chore: support proxied frontend dev hosts

README.md

@@ -378,6 +378,14 @@ docker compose -p medassist-dev -f docker-compose.dev.yml up
 - API docs UI: `http://localhost:3000/docs` (when docs are enabled)
 - OpenAPI JSON: `http://localhost:3000/docs/json` (when docs are enabled)
 
+If you run the frontend dev server behind a reverse proxy or on a remote host, you can optionally set these frontend-only environment variables before starting Vite:
+
+- `VITE_ALLOWED_HOSTS`: comma-separated hostnames allowed to connect to the dev server; defaults to `localhost,127.0.0.1`
+- `VITE_HMR_HOST`: public hostname used for HMR websocket connections
+- `VITE_HMR_PROTOCOL`: optional websocket protocol override (`ws` or `wss`)
+- `VITE_HMR_CLIENT_PORT`: optional public websocket port exposed to the browser
+- `VITE_HMR_PORT`: optional server-side websocket port for the Vite process
+
 Useful local commands:
 
 ```bash

frontend/vite.config.ts

@@ -2,6 +2,24 @@ import { existsSync, readFileSync } from "fs";
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
 
+function parseCsvEnv(value: string | undefined, fallback: string[]) {
+  const entries = value
+    ?.split(",")
+    .map((entry) => entry.trim())
+    .filter((entry) => entry.length > 0);
+
+  return entries && entries.length > 0 ? entries : fallback;
+}
+
+function parseOptionalPort(value: string | undefined) {
+  if (!value) {
+    return undefined;
+  }
+
+  const parsed = Number.parseInt(value, 10);
+  return Number.isFinite(parsed) ? parsed : undefined;
+}
+
 // Read version from package.json at build time
 const packageJson = JSON.parse(readFileSync("./package.json", "utf-8"));
 
@@ -9,6 +27,19 @@ const packageJson = JSON.parse(readFileSync("./package.json", "utf-8"));
 // In Docker, prefer backend-dev to avoid localhost proxy failures.
 const defaultBackendTarget = existsSync("/.dockerenv") ? "http://backend-dev:3000" : "http://localhost:3000";
 const backendTarget = process.env.BACKEND_URL || defaultBackendTarget;
+const allowedHosts = parseCsvEnv(process.env.VITE_ALLOWED_HOSTS, ["localhost", "127.0.0.1"]);
+const hmrHost = process.env.VITE_HMR_HOST?.trim();
+const hmrProtocol = process.env.VITE_HMR_PROTOCOL === "ws" ? "ws" : process.env.VITE_HMR_PROTOCOL === "wss" ? "wss" : undefined;
+const hmrClientPort = parseOptionalPort(process.env.VITE_HMR_CLIENT_PORT);
+const hmrPort = parseOptionalPort(process.env.VITE_HMR_PORT);
+const hmr = hmrHost
+  ? {
+      host: hmrHost,
+      protocol: hmrProtocol ?? "wss",
+      clientPort: hmrClientPort ?? (hmrProtocol === "ws" ? 80 : 443),
+      port: hmrPort ?? 5173,
+    }
+  : undefined;
 
 export default defineConfig({
   plugins: [react()],
@@ -19,6 +50,8 @@ export default defineConfig({
   server: {
     port: 5173,
     strictPort: true,
+    allowedHosts,
+    hmr,
     proxy: {
       "/api": {
         target: backendTarget,