R in Positron on macOS not respecting symlinked OpenBLAS, but works in terminal R session

[uhkeller]

I've symlinked OpenBLAS to be used in R on my Mac. This works in R sessions started in a terminal:

> sessionInfo()
R version 4.5.2 (2025-10-31)
Platform: aarch64-apple-darwin20
Running under: macOS Sequoia 15.7.1

Matrix products: default
BLAS:   /opt/homebrew/Cellar/openblas/0.3.30/lib/libopenblasp-r0.3.30.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.1

But curiously, when running R within Positron (or RStudio), R is using Apple's accelerated BLAS.

> sessionInfo()
R version 4.5.2 (2025-10-31)
Platform: aarch64-apple-darwin20
Running under: macOS Sequoia 15.7.1

Matrix products: default
BLAS:   /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib 
LAPACK: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.1

Anybody have an idea why this is happening? I'm using R 4.5.2 installed through rig.

[juliasilge]

Thanks for this report! Can you say more about how you have symlinked to OpenBLAS?