Renew from the provider's session, for installs that can

charts/chat-app/values.yaml

@@ -204,6 +204,22 @@ metrics:
 
 oidcAuthority: ""
 oidcClientId: ""
+# offline_access stays in the default: a refresh token is the only renewal that
+# works against an arbitrary provider. The alternative -- renewing from the
+# provider's session through a hidden frame -- needs that frame to be first-party
+# to the issuer, and browsers block it wherever the app and the issuer are not
+# the same site. Nothing in discovery says which case an install is in.
+#
+# An install whose issuer is a sibling hostname should drop offline_access and
+# hold no refresh token at all; the umbrella does exactly that for the bundled
+# provider. Dex rotates refresh tokens either way, which is what RFC 9700 asks
+# of a public client that keeps one.
+#
+# Dropping it against a provider this chart does not configure takes one more
+# step there: <origin>/silent-renew has to be registered as a redirect URI, the
+# same way the callback is. The app cannot do that or detect that it is missing
+# -- the provider answers the renewal with an error the frame swallows, and
+# sessions end at token expiry instead.
 oidcScope: "openid profile email offline_access"
 oidcResource: ""
 apiBaseUrl: /api

src/auth/AuthGate.tsx

@@ -2,6 +2,7 @@ import { type ReactNode, useEffect, useRef } from 'react';
 import { AuthProvider, useAuth, withAuthenticationRequired } from 'react-oidc-context';
 import { Button } from '@/components/Button';
 import { oidcConfig } from '@/config';
+import { SilentRenewCallback } from './SilentRenewCallback';
 import { userManager } from './user-manager';
 
 type AuthGateProps = {
@@ -56,10 +57,19 @@ function AuthErrorBoundary({ children }: { children: ReactNode }) {
   return <>{children}</>;
 }
 
+export const silentRenewPath = '/silent-renew';
+
 export function AuthGate({ children }: AuthGateProps) {
   if (!oidcConfig.enabled) return <>{children}</>;
   if (!userManager) throw new Error('auth: user manager not initialized');
 
+  // Checked on the raw location rather than through the router: this has to win
+  // before AuthProvider mounts, or the renewal frame runs the sign-in flow in
+  // its own context instead of answering the parent.
+  if (window.location.pathname === silentRenewPath) {
+    return <SilentRenewCallback />;
+  }
+
   return (
     <AuthProvider userManager={userManager} onSigninCallback={handleSigninCallback}>
       <AuthErrorBoundary>

src/auth/SilentRenewCallback.tsx

@@ -0,0 +1,23 @@
+import { useEffect } from 'react';
+import { userManager } from './user-manager';
+
+/**
+ * The page the renewal iframe lands on. It hands the code back to the parent
+ * window and renders nothing -- the frame is hidden and torn down as soon as
+ * oidc-client-ts resolves the promise.
+ *
+ * It has to render before AuthGate, not inside it: the frame would otherwise run
+ * the whole sign-in flow again in its own context.
+ */
+export function SilentRenewCallback() {
+  useEffect(() => {
+    if (!userManager) return;
+    userManager.signinSilentCallback().catch((error) => {
+      // The parent already sees this as a rejected renewal and falls back to a
+      // redirect, so there is nothing to do here but leave a trace.
+      console.warn('[auth] silent renew callback failed', error);
+    });
+  }, []);
+
+  return null;
+}

src/auth/user-manager.ts

@@ -7,6 +7,11 @@ export const userManager = oidcConfig.enabled
       client_id: oidcConfig.clientId,
       redirect_uri: `${window.location.origin}/callback`,
       post_logout_redirect_uri: window.location.origin,
+      // Renewal runs through a hidden frame against the provider's own session
+      // rather than a refresh token, so the app holds nothing long-lived. Dex
+      // compares redirect URIs whole, so this is registered alongside the
+      // callback rather than covered by it.
+      silent_redirect_uri: `${window.location.origin}/silent-renew`,
       scope: oidcConfig.scope,
       // `resource` skips the code->token exchange; extraTokenParams forces it in.
       resource: oidcConfig.resource ?? undefined,