fix(auth): stabilize cookie domain handling behind proxy and add auth debug logs

middleware.ts

@@ -4,14 +4,55 @@ import { canAccessPath, getDefaultPathForRole, parseSessionCookie, SESSION_COOKI
 import { DEFAULT_LOCALE, isLocale, LOCALE_COOKIE } from "@/lib/i18n";
 import { getRequestBaseUrl } from "@/lib/request-url";
 
+const AUTH_DEBUG = process.env.AUTH_DEBUG === "true" || process.env.AUTH_DEBUG === "1";
+
 const publicPaths = ["/login", "/forgot-password", "/reset-password", "/unauthorized", "/invite", "/auth"];
 
 function isPublicPath(pathname: string) {
   return publicPaths.some((path) => pathname === path || pathname.startsWith(`${path}/`));
 }
 
+function shouldUseSecureCookies(request: NextRequest) {
+  const explicit = process.env.COOKIE_SECURE?.toLowerCase() ?? "";
+  if (explicit === "true" || explicit === "1") {
+    return true;
+  }
+
+  if (explicit === "false" || explicit === "0") {
+    return false;
+  }
+
+  const forwardedProto = request.headers.get("x-forwarded-proto");
+  return request.nextUrl.protocol === "https:" || (forwardedProto?.split(",")[0]?.toLowerCase() === "https");
+}
+
+function debugAuth(message: string, details: Record<string, unknown> = {}) {
+  if (!AUTH_DEBUG) {
+    return;
+  }
+
+  console.warn(`[AUTH] ${message}`, details);
+}
+
+function setDebugHeaders(response: NextResponse, headers: Record<string, string>) {
+  if (!AUTH_DEBUG) {
+    return;
+  }
+
+  Object.entries(headers).forEach(([key, value]) => {
+    response.headers.set(key, value);
+  });
+}
+
 async function decodeSessionCookie(value: string) {
-  return (await parseSessionCookie(value)) as null | { role: UserRole };
+  const parsed = (await parseSessionCookie(value)) as null | { role: UserRole };
+  if (!parsed) {
+    debugAuth("invalid_session_cookie", {
+      cookieLength: value.length,
+      cookiePreview: `${value.slice(0, 28)}...${value.slice(-14)}`
+    });
+  }
+  return parsed;
 }
 
 export async function middleware(request: NextRequest) {
@@ -33,19 +74,37 @@ export async function middleware(request: NextRequest) {
     response.cookies.set(LOCALE_COOKIE, detected, {
       path: "/",
       maxAge: 365 * 24 * 60 * 60,
-      secure: process.env.NODE_ENV === "production",
+      secure: shouldUseSecureCookies(request),
       sameSite: "lax"
     });
   } else if (!isLocale(localeCookie)) {
     response.cookies.set(LOCALE_COOKIE, DEFAULT_LOCALE, {
       path: "/",
       maxAge: 365 * 24 * 60 * 60,
-      secure: process.env.NODE_ENV === "production",
+      secure: shouldUseSecureCookies(request),
       sameSite: "lax"
     });
   }
 
   if (!session && !isPublicPath(pathname) && pathname !== "/") {
+    const clientIp =
+      request.headers.get("x-forwarded-for")?.split(",")[0]?.trim() ||
+      request.headers.get("x-real-ip") ||
+      "unknown";
+
+    debugAuth("missing_or_invalid_session", {
+      pathname,
+      method: request.method,
+      ip: clientIp,
+      userAgent: request.headers.get("user-agent") || "unknown",
+      hasSessionCookie: Boolean(sessionCookie),
+      sessionCookieLength: sessionCookie?.length || 0,
+      host: request.headers.get("host") || "unknown",
+      protocol: request.nextUrl.protocol,
+      forwardedProto: request.headers.get("x-forwarded-proto") || "unknown",
+      secureCookies: shouldUseSecureCookies(request)
+    });
+
     const loginUrl = new URL("/login", baseUrl);
     loginUrl.searchParams.set("next", pathname);
     return NextResponse.redirect(loginUrl);
@@ -56,13 +115,42 @@ export async function middleware(request: NextRequest) {
     const hasSafeNext = typeof requested === "string" && requested.startsWith("/") && !requested.startsWith("//");
     const nextPath = hasSafeNext ? requested : null;
     const destination = nextPath && canAccessPath(session.role, nextPath) ? nextPath : getDefaultPathForRole(session.role);
-    return NextResponse.redirect(new URL(destination, baseUrl));
+    const redirectResponse = NextResponse.redirect(new URL(destination, baseUrl));
+    setDebugHeaders(redirectResponse, {
+      "X-Auth-Session": "valid",
+      "X-Auth-Session-Has-Cookie": String(Boolean(sessionCookie)),
+      "X-Auth-Session-Role": session.role,
+      "X-Auth-Path": pathname,
+      "X-Auth-Base-Url": baseUrl.toString()
+    });
+    return redirectResponse;
   }
 
   if (session && !isPublicPath(pathname) && !canAccessPath(session.role, pathname)) {
-    return NextResponse.redirect(new URL("/unauthorized", baseUrl));
+    debugAuth("role_forbidden", {
+      pathname,
+      role: session.role
+    });
+    const forbiddenResponse = NextResponse.redirect(new URL("/unauthorized", baseUrl));
+    setDebugHeaders(forbiddenResponse, {
+      "X-Auth-Session": "forbidden",
+      "X-Auth-Session-Has-Cookie": String(Boolean(sessionCookie)),
+      "X-Auth-Session-Role": session.role,
+      "X-Auth-Path": pathname,
+      "X-Auth-Base-Url": baseUrl.toString()
+    });
+    return forbiddenResponse;
   }
 
+  setDebugHeaders(response, {
+    "X-Auth-Session": session ? "valid" : "missing",
+    "X-Auth-Session-Has-Cookie": String(Boolean(sessionCookie)),
+    "X-Auth-Session-Valid-Role": session?.role || "n/a",
+    "X-Auth-Path": pathname,
+    "X-Auth-Base-Url": baseUrl.toString(),
+    "X-Auth-Host": request.headers.get("host") || "unknown"
+  });
+
   return response;
 }