fix production attachment file origin

web/src/lib/api/client.ts

@@ -12,6 +12,7 @@ import { useSessionStore } from '@/stores/session';
 
 const DEFAULT_API_BASE = '/v1/im';
 const DEFAULT_FILE_BASE = '/v0/file';
+const CONFIGURED_FILE_BASE = import.meta.env.VITE_TINODE_FILE_BASE?.trim();
 
 export class ImApiError extends Error {
   reason?: string;
@@ -123,7 +124,11 @@ export function apiBase(): string {
 
 export function fileBase(): string {
   const endpoints = useSessionStore.getState().tenant?.endpoints;
-  return (endpoints?.file || DEFAULT_FILE_BASE).replace(/\/$/, '');
+  // Production may expose the web UI and the IM API through different deployments. Prefer the
+  // build-time canonical file origin so a tenant context previously resolved through the web host
+  // cannot keep routing attachments to that host's stale /v0/file proxy. Local development leaves
+  // this unset and continues to use the resolved relative endpoint through Vite's proxy.
+  return (CONFIGURED_FILE_BASE || endpoints?.file || DEFAULT_FILE_BASE).replace(/\/$/, '');
 }
 
 export function currentTenantCode(): string {