Vite Build Configuration#

Overview#

The Strapi admin panel uses Vite as its bundler. The central configuration lives in packages/core/strapi/src/node/vite/config.ts and exports three factory functions 1:

• resolveBaseConfig — shared base applied to all modes
• resolveProductionConfig — adds minification, sourcemaps, and a single Rollup entry point
• resolveDevelopmentConfig — adds HMR, middleware mode, and monorepo dev aliases

User overrides go in src/admin/vite.config.{js,mjs,ts,mts} as a transform function (config) => config merged with Vite's mergeConfig 1.

The Three-Layer Deduplication System#

The core problem this config solves: dynamically-loaded plugin chunks may resolve a different physical copy of a shared package than the main admin bundle. When a package keeps state in module scope (React context, Redux store, DnD context, CodeMirror extension registry), two copies means two independent instances that can't communicate — causing crashes, blank screens, or instanceof failures.

Three Vite mechanisms are layered together to guarantee a single runtime instance:

Controlled by ADMIN_VITE_ALIAS_MODULES#

The canonical list of packages that receive all three treatments is defined in admin-vite-alias-modules.ts 2:

• React core: react, react-dom, react-router-dom, styled-components
• Redux stack: react-redux, @reduxjs/toolkit
• DnD: react-dnd, react-dnd-html5-backend
• Design system: @strapi/design-system, @radix-ui/react-tooltip
• Utilities: lodash, invariant, prismjs

Packages only direct-declared in @strapi/admin (not re-exported via the exports map) live in a separate ADMIN_PINNED_ALIAS_MODULES subset 3.

CodeMirror Singletons (ADMIN_VITE_SINGLETON_MODULES)#

CodeMirror v6 packages — @codemirror/state, @codemirror/view, @codemirror/language, @codemirror/lang-json, @codemirror/commands, @codemirror/lint, @uiw/react-codemirror — are managed in a separate file admin-vite-singleton-modules.ts. These use resolve.dedupe and resolve.alias (resolved from @strapi/design-system's closure) but are not in ADMIN_VITE_ALIAS_MODULES because they are not direct @strapi/admin dependencies.

Dedupe-Only: @strapi/strapi#

@strapi/strapi is added to resolve.dedupe but deliberately not aliased. Aliasing packages that use exports maps causes [vite:load-fallback] errors because resolve.alias bypasses the package exports map. Adding @strapi/strapi to dedupe alone collapses ~98% of module duplication from local plugins 4.

Alias Resolution: Scoped to @strapi/admin#

All aliases are built by buildAdminViteResolveAliases() using getModulePath(mod), which resolves each package path starting from @strapi/admin's package directory (not @strapi/strapi's), preventing pnpm's strict isolation from picking up a hoisted incompatible version 5.

Auto-Exclude Heuristic for Plugin UI Libs#

PR #26944 introduced admin-vite-optimize-exclude.ts, which automatically adds pre-built ESM plugin UI libraries to optimizeDeps.exclude 6. A package is auto-excluded if all three conditions hold:

1. react/react-dom in its peerDependencies
2. ESM (type: module or exports.import)
3. Pre-built dist output (dist/ entry or files: ['dist'])

Safety guards: official @strapi/* packages are never auto-excluded, and packages on ADMIN_VITE_ALIAS_MODULES are always kept on the include path 7.

Notable Regressions & Fixes#

Key Source Files#

Extending the Config#

Add a src/admin/vite.config.ts exporting a transform function:

import { mergeConfig, type UserConfig } from 'vite';

export default (config: UserConfig) => mergeConfig(config, {
  resolve: {
    dedupe: ['my-singleton'],
  },
});

See Strapi docs — admin panel customization for the full pattern 11.