Forward verified bearer identity to backend

frontend/components/account/__tests__/paymentShell.test.ts

@@ -343,7 +343,7 @@ export function runTests() {
   assert(
     backendAuthSource.includes("headers.set(FORWARDED_SUPABASE_USER_ID_HEADER") &&
       backendAuthSource.includes("headers.set(FORWARDED_SUPABASE_EMAIL_HEADER") &&
-      backendAuthSource.indexOf("headers.set(FORWARDED_SUPABASE_USER_ID_HEADER") >
+      backendAuthSource.lastIndexOf("headers.set(FORWARDED_SUPABASE_USER_ID_HEADER") >
         backendAuthSource.indexOf("const sessionUser = session?.user"),
     "backend proxy must forward Supabase session user id/email with the backend token so Python can skip duplicate /auth/v1/user validation",
   );

frontend/components/ops/__tests__/backendAuthHeaders.test.ts

@@ -37,4 +37,17 @@ export function runTests() {
       helperSource.includes('result.set("Content-Type", "application/json")'),
     "backend auth must expose a safe JSON header builder",
   );
+
+  assert(
+    helperSource.includes("getVerifiedBearerIdentity") &&
+      helperSource.includes("/auth/v1/user") &&
+      helperSource.includes("apikey: anonKey") &&
+      helperSource.includes("incomingAuth") &&
+      helperSource.includes("const identity = await getVerifiedBearerIdentity(incomingAuth)") &&
+      helperSource.includes("headers.set(FORWARDED_SUPABASE_USER_ID_HEADER, identity.userId)") &&
+      helperSource.includes("headers.set(FORWARDED_SUPABASE_EMAIL_HEADER, identity.email)") &&
+      helperSource.includes("authUserId: identity?.userId || null") &&
+      helperSource.includes("authEmail: identity?.email || null"),
+    "backend auth helper must verify incoming Supabase bearer tokens and forward trusted user identity headers to backend services",
+  );
 }

frontend/lib/backend-auth.ts

@@ -18,6 +18,11 @@ type HeaderBuildOptions = {
   includeSupabaseIdentity?: boolean;
 };
 
+type VerifiedBearerIdentity = {
+  email: string;
+  userId: string;
+};
+
 function extractBearerToken(headerValue: string | null) {
   if (!headerValue) return "";
   const parts = headerValue.trim().split(/\s+/);
@@ -27,6 +32,40 @@ function extractBearerToken(headerValue: string | null) {
   return "";
 }
 
+async function getVerifiedBearerIdentity(
+  accessToken: string,
+): Promise<VerifiedBearerIdentity | null> {
+  const token = String(accessToken || "").trim();
+  const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL?.trim();
+  const anonKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY?.trim();
+  if (!token || !supabaseUrl || !anonKey) return null;
+
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), 4000);
+  try {
+    const res = await fetch(`${supabaseUrl.replace(/\/+$/, "")}/auth/v1/user`, {
+      cache: "no-store",
+      headers: {
+        apikey: anonKey,
+        Authorization: `Bearer ${token}`,
+      },
+      signal: controller.signal,
+    });
+    if (!res.ok) return null;
+    const user = await res.json();
+    const userId = String(user?.id || "").trim();
+    if (!userId) return null;
+    return {
+      email: String(user?.email || "").trim(),
+      userId,
+    };
+  } catch {
+    return null;
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}
+
 function hasSupabaseSessionCookie(request: NextRequest) {
   return request.cookies.getAll().some((cookie) => {
     const name = cookie.name.toLowerCase();
@@ -54,11 +93,18 @@ export async function buildBackendRequestHeaders(
   const incomingAuth = extractBearerToken(request.headers.get("authorization"));
   if (incomingAuth) {
     headers.set("Authorization", `Bearer ${incomingAuth}`);
+    const identity = await getVerifiedBearerIdentity(incomingAuth);
+    if (identity?.userId) {
+      headers.set(FORWARDED_SUPABASE_USER_ID_HEADER, identity.userId);
+      if (identity.email) {
+        headers.set(FORWARDED_SUPABASE_EMAIL_HEADER, identity.email);
+      }
+    }
     return {
       headers,
       response: null,
-      authUserId: null,
+      authUserId: identity?.userId || null,
-      authEmail: null,
+      authEmail: identity?.email || null,
       hasBearerAuth: true,
     };
   }