Fix DASVader anonymous reference handling

[d-chambers]

Description

Legacy DASVader JLD2 files can contain readable HDF5 object references without linked object names. The compatibility guard introduced in #647 treated h5r.get_name(...) is None as proof that a reference could not be read, so DASCore raised DASVaderCompatibilityError on compatible h5py/HDF5 stacks before attempting dereferencing.

This change attempts h5[value] first and translates an actual KeyError into the existing compatibility error. It restores legacy-file reads with h5py 3.15/HDF5 1.14 while retaining the clear error under h5py 3.16/HDF5 2.0. The reader note now describes that behavior, and a self-contained regression test covers an anonymous but readable reference.

Validation

• pytest -q tests/test_io/test_dasvader/test_dasvader.py with h5py 3.15.1/HDF5 1.14.6: 8 passed.
• Same focused suite with h5py 3.16.0/HDF5 2.0.0: 7 passed, 1 compatibility skip.
• Bounded read of the reported legacy file with h5py 3.15.1: one (235000, 2) float32 patch.
• pytest -q tests: 6320 passed, 83 skipped, 4 xfailed.
• pre-commit run --all: passed.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes.
• documented the new feature with docstrings and/or appropriate doc page.
• included tests. See testing guidelines.
• added the "ready_for_review" tag once the PR is ready to be reviewed.

Summary by CodeRabbit

• Bug Fixes
  • Improved compatibility when reading legacy DASVader files that include anonymous HDF5 references.
  • Reference resolution now uses direct dereferencing behavior when supported, with clearer fallback when resolution fails.
  • Compatibility guidance is provided when anonymous references cannot be dereferenced.
• Tests
  • Added coverage for anonymous HDF5 reference dereferencing and confirmed expected behavior on dereference failure.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: cca617c6-5621-4672-8a03-3e5b455e1024

📥 Commits

Reviewing files that changed from the base of the PR and between b1fc1a7 and 4659ee7.

📒 Files selected for processing (1)

• tests/test_io/test_dasvader/test_dasvader.py

🚧 Files skipped from review as they are similar to previous changes (1)

• tests/test_io/test_dasvader/test_dasvader.py

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📝 Walkthrough

Walkthrough

Changes

DASVader reference handling now directly dereferences HDF5 references, raises compatibility errors when resolution fails, and tests both anonymous-reference success and unresolved-reference failure.

DASVader reference handling

Layer / File(s)	Summary
Direct HDF5 reference resolution dascore/io/dasvader/core.py, dascore/io/dasvader/utils.py	_dereference now indexes HDF5 references directly, converts failed dereferences into the existing compatibility error, and updates the related documentation.
Anonymous reference validation tests/test_io/test_dasvader/test_dasvader.py	Adds coverage for resolving anonymous HDF5 dataset references and asserting compatibility errors for unresolved references.

Possibly related PRs

• DASDAE/dascore#595: Initial DASVader format support introduced the related legacy reference handling.
• DASDAE/dascore#601: Updates reference resolution in the same DASVader conversion path.
• DASDAE/dascore#647: Includes related _dereference behavior and tests for legacy references.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: fixing DASVader anonymous reference handling.
Description check	✅ Passed	The PR description includes the required Description and Checklist sections plus validation details, and is complete overall.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch agent/fix-dasvader-anonymous-refs

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[coderabbitai]

🧹 Nitpick comments (1)

tests/test_io/test_dasvader/test_dasvader.py (1)

243-255: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Cover the compatibility-error branch too.

This test only proves successful dereferencing. Add a focused case where h5[value] raises KeyError, then assert DASVaderCompatibilityError and its guidance; otherwise the central error-handling regression could break while this test remains green.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@tests/test_io/test_dasvader/test_dasvader.py` around lines 243 - 255, Add a
focused test alongside test_dereference_anonymous_reference that exercises
_dereference when resolving the reference through h5[value] raises KeyError.
Assert that DASVaderCompatibilityError is raised and that its message includes
the expected compatibility guidance, while keeping the existing successful
dereference coverage unchanged.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@tests/test_io/test_dasvader/test_dasvader.py`:
- Around line 243-255: Add a focused test alongside
test_dereference_anonymous_reference that exercises _dereference when resolving
the reference through h5[value] raises KeyError. Assert that
DASVaderCompatibilityError is raised and that its message includes the expected
compatibility guidance, while keeping the existing successful dereference
coverage unchanged.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: c5f6edc0-ab4a-432c-b297-2f9053c47f22

📥 Commits

Reviewing files that changed from the base of the PR and between 09aac2f and b1fc1a7.

📒 Files selected for processing (3)

• dascore/io/dasvader/core.py
• dascore/io/dasvader/utils.py
• tests/test_io/test_dasvader/test_dasvader.py

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.93%. Comparing base (09aac2f) to head (4659ee7).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #774   +/-   ##
=======================================
  Coverage   99.93%   99.93%           
=======================================
  Files         145      145           
  Lines       12859    12859           
=======================================
  Hits        12851    12851           
  Misses          8        8           

Flag	Coverage Δ
unittests	99.93% <100.00%> (ø)

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