diff --git a/web/vite.config.ts b/web/vite.config.ts
index f3908f8..a088776 100644
--- a/web/vite.config.ts
+++ b/web/vite.config.ts
@@ -18,7 +18,9 @@ export default defineConfig({
   },
   server: {
     proxy: {
-      "/api": { target: backendTarget, changeOrigin: true },
+      // ws:true is required for the terminal WebSocket to be proxied to the
+      // Go backend in dev. http-only proxies strip the Upgrade header.
+      "/api": { target: backendTarget, changeOrigin: true, ws: true },
       "/healthz": { target: backendTarget, changeOrigin: true },
     },
   },