SSR Lifecycle Methods

Catalyst exposes server lifecycle hooks from server/index.js so you can customise app startup, request handling, and SSR error reporting.

Supported Server Hooks

These hooks are part of the current server hook surface:

Hook	When it runs	Typical use cases
preServerInit	Before the Express server starts	Bootstrapping config, creating DB connections, warming shared services
onRouteMatch	After the incoming request is matched to a route	Auth checks, redirects, request-scoped setup
onServerError	When the server hits an uncaught startup error	Logging, alerting, custom process handling

server/index.js

export default {
  async preServerInit() {
    // Perform startup work before the server begins accepting traffic.
  },

  async onRouteMatch({ req, res, route }) {
    // Inspect the matched route and request context.
  },

  onServerError(error) {
    // Send the error to your monitoring pipeline.
    console.error(error);
  },
};

If you do not need any hooks yet, export default {} is valid.

Rendering Flow

Catalyst uses React 18 streaming SSR for the main HTML response. The high-level flow is:

1. The Node server receives the request.
2. Catalyst matches the request to a route definition.
3. Route data is prepared for SSR.
4. React renders the shell and route tree on the server.
5. HTML is streamed to the browser.
6. The client hydrates the tree and takes over navigation.

Error Handling During Render

Render failures are surfaced through the server render pipeline and should be handled through your logging and monitoring setup. In practice:

• use onServerError for startup-level failures
• keep route data fetching defensive
• wire app monitoring in the server process for SSR visibility

For request and route-level data behavior, see Data Fetching.