krow_employer/vite.config.js

import path from 'node:path';
import react from '@vitejs/plugin-react';
import { defineConfig, loadEnv } from 'vite';

// The `@/*` alias is declared directly rather than through a plugin.
// The API host the dev server forwards to. Only read here; nothing in client
// code names a backend host.
//
// It has to come from `loadEnv`, not `process.env`. Vite reads `.env` files for
// *client* code and exposes them on `import.meta.env`; it never copies them into
// `process.env`, and this config file runs in Node before any of that happens.
// So `process.env.VITE_API_PROXY_TARGET` was always undefined unless the
// variable was exported in the shell, and the line in `.env` documenting this
// knob did nothing at all — every dev server silently used the hard-coded
// fallback no matter what `.env` said. `loadEnv(mode, cwd, '')` reads the same
// files Vite would, with no prefix filter, so the `.env` value now actually
// takes effect.
function proxyTargetFor(mode) {
  const env = loadEnv(mode, process.cwd(), '');
  return env.VITE_API_PROXY_TARGET || 'https://mcp.krowforce.com';
}

/**
 * One proxy entry per path prefix, all pointing at the same backend.
 *
 * `secure: true` keeps certificate verification on — the target is a real host
 * with a real certificate, and turning verification off would hide a genuine
 * TLS failure behind a working-looking proxy.
 *
 * `changeOrigin` rewrites the Host header to the target, which the backend's
 * TLS termination requires to route the request at all.
 */
function proxyRoutes(prefixes, PROXY_TARGET) {
  return Object.fromEntries(prefixes.map((prefix) => [prefix, {
    target: PROXY_TARGET,
    changeOrigin: true,
    secure: true,
    configure: (proxy) => {
      proxy.on('error', (err, req, res) => {
        // ECONNREFUSED here means there is no server on the other end at all,
        // which is a different situation from a backend that answered badly.
        // Say so, because the browser only ever shows "502 Bad Gateway" and
        // that phrasing sends people looking at the backend's *response*.
        const refused = err.code === 'ECONNREFUSED' || err.code === 'ECONNRESET';
        if (refused) {
          console.error(
            `\n[vite proxy] ${req?.method || ''} ${req?.url || ''} -> 502: nothing is ` +
            `listening on ${PROXY_TARGET}.\n` +
            '            The API is a separate process. Start it with:\n' +
            '              cd <krow-backend> && make run\n' +
            "            `npm run dev` normally starts it for you (scripts/dev.mjs); " +
            'this path means it exited mid-session.\n',
          );
        } else {
          console.error('[vite proxy error]:', err.code || '', err.message);
        }

        if (res && res.writeHead && !res.headersSent) {
          res.writeHead(502, { 'Content-Type': 'application/json' });
          // Shaped as the API's own error envelope — {error:{code,message,details}}.
          // src/api/httpClient.js reads `payload.error.message`, so a bare string
          // here was silently dropped and the UI fell back to a generic
          // "Request failed with status 502" that named neither the cause nor
          // the fix.
          res.end(JSON.stringify({
            error: {
              code: refused ? 'api_not_running' : 'bad_gateway',
              message: refused
                ? `The API is not running. Nothing is listening on ${PROXY_TARGET}.`
                : `Could not reach the API at ${PROXY_TARGET}: ${err.message}`,
              details: { target: PROXY_TARGET, cause: err.code || err.message },
            },
          }));
        }
      });
    },
  }]));
}

export default defineConfig(({ mode }) => {
  const PROXY_TARGET = proxyTargetFor(mode);

  console.log(`[vite] proxying /api and /health to ${PROXY_TARGET}`);

  return {
    plugins: [react()],
    resolve: {
      alias: {
        '@': path.resolve(import.meta.dirname, './src'),
      },
    },
    build: {
      rollupOptions: {
        output: {
          // Split the heavy libraries out of the app bundle. They change far less
          // often than app code, so browsers keep them cached across deploys.
          manualChunks: {
            react: ['react', 'react-dom', 'react-router-dom'],
            charts: ['recharts'],
            motion: ['framer-motion'],
            mui: ['@mui/x-charts'],
          },
        },
      },
    },
    server: {
      // Expose server over network (0.0.0.0)
      host: true,
      // Honor a port assigned by the environment; fall back to Vite's default.
      port: process.env.PORT ? Number(process.env.PORT) : 5173,

      /**
       * Proxy the API so the browser only ever talks to one origin.
       *
       * This exists for the session cookie. The cookie is HttpOnly with
       * SameSite=Lax, and a Lax cookie is not sent on a cross-site subresource
       * request — which is exactly what `fetch('http://127.0.0.1:8080/...')` from
       * a page served by `http://localhost:5173` is, because a browser treats
       * those two as different sites. Every request after login would arrive
       * without the cookie and be answered 401.
       *
       * The alternatives are both worse. SameSite=None would send the cookie on
       * genuine cross-site requests too, which is the CSRF hole Lax closes, and
       * it requires Secure — so it cannot work over plain HTTP on localhost at
       * all. Widening CORS with credentials would keep the cross-site problem and
       * add a second one.
       *
       *   browser → localhost:5173/api/v1 → this proxy → 127.0.0.1:8080/api/v1
       *
       * Same origin from the browser's point of view, so the cookie is a
       * first-party cookie, CORS never enters into it, and nothing in the React
       * code names a backend host.
       *
       * Production serves the built assets and the API from one origin (see
       * nginx.conf), so this is a development-only shim for a property the
       * deployed app has for free.
       */
      proxy: proxyRoutes(['/api', '/health'], PROXY_TARGET),
    },
  };
});