Astro.rewrite does not respect the base path in configuration

[fa0311]

Astro Info

Astro                    v5.1.8
Node                     v23.1.0
System                   macOS (arm64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             none

If this issue only occurs in one browser, which browser is a problem?

Describe the Bug

When using Astro.rewrite, the configured base path is not considered. Below is a minimal example demonstrating the issue:

astro.config.mjs

import { defineConfig } from 'astro/config';
export default defineConfig({
    base: "/base",
});

src/pages/aaa.astro

---
const url = Astro.url;
---
{url}

src/pages/bbb.astro

---
return Astro.rewrite('/aaa');
---

Steps to Reproduce

1. Run the Astro application with the above configuration.
2. Access http://localhost:4322/base/bbb.

Expected Behavior

The page should output:

http://localhost:4322/base/aaa

Actual Behavior

The page outputs:

http://localhost:4322/aaa

It appears that Astro.rewrite does not respect the base path specified in the configuration.

Would appreciate any clarification or fixes for this behavior.

What's the expected result?

1. Run the Astro application with the above configuration.
2. Access http://localhost:4322/base/bbb.

The page should output:

http://localhost:4322/base/aaa

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-hxasy4zm

Participation

• I am willing to submit a pull request for this issue.

[ematipico]

You're right, Astro.url, during a rewrite, should contain base

[fa0311]

Workaround

By explicitly including the base path in the rewrite, the issue can be resolved:

Updated src/pages/bbb.astro

---
+ return Astro.rewrite('/base/aaa');
- return Astro.rewrite('/aaa');
---

[fa0311]

Issue with trailingSlash: "always"

If trailingSlash is set to "always" in the configuration, the above workaround does not work properly:

Updated astro.config.mjs

import { defineConfig } from 'astro/config';
export default defineConfig({
    base: "/base",
+     trailingSlash: "always",
});

Updated src/pages/bbb.astro

---
+ return Astro.rewrite('/base/aaa/');
- return Astro.rewrite('/base/aaa');
---

When accessing http://localhost:4322/base/bbb/, the following problems occur:

1. A 404: Not Found error is returned.
2. The following strange warning is logged:

15:40:28 [WARN] `Astro.request.headers` was used when rendering the route `src/pages/bbb.astro`. `Astro.request.headers` is not available on prerendered pages. If you need access to request headers, make sure that the page is server-rendered using `export const prerender = false;` or by setting `output` to `"server"` in your Astro config to make all your pages server-rendered by default.
15:40:28 [404] (rewrite) /bbb/ 5ms

This suggests further inconsistencies in how Astro.rewrite handles base paths and trailing slashes.