fix: apply VFS conversation schema compatibility at backend boot

api/startup_migration.py

@@ -36,6 +36,18 @@ _SENSITIVE_TABLES = [
 
 _RLS_FIX_SQL = """
 -- ARCH-F1.5 + SEC-RLS-FIX: RLS GRANT fix — idempotente, sicuro da ri-eseguire.
+-- Compatibility fix: older Supabase projects created vfs_files without the
+-- conversation namespace used by the VFS router. Keep this safe on every boot.
+DO $$
+BEGIN
+  IF to_regclass('public.vfs_files') IS NOT NULL THEN
+    ALTER TABLE public.vfs_files
+      ADD COLUMN IF NOT EXISTS conversation_id TEXT NOT NULL DEFAULT '';
+    CREATE INDEX IF NOT EXISTS vfs_files_conversation_idx
+      ON public.vfs_files (conversation_id);
+  END IF;
+END $$;
+
 GRANT USAGE ON SCHEMA public TO anon;
 GRANT USAGE ON SCHEMA public TO authenticated;