Harden authenticated API same-origin defaults

README.md

@@ -29,10 +29,13 @@ Sysnode is designed to make that information easier to read, easier to verify, a
 
 ## Data Source
 
-The frontend reads live dashboard data from the Sysnode backend API. The default production build targets:
+The frontend reads live dashboard data from the Sysnode backend API. Anonymous public data can still be retargeted with `REACT_APP_API_BASE`, but the authenticated custody surface (`/auth`, `/vault`, `/gov`) is designed for same-origin production deployment:
 
 ```text
-https://syscoin.dev
+https://sysnode.info/        -> SPA
+https://sysnode.info/auth/*  -> backend
+https://sysnode.info/vault/* -> backend
+https://sysnode.info/gov/*   -> backend
 ```
 
 The backend aggregates data from a Syscoin Core node, Sentry Node RPC responses, market APIs, and supporting network datasets. For a fork or private deployment, override the API base URL at build time (no code change required):
@@ -41,7 +44,7 @@ The backend aggregates data from a Syscoin Core node, Sentry Node RPC responses,
 REACT_APP_API_BASE=https://your-backend.example npm run build
 ```
 
-The value is read at build time by both `src/lib/apiClient.js` (authenticated surface) and `src/lib/api.js` (anonymous surface — superblock timing, governance feed, masternode stats); without it, development builds use `http://localhost:3001` and production builds use `https://syscoin.dev`. Keeping both clients on the same override means `REACT_APP_API_BASE` retargets the entire app in a single build.
+The value is read at build time by both `src/lib/apiClient.js` (authenticated surface) and `src/lib/api.js` (anonymous surface — superblock timing, governance feed, masternode stats). Without it, development authenticated requests use `http://localhost:3001`; production authenticated requests use same-origin relative paths. Keeping the authenticated API under the SPA origin preserves host-only `Secure; SameSite=Lax` cookies and lets the SPA mirror the CSRF cookie into `X-CSRF-Token` without cross-site credentialed fetches.
 
 ## Getting Started
 

src/lib/apiClient.js

@@ -20,25 +20,22 @@ import axios from 'axios';
 
 // Default API base URL.
 //
-// DO NOT fall back to `window.location.origin`. The sysnode-info SPA
-// and the sysnode-backend are hosted on different origins — the SPA
-// server only serves static files, it does not proxy /auth/* anywhere
-// — so defaulting to the current browser origin makes login, register,
-// and session hydration silently hit the wrong host and fail unless
-// an operator remembers to set `REACT_APP_API_BASE`. (Codex round 5
-// P1.)
-//
 // Priority:
 //   1. REACT_APP_API_BASE (build-time override for bespoke deployments)
-//   2. Production builds → https://syscoin.dev (same host as the legacy
-//      public client in `./api.js`, which is where sysnode-backend is
-//      reachable)
+//   2. Production builds → same-origin relative paths. Production must
+//      reverse-proxy /auth, /vault, and /gov under the SPA origin so
+//      host-only SameSite=Lax cookies and the readable csrf cookie work
+//      without cross-site credentialed fetches.
 //   3. Development builds → http://localhost:3001 (backend dev server)
-const DEFAULT_BASE =
-  process.env.REACT_APP_API_BASE ||
-  (process.env.NODE_ENV === 'production'
-    ? 'https://syscoin.dev'
-    : 'http://localhost:3001');
+export function resolveDefaultApiBase({
+  apiBase = process.env.REACT_APP_API_BASE,
+  nodeEnv = process.env.NODE_ENV,
+} = {}) {
+  if (apiBase) return apiBase;
+  return nodeEnv === 'production' ? '' : 'http://localhost:3001';
+}
+
+const DEFAULT_BASE = resolveDefaultApiBase();
 
 const STATE_CHANGING = /^(POST|PUT|PATCH|DELETE)$/i;
 

src/lib/apiClient.test.js

@@ -4,6 +4,7 @@ import {
   createApiClient,
   parseRetryAfter,
   readCsrfCookie,
+  resolveDefaultApiBase,
   setAuthLostHandler,
   toApiError,
 } from './apiClient';
@@ -38,6 +39,29 @@ describe('readCsrfCookie', () => {
   });
 });
 
+describe('resolveDefaultApiBase', () => {
+  test('uses explicit REACT_APP_API_BASE override', () => {
+    expect(
+      resolveDefaultApiBase({
+        apiBase: 'https://api.example.test',
+        nodeEnv: 'production',
+      })
+    ).toBe('https://api.example.test');
+  });
+
+  test('defaults production authenticated calls to same-origin relative paths', () => {
+    expect(resolveDefaultApiBase({ apiBase: '', nodeEnv: 'production' })).toBe(
+      ''
+    );
+  });
+
+  test('keeps localhost backend default for development', () => {
+    expect(resolveDefaultApiBase({ apiBase: '', nodeEnv: 'development' })).toBe(
+      'http://localhost:3001'
+    );
+  });
+});
+
 describe('createApiClient — CSRF attachment', () => {
   test('attaches X-CSRF-Token to state-changing methods', async () => {
     const client = createApiClient({