diff --git a/apps/web/src/components/settings/AddCodexAccountDialog.tsx b/apps/web/src/components/settings/AddCodexAccountDialog.tsx
index d3085a5044a7c..3bf341003131a 100644
--- a/apps/web/src/components/settings/AddCodexAccountDialog.tsx
+++ b/apps/web/src/components/settings/AddCodexAccountDialog.tsx
@@ -18,8 +18,11 @@ import { Button } from "../ui/button";
 import { Dialog } from "../ui/dialog";
 import { Input } from "../ui/input";
 import { WizardFooter, WizardHeader, WizardPanel, WizardPopup } from "../ui/wizard";
+import { MultipleAccountsNote } from "./MultipleAccountsNote";
 import { SettingsRow } from "./settingsLayout";
 
+const CODEX_DRIVER_KIND = ProviderDriverKind.make("codex");
+
 export function AddCodexAccountDialog({
   environmentId,
   onClose,
@@ -60,7 +63,7 @@ export function AddCodexAccountDialog({
           providerInstances: {
             ...settings.providerInstances,
             [id]: {
-              driver: ProviderDriverKind.make("codex"),
+              driver: CODEX_DRIVER_KIND,
               displayName,
               enabled: true,
               config: { enabled: true, setupMode: "managed" },
@@ -102,6 +105,7 @@ export function AddCodexAccountDialog({
           ) : (
             <form
               id="add-codex-account"
+              className="grid gap-3"
               onSubmit={(event) => {
                 event.preventDefault();
                 void createAccount();
@@ -120,6 +124,7 @@ export function AddCodexAccountDialog({
                   />
                 }
               />
+              <MultipleAccountsNote environmentId={environmentId} driver={CODEX_DRIVER_KIND} />
             </form>
           )}
         </WizardPanel>
diff --git a/apps/web/src/components/settings/AddProviderInstanceDialog.tsx b/apps/web/src/components/settings/AddProviderInstanceDialog.tsx
index 85ea937ebaa3c..5dabd9ff40fa4 100644
--- a/apps/web/src/components/settings/AddProviderInstanceDialog.tsx
+++ b/apps/web/src/components/settings/AddProviderInstanceDialog.tsx
@@ -51,6 +51,7 @@ import { AcpRegistrySearchStep, useAcpRegistrySearch } from "./AcpRegistrySearch
 import { ProviderWizardAuthenticationStep } from "./ProviderWizardAuthenticationStep";
 import { resolveOfficialAcpRegistryIconUrl } from "./AcpRegistryIcon";
 import { AddManagedCodexAccountDialog } from "./CodexSetupSection";
+import { MultipleAccountsNote } from "./MultipleAccountsNote";
 import { ProviderEnvironmentSection } from "./ProviderInstanceCard";
 
 /** Limit the slug to 48 chars so the composed ProviderInstanceId fits its 64-char cap. */
@@ -442,6 +443,7 @@ export function AddProviderInstanceDialog({
                       );
                     })}
                 </RadioGroup>
+                <MultipleAccountsNote environmentId={environmentId} driver={driver} />
               </div>
 
               {wizardStep === 0 ? (
diff --git a/apps/web/src/components/settings/MultipleAccountsNote.tsx b/apps/web/src/components/settings/MultipleAccountsNote.tsx
new file mode 100644
index 0000000000000..2185351c77ff4
--- /dev/null
+++ b/apps/web/src/components/settings/MultipleAccountsNote.tsx
@@ -0,0 +1,50 @@
+import { useAtomValue } from "@effect/atom-react";
+import type { EnvironmentId, ProviderDriverKind } from "@t3tools/contracts";
+import { InfoIcon } from "lucide-react";
+
+import { serverEnvironment } from "../../state/server";
+import { Alert, AlertDescription } from "../ui/alert";
+
+const MULTIPLE_ACCOUNTS_FAQ_URL =
+  "https://github.com/pingdotgg/t3code/blob/main/docs/user/faq.md#can-i-add-a-bunch-of-accounts-for-one-provider";
+
+const PROVIDER_NAMES = new Map<string, string>([
+  ["codex", "Codex"],
+  ["claudeAgent", "Claude"],
+]);
+
+/** Shown while adding a Claude or Codex account when the environment already has one signed in. */
+export function MultipleAccountsNote({
+  environmentId,
+  driver,
+}: {
+  readonly environmentId: EnvironmentId;
+  readonly driver: ProviderDriverKind;
+}) {
+  const providers = useAtomValue(serverEnvironment.providersValueAtom(environmentId));
+  const providerName = PROVIDER_NAMES.get(driver);
+  const hasSignedInAccount =
+    providerName !== undefined &&
+    providers?.some(
+      (provider) => provider.driver === driver && provider.auth.status === "authenticated",
+    );
+  if (!hasSignedInAccount) return null;
+  return (
+    <Alert variant="info" role="note">
+      <InfoIcon aria-hidden />
+      <AlertDescription>
+        <p>
+          We do not recommend managing multiple {providerName} accounts in T3 Code.{" "}
+          <a
+            href={MULTIPLE_ACCOUNTS_FAQ_URL}
+            target="_blank"
+            rel="noreferrer"
+            className="underline underline-offset-2 hover:text-foreground"
+          >
+            More info
+          </a>
+        </p>
+      </AlertDescription>
+    </Alert>
+  );
+}