Closes #17060

Problem

In hybrid mode (output: 'static' + adapter), prerendered pages that are redirect targets were incorrectly being included in the SSR bundle, causing massive bundle size inflation. The reporter saw their deployment grow from ~1.4MB to 68MB due to this issue.

Root Cause

The getRoutesForEnvironment function in packages/astro/src/vite-plugin-pages/pages.ts was unconditionally adding redirect target routes to the result set without checking their prerender flag. This meant that even when a redirect target was meant to be prerendered (and thus should only exist in the static environment), it would still get bundled into the SSR function.

Solution

Added a prerender check to the redirect target filtering logic:

if (route.redirectRoute && route.redirectRoute.prerender === isPrerender)

This ensures redirect targets are only included in their appropriate environment - prerendered redirects stay in static, and SSR redirects stay in SSR.

Verification

• All 65 existing redirect tests continue to pass
• Added comprehensive unit tests covering the environment filtering logic
• Issue reporter (@spaceemotion) confirmed the fix works - their deployment is now 990KB (down from 68MB) and builds 30 seconds faster

Files Changed

• packages/astro/src/vite-plugin-pages/pages.ts — Added prerender check to redirect target filtering
• packages/astro/test/units/redirects/environment-filtering.test.ts — New unit tests covering the filtering logic