diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index 30e5aaa..969c73b 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -74,12 +74,18 @@ jobs:
         npm link
       working-directory: ./packages/cli
 
+    - name: npm link editor locally
+      run: |
+        npm link
+      working-directory: ./packages/editor
+
     # multiplayer-template has its own nested workspaces (client/server) that npm
     # workspaces does not handle recursively, so we need a separate npm ci here.
-    # Both in one call: each `npm link <pkg>` replaces the links of an earlier one
+    # Both in one call: each `npm link <pkg>` replaces the links of an earlier one.
+    # The editor is linked for the editor dist test; the other steps alias it to its src/
     - name: Build multiplayer-template
       run: |
-        npm link @mavonengine/core @mavonengine/cli
+        npm link @mavonengine/core @mavonengine/cli @mavonengine/editor
         npm run typecheck
         npm run build
         npm run lint
@@ -125,3 +131,17 @@ jobs:
         name: mcp-e2e-screenshots-${{ matrix.os }}
         path: e2e/mcp/screenshots
         if-no-files-found: ignore
+
+    # The template aliases core and the editor to their src/, so nothing above loads their dist/. This runs
+    # the template against the built packages, like a project that installed them, and opens the editor
+    - name: Editor dist end-to-end test
+      timeout-minutes: 5
+      run: npm run test:editor-dist-e2e
+
+    - name: Upload editor dist end-to-end screenshots
+      if: failure()
+      uses: actions/upload-artifact@v4
+      with:
+        name: editor-dist-e2e-screenshots-${{ matrix.os }}
+        path: e2e/editor-dist/screenshots
+        if-no-files-found: ignore
diff --git a/.gitignore b/.gitignore
index 0ec7630..129269a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,3 +30,4 @@ packages/core/src/version.ts
 e2e/http-monitoring/screenshots
 e2e/scenes/screenshots
 e2e/mcp/screenshots
+e2e/editor-dist/screenshots
diff --git a/e2e/editor-dist/run.mjs b/e2e/editor-dist/run.mjs
new file mode 100644
index 0000000..1a55309
--- /dev/null
+++ b/e2e/editor-dist/run.mjs
@@ -0,0 +1,99 @@
+/**
+ * End-to-end test for the built editor, the way a project that installed @mavonengine/core and
+ * @mavonengine/editor from npm loads them:
+ *
+ * The template's Vite config aliases both packages to their src/ in this repository, so the other tests
+ * never load dist/. Bundling problems (a missing external, a require() left in a chunk, a chunk that
+ * doesn't load) only show up in dist. Here MAVONENGINE_USE_DIST=1 turns the aliases off, so the template
+ * resolves the packages through node_modules, then the test opens the editor in Chrome and checks that
+ * its UI mounts with no errors.
+ *
+ * Needs Chrome, core and the editor built and npm-linked into the template, and the template's
+ * dependencies installed.
+ *
+ *   node e2e/editor-dist/run.mjs
+ */
+import { mkdirSync, realpathSync, rmSync } from 'node:fs'
+import { dirname, join } from 'node:path'
+import process from 'node:process'
+import { setTimeout as delay } from 'node:timers/promises'
+import { fileURLToPath } from 'node:url'
+import { chromium } from 'playwright-core'
+import { base, check, log, repo, run, startServer, template } from '../helpers.mjs'
+
+const here = dirname(fileURLToPath(import.meta.url))
+const screenshots = join(here, 'screenshots')
+
+/** The package `name` in the template's node_modules must be this repository's, or the test checks a published one */
+function checkLinked(name, dir) {
+  const linked = realpathSync(join(template, 'node_modules', name))
+  const expected = realpathSync(join(repo, 'packages', dir))
+  check(linked === expected, `${name} in the template is this repository's packages/${dir}${linked === expected ? '' : ` (it is ${linked}, run npm link in packages/${dir} and the template)`}`)
+}
+
+async function main() {
+  let server
+  let browser
+  const errors = []
+
+  rmSync(screenshots, { recursive: true, force: true })
+  mkdirSync(screenshots, { recursive: true })
+
+  try {
+    log('\n== setup')
+    checkLinked('@mavonengine/core', 'core')
+    checkLinked('@mavonengine/editor', 'editor')
+    // Deps pre-bundled while the aliases pointed at src/ would be reused otherwise
+    rmSync(join(template, 'client/node_modules/.vite'), { recursive: true, force: true })
+    await run('npm', ['run', 'build'], { cwd: join(template, 'server') })
+    server = await startServer({ MAVONENGINE_DEV_CLIENT: '1', MAVONENGINE_USE_DIST: '1' })
+
+    log('\n== editor')
+    browser = await chromium.launch({ channel: 'chrome', headless: true, args: ['--use-gl=angle', '--use-angle=swiftshader', '--enable-unsafe-swiftshader'] })
+    const page = await browser.newPage({ viewport: { width: 1400, height: 900 } })
+    page.on('console', (message) => {
+      if (message.type() === 'error')
+        errors.push(message.text())
+    })
+    page.on('pageerror', error => errors.push(error.stack ?? error.message))
+
+    await page.goto(base)
+    await page.waitForFunction(() => window.Game?.activeScene?.name === 'main', null, { timeout: 60000, polling: 200 })
+    check(true, 'the game loads with core from dist')
+
+    await page.locator('canvas').click({ position: { x: 700, y: 450 }, force: true })
+    await page.keyboard.press('Period')
+    await page.waitForFunction(() => !!window.Game.editor && document.title === 'MavonEngine | Editor', null, { timeout: 30000, polling: 200 })
+    check(true, 'the editor boots')
+
+    // The UI is loaded with a dynamic import after the editor boots; a chunk that fails to load is logged, not thrown,
+    // so stop waiting as soon as an error shows up
+    const sceneTab = page.getByRole('tab', { name: 'Scene' })
+    const deadline = Date.now() + 30000
+    while (!errors.length && Date.now() < deadline && !await sceneTab.isVisible())
+      await delay(200)
+    check(await sceneTab.isVisible(), `the editor's UI mounts${errors.length ? `:\n${errors.join('\n')}` : ''}`)
+
+    const loaded = await page.evaluate(() => performance.getEntriesByType('resource').map(e => e.name))
+    check(loaded.some(url => url.includes('/editor/dist/')) && !loaded.some(url => url.includes('/editor/src/')), 'the editor came from dist, not src')
+    check(!loaded.some(url => url.includes('/core/src/')), 'core came from dist, not src')
+    await page.screenshot({ path: join(screenshots, 'editor.png') })
+
+    const relevant = errors.filter(e => !e.includes('favicon'))
+    check(relevant.length === 0, `no console errors${relevant.length ? `:\n${relevant.join('\n')}` : ''}`)
+    log('\nAll editor dist checks passed')
+  }
+  catch (err) {
+    log(`\n== server output\n${server?.output().slice(-4000)}`)
+    throw err
+  }
+  finally {
+    await browser?.close()
+    await server?.stop()
+  }
+}
+
+main().catch((err) => {
+  console.error(err)
+  process.exitCode = 1
+})
diff --git a/package.json b/package.json
index 8825306..89fbd0d 100644
--- a/package.json
+++ b/package.json
@@ -24,6 +24,7 @@
     "test:plugin-e2e": "node e2e/plugin/run.mjs",
     "test:monitoring-e2e": "node e2e/http-monitoring/run.mjs",
     "test:scenes-e2e": "node e2e/scenes/run.mjs",
-    "test:mcp-e2e": "node e2e/mcp/run.mjs"
+    "test:mcp-e2e": "node e2e/mcp/run.mjs",
+    "test:editor-dist-e2e": "node e2e/editor-dist/run.mjs"
   }
 }
diff --git a/packages/editor/vite.config.mjs b/packages/editor/vite.config.mjs
index fe52fa6..fd19359 100644
--- a/packages/editor/vite.config.mjs
+++ b/packages/editor/vite.config.mjs
@@ -9,6 +9,11 @@ import glsl from 'vite-plugin-glsl'
 const EXTENDS_RE = /\bclass\s+\w+\s+extends\s+(?:ParticleEffect|Emitter)\b/
 const ASSETS_RE = /Assets\.tsx$/
 const TS_EXT_RE = /\.ts$/
+// Peer dependencies the game provides. A copy of one in the bundle means an `external` entry misses it
+const PEER_IN_BUNDLE_RE = /[\\/]node_modules[\\/](?:react|react-dom|three|@mavonengine[\\/]core)[\\/]/
+// Rolldown's error for a CommonJS require() of an external it couldn't turn into an import.
+// Browsers have no require, so the chunk throws when it loads
+const REQUIRE_SHIM = 'in an environment that doesn\'t expose the `require` function'
 
 const editorRoot = dirname(fileURLToPath(import.meta.url))
 const coreRoot = resolve(editorRoot, '../core')
@@ -89,7 +94,7 @@ export default defineConfig(({ command }) => ({
       formats: ['es'],
     },
     rolldownOptions: {
-      external: id => ['react', 'react-dom', 'react/jsx-runtime', 'three'].includes(id) || id.startsWith('react/') || id.startsWith('@mavonengine/core') || id.startsWith(coreRoot),
+      external: id => ['react', 'react-dom', 'react/jsx-runtime', 'three'].includes(id) || id.startsWith('react/') || id.startsWith('react-dom/') || id.startsWith('three/') || id.startsWith('@mavonengine/core') || id.startsWith(coreRoot),
       plugins: [
         {
           name: 'inject-css-into-mount-chunk',
@@ -101,6 +106,23 @@ export default defineConfig(({ command }) => ({
               mountChunk.code = `import './${cssFile}';\n${mountChunk.code}`
           },
         },
+        {
+          // Source builds alias the editor to src/, so a bundle that only breaks in the browser goes unnoticed there
+          name: 'check-bundle-for-browser',
+          generateBundle(_, bundle) {
+            const problems = []
+            for (const chunk of Object.values(bundle)) {
+              if (chunk.type !== 'chunk')
+                continue
+              for (const id of chunk.moduleIds.filter(id => PEER_IN_BUNDLE_RE.test(id)))
+                problems.push(`${chunk.fileName} bundles ${id}, it should be external`)
+              if (chunk.code.includes(REQUIRE_SHIM))
+                problems.push(`${chunk.fileName} calls require() at runtime, which fails in the browser`)
+            }
+            if (problems.length)
+              this.error(`The editor bundle would break in projects that install it:\n  ${problems.join('\n  ')}\nCheck build.rolldownOptions.external`)
+          },
+        },
       ],
     },
   },
diff --git a/packages/multiplayer-template/client/vite.config.js b/packages/multiplayer-template/client/vite.config.js
index bac2aa6..6944fb6 100644
--- a/packages/multiplayer-template/client/vite.config.js
+++ b/packages/multiplayer-template/client/vite.config.js
@@ -1,5 +1,6 @@
 import { existsSync } from 'node:fs'
 import { dirname, resolve } from 'node:path'
+import process from 'node:process'
 import { fileURLToPath } from 'node:url'
 import config from '@mavonengine/core/vite.config'
 import vue from '@vitejs/plugin-vue'
@@ -10,6 +11,9 @@ const coreRoot = resolve(clientRoot, '../../core')
 const coreSrc = resolve(coreRoot, 'src')
 const editorRoot = resolve(clientRoot, '../../editor')
 const editorSrc = resolve(editorRoot, 'src/Editor.ts')
+// MAVONENGINE_USE_DIST=1 resolves @mavonengine/core and @mavonengine/editor through node_modules,
+// to their built dist like in a project that installed them, instead of the monorepo's source
+const useSource = process.env.MAVONENGINE_USE_DIST !== '1'
 
 export default {
   ...config,
@@ -26,8 +30,8 @@ export default {
   resolve: {
     ...config.resolve,
     alias: {
-      ...(existsSync(editorSrc) ? { '@mavonengine/editor': editorSrc } : {}),
-      ...(existsSync(coreSrc) ? { '@mavonengine/core': coreSrc } : {}),
+      ...(useSource && existsSync(editorSrc) ? { '@mavonengine/editor': editorSrc } : {}),
+      ...(useSource && existsSync(coreSrc) ? { '@mavonengine/core': coreSrc } : {}),
       '@template/server': resolve(templateRoot, 'server/src'),
     },
     dedupe: ['@mavonengine/core', 'three', 'vue', 'react', 'react-dom', '@dimforge/rapier3d-compat'],