Bug: client-mode build crashes (`ERR_MODULE_NOT_FOUND`) when adding nitro v3's vite plugin — prerender hook hardcodes `dist/server/server.js`

Reproduce the failure with the linked solid-2-nitro-repro at commit e31c0fa by running pnpm build, then inspect the client-mode solid:start/prerender hook and configurePreviewServer behavior described in dist/esm/index.mjs. Compare the Vite environment outputs with the hardcoded dist/server/server.js and dist/client/index.html paths. Done means the Nitro configuration builds without ERR_MODULE_NOT_FOUND and the integration has a clear ownership or path-handling behavior.

Description

Adding nitro v3 (nitro/vite) next to a client-mode start: true setup breaks the production build. The plugin's solid:start/prerender buildApp hook imports the SSR handler from a hardcoded dist/server/server.js, but nitro's vite plugin reroutes both environment outputs before that, so the file never exists and the build dies with a bare ERR_MODULE_NOT_FOUND pointing into the plugin's own dist/esm/index.mjs.

The same config with ssr: true (SSR mode) builds fine — nitro runs its own [SSR] → [Nitro] stages and produces .output/server/index.mjs (node-server preset). The crash is specific to client mode (ssr: false), where the prerender hook unconditionally reads dist/server.

Note that ssr: false + serverFunctions: true is a documented, legitimate server-bearing setup — not user error: the README's client-mode section says no server bundle remains "unless serverFunctions is enabled, in which case dist/server is kept and its handleRequest serves the endpoint". With server functions enabled there is server code by design even when SSR is off, and the README lists Nitro among the hosts that consume that { fetch }/handleRequest shape. So "Solid builds the server bundle, nitro hosts it" is the intended integration; only the client-mode build-time glue breaks it.

Reproduction

Two-commit repro repo: https://github.com/lkwr/solid-2-nitro-repro

Commit	Config	pnpm build
9fb2261 — "init bare solid 2.0 template"	solid({ start: true, diagnostics: true })	✅ works
e31c0fa — "add nitro & enable server functions"	solid({ start: true, diagnostics: true, ssr: false, serverFunctions: true }) + nitro()	❌ crashes

git clone https://github.com/lkwr/solid-2-nitro-repro
pnpm install
git checkout e31c0fa
pnpm build

The only changes in commit 2 are vite.config.ts and package.json:

 import { defineConfig } from 'vite';
 import solid from '@solidjs/vite-plugin';
+import { nitro } from 'nitro/vite';

   plugins: [
-    solid({ start: true, diagnostics: true }),
+    solid({ start: true, diagnostics: true, ssr: false, serverFunctions: true }),
+    nitro()
   ],

+    "nitro": "^3.0.260903-beta",

Observed

vite v8.3.1 building client environment for production...
✓ 43 modules transformed.
.output/public/.vite/manifest.json                 0.45 kB
.output/public/assets/logo-BKhbptE1.svg            1.59 kB
.output/public/assets/virtual_solid-ssr-entry-client-2z-wuqR5.js   39.63 kB

✓ built in 65ms
vite v8.3.1 building ssr environment for production...
✓ 8 modules transformed.
node_modules/.nitro/vite/services/ssr/server.js    6.62 kB

✓ built in 1.01s
error during build:
Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/Users/Lukas/test/solid-nitro/dist/server/server.js' imported from /Users/Lukas/test/solid-nitro/node_modules/.pnpm/@[email protected][email protected]/node_modules/@solidjs/vite-plugin/dist/esm/index.mjs
    at finalizeResolution (node:internal/modules/esm/resolve:241:11)
    ...
  code: 'ERR_MODULE_NOT_FOUND',
  url: 'file:///Users/Lukas/test/solid-nitro/dist/server/server.js'

Notes from bisecting the repro:

• Removing serverFunctions: true (keeping start: true, ssr: false + nitro()) still crashes identically — the prerender hook's import is unconditional in client mode.
• Setting ssr: true makes the build succeed (nitro consumes the server side, .output/server/index.mjs). Only client mode crashes.

Root cause

In @solidjs/vite-plugin 3.0.0-next.46, dist/esm/index.mjs, the client-mode prerender hook (solid:start/prerender, order: 'post'):

const serverDir = path.resolve(root, "dist/server"); // hardcoded
const handler = await import(
  pathToFileURL(path.join(serverDir, "server.js")).href
);
const response = await handler.handleRequest(
  new Request(new URL(base || "/", "http://localhost")),
);
writeFileSync(
  path.resolve(root, "dist/client/index.html"),
  await response.text(),
); // hardcoded

nitro's vite plugin patches the environments first: the client build lands in .output/public/…, the ssr environment in node_modules/.nitro/vite/services/ssr/server.js, and nitro then builds its own .output/server/…. Nothing ever writes dist/server/server.js, so the prerender import fails.

Affected assumptions in that hook (and the same hardcode family elsewhere — e.g. configurePreviewServer also does import(path.resolve(root, 'dist/server/server.js'))):

1. The SSR handler is at dist/server/server.js — but nitro (as a supported { fetch } consumer per the README) reroutes environment outputs.
2. The prerendered shell is written to dist/client/index.html — nitro's layout is .output/public.
3. In client mode start.external is documented as inert ("Server-only options are inert here … and so is start.external"), so there is currently no supported seam to point the prerender/preview steps at a relocated server bundle.

What's missing is the build-time seam: the plugin's dev middlewares stand down automatically when a host adopts the ssr environment, but the client-mode prerender (and preview dispatch) still read the hardcoded path.

Expected behavior

One (or more) of:

• Derive the SSR handler location from the resolved environment (the outDir/entry the ssr environment was actually built to) rather than a hardcoded dist/server.
• When another plugin has taken ownership of / rerouted the ssr environment (as nitro v3 does — the same ownership the plugin already detects in dev to stand its middlewares down), skip the plugin's own prerender/preview dispatch (nitro can prerender itself) instead of importing a path that no longer matches.
• At minimum, surface a clear diagnostic ("SSR handler not found at <root>/dist/server/server.js — if another plugin owns the server build, configure X") instead of a bare ERR_MODULE_NOT_FOUND whose only importer reference points into @solidjs/vite-plugin/dist/esm/index.mjs.

Environment

@solidjs/vite-plugin	3.0.0-next.46
solid-js / @solidjs/web / @solidjs/diagnostics	2.0.0-rc.11
vite	8.3.1
nitro	3.0.260903-beta (nitro/vite)
node / pnpm	v26.10.0 / 12.6.0
OS	macOS