fix: serve public assets under base path with Cloudflare adapter

[dataCenter430]

Changes

Fixes #15914: public assets in astro dev are now served under the configured base path when using the @astrojs/cloudflare adapter.

Problem

With base: "/docs/" and the Cloudflare adapter enabled:

• The page correctly renders URLs like /docs/test.svg.
• GET /docs/test.svg returns 404.
• GET /test.svg returns 200.

Without the adapter, /docs/test.svg works as expected. The bug is adapter-specific.

Root cause

Astro’s dev server uses custom middleware (baseMiddleware, etc.) to strip the base prefix from requests before Vite’s static middleware serves files from public/. That middleware is only registered when at least one runnable SSR/prerender environment exists.

With @astrojs/cloudflare, the SSR environment is a workerd-backed CloudflareDevEnvironment, which is not “runnable” in Node. So configureServer returned early and never registered the middleware stack. As a result, requests like /docs/test.svg reached Vite with the base prefix intact, and Vite looked for public/docs/test.svg → 404.

Solution

• Always return the post-hook from configureServer and always register the core dev middleware (baseMiddleware, trailingSlashMiddleware, routeGuardMiddleware, secFetchMiddleware), regardless of whether the SSR/prerender environments are runnable.
• SSR/prerender request handlers remain conditional on ssrHandler / prerenderHandler, so Cloudflare’s workerd still handles those requests; only the base-path and security middleware are now applied in all cases.
• The unhandledRejection listener is only registered when at least one runnable handler exists, to avoid attaching it when no handlers are present.

Testing

• Reproduced the issue with the minimal repro from @astrojs/cloudflare dev server does not serve public assets under base path #15914 (Cloudflare adapter + base: "/docs/").
• After the fix, GET /docs/test.svg returns 200 when public/test.svg exists.
• Verified astro dev without the Cloudflare adapter still behaves as before.

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Latest commit: 1cd3d8d

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[matthewp]

@dataCenter430 is this with prerenderEnvironment: 'node'?

[dataCenter430]

@dataCenter430 is this with prerenderEnvironment: 'node'?

No. The bug shows up with the default setup (workerd for both SSR and prerender). With prerenderEnvironment: 'node' you get a runnable prerender environment, so the old code did register the middleware and the bug typically didn’t appear.

Also, the CI test failure (CI/test integration) does not seem to be related to my code changes.
Should I fix the issue to get a PR merged?

[codspeed-hq]

Merging this PR will not alter performance

✅ 18 untouched benchmarks

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_{Comparing dataCenter430:fix/serve-public-assets-under-base-path (1cd3d8d) with main (325901e)¹}

Footnotes

1. No successful run was found on main (85060cd) during the generation of this report, so 325901e was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩