[jhamman]

Summary

Adds a builtin zip: URL pipeline adapter, built on the adapter API from #4192. It reads a ZIP archive that the preceding pipeline resolves to: a local file, an fsspec object, a memory: entry, or a member of another archive. Reads use async byte-range requests on the preceding store, so a remote archive isn't downloaded whole.

from zarr.storage import URLPipeline

group = zarr.open_group(URLPipeline.from_url("s3://bucket/data.zip|zip:inner|zarr3:"), mode="r")

• Read-only: only mode="r" is accepted. "a" (the open_group default), "w", "w-", "r+" and None raise URLPipelineError. To write an archive, use ZipStore.
• zip: at the root of a pipeline raises URLPipelineError, and so does a missing, truncated or non-ZIP archive. On error, the preceding store is closed.
• The segment body is the path inside the archive. A query, ./.. components, or a leading // are rejected.
• Registered as an entry point under zarr.url_adapters in zarr's pyproject.toml, so it loads lazily, like a third-party adapter. The implementation is private: zarr.storage._zip_url_adapter.

For reviewers

• Reading an archive that is the pipeline root relies on LocalStore / FsspecStore treating the empty key as the root object. That reliance is isolated in _read_resource_range / _resource_size, so a future file-resource primitive can replace them.
• The central directory is parsed with the stdlib zipfile over a sparse view of the archive. Any range the view lacks is fetched and the parse retried.

Author attestation

• I am a human, these are my changes, and I have reviewed and understood every change and can explain why each is correct.

TODO

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.md
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.92%. Comparing base (01fa6d9) to head (65eaae7).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4477      +/-   ##
==========================================
+ Coverage   94.84%   94.92%   +0.08%     
==========================================
  Files          96       97       +1     
  Lines       13998    14218     +220     
==========================================
+ Hits        13276    13497     +221     
+ Misses        722      721       -1     

Files with missing lines	Coverage Δ
src/zarr/storage/_zip_url_adapter.py	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes

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