#Diagnostics and Leak Scan

Leak Scan protects the browser bundle from accidentally importing server-only modules.

#Default Behavior

export default {
  frontend: {
    build: {
      diagnostics: {
        leakScan: true,
      },
    },
  },
};

When enabled, Vext checks the frontend import graph before emitting browser output.

#Blocked Imports

Common blocked imports include:

• src/routes/**
• src/services/**
• src/config/**
• database clients
• Node built-ins such as node:fs
• files named *.server.*

#Friendly Error Shape

If a page imports a service directly:

import { db } from "../../services/db";

Vext should report:

VEXT_FRONTEND_BOUNDARY
Browser bundle imported a server-only module.
Importer: src/frontend/pages/dashboard.tsx
Import: ../../services/db
Resolved: src/services/db.ts
Reason: src/services/** belongs to the server graph.
Fix: call the service in src/routes/** and pass data with res.render().

The goal is to teach the physical boundary, not to expose a low-level bundler stack trace as the only clue.

#Fix Patterns