fix(vercel): handle isr requests with passQuery: true

[pi0]

Resolves #1880, #3594, #3651

Normally, with ISR matched routes, there is an (undocumented/legacy) x-now-route-matches header that contains the full pathname of the matched route. And Nitro vercel entry uses this header value to restore the original URL, but when passQuery isr route rule config is set, this header won't exist anymore, and the path is invalid (isr function name). We cannot always assume url query param is for ISR functions (it can be an actual query in normal routes!)

This PR changes the internal url query param to __isr_route and, if it exists, also attempts to rewrite without relying on legacy header but instead using a runtime protection check to make sure the requested route matches ISR route patterns.

We also make sure internal "__isr_route" is added to passQuery (if specified)

---

Beta testing:

package.json:

 "resolutions": {
    "nitropack": "https://pkg.pr.new/nitrojs/nitro/nitropack@3539"
  },

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
nitro.build	Ready	Preview	Comment	Oct 14, 2025 10:58am

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/nitrojs/nitro/nitropack@3539

commit: 57d8f1f

[mkucmus]

hey @pi0, do you plan to release the fix in upcoming version maybe?

[fmoessle]

Would love to see this merged. Using

  "resolutions": {
    "nitropack": "https://pkg.pr.new/nitrojs/nitro/nitropack@3539"
  }

works but is not ideal.

[fmoessle]

The problem I face with https://pkg.pr.new/nitrojs/nitro/nitropack@3539: Building and starting the application with node-presets causes an issue with the public folder resolution in .output

Reproduction: https://github.com/fmoessle/nitro-vercel-isr/tree/test-3539-fix

pnpm build
pnpm preview

results in errors like this:

request error] [unhandled] [GET] http://[::]:3000/favicon.ico
 H3Error: ENOENT: no such file or directory, open 'XXX/florian/projects/test/nitro-vercel-isr/.output/server/chunks/public/favicon.ico'
    at async open (node:internal/fs/promises:634:25)
    ... 2 lines matching cause stack trace ...
    at async Server.toNodeHandle (file:///XXX/.output/server/chunks/nitro/nitro.mjs:1917:7) {
  cause: Error: ENOENT: no such file or directory, open 'XXX/.output/server/chunks/public/favicon.ico'
      at async open (node:internal/fs/promises:634:25)
      at async Object.readFile (node:internal/fs/promises:1238:14)
      at async Object.handler (file:///XXX/.output/server/chunks/nitro/nitro.mjs:1646:19)
      at async Server.toNodeHandle (file:///XXX/.output/server/chunks/nitro/nitro.mjs:1917:7) {
    errno: -2,
    code: 'ENOENT',
    syscall: 'open',
    path: 'XXX/.output/server/chunks/public/favicon.ico'
  },
  statusCode: 500,
  fatal: false,
  unhandled: true,
  statusMessage: undefined,
  data: undefined
}

There is no public folder in .output/server/chunks