Image import collisions

Astro Info

Astro                    v7.1.6
Vite                     v8.1.5
Node                     v24.15.0
System                   macOS (arm64)
Package Manager          npm
Output                   static
Adapter                  none
Integrations             @astrojs/mdx (v7.0.5)
                         @astrojs/sitemap (v3.7.3)

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

No response

Describe the Bug

From Claude (apologies if anything is overstated):

At a large enough number of unique content-collection image references, the build fails with:

[PARSE_ERROR] Identifier `__ASTRO_IMAGE_IMPORT_26gozP` has already been declared
       ╭─[ .astro/content-assets.mjs:16929:8 ]
       │
 16929 │ import __ASTRO_IMAGE_IMPORT_26gozP from "../../../assets/generated/post-2588-body-3.png?astroContentImageFlag=&importer=src%2Fcontent%2Fblog%2Fpost-2588%2Findex.ru.md";

The two import statements sharing this identifier reference completely unrelated images from unrelated content entries:

import __ASTRO_IMAGE_IMPORT_26gozP from "../../../assets/generated/post-2588-body-3.png?astroContentImageFlag=&importer=src%2Fcontent%2Fblog%2Fpost-2588%2Findex.ru.md";
import __ASTRO_IMAGE_IMPORT_26gozP from "../../../assets/generated/post-2777-hero.jpg?astroContentImageFlag=&importer=src%2Fcontent%2Fblog%2Fpost-2777%2Findex.fil.md";

This is a hash collision, not a duplicate declaration of the same import. importIdToSymbolName() in packages/astro/src/assets/utils/resolveImports.ts derives the generated identifier by running the full import specifier (image path + importer query param) through shorthash() (packages/astro/src/runtime/server/shorthash.ts):

const importIdToSymbolName = (importId) => `__ASTRO_IMAGE_IMPORT_${shorthash(importId)}`;

shorthash()'s internal bitwise() function is a 32-bit rolling hash (hash = (hash << 5) - hash + charCode, then hash & hash to pin it to a 32-bit signed integer) before being base-61 encoded. Regardless of input string length, the output space is capped at 2³² (~4.29 billion) possible values.

Since content-collection images get one generated import per (image path, importing file) pair, a project with a large number of content entries referencing images (directly, or the same images repeated across many entries — e.g. translated content that duplicates hero/body images across locales) can easily generate hundreds of thousands of these import identifiers. At that volume, the birthday paradox makes collisions in a 32-bit space a near-certainty rather than a rare fluke.

What's the expected result?

The build should not fail due to two unrelated images being assigned the same generated import identifier.

Link to Minimal Reproducible Example

https://github.com/AlanBreck/astro-image-import-collision-repro

Participation

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