diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 622b8cd9f86..ce894d23248 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -118,13 +118,10 @@ In PowerShell, use `$env:ORCA_DEV_MAIN_SOURCEMAPS='0'` before `pnpm dev`.
 Remove the variable when debugging the main process with source maps. Renderer and
 preload settings are unaffected; production builds always keep their hidden main maps.
 
-To try Vite's experimental bundled dev mode for the renderer, set `ORCA_DEV_BUNDLED=1`
-before `pnpm dev` (PowerShell: `$env:ORCA_DEV_BUNDLED='1'`). The renderer is served as a
-few bundled chunks instead of thousands of module requests, so the first render and full
-reloads are faster. HMR still works, but each edit rebuilds the affected chunks. While a
-rebuild is pending, a newly opened pop-out, space, or web window may get placeholder HTML
-until the bundle is ready. The mode is opt-in and experimental. Unset the variable if the renderer
-misbehaves, and report the problem with the variable noted.
+`pnpm dev` serves the renderer with Vite's bundled dev mode: a few bundled chunks instead of
+thousands of module requests, so the first render and full reloads are faster. While a rebuild is
+pending, a newly opened pop-out, space, or web window may briefly get placeholder HTML. If the
+renderer misbehaves, set `ORCA_DEV_BUNDLED=0` (PowerShell: `$env:ORCA_DEV_BUNDLED='0'`) and report it.
 
 Local installs use pnpm's global virtual store: each package version is one slot
 under `~/pnpm/store` that every worktree links to, instead of a full `node_modules` per worktree.
diff --git a/config/build-plugins/renderer-bundled-dev.ts b/config/build-plugins/renderer-bundled-dev.ts
index 22feecf7f08..0c230dd89f1 100644
--- a/config/build-plugins/renderer-bundled-dev.ts
+++ b/config/build-plugins/renderer-bundled-dev.ts
@@ -1,7 +1,7 @@
 import type { UserConfig } from 'electron-vite'
 
 /**
- * Opt-in (`ORCA_DEV_BUNDLED=1`): Vite's experimental bundled dev mode serves the renderer as
+ * Default in dev (opt out with `ORCA_DEV_BUNDLED=0`): Vite's bundled dev mode serves the renderer as
  * bundled chunks instead of thousands of per-module requests, which shortens dev startup and reloads.
  */
 export function withBundledRendererDev(
@@ -9,7 +9,7 @@ export function withBundledRendererDev(
   env: NodeJS.ProcessEnv = process.env
 ): UserConfig {
   const renderer = config.renderer
-  if (env.ORCA_DEV_BUNDLED !== '1' || !renderer || typeof renderer === 'function') {
+  if (env.ORCA_DEV_BUNDLED === '0' || !renderer || typeof renderer === 'function') {
     return config
   }
   const rollupOptions = renderer.build?.rollupOptions
diff --git a/config/scripts/electron-vite-output-contract.test.ts b/config/scripts/electron-vite-output-contract.test.ts
index 77e02836261..7ff5e5699eb 100644
--- a/config/scripts/electron-vite-output-contract.test.ts
+++ b/config/scripts/electron-vite-output-contract.test.ts
@@ -110,10 +110,13 @@ describe('Electron Vite output contract', () => {
   it('can skip main source maps during development without changing build output settings', () => {
     try {
       vi.stubEnv('ORCA_DEV_MAIN_SOURCEMAPS', undefined)
+      vi.stubEnv('ORCA_DEV_BUNDLED', undefined)
       const defaults = configureElectronVite({ command: 'serve', mode: 'development' })
       expect(defaults.main?.build?.sourcemap).toBe('hidden')
       expect(defaults.main?.build?.minify).toBe(false)
+      expect(defaults.renderer?.experimental?.bundledDev).toBe(true)
       vi.stubEnv('ORCA_DEV_MAIN_SOURCEMAPS', '0')
+      vi.stubEnv('ORCA_DEV_BUNDLED', '0')
       const development = configureElectronVite({ command: 'serve', mode: 'development' })
       expect(development.main?.build?.sourcemap).toBe(false)
       expect(development.main?.build?.minify).toBe(false)