Fix stardist worker crash: pin setuptools<82 for pkg_resources

[arjunrajlab]

Problem

The stardist worker crashed at runtime in the deployment build with:

File "/root/miniforge3/envs/worker/lib/python3.10/site-packages/stardist/bioimageio_utils.py", line 2, in <module>
    from pkg_resources import get_distribution
ModuleNotFoundError: No module named 'pkg_resources'

Root cause

stardist==0.9.1 imports from pkg_resources import get_distribution at import time — stardist/__init__.py pulls in bioimageio_utils.py, which fails immediately. pkg_resources was bundled with setuptools, but setuptools 82.0.0 (released Feb 2026) removed it entirely.

workers/annotations/stardist/environment.yml did not pin setuptools, so fresh builds resolved setuptools ≥82 and shipped an image without pkg_resources. The image used to build/run fine only because earlier builds happened to get setuptools <82. This is unpinned-transitive-dependency drift.

Why the build didn't catch it

download_models.py runs at build time and does from stardist.models import StarDist2D, so the build touched the broken import — but it wrapped the import in except ImportError / except Exception that only printed the traceback and then exited 0. Docker saw a successful RUN, so the image built and pushed "successfully" (with the models never cached), and the failure only surfaced at runtime.

Fixes

1. Pin setuptools<82 in the conda dependencies so pkg_resources stays available. This is the layer where setuptools is installed; none of the later pip steps require setuptools ≥82, so the pin holds through the build.
2. Make download_models.py exit non-zero on import/download failure, so future dependency drift fails the Docker build loudly instead of shipping a broken image.

Tests

Added workers/annotations/stardist/tests/test_download_models.py (stdlib-only, runs under plain pytest). It runs the script with a fake stardist package shadowing any real install so the import fails deterministically, and asserts the script exits non-zero and reports the error. Written test-first (failed against the old swallow-and-exit-0 behavior, passes after the fix).

$ pytest workers/annotations/stardist/tests -q
2 passed

Verification

The setuptools<82 pin itself can't be validated by a local rebuild here (GPU/CUDA worker, not buildable on a Mac dev machine). After the next deployment build, confirm the worker imports cleanly:

docker run --rm --entrypoint conda <image> run -n worker \
  python -c "import pkg_resources, stardist; print('ok', stardist.__version__)"

Sources for the setuptools 82.0.0 pkg_resources removal:

• [BUG] Restore pkg_resources pypa/setuptools#5174
• Bug: pkg_resources is removed in setuptools 82.0 ==> replace pkg_resources.parse_version by packaging.version.parse tensorflow/hub#934

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