[quwin]

Which issue does this PR close?

• Closes unnest drops the list item field's metadata (e.g. Arrow extension types) #26331.

Rationale for this change

In SedonaDB, unnesting a list of GeoArrow geometries currently returns plain binary values, losing the geometry type and CRS metadata needed by downstream spatial operations; metadata-aware SQL functions can also reject the field during planning.

What changes are included in this PR?

• Preserve list-item fields in expression inference and logical-plan schemas while retaining output naming and nullability behavior.

What is the testing strategy for this PR?

• DataFrame regressions cover all five list variants, nested unnesting, aliases, NULL/empty lists, and metadata-sensitive UDF planning. The targeted regression run passed all 7 cases.
• The logical_unnest_plus_1000_columns benchmark in the optimized release-nonlto profile measured 47.58 ms on base 0d79252f and 48.75 ms on this branch (+2.5% median). This is within the noise threshold.
• The full extended workspace suite and all-features Clippy were not rerun; the existing Clippy issue Clippy fails with all features enabled #26181 remains noted.

Are there any user-facing changes?

UNNEST retains list-item metadata, including Arrow extension metadata, in inferred fields and result schemas. No public Rust API changes.

[quwin]

@jayzhan211 Could you review this UNNEST bug fix and run CI? Thanks!

[jayzhan211]

Thanks @quwin , overall LGTM

[codecov-commenter]

Codecov Report

❌ Patch coverage is 85.36585% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.93%. Comparing base (d89a85d) to head (049fbd2).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
datafusion/expr/src/expr_schema.rs	83.33%	0 Missing and 3 partials ⚠️
datafusion/expr/src/utils.rs	88.23%	2 Missing ⚠️
datafusion/expr/src/logical_plan/plan.rs	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #26433      +/-   ##
==========================================
- Coverage   82.93%   82.93%   -0.01%     
==========================================
  Files        1154     1154              
  Lines      457933   457954      +21     
  Branches   457933   457954      +21     
==========================================
+ Hits       379786   379796      +10     
- Misses      55128    55133       +5     
- Partials    23019    23025       +6     

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