start-compiler-plugin: hotUpdate crashes with TypeError under vite experimental.bundledDev

Start in src/vite/start-compiler-plugin/plugin.ts and inspect the hotUpdate hook alongside watchChange. Reproduce with pnpm install && pnpm dev in the linked repro using experimental.bundledDev, then edit a source file. Done means hot updates no longer fail when the hook lacks an environment context and the dev server does not serve stale output.

Which project does this relate to?

Start

Describe the bug

The hotUpdate hook in @tanstack/start-plugin-core (src/vite/start-compiler-plugin/plugin.ts) reads this.environment.name unconditionally.

When Vite's experimental.bundledDev (full bundle mode) is enabled, the client environment is driven by Rolldown's dev engine. Vite passes environment plugins into that build, but injectEnvironmentToHooks only wraps hooks listed in ROLLUP_HOOKS, and hotUpdate is not in that list. Rolldown therefore invokes hotUpdate with its own PluginContextImpl as this. It has no environment property, so the hook throws TypeError: Cannot read properties of undefined (reading 'name'). On this path ctx is {type: 'update', file, modules: [null]}.

The dev server does not crash. Rolldown wraps the throw into a build error, the rebuild fails, and the dev server serves stale output on every subsequent edit until restart. Fires on 100% of hot updates.

✘ Build error: Build failed with 1 error:

[plugin tanstack-start-core::server-fn:client]
TypeError: Cannot read properties of undefined (reading 'name')
    at PluginContextImpl.hotUpdate (.../start-plugin-core/dist/esm/vite/start-compiler-plugin/plugin.js:183:53)
    at plugin (.../rolldown/dist/shared/bindingify-input-options-C-Zsy1EG.mjs:1734:24)

Present in 1.171.17 through latest (1.171.34).

Your Example Website or App

https://github.com/TIMTOMTOP/tanstack-hotupdate-repro

Steps to Reproduce the Bug or Issue

1. pnpm install && pnpm dev in the repro (vite 8.2.1, one createServerFn, experimental: { bundledDev: true })
2. Open http://localhost:3000 in a browser. The bundled-dev HMR client must register. Note: Start's SSR HTML does not inject /bundledDevClient.mjs, so the repro adds that script tag in __root.tsx.
3. Edit any source file.
4. Build error on every edit, browser keeps stale content.

Expected behavior

An invocation without an environment context should be a no-op, not wedge the dev server. The plugin already handles bundledDev compiler invalidation via watchChange, which does get environment injection, so nothing is lost.

Platform

• OS: macOS and Linux
• vite: 8.2.1 (rolldown 1.2.2 to 1.2.4)
• @tanstack/start-plugin-core: 1.171.17 to 1.171.34

Additional context

Not specific to TanStack: nitro's hotUpdate hooks crash the same way once this one is guarded, so the systemic fix probably belongs in Vite (wrap or strip hotUpdate in injectEnvironmentToHooks). The guard is still correct defensively.

Fix in #8061.