
 
     if (method === 'setup.runtime_check') {
-      return { error: 'Selected runtime is not available.', ok: false } as never
+      return { error: 'No usable credentials found for openrouter.', ok: false, provider: 'openrouter' } as never
+    }
+
+    throw new Error(`unexpected gateway method: ${method}`)
+  }
+}
+
+function keylessCustomGateway(): OnboardingContext['requestGateway'] {
+  return async method => {
+    if (method === 'setup.status') {
+      return { provider_configured: true } as never
+    }
+
+    if (method === 'setup.runtime_check') {
+      return { ok: true, provider: 'custom' } as never
     }
 
     throw new Error(`unexpected gateway method: ${method}`)
@@ -99,12 +113,12 @@ describe('refreshOnboarding', () => {
     $desktopOnboarding.set(baseState({ providers: [provider('cached')] }))
     requestDesktopOnboarding('Need provider setup')
 
-    const ready = await refreshOnboarding(onboardingContext(runtimeMismatchGateway()))
+    const ready = await refreshOnboarding(onboardingContext(emptyOpenRouterGateway()))
 
     expect(ready).toBe(false)
     expect(api).toHaveBeenCalledTimes(1)
     expect($desktopOnboarding.get().providers?.map(p => p.id)).toEqual(['fresh'])
-    expect($desktopOnboarding.get().reason).toContain('Selected runtime is not available.')
+    expect($desktopOnboarding.get().reason).toContain('No usable credentials found for openrouter.')
     expect($desktopOnboarding.get().reason).toContain('setup.status reports configured credentials')
   })
 
@@ -120,7 +134,7 @@ describe('refreshOnboarding', () => {
     installApiMock(api)
     $desktopOnboarding.set(baseState({ providers: [provider('cached')] }))
 
-    const ready = await refreshOnboarding(onboardingContext(runtimeMismatchGateway()))
+    const ready = await refreshOnboarding(onboardingContext(emptyOpenRouterGateway()))
 
     expect(ready).toBe(false)
     expect(api).not.toHaveBeenCalled()
@@ -182,6 +196,43 @@ describe('refreshOnboarding', () => {
     expect($desktopOnboarding.get().configured).toBe(true)
   })
 
+  it('enters setup when the selected OpenRouter credential is genuinely empty', async () => {
+    installApiMock(vi.fn())
+    window.localStorage.setItem('hermes-desktop-onboarded-v1', '1')
+    $desktopOnboarding.set(
+      baseState({
+        configured: true,
+        providers: [provider('cached')],
+        reason: null,
+        requested: false
+      })
+    )
+
+    const ready = await refreshOnboarding(onboardingContext(emptyOpenRouterGateway()))
+
+    expect(ready).toBe(false)
+    expect($desktopOnboarding.get().configured).toBe(false)
+    expect($desktopOnboarding.get().reason).toContain('No usable credentials found for openrouter.')
+    expect(window.localStorage.getItem('hermes-desktop-onboarded-v1')).toBeNull()
+  })
+
+  it('keeps a keyless custom runtime out of setup', async () => {
+    const api = vi.fn()
+
+    installApiMock(api)
+    $desktopOnboarding.set(baseState({ configured: false, reason: 'stale setup error', requested: true }))
+
+    const ready = await refreshOnboarding(onboardingContext(keylessCustomGateway()))
+
+    expect(ready).toBe(true)
+    expect(api).not.toHaveBeenCalled()
+    expect($desktopOnboarding.get()).toMatchObject({
+      configured: true,
+      reason: null,
+      requested: false
+    })
+  })
+
   it('does not preserve configured when onboarding was explicitly requested', async () => {
     const api = vi.fn(async ({ path }: { path: string }) => {
       if (path === '/api/providers/oauth') {
@@ -249,8 +300,8 @@ describe('refreshOnboarding', () => {
     installApiMock(api)
     $desktopOnboarding.set(baseState({ requested: true }))
 
-    const first = refreshOnboarding(onboardingContext(runtimeMismatchGateway()))
-    const second = refreshOnboarding(onboardingContext(runtimeMismatchGateway()))
+    const first = refreshOnboarding(onboardingContext(emptyOpenRouterGateway()))
+    const second = refreshOnboarding(onboardingContext(emptyOpenRouterGateway()))
 
     await vi.waitFor(() => expect(api).toHaveBeenCalledTimes(1))
 
diff --git a/apps/desktop/src/store/onboarding.ts b/apps/desktop/src/store/onboarding.ts
index 2472ae8910bc..83a81598b627 100644
--- a/apps/desktop/src/store/onboarding.ts
+++ b/apps/desktop/src/store/onboarding.ts
@@ -12,6 +12,7 @@ import {
   submitOAuthCode,
   validateProviderCredential
 } from '@/hermes'
+import { isProviderSetupErrorMessage } from '@/lib/provider-setup-errors'
 import { evaluateRuntimeReadiness, type RuntimeReadinessResult } from '@/lib/runtime-readiness'
 import { notify, notifyError } from '@/store/notifications'
 import type { ModelOptionProvider, OAuthProvider, OAuthStartResponse } from '@/types/hermes'
@@ -185,9 +186,8 @@ async function checkRuntime(ctx: OnboardingContext, requestedProvider?: string):
 }
 
 function shouldPreserveConfiguredOnFallback(runtime: RuntimeReadinessResult, state: DesktopOnboardingState): boolean {
-  // A fallback result means both runtime probes were non-authoritative
-  // (transport timeout/disconnect). Keep a previously verified configured
-  // state instead of forcing the blocking onboarding overlay.
+  // Non-authoritative transport fallback only — keep a previously verified
+  // configured state instead of forcing the blocking onboarding overlay.
   return runtime.source === 'fallback' && state.configured === true && !state.requested
 }
 
@@ -390,6 +390,16 @@ export function requestDesktopOnboarding(reason = DEFAULT_ONBOARDING_REASON) {
   patch({ reason: reason.trim() || DEFAULT_ONBOARDING_REASON, requested: true })
 }
 
+export function requestDesktopOnboardingForCredentialWarning(reason: null | string | undefined) {
+  const warning = reason?.trim()
+
+  if (!warning || !isProviderSetupErrorMessage(warning)) {
+    return
+  }
+
+  requestDesktopOnboarding(warning)
+}
+
 // Open the onboarding provider selector on demand from an already-configured
 // app — e.g. the model picker's "Add provider" button. Reuses the entire
 // onboarding flow (OAuth rows, API-key form, model-confirm) instead of