fix: restore remote OpenCode providers and startup errors

- Fix OpenChamber proxying to the correct OpenCode host for remote VPS setups
- Show a clear empty-state error when OpenCode is not reachable
- Harden session event routing for early or mismatched directory events

packages/ui/src/components/chat/ChatEmptyState.tsx

@@ -1,16 +1,27 @@
 import React from 'react';
 import { OpenChamberLogo } from '@/components/ui/OpenChamberLogo';
 import { useThemeSystem } from '@/contexts/useThemeSystem';
+import { useGlobalSyncStore } from '@/sync/global-sync-store';
 
 const ChatEmptyState: React.FC = () => {
     const { currentTheme } = useThemeSystem();
+    const initError = useGlobalSyncStore((s) => s.error);
 
     const textColor = currentTheme?.colors?.surface?.mutedForeground || 'var(--muted-foreground)';
 
     return (
         <div className="flex flex-col items-center justify-center min-h-full w-full gap-6">
             <OpenChamberLogo width={140} height={140} className="opacity-20" />
-            <span className="text-body-md" style={{ color: textColor }}>Start a new chat</span>
+            {initError ? (
+                <div className="flex flex-col items-center gap-2 max-w-md text-center px-4">
+                    <span className="text-body-md font-medium text-destructive">OpenCode is not reachable</span>
+                    <span className="text-body-sm" style={{ color: textColor }}>
+                        {initError.message}
+                    </span>
+                </div>
+            ) : (
+                <span className="text-body-md" style={{ color: textColor }}>Start a new chat</span>
+            )}
         </div>
     );
 };