[guhou-hvi]

Summary

Addresses #2451.

MemoryStore preserves foo/bar when asked to delete the nonexistent key foo.
LocalStore can instead remove the objects beneath that prefix. A request to
delete one nonexistent key should not delete several other objects. The
maintainer distinguished single-key delete from recursive delete_dir in
#2451; #2606 documented the existing behavior without fixing it.

This change makes directory prefixes a no-op for LocalStore's delete and
delete_sync. Actual file deletion is unchanged. Callers relying on recursive
deletion must use delete_dir, or clear for the whole store.

For reviewers

The compatibility change is intentional. The old recursive-directory test is
replaced, the docstring and changelog explain migration, and an API test that
used root delete() for cleanup now uses delete_dir(). No public API or
dependency is added.

The 12 regression cases check complete key lists and bytes for directory/root
prefixes, plus file deletion, missing keys, explicit recursive deletion and
read-only protection. They give 8 failures and 4 passes on main, and all pass
with the fix. Selected store, group, array and API modules report 4642 passed
and 1134 skipped. Ruff, formatting, numpydoc and changelog checks pass. Mypy
reports the same 9 optional-obstore unused-ignore errors on main. File and
missing-key deletion medians increased by 2.4 and 0.7 microseconds in local
microbenchmarks. Actual symlink probes were skipped for Windows privileges.

Codex implemented the change and tests, ran the local checks, and helped
translate and organize this description; a separate Codex agent reviewed
the change. I have reviewed and understand the changes.

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.
• Update the modified user-facing docstring.
• Document changes and the migration in changes/.
• GitHub Actions have all passed.
• Test coverage is 100% (Codecov passes).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.68%. Comparing base (500673d) to head (da7869a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4468      +/-   ##
==========================================
- Coverage   94.69%   94.68%   -0.01%     
==========================================
  Files          94       94              
  Lines       13597    13596       -1     
==========================================
- Hits        12875    12874       -1     
  Misses        722      722              

Files with missing lines	Coverage Δ
src/zarr/storage/_local.py	98.59% <100.00%> (-0.01%)	⬇️

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