Vite Build Configuration#

The Strapi admin's Vite configuration is centralized in packages/core/strapi/src/node/vite/config.ts. It exports three functions consumed by the build pipeline:

• resolveBaseConfig — shared base configuration applied to all modes 1
• resolveProductionConfig — extends base with minification, sourcemaps, and a single Rollup entry point (strapi) 2
• resolveDevelopmentConfig — extends base with HMR, middleware mode, monorepo aliases, and allowedHosts: true for reverse-proxy compatibility 3

User overrides are supported via a vite.config.{js,mjs,ts,mts} file placed in src/admin/. The mergeConfigWithUserConfig function loads the first matching file and calls it as a transform function (config: UserConfig) => UserConfig, letting projects augment but not fully replace the base config 4.

Dependency Pre-Bundling (optimizeDeps.include)#

Vite pre-bundles the following dependencies to guarantee a single ESM instance is resolved across all chunks — including lazily-loaded plugin chunks 5:

When @strapi/design-system is symlinked (via portal:, file:, or yarn link), it is excluded from pre-bundling and added to exclude instead, so local changes are reflected without clearing the cache .

Extra packages for the internal monorepo example app are gated behind a UUID check (isMonorepoExampleApp) and are never pre-bundled in real user apps 11.

Deduplication and Alias Resolution#

Two additional mechanisms reinforce the single-instance guarantee:

resolve.dedupe 12 — tells Vite/Rollup to always resolve these packages to the same copy: react, react-dom, react-router-dom, styled-components, react-redux, @reduxjs/toolkit, @strapi/design-system, @radix-ui/react-tooltip, lodash.

resolve.alias 13 — maps each package name to an explicit filesystem path via getModulePath. This is specifically required under pnpm's strict dependency isolation, where plugin chunks may not be able to walk up to a hoisted copy of a shared package 14.

Together, pre-bundling + dedupe + alias form a three-layer defence against duplicate module instances.

Redux Duplicate Context Fix (PR #26249)#

react-redux and @reduxjs/toolkit were added to all three mechanisms — optimizeDeps.include, resolve.dedupe, and resolve.alias — in PR #26249 to fix a post-upgrade regression where stale Vite cache entries caused the admin panel to load a second copy of the Redux context, producing a runtime crash. The same PR extended the upgrade CLI to offer to delete node_modules/.strapi/vite after dependency installation 15, with deletion gated behind user confirmation to avoid unexpected build slowdowns 16.

Development-Mode Extras#

In development, resolveDevelopmentConfig adds:

• Monorepo aliases via getMonorepoAliases — maps @strapi/admin/strapi-admin and other internal packages directly to src/ for hot rebuilds without a separate watcher.
• HMR on Strapi's HTTP server — reuses ctx.strapi.server.httpServer so websocket connections work behind reverse proxies that only expose the Strapi port 17.
• appType: 'custom' and middlewareMode: true — embeds Vite as middleware inside the Strapi server process 18.

Key Files#