rwsdk/dist/vite/hmrStabilityPlugin.mjs

Build fast, server-driven webapps on Cloudflare with SSR, RSC, and realtime

import debug from "debug";
const log = debug("rws-vite-plugin:hmr-stability");
let stabilityPromise = null;
let stabilityResolver = null;
let debounceTimer = null;
const DEBOUNCE_MS = 500;
function startWaitingForStability() {
    if (!stabilityPromise) {
        log("Starting to wait for server stability...");
        stabilityPromise = new Promise((resolve) => {
            stabilityResolver = resolve;
        });
        // Start the timer. If it fires, we're stable.
        debounceTimer = setTimeout(finishWaiting, DEBOUNCE_MS);
    }
}
function activityDetected() {
    if (stabilityPromise) {
        // If we're waiting for stability, reset the timer.
        log("Activity detected, resetting stability timer.");
        if (debounceTimer)
            clearTimeout(debounceTimer);
        debounceTimer = setTimeout(finishWaiting, DEBOUNCE_MS);
    }
}
function finishWaiting() {
    if (stabilityResolver) {
        log("Server appears stable. Resolving promise.");
        stabilityResolver();
    }
    stabilityPromise = null;
    stabilityResolver = null;
    debounceTimer = null;
}
export function hmrStabilityPlugin() {
    return {
        name: "rws-vite-plugin:hmr-stability",
        // Monitor server activity
        transform() {
            activityDetected();
            return null;
        },
        configureServer(server) {
            // context(justinvdm, 19 Nov 2025): This hook adds an error handling
            // middleware for stale dependency errors. It runs in a returned function,
            // which intentionally places it late in the middleware stack. Unlike
            // other plugins that must run before the Cloudflare plugin to prevent
            // startup deadlocks, its timing is not critical, so `enforce: 'pre'`
            // is not needed.
            return () => {
                server.middlewares.use(async function rwsdkStaleBundleErrorHandler(err, req, res, next) {
                    if (err &&
                        typeof err.message === "string" &&
                        err.message.includes("new version of the pre-bundle")) {
                        log("Caught stale pre-bundle error. Waiting for server to stabilize...");
                        startWaitingForStability();
                        await stabilityPromise;
                        log("Server stabilized. Sending full-reload and redirecting.");
                        // Signal the client to do a full page reload.
                        server.environments.client.hot.send({
                            type: "full-reload",
                        });
                        // No need to wait further here, the stability promise handled it.
                        res.writeHead(307, { Location: req.url });
                        res.end();
                        return;
                    }
                    next(err);
                });
            };
        },
    };
}