fix(mcp): harden list_cubes member arrays

[Bartok9]

What failure does this repair?

MCP list_cubes raised AttributeError: 'str' object has no attribute 'get' when a cube's measures/dimensions/time_dimensions was non-list or held non-dict members. Repro: call the list_cubes tool against a manifest whose cube has "measures": ["revenue"] — name extraction called .get("name") on the string and the tool failed.

Summary

list_cubes now ignores invalid cube entries and extracts names only from valid dictionary members.

Verification

pytest tests/unit/test_mcp_server.py::test_list_cubes_skips_non_dict_members -q
# 1 passed

Duplicate check

Searched open/closed PRs; #2615 hardens related cube listing but not the member-array normalization in this path. No overlap.

[coderabbitai]

Walkthrough

list_cubes now handles malformed cube and member structures defensively, while a unit test verifies filtering and name extraction behavior.

Changes

Cube enumeration robustness

Layer / File(s)	Summary
Normalize cube members and validate malformed input core/wren/src/wren/mcp_server.py, core/wren/tests/unit/test_mcp_server.py	list_cubes ignores invalid cube entries and extracts names only from valid dictionary members; the unit test covers malformed measures and mixed dimensions.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• Canner/WrenAI#2615: Related hardening of cube listing and tests for malformed cube members.

Poem

I hop through cubes, both neat and strange,
And skip the shapes that drift or change.
Valid names sparkle in my tray,
While malformed bits bounce away.
Tests thump softly—hip-hop, hooray!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.
Title check	✅ Passed	The title is concise and accurately describes the main change: hardening list_cubes member array handling.
Description check	✅ Passed	The description covers the required sections with a clear failure, summary, test verification, and duplicate check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}