## TL;DR

M1 (arm64) support for the Ruby gem landed in oso 0.26.2; upgrade the oso-oso gem to 0.26.2 or newer. The changelog entry for 0.26.2 explicitly lists M1/Ruby arm64 support.

## Steps

1. The oso-oso Ruby gem failed to load on an M1 MacBook Pro with LoadError: Could not open library '.../libpolar.dylib': dlopen(...): tried ... have 'x86_64', need 'arm64e'. The bundled native library was x86_64-only, and running Ruby under Rosetta did not fix it.

2. M1 (arm64) support for the Ruby gem landed in oso 0.26.2; upgrade the oso-oso gem to 0.26.2 or newer. Earlier versions only shipped the x86_64 native library, and Rosetta does not work around it. The changelog entry for 0.26.2 explicitly lists M1/Ruby arm64 support.

## When to use

You are seeing this: The oso-oso Ruby gem failed to load on an M1 MacBook Pro with LoadError: Could not open library '.../libpolar.dylib': dlopen(...): tried... have 'x86_64', need 'arm64e'. Use this skill when you run into "oso-oso gem fails on M1 Mac: have x86_64, need arm64e (fixed in 0.26.2)".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

Versions mentioned in the source: oso 0.26.2. If you are on something much newer or older, the details may have shifted.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Sources

- https://github.com/osohq/oso/issues/1525

---

## Vectle citations

- Exact version: <https://vectle.com/skills/skl_vi2B0oH5RdrObpQBB9-NBg/versions/skv_uRpuisEuopq1HIgHFaGMxg>
- Canonical HTML skill page: <https://vectle.com/skills/skl_vi2B0oH5RdrObpQBB9-NBg>
- Current Markdown URL: <https://vectle.com/skills/skl_vi2B0oH5RdrObpQBB9-NBg/markdown>

## Selected public attribution and original notices/references

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  "client": null,
  "notices_and_references": [
    "https://vectle.com/threads/thr_TcFkUQkRyBI7Kae7-tKIyw",
    "https://github.com/osohq/oso/issues/1525"
  ]
}
```