Minimal reproduction for: Astro 6 hybrid build emits dynamic-import URLs with chunk hashes that don't match emitted chunks (runtime 404 on /_astro/*.js).

• output: 'static' + adapter: vercel()
• A single page with export const prerender = false (src/pages/preview.astro) silently flips the build into hybrid mode (the build log will say mode: "server" even though output is "static")
• A prerendered page (src/pages/index.astro) mounts <Sections client:load />. Mounting with client:load (not client:only) is important: it forces the Server, Prerender, and Client Vite passes to all process the same component graph
• Sections.vue renders a Section.vue dispatcher per item. Section.vue uses a template-literal dynamic import (import(\../sections/${component}.vue`)`) so Rollup expands it to a glob and emits a chunk per matching file
• Each section component statically imports glightbox/dist/css/glightbox.min.css at the top, then uses await import('glightbox') at runtime — both shapes appear in the chunk graph
• MediaGalleryGrid.vue adds a static top-level import Hls from 'hls.js' to widen the dependency graph
• When deployed to Vercel, runtime import() URLs baked into the parent chunk bodies reference content hashes that the Client pass never emitted, producing 404s on /_astro/<chunk>.<wrongHash>.js

1. Install and build:

   npm install
   VERCEL=1 npx astro build

   The build log will print mode: "server" even though astro.config.mjs declares output: 'static' — that's the silent flip into hybrid mode caused by src/pages/preview.astro's export const prerender = false.

2. Deploy to Vercel:

   npx vercel deploy --prebuilt

3. Open the deployed / page in a browser, open DevTools → Network. The dynamically imported chunks (one per section component, plus glightbox) will return 404 on URLs like /_astro/glightbox.min.<hash>.js?dpl=... — the hash in the request URL does not match any file emitted on disk.

The hash mismatch is most visible in the deployed build because it appears to depend on the Vercel build environment (Linux + parallel Vite passes). On a local macOS build, the multi-pass hashes happen to converge and the artifacts look correct on disk:

ls .vercel/output/static/_astro/ | grep -E 'glightbox|BioCardGrid|Itinerary|MediaGalleryGrid'
# glightbox.min.CSueQNvw.js
# BioCardGrid.sG7YzeDA.js
# Itinerary.D4mcpWvm.js
# MediaGalleryGrid.CN7SAn08.js

grep -hoE '/_astro/(glightbox\.min|BioCardGrid|Itinerary|MediaGalleryGrid)\.[A-Za-z0-9_-]+\.js' .vercel/output/static/_astro/*.js | sort -u

After deploying to Vercel, the deployed /_astro/*.js parent chunks will contain import() URLs with different hashes than the on-disk filenames. The same comparison performed against the deployed assets shows the mismatch.

The presence of any single prerender = false page is enough to flip an output: 'static' Astro 6 project into hybrid mode internally. Any project using Vue/React component code-splitting or any third-party library loaded via import() is exposed to runtime 404s in production.

The same project on Astro 5 / @astrojs/vercel v9 (which used the /static and /serverless subpath adapters that kept build environments fully separate) does not exhibit this bug.

• withastro/astro#16209 — chunk-hash placeholder regression in 6.1.3 (Linux-specific)
• withastro/astro#16048 — hybrid-environment manifest invalidation fix