Frontend Upgrade Operations

The two front-end upgrades a Craft CMS (or any Twig/PHP) agency keeps meeting: an asset pipeline still on Laravel Mix or raw Webpack, and widgets still on Vue 2. Both are frozen - Mix's last release was 6.0.49 in June 2022 and Laravel calls it "a legacy package that is no longer actively maintained"; Vue 2 reached end of life on 31 December 2023. This skill is the playbook for moving a server-rendered site to Vite 8 + craft-vite and Vue 3, or for deciding that a widget should not be Vue at all.

Version facts verified as of 2026-10-05 against npm, Packagist, vite.dev, v3-migration.vuejs.org and nystudio107.com/docs/vite. Each reference cites its sources.

Start here: what does this repo need?

You find	Do	Read
webpack.mix.js, mix-manifest.json, mix() in Twig	Replace Mix with Vite + craft-vite	mix-webpack-to-vite.md, then craft-vite-twig.md
A hand-written webpack.config.js	Same move; translate loaders and plugins one by one	mix-webpack-to-vite.md
craft-vite already, but the dev server fails behind DDEV	CORS / allowedHosts / one port in four places	craft-vite-twig.md
"vue": "^2 in package.json	Decide per widget: migrate or replace (table below)	this file, then vue2-to-vue3.md
Mix and Vue 2	Bundler first, framework second - never one deploy	Sequencing
vuex, vue-router 3, Vue 2-only plugins	Pinia; check every plugin for a Vue 3 path before estimating	vue-state-and-plugins.md
Vue templates written in Twig (inline-template, in-DOM)	Convert to SFC islands; mind the compiler build and template injection	vue-islands-in-twig.md
Vue 3 + Vite already	Out of scope here - steady-state Vue is vue-ops, steady-state Craft is craftcms-ops	-

Migrate Vue, or replace it?

Most agency Vue 2 code is not an app; it is a handful of widgets. Migrating a widget that a dozen lines of Alpine would do costs more than replacing it. Decide per island, before estimating the migration.

The widget is...	Verdict	Why
Toggle, accordion, tabs, mobile nav, show/hide	Native HTML or Alpine.js	<details>, <dialog>, popover cover much of it with zero JS; the rest is a boolean in x-data written straight into Twig
A form with validation and a submit spinner	Alpine + native constraint validation	No component tree, no store; Alpine keeps the markup in Twig where editors expect it
A thin wrapper around a framework-free library (slider, date picker, map, lightbox)	Vanilla JS or Alpine calling the library directly	The Vue wrapper was the only Vue 2-specific part
Renders server data and never changes it	Delete it; render in Twig	It's a template, not an app
Filtering/sorting a list with derived counts, several child components	Vue 3	Computed state and components earn their weight
Several islands sharing state (cart, saved items, auth)	Vue 3 + Pinia	A shared store across apps is what Vue + Pinia does well
Routing inside a section (multi-step tool, dashboard)	Vue 3 (+ vue-router)	Alpine has no answer for this
Built on a Vue 2 UI kit with no Vue 3 release	Rewrite budget, Vue 3 or Alpine, decided by the rows above	The kit, not Vue, is the migration

Rules of thumb for the grey zone: under ~150 lines with one level of state, Alpine wins; any use of Vuex, a router, or more than two child components, Vue 3 wins. A site that ends up with both is normal - see the Alpine coexistence rules in vue-islands-in-twig.md.

Sequencing both upgrades

Each numbered step is a separate deploy with its own parity check. Combining the bundler swap with the framework swap is the classic mistake: when a page breaks you cannot tell which change did it.

0. Inventory      rg the repo (below); list page types that render JS widgets
1. Vue 2.7.16     if on Vue 2.6 - backports Composition API + <script setup>
2. Mix -> Vite    still on Vue 2: Vite 7.3 + @vitejs/plugin-vue2
                  (plugin-vue2's peer range ends at vite ^7.0.0 as of 2026-10-05;
                   Vite 7.3 still gets important fixes + security patches)
3. Replace        widgets the table above says shouldn't be Vue -> Alpine/vanilla
4. Vuex -> Pinia 2 (optional, still on Vue 2.7; Pinia 3+ dropped Vue 2)
5. Vue 3          @vue/compat on Vite 8 + @vitejs/plugin-vue; burn down warnings
6. Drop compat    then Pinia 4, then remove @vitejs/plugin-legacy if analytics allow

No Vue on the site? Steps 1, 3-6 vanish: go straight to Vite 8.

If Vue 2 must die first (a security finding, a hosting rule), the order flips: Vue 3 via @vue/compat on Webpack is supported by the migration guide, then Vite. It is the slower path - two configurations of Vue 3 tooling instead of one.

# Step 0 - inventory in one pass
fd -H "webpack.mix.js|webpack.config.js|mix-manifest.json|vite.config" -E node_modules
jq '{vue:.dependencies.vue, mix:.devDependencies["laravel-mix"], webpack:.devDependencies.webpack, vite:.devDependencies.vite, vuex:.dependencies.vuex}' package.json
rg -n "mix\(|craft\.vite|data-vue-island|inline-template|new Vue\(" templates/ src/ | head -50

Cutover checklist: Mix/Webpack to Vite

Work top to bottom; each line links to the detail.

• Branch from a green build; record a parity baseline - screenshots of every page type + the network panel's JS/CSS list on the Mix build, plus lab LCP/CLS/TBT for the key templates (median of 5 runs, method in web-perf-ops)
• npm pkg set type="module" (or name configs .mjs/.cjs explicitly)
• vite.config.js: base, build.manifest, outDir: web/dist, entries in build.rolldownOptions.input (config)
• Every webpack.mix.js call mapped (translation table)
• Source rewrites: require, require.context, .vue extensions, process.env, MIX_ to VITE_, Sass ~ imports (rewrites)
• postcss.config.js + tailwind.config.js load; content globs still find templates/**/*.twig - stay on Tailwind v3 for this deploy
• composer require nystudio107/craft-vite (5.x Craft 5, 4.x Craft 4); config/vite.php with manifestPath = @webroot/dist/.vite/manifest.json
• DDEV: the same port in web_extra_exposed_ports, server.port, server.origin, devServerPublic; cors + allowedHosts for .ddev.site (DDEV)
• Twig: every mix() / hard-coded /js/, /css/ tag replaced with craft.vite.script(...); main CSS with asyncCss = false unless critical CSS exists
• Inline scripts that used bundle globals at parse time fixed (module scripts are deferred) (why)
• Twig-referenced images resolved via craft.vite.asset() or left in web/
• Legacy build: decided from analytics, @vitejs/plugin-legacy only if needed (legacy)
• HMR works for CSS + JS; Twig edits reload (vite-plugin-restart)
• vite build in CI/deploy; web/dist/ gitignored; no hashed files committed
• Parity check against the baseline: every page type, fonts, icons, console clean, and the lab metrics - async CSS and modulepreload move LCP and CLS (web-perf-ops has the LCP/CLS fixes)
• Deploy keeps the previous build until full-page caches are purged
• Delete webpack.mix.js, mix-manifest.json, old web/js + web/css, laravel-mix and webpack-only devDependencies - in a follow-up commit

Vue 2 to 3 at a glance

The full workflow, the breaking-change table and testing live in vue2-to-vue3.md. The shape:

1. Alias vue to @vue/compat, set compatConfig: { MODE: 2 } in @vitejs/plugin-vue.
2. Port new Vue({ el }) to createApp(...).mount(el) - per island.
3. Fix compile errors, rename transition classes, upgrade Vuex/router, then runtime warnings one compat ID at a time (compatConfig: { MODE: 3 } per clean component).
4. Global MODE: 3, zero warnings, remove compat.

Three Twig-site landmines worth knowing before you start:

• inline-template is removed - Twig-authored templates need a scoped slot, a <script type="text/html"> template, or conversion to an SFC island.
• Removing compat removes the template compiler. @vue/compat resolves to the full build, plain vue to runtime-only; in-DOM islands go blank unless vue is aliased to vue/dist/vue.esm-bundler.js.
• In-DOM templates execute {{ }} from content - client-side template injection. SFC islands with props avoid it (security).

Common gotchas

Gotcha	Prevention
Bundler and framework upgraded in one deploy	Sequencing above; one parity check per step
Tailwind v4 "while we're at it"	Separate migration with its own visual diff (tailwind-ops)
cors: true / allowedHosts: true copied from a sample	Regex + .ddev.site; true opens the dev server to DNS rebinding
Each island calls createPinia()	One exported instance, app.use(pinia) everywhere
@vitejs/plugin-vue2 on Vite 8	Its peer range ends at Vite 7; finish Vue 3 before Vite 8, or stay on Vite 7.3 meanwhile
Secrets moved from MIX_ to VITE_ vars	VITE_* is inlined into public JS - keep secrets server-side
Old Mix files deleted in the cutover deploy	Delete in a follow-up once nothing references them
Estimating Vue 3 before checking plugins	One Vue 2-only plugin can be the critical path - inventory first

Reference files

File	Contents	Lines
references/mix-webpack-to-vite.md	Mix API to Vite map, vite.config.js for Craft, source rewrites, Tailwind v3/PostCSS/Sass, legacy builds, output	~200
references/craft-vite-twig.md	craft-vite install + config/vite.php, DDEV dev server/HMR, Twig tags, asset URLs, deploy, troubleshooting	~220
references/vue2-to-vue3.md	Migration build under Vite, warning burn-down, Twig-relevant breaking changes, removing compat, testing	~190
references/vue-state-and-plugins.md	Vuex to Pinia (2 vs 4), shared store across islands, Vue 2 plugin replacement table	~170
references/vue-islands-in-twig.md	Island bootstrap, props from Twig, in-DOM templates, template injection, Alpine/Sprig/cache coexistence	~190

Staleness verifier

The versions above move. scripts/check-frontend-upgrade-facts.py guards them against silent drift; the catalogue is assets/frontend-upgrade-facts.json.

# Structural (PR CI, no network): every catalogued package/fact is still named in the
# prose, and SKILL.md keeps a dated "as of" note.
python scripts/check-frontend-upgrade-facts.py --offline   # exit 0 consistent, 10 drift

# Live (freshness job, never blocks a PR): npm + Packagist majors vs documented majors.
python scripts/check-frontend-upgrade-facts.py --live      # exit 10 a major moved, 7 unreachable

A --live drift means the world moved (say, Vite 9 or Pinia 5): re-verify the affected reference against its cited source, then bump documented_major - never just the number.

See also

Skill	When to combine
migrate-ops	Generic upgrade strategy, rollback, codemods, other frameworks
vue-ops	Steady-state Vue 3: Composition API, Pinia, Vue Router, testing
craftcms-ops	Steady-state Craft 5: Twig, element queries, Matrix-as-entries
ddev-ops	DDEV itself: Node pinning and EOL majors, exposed ports and daemons, Mutagen and node_modules
web-perf-ops	Before/after Core Web Vitals for the cutover; LCP/INP/CLS fixes once on Vite
tailwind-ops	The separate Tailwind v3 to v4 migration
playwright-ops	Page-type smoke tests for the parity checks
security-ops	Reviewing in-DOM template injection and VITE_* exposure
package-manager-ops	The install side: one lockfile, npm ci in CI and deploy, the Node pin, node-sass to Dart Sass, Bower to npm