From 0bf2eb37f6b37068349ec6e0790a2d2736d6483e Mon Sep 17 00:00:00 2001
From: ciregenz <ciregenz@berkeley.edu>
Date: Wed, 10 Jun 2026 17:37:57 -0700
Subject: [PATCH] [eric] desktop: renderer self-heals a stale backend port,
 fixes the post-signin CORS wall

---
 electron/preload.js           |  6 ++++++
 frontend/src/shared/config.ts | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/electron/preload.js b/electron/preload.js
index 6bffbaa1..e7e70ab2 100644
--- a/electron/preload.js
+++ b/electron/preload.js
@@ -22,6 +22,12 @@ contextBridge.exposeInMainWorld('__OPENSWARM_PORT__', port);
 
 contextBridge.exposeInMainWorld('openswarm', {
   getBackendPort: () => port,
+  // Fresh re-query of the LIVE backend port (not the cached preload value).
+  // Used by the renderer to self-heal if its cached port ever resolved wrong
+  // (raced null -> 8324, or backend on a fallback port because 8324 was held).
+  getBackendPortLive: () => {
+    try { return ipcRenderer.sendSync('get-backend-port-sync'); } catch (_) { return port; }
+  },
   getWebviewPreloadPath: () => webviewPreloadPath,
 
   // Per-install auth token required for WS + HTTP calls to the
diff --git a/frontend/src/shared/config.ts b/frontend/src/shared/config.ts
index 00b47eaf..1e9f031e 100644
--- a/frontend/src/shared/config.ts
+++ b/frontend/src/shared/config.ts
@@ -1,4 +1,14 @@
-const port = (window as any).__OPENSWARM_PORT__ || 8324;
+const _w = window as any;
+// Prefer the preload-injected port; if it's missing (preload raced the backend
+// port being picked), re-query the live value before falling back to 8324. The
+// bare 8324 guess is wrong on any machine where the backend landed on a fallback
+// port (e.g. 8324 was held by a leftover backend); see the self-heal below.
+const port =
+  _w.__OPENSWARM_PORT__ ||
+  (_w.openswarm && typeof _w.openswarm.getBackendPortLive === 'function'
+    ? _w.openswarm.getBackendPortLive()
+    : 0) ||
+  8324;
 const host = window.location.hostname || 'localhost';
 
 export const API_BASE = `http://${host}:${port}/api`;
@@ -46,6 +56,25 @@ export function ensureAuthToken(): Promise<string> {
   return _authTokenPromise;
 }
 
+// Self-heal: if our backend calls start failing with a network error (the
+// renderer is pinned to a stale/wrong port), re-query the live port and reload
+// once onto it. Guarded to one attempt per page-load and only when the live
+// port actually differs, so a genuinely-down backend can't cause a reload loop.
+let _portHealTried = false;
+function _maybeHealBackendPort(): void {
+  if (_portHealTried) return;
+  try {
+    const ow = (window as any).openswarm;
+    const live = ow && typeof ow.getBackendPortLive === 'function' ? ow.getBackendPortLive() : null;
+    if (typeof live === 'number' && live > 0 && live !== port) {
+      _portHealTried = true;
+      window.location.reload();
+    }
+  } catch {
+    /* never let a heal attempt throw into the fetch path */
+  }
+}
+
 // Global fetch interceptor: attaches bearer for our API + dedupes/caches GETs in a 1s window.
 // Cache is keyed `METHOD URL`, GET-only (mutations pass through); non-2xx never cached.
 const _inflightFetches = new Map<string, Promise<Response>>();
@@ -117,6 +146,8 @@ function _installAuthFetchInterceptor() {
         _inflightFetches.delete(cacheKey);
       }
     } catch {
+      // A network failure reaching our backend may mean we're on a stale port.
+      _maybeHealBackendPort();
       return originalFetch(input, init);
     }
   };