[Bug]: returning `redirect` from SSR data loader works weirdly when CSRing

[vegerot]

Version

System:
    OS: macOS 26.2
    CPU: (12) arm64 Apple M3 Pro
    Memory: 176.66 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Browsers:
    Chrome: 141.0.7390.124
    Firefox Developer Edition: 147.0
    Safari: 26.2
    Safari Technology Preview: 26.0
  npmPackages:
    @edenx/app-tools: 1.70.2 => 1.70.2 
    @edenx/plugin-fetch: 1.70.2 => 1.70.2 
    @edenx/plugin-slardar-web: 1.70.2 => 1.70.2 
    @edenx/plugin-starling-intl: 1.70.2 => 1.70.2 
    @edenx/runtime: 1.70.2 => 1.70.2 
    @edenx/tsconfig: 1.70.2 => 1.70.2

Details

note: This bug is on SSRd apps

My SSR project structure looks like:

• src/routes/
  • layout.tsx
  • layout.data.ts
  • A/
    • page.tsx
    • page.data.ts
  • B/page.tsx

Inside layout.data.ts I have some code like

// layout.data.ts
export const loader = ()=> {
  return {
    key1: {
      subkey1: "subvalue1"
    },
    key2: "value2",
  }
}

and inside layout.tsx

// layout.tsx
const Layout = (): JSX.Element => {
	const loaderData = useLoaderData() as LayoutData;
	console.log({ loaderData });
        console.log(loaderData.key1.subkey1);

.

Inside A/page.data.ts I have something like

// A/page.data.ts

import { redirect } from "@edenx/runtime/router";

export const loader = ({request))=> {
  let isProblem = new URL(request.url).searchParams.get("isProblem") === "true";
  if (isProblem) {
    return redirect("/A?isProblem=false");
  } else {
    return {
      A: {
         "aKey3: "value3",
      }
    }
  }
}

in A/page.tsx I have

// A/page.tsx

const A = ()=> {
  const AData = useLoaderData() as CourseData;
  console.log({AData});

}

and finally inside B/page.tsx I have

const B = () => {
  return (<>
    <Link to="/A" />
    <Link to="/A?isProblem=true" />
  </>
  )
}

.

In my app, if I visit /B and click on the link to /A, if there is no problem in A/page.data.ts it works great. Inside my console I see logged

// fetch /A?__loader=layout&__ssrDirect=true
// fetch /A?__loader=A&__ssrDirect=true
{
  loaderData: {
    key1: {
      subkey1: "subvalue1"
    },
    key2: "value2",
  }
}
"subvalue1"
{
  AData: {
      A: {
         "aKey3: "value3",
      }
    }
}

. However, clicking on /A?isProblem=true is bad. Here is what's logged:

// fetch /A?isProblem=true&__loader=layout&__ssrDirect=true
// fetch /A?isProblem=true&__loader=A&__ssrDirect=true RETURNS 204
// fetch /A?isProblem=false&__loader=A&__ssrDirect=true
{
  loaderData: {
      A: {
         "aKey3: "value3",
      }
    }
}
TypeError: Cannot read properties of undefined (reading 'subkey1')

The BUG is that the loader data for A/page.data.ts is returned in layout.tsx. This shouldn't ever happen.

Reproduce link

I'm having trouble coming up with a minimal repo. I sent a maximal repo in the Lark EdenX group

Reproduce Steps

See above

[caohuilin]

@vegerot https://github.com/web-infra-dev/modern.js/tree/feat/router-redirect-test/tests/integration/routes-redirect 是这样的 case 吗？我貌似没复现这个问题，你在这里试试看