This is a minimal reproduction case for image compression failures when using @rsbuild/plugin-image-compress with rspack 1.6.x.

After upgrading from rspack 1.5.3 to 1.6.2, image compression fails with:

• JPEG files: Compress JPEG failed Any { .. }
• PNG files: Optimize failed Invalid header detected; Not a PNG file

• @rspack/core: 1.6.2 (fails) vs 1.5.3 (works)
• @rsbuild/plugin-image-compress: 1.3.1
• @napi-rs/image: 1.11.2 (transitive dependency)

• src/test.jpg - 259KB progressive JPEG
• src/test.png - 681KB PNG

Both images are valid and verified with file command.

cd repro
npm install

This will install both rspack versions using npm aliases:

• rspack-core-1.5 (rspack 1.5.3)
• rspack-core-1.6 (rspack 1.6.2)

npm run build:1.5

Expected: Build succeeds ✅

Actual Result:

Rspack 1.5.3 compiled with 2 warnings in 5.94 s
Build completed!

Images are successfully compressed and output to dist/.

npm run build:1.6

Expected: Build fails with image compression errors ❌

Actual Result:

ERROR in × "d37f2fa28b53c09c.jpg" in "/path/to/repro" from Image Minimizer:
│ Compress JPEG failed Any { .. }

ERROR in × "211c9e79656758be.png" in "/path/to/repro" from Image Minimizer:
│ Optimize failed Invalid header detected; Not a PNG file

Rspack 1.6.2 compiled with 2 errors in 42 ms

npm run test:both

This will run both builds in sequence to demonstrate the difference.

npm run clean

This reproduction uses npm package aliases to install both rspack versions simultaneously:

• rspack-core-1.5: Alias for @rspack/core@1.5.3
• rspack-core-1.6: Alias for @rspack/core@1.6.2

The build scripts (build-1.5.js and build-1.6.js) are Node.js wrappers that:

1. Explicitly require the correct rspack version using the alias
2. Load the shared rspack.config.js
3. Run the rspack compiler programmatically
4. Report build status and errors

This approach ensures that each build uses the exact rspack version being tested.

See rspack.config.js for the minimal configuration using ImageMinimizerPlugin with:

• JPEG compression using @napi-rs/image
• PNG lossless compression using @napi-rs/image

Expected: Images should be compressed successfully in both rspack versions.

Actual:

• rspack 1.5.3: ✅ Works correctly
• rspack 1.6.2: ❌ Fails with cryptic Rust error messages

• The error messages Any { .. } suggest Rust error details are being lost in the FFI boundary
• The images are valid (verified with file and hexdump)
• Disabling image compression allows the build to succeed
• The issue affects both JPEG and PNG formats