diff --git a/apps/desktop/src/lib/json-rpc-gateway-url-guard.test.ts b/apps/desktop/src/lib/json-rpc-gateway-url-guard.test.ts
index 9989c669f5d4..7cedfe9c69c8 100644
--- a/apps/desktop/src/lib/json-rpc-gateway-url-guard.test.ts
+++ b/apps/desktop/src/lib/json-rpc-gateway-url-guard.test.ts
@@ -43,6 +43,12 @@ describe('JsonRpcGatewayClient connect() URL guard', () => {
     )
   })
 
+  it('rejects a malformed ws URL before opening a socket', async () => {
+    const client = new JsonRpcGatewayClient()
+    await expect(client.connect('ws://')).rejects.toThrow(/requires a ws:\/\/ or wss:\/\/ URL string/)
+    expect(client.connectionState).toBe('idle')
+  })
+
   it('keeps connection state idle on rejection', async () => {
     const client = new JsonRpcGatewayClient()
     await client.connect(undefined as unknown as string).catch(() => undefined)
diff --git a/apps/shared/src/json-rpc-gateway.ts b/apps/shared/src/json-rpc-gateway.ts
index de67806ddc4b..37714b8e2d4b 100644
--- a/apps/shared/src/json-rpc-gateway.ts
+++ b/apps/shared/src/json-rpc-gateway.ts
@@ -97,9 +97,25 @@ export class JsonRpcGatewayClient {
   async connect(wsUrl: string): Promise<void> {
     // Refuse garbage; WebSocket coerces non-strings into
     // `ws://<origin>/[object%20Object]` (#68250 stale-emit boot loop).
-    if (typeof wsUrl !== 'string' || !/^wss?:\/\//i.test(wsUrl)) {
+    const invalidUrl = () => {
       const got = typeof wsUrl === 'string' ? JSON.stringify(wsUrl) : `type "${typeof wsUrl}"`
-      throw new Error(`gateway connect() requires a ws:// or wss:// URL string, got ${got}`)
+
+      return new Error(`gateway connect() requires a ws:// or wss:// URL string, got ${got}`)
+    }
+
+    if (typeof wsUrl !== 'string') {
+      throw invalidUrl()
+    }
+
+    let url: URL
+    try {
+      url = new URL(wsUrl)
+    } catch {
+      throw invalidUrl()
+    }
+
+    if (url.protocol !== 'ws:' && url.protocol !== 'wss:') {
+      throw invalidUrl()
     }
 
     if (this.socket?.readyState === WebSocket.OPEN || this.state === 'connecting') {