sync

[henrydingliu]

Summary of Changes

Related GitHub Issue(s)

Additional Context for Reviewers

• I passed tests locally for both code (uv run pytest) and documentation changes (uv run jb build docs --builder=custom --custom-builder=doctest)

---

Note

Low Risk
Changes are documentation, static typing, and tests with no intentional reserve-calculation behavior changes; dependency pin is a minor compatibility guard.

Overview
Adds ARCHITECTURE.md documenting package layout, the Triangle mixin stack, composition of indexers, and the TYPE_CHECKING + TriangleProtocol pattern for mixins without runtime Protocol MRO issues.

Typing: TrianglePandas now uses a conditional _TrianglePandasBase (TriangleProtocol under TYPE_CHECKING, object at runtime). TriangleProtocol gains axis setters, __round__, and stricter fillna typing; _auto_sparse() is annotated to return Triangle. The pandas-style API on TrianglePandas gets clearer return types and small cleanups (round delegates to __round__, pct_chg DataFrame passthrough, concat import at module level).

Tests: Broad new coverage for arithmetic unions/broadcasting, __array__ / __array_function__, auto-sparse behavior, polars __dataframe__ init, invalid origin/development rows, and related edge cases.

Deps: uv.lock caps pandas at <=3.0.3.

^{Reviewed by Cursor Bugbot for commit 55f9524. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 14.7% of exported symbols fully typed (184 / 1252)

	Known	Ambiguous	Unknown	Total
Project (head)	184	106	962	1252

Other symbols referenced but not exported by chainladder: 13

	Known	Ambiguous	Unknown	Total
Other (head)	3	1	9	13

Symbols without documentation:

• Functions without docstring: 313
• Functions without default param: 0
• Classes without docstring: 10

Patch (exported symbols added or changed by this PR): 39.1% fully typed (9 / 23); 3 no longer exported

	Known	Ambiguous	Unknown	Total
Patch	9	3	11	23

Patch symbol details

Symbol	Status	Change
chainladder.adjustments.disposal.DisposalRate.xp	⚠️ ambiguous	changed (was ❌ unknown)
chainladder.core.pandas.TrianglePandas.T	✅ known	changed (was ❌ unknown)
chainladder.core.pandas.TrianglePandas.columns	✅ known	changed (was ❌ unknown)
chainladder.core.pandas.TrianglePandas.development	✅ known	changed (was ❌ unknown)
chainladder.core.pandas.TrianglePandas.index	✅ known	changed (was ⚠️ ambiguous)
chainladder.core.pandas.TrianglePandas.origin	✅ known	changed (was ❌ unknown)
chainladder.core.pandas.TrianglePandas.to_frame	✅ known	changed (was ❌ unknown)
chainladder.core.pandas.func	⚠️ ambiguous	new
chainladder.core.pandas.method	⚠️ ambiguous	new
chainladder.core.tests.test_arithmetic.test_arithmetic_union_val_tri	❌ unknown	new
chainladder.core.tests.test_arithmetic.test_eq_non_triangle	❌ unknown	new
chainladder.core.tests.test_arithmetic.test_non_overlapping_odims	❌ unknown	new
chainladder.core.tests.test_arithmetic.test_origin_broadcasting	❌ unknown	new
chainladder.core.tests.test_arithmetic.test_pow_groupby	❌ unknown	new
chainladder.core.tests.test_triangle.test_array_dunder	❌ unknown	new
chainladder.core.tests.test_triangle.test_array_function_mixed_types_raises	❌ unknown	new
chainladder.core.tests.test_triangle.test_array_function_unhandled_raises	❌ unknown	new
chainladder.core.tests.test_triangle.test_auto_sparse_converts_numpy_to_sparse	❌ unknown	new
chainladder.core.tests.test_triangle.test_auto_sparse_disabled_returns_self	❌ unknown	new
chainladder.core.tests.test_triangle.test_development_before_origin_warns_and_drops	✅ known	new
chainladder.core.tests.test_triangle.test_subtriangles	❌ unknown	new
chainladder.core.tests.test_triangle.test_triangle_from_dataframe_interchange_protocol	✅ known	new
chainladder.core.typing.TriangleProtocol.__round__	✅ known	new
chainladder.core.pandas.item	—	no longer exported (was ⚠️ ambiguous)
chainladder.core.pandas.k	—	no longer exported (was ⚠️ ambiguous)
chainladder.core.pandas.v	—	no longer exported (was ⚠️ ambiguous)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.18%. Comparing base (921bfca) to head (55f9524).
⚠️ Report is 23 commits behind head on experimental.

Additional details and impacted files

@@               Coverage Diff                @@
##           experimental    #1085      +/-   ##
================================================
+ Coverage         89.75%   90.18%   +0.42%     
================================================
  Files                91       91              
  Lines              5408     5409       +1     
  Branches            696      696              
================================================
+ Hits               4854     4878      +24     
+ Misses              389      375      -14     
+ Partials            165      156       -9     

Flag	Coverage Δ
unittests	90.18% <100.00%> (+0.42%)	⬆️

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