diff --git a/apps/x/apps/renderer/src/App.tsx b/apps/x/apps/renderer/src/App.tsx
index e6c050b3..0ca4b6b3 100644
--- a/apps/x/apps/renderer/src/App.tsx
+++ b/apps/x/apps/renderer/src/App.tsx
@@ -63,6 +63,8 @@ import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/comp
 import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription, DialogFooter } from "@/components/ui/dialog"
 import { Button } from "@/components/ui/button"
 import { Toaster } from "@/components/ui/sonner"
+import { BillingErrorDialog } from "@/components/billing-error-dialog"
+import { matchBillingError, type BillingErrorMatch } from "@/lib/billing-error"
 import { stripKnowledgePrefix, toKnowledgePath, wikiLabel } from '@/lib/wiki-links'
 import { splitFrontmatter, joinFrontmatter } from '@/lib/frontmatter'
 import { extractConferenceLink } from '@/lib/calendar-event'
@@ -793,7 +795,25 @@ function App() {
   // Chat state
   const [, setMessage] = useState<string>('')
   const [conversation, setConversation] = useState<ConversationItem[]>([])
+  const [billingErrorMatch, setBillingErrorMatch] = useState<BillingErrorMatch | null>(null)
+  const [billingErrorOpen, setBillingErrorOpen] = useState(false)
+  const lastHandledBillingErrorIdRef = useRef<string | null>(null)
   const [currentAssistantMessage, setCurrentAssistantMessage] = useState<string>('')
+
+  useEffect(() => {
+    for (let i = conversation.length - 1; i >= 0; i--) {
+      const item = conversation[i]
+      if (!isErrorMessage(item)) continue
+      if (item.id === lastHandledBillingErrorIdRef.current) return
+      const match = matchBillingError(item.message)
+      if (match) {
+        lastHandledBillingErrorIdRef.current = item.id
+        setBillingErrorMatch(match)
+        setBillingErrorOpen(true)
+      }
+      return
+    }
+  }, [conversation])
   const [, setModelUsage] = useState<LanguageModelUsage | null>(null)
   const [runId, setRunId] = useState<string | null>(null)
   const runIdRef = useRef<string | null>(null)
@@ -5399,6 +5419,11 @@ function App() {
         />
       </SidebarSectionProvider>
       <Toaster />
+      <BillingErrorDialog
+        open={billingErrorOpen}
+        match={billingErrorMatch}
+        onOpenChange={setBillingErrorOpen}
+      />
       <OnboardingModal
         open={showOnboarding}
         onComplete={handleOnboardingComplete}
diff --git a/apps/x/apps/renderer/src/components/billing-error-dialog.tsx b/apps/x/apps/renderer/src/components/billing-error-dialog.tsx
new file mode 100644
index 00000000..e93b2661
--- /dev/null
+++ b/apps/x/apps/renderer/src/components/billing-error-dialog.tsx
@@ -0,0 +1,61 @@
+import { useEffect, useState } from "react"
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog"
+import { Button } from "@/components/ui/button"
+import type { BillingErrorMatch } from "@/lib/billing-error"
+
+interface BillingRowboatAccount {
+  config?: {
+    appUrl?: string | null
+  } | null
+}
+
+interface BillingErrorDialogProps {
+  open: boolean
+  match: BillingErrorMatch | null
+  onOpenChange: (open: boolean) => void
+}
+
+export function BillingErrorDialog({ open, match, onOpenChange }: BillingErrorDialogProps) {
+  const [appUrl, setAppUrl] = useState<string | null>(null)
+
+  useEffect(() => {
+    if (!open) return
+    window.ipc
+      .invoke('account:getRowboat', null)
+      .then((account: BillingRowboatAccount) => setAppUrl(account.config?.appUrl ?? null))
+      .catch(() => {})
+  }, [open])
+
+  if (!match) return null
+
+  const handleUpgrade = () => {
+    if (appUrl) window.open(`${appUrl}?intent=upgrade`)
+    onOpenChange(false)
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="sm:max-w-md">
+        <DialogHeader>
+          <DialogTitle>{match.title}</DialogTitle>
+          <DialogDescription>{match.subtitle}</DialogDescription>
+        </DialogHeader>
+        <DialogFooter className="gap-2 sm:gap-2">
+          <Button variant="outline" onClick={() => onOpenChange(false)}>
+            Dismiss
+          </Button>
+          <Button onClick={handleUpgrade} disabled={!appUrl}>
+            {match.cta}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  )
+}
diff --git a/apps/x/apps/renderer/src/components/chat-sidebar.tsx b/apps/x/apps/renderer/src/components/chat-sidebar.tsx
index 06680652..4ce3e533 100644
--- a/apps/x/apps/renderer/src/components/chat-sidebar.tsx
+++ b/apps/x/apps/renderer/src/components/chat-sidebar.tsx
@@ -52,6 +52,7 @@ import {
   parseAttachedFiles,
   toToolState,
 } from '@/lib/chat-conversation'
+import { matchBillingError } from '@/lib/billing-error'
 
 const streamdownComponents = { pre: MarkdownPreOverride }
 
@@ -87,31 +88,6 @@ function AutoScrollPre({ className, children }: { className?: string; children:
 
 /* ─── Billing error helpers ─── */
 
-const BILLING_ERROR_PATTERNS = [
-  {
-    pattern: /upgrade required/i,
-    title: 'A subscription is required',
-    subtitle: 'Get started with a plan to access AI features in Rowboat.',
-    cta: 'Subscribe',
-  },
-  {
-    pattern: /not enough credits/i,
-    title: 'You\'ve run out of credits',
-    subtitle: 'Upgrade your plan for more credits. Free usage resets daily at 00:00 UTC.',
-    cta: 'Upgrade plan',
-  },
-  {
-    pattern: /subscription not active/i,
-    title: 'Your subscription is inactive',
-    subtitle: 'Reactivate your subscription to continue using AI features.',
-    cta: 'Reactivate',
-  },
-] as const
-
-function matchBillingError(message: string) {
-  return BILLING_ERROR_PATTERNS.find(({ pattern }) => pattern.test(message)) ?? null
-}
-
 interface BillingRowboatAccount {
   config?: {
     appUrl?: string | null
diff --git a/apps/x/apps/renderer/src/lib/billing-error.ts b/apps/x/apps/renderer/src/lib/billing-error.ts
new file mode 100644
index 00000000..ffb77470
--- /dev/null
+++ b/apps/x/apps/renderer/src/lib/billing-error.ts
@@ -0,0 +1,26 @@
+export const BILLING_ERROR_PATTERNS = [
+  {
+    pattern: /upgrade required/i,
+    title: 'A subscription is required',
+    subtitle: 'Get started with a plan to access AI features in Rowboat.',
+    cta: 'Subscribe',
+  },
+  {
+    pattern: /not enough credits/i,
+    title: "You've run out of credits",
+    subtitle: 'Upgrade your plan for more credits. Free usage resets daily at 00:00 UTC.',
+    cta: 'Upgrade plan',
+  },
+  {
+    pattern: /subscription not active/i,
+    title: 'Your subscription is inactive',
+    subtitle: 'Reactivate your subscription to continue using AI features.',
+    cta: 'Reactivate',
+  },
+] as const
+
+export type BillingErrorMatch = (typeof BILLING_ERROR_PATTERNS)[number]
+
+export function matchBillingError(message: string): BillingErrorMatch | null {
+  return BILLING_ERROR_PATTERNS.find(({ pattern }) => pattern.test(message)) ?? null
+}