Package sync unpins packages with linux-x64 client vs. linux-aarch64 cluster

[crusaderky]

coiled 1.131.0

I'm on a Linux Intel x64 client and I want to spin up an AWS Graviton cluster.
package-sync does not respect version pins, and instead installs the latest version of binary packages.

From my Linux Intel x64 desktop:

conda create -n test coiled pandas==3.0.0
conda activate test

then run:

import coiled
import distributed
import pandas

def pd_version():
    return pandas.__version__

with coiled.Cluster(
    n_workers=1,
    worker_vm_types=["m8g.large"],
    scheduler_vm_types=["m8g.large"],
) as cluster:
    with distributed.Client(cluster) as client:
        print(client.submit(pd_version).result())

output:

[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - bcrypt, bcrypt~=5.0.0 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - lz4, lz4~=4.4.5 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - numpy, numpy==2.4.2 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - pandas, pandas==3.0.0 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - pillow, pillow~=12.1.1 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
[2026-02-19 11:20:04,370][WARNING ][coiled.package_sync] Package - psutil, psutil~=7.2.2 has no install candidate for Python 3.14 linux-aarch64 on conda-forge
3.0.1

What I think is happening is that pandas=3.0.0 exists on both linux-x64 and linux-aarch64, but the build differs between architectures:

• https://conda.anaconda.org/conda-forge/linux-64/pandas-3.0.0-py314hb4ffadd_0.conda
• https://conda.anaconda.org/conda-forge/linux-aarch64/pandas-3.0.0-py314h3df833d_0.conda
• https://conda.anaconda.org/conda-forge/osx-arm64/pandas-3.0.0-py314h5e21a50_0.conda

Expected behaviour

When client architecture does not match cluster architecture, match the version and silently unpin the build.
I did not test this with a osx-arm64 client but I would be surprised to find the issue there already as it's such a common use case? Which would mean that the special case code is already there but it's too specific.

[ntabris]

Yes, if you aren't on same platform and arch package sync doesn't do strict version matching because, while sometimes that works, sometimes it doesn't, so we do the easier thing that's more likely to solve.

We do currently support uv lockfiles (which already have multi-platform solves) if that would work for you, but don't yet support pixi lockfiles or other lockfiles that can use conda packages (and don't currently have a timeline on adding support).

[crusaderky]

To my understanding, this is not specific to pixi; anybody with a conda environment.yaml with a pin on a package that isn't noarch is affected

[ntabris]

That's correct