diff --git a/.github/workflows/build-desktop.yml b/.github/workflows/build-desktop.yml
index 44f879a2d..1a117613d 100644
--- a/.github/workflows/build-desktop.yml
+++ b/.github/workflows/build-desktop.yml
@@ -207,6 +207,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           VITE_VARIANT: full
           VITE_DESKTOP_RUNTIME: '1'
+          VITE_WS_API_URL: https://worldmonitor.app
           CONVEX_URL: ${{ secrets.CONVEX_URL }}
           APPLE_CERTIFICATE: ${{ secrets.APPLE_CERTIFICATE }}
           APPLE_CERTIFICATE_PASSWORD: ${{ secrets.APPLE_CERTIFICATE_PASSWORD }}
@@ -231,6 +232,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           VITE_VARIANT: full
           VITE_DESKTOP_RUNTIME: '1'
+          VITE_WS_API_URL: https://worldmonitor.app
           CONVEX_URL: ${{ secrets.CONVEX_URL }}
         with:
           tagName: v__VERSION__
@@ -249,6 +251,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           VITE_VARIANT: tech
           VITE_DESKTOP_RUNTIME: '1'
+          VITE_WS_API_URL: https://worldmonitor.app
           CONVEX_URL: ${{ secrets.CONVEX_URL }}
           APPLE_CERTIFICATE: ${{ secrets.APPLE_CERTIFICATE }}
           APPLE_CERTIFICATE_PASSWORD: ${{ secrets.APPLE_CERTIFICATE_PASSWORD }}
@@ -274,6 +277,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           VITE_VARIANT: tech
           VITE_DESKTOP_RUNTIME: '1'
+          VITE_WS_API_URL: https://worldmonitor.app
           CONVEX_URL: ${{ secrets.CONVEX_URL }}
         with:
           tagName: v__VERSION__-tech
diff --git a/package-lock.json b/package-lock.json
index 94542a739..962b4f0d2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "world-monitor",
-  "version": "2.5.20",
+  "version": "2.5.21",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "world-monitor",
-      "version": "2.5.20",
+      "version": "2.5.21",
       "license": "AGPL-3.0-only",
       "dependencies": {
         "@deck.gl/aggregation-layers": "^9.2.6",
@@ -29,7 +29,7 @@
         "maplibre-gl": "^5.16.0",
         "onnxruntime-web": "^1.23.2",
         "papaparse": "^5.5.3",
-        "posthog-js": "^1.352.0",
+        "posthog-js": "^1.356.1",
         "telegram": "^2.26.22",
         "topojson-client": "^3.1.0",
         "ws": "^8.19.0",
@@ -3661,9 +3661,9 @@
       }
     },
     "node_modules/@posthog/types": {
-      "version": "1.352.0",
-      "resolved": "https://registry.npmjs.org/@posthog/types/-/types-1.352.0.tgz",
-      "integrity": "sha512-pp7VBMlkhlLmv2TyOoss028lPPD4ElnZlX5y3hqq6oijK5BMZbjVuTAgvFYNLiKbuze/i5ndFGyXTtfCwlMQeA==",
+      "version": "1.356.1",
+      "resolved": "https://registry.npmjs.org/@posthog/types/-/types-1.356.1.tgz",
+      "integrity": "sha512-miIUjs4LiBDMOxKkC87HEJLIih0pNGMAjxx+mW4X7jLpN41n0PLMW7swRE6uuxcMV0z3H6MllRSCYmsokkyfuQ==",
       "license": "MIT"
     },
     "node_modules/@probe.gl/env": {
@@ -11120,9 +11120,9 @@
       }
     },
     "node_modules/posthog-js": {
-      "version": "1.352.0",
-      "resolved": "https://registry.npmjs.org/posthog-js/-/posthog-js-1.352.0.tgz",
-      "integrity": "sha512-LxLKyoE+Y2z+WQ8CTO3PqQQDBuz64mHLJUoRuAYNXmp3vtxzrygZEz7UNnCT+BZ4/G44Qeq6JDYk1TRS7pIRDA==",
+      "version": "1.356.1",
+      "resolved": "https://registry.npmjs.org/posthog-js/-/posthog-js-1.356.1.tgz",
+      "integrity": "sha512-4EQliSyTp3j/xOaWpZmu7fk1b4S+J3qy4JOu5Xy3/MYFxv1SlAylgifRdCbXZxCQWb6PViaNvwRf4EmburgfWA==",
       "license": "SEE LICENSE IN LICENSE",
       "dependencies": {
         "@opentelemetry/api": "^1.9.0",
@@ -11131,7 +11131,7 @@
         "@opentelemetry/resources": "^2.2.0",
         "@opentelemetry/sdk-logs": "^0.208.0",
         "@posthog/core": "1.23.1",
-        "@posthog/types": "1.352.0",
+        "@posthog/types": "1.356.1",
         "core-js": "^3.38.1",
         "dompurify": "^3.3.1",
         "fflate": "^0.4.8",
diff --git a/package.json b/package.json
index c71d1c575..6671c4f50 100644
--- a/package.json
+++ b/package.json
@@ -91,7 +91,7 @@
     "maplibre-gl": "^5.16.0",
     "onnxruntime-web": "^1.23.2",
     "papaparse": "^5.5.3",
-    "posthog-js": "^1.352.0",
+    "posthog-js": "^1.356.1",
     "telegram": "^2.26.22",
     "topojson-client": "^3.1.0",
     "ws": "^8.19.0",
diff --git a/src-tauri/sidecar/local-api-server.mjs b/src-tauri/sidecar/local-api-server.mjs
index f5b3ff69e..a2f2fd466 100644
--- a/src-tauri/sidecar/local-api-server.mjs
+++ b/src-tauri/sidecar/local-api-server.mjs
@@ -1002,12 +1002,14 @@ async function dispatch(requestUrl, req, routes, context) {
     }
     return json({ verboseMode });
   }
-  // Registration — call Convex directly (desktop frontend bypasses sidecar for this endpoint;
-  // this handler only runs when CONVEX_URL is available, e.g. self-hosted deployments)
+  // Registration — call Convex directly when CONVEX_URL is available (self-hosted),
+  // otherwise proxy to cloud (desktop sidecar never has CONVEX_URL).
   if (requestUrl.pathname === '/api/register-interest' && req.method === 'POST') {
     const convexUrl = process.env.CONVEX_URL;
     if (!convexUrl) {
-      return json({ error: 'Registration service not configured — use cloud endpoint directly' }, 503);
+      const cloudResponse = await tryCloudFallback(requestUrl, req, context, 'no CONVEX_URL');
+      if (cloudResponse) return cloudResponse;
+      return json({ error: 'Registration service unavailable' }, 503);
     }
     try {
       const body = await new Promise((resolve, reject) => {
diff --git a/src/services/runtime.ts b/src/services/runtime.ts
index 245434691..9b169d8bb 100644
--- a/src/services/runtime.ts
+++ b/src/services/runtime.ts
@@ -113,7 +113,12 @@ export function getRemoteApiBaseUrl(): string {
   }
 
   const variant = import.meta.env.VITE_VARIANT || 'full';
-  return DEFAULT_REMOTE_HOSTS[variant] ?? DEFAULT_REMOTE_HOSTS.full ?? '';
+  const fromHosts = DEFAULT_REMOTE_HOSTS[variant] ?? DEFAULT_REMOTE_HOSTS.full ?? '';
+  if (fromHosts) return fromHosts;
+
+  // Desktop builds may not set VITE_WS_API_URL; default to production.
+  if (isDesktopRuntime()) return 'https://worldmonitor.app';
+  return '';
 }
 
 export function toRuntimeUrl(path: string): string {