[priyam0k]

Summary of Changes

• Initialize origin and development on Triangle via TriangleAxis descriptors (axis 2 and 3), centralizing axis storage into Triangle._axes alongside index and columns (incorporates [FEAT] Centralize axis descriptors #1454).
• Move _set_origin, _get_origin, _set_development, and _get_development helpers to chainladder.core.axis.
• Deprecate odims (Deprecate odims #1012) and ddims (Deprecate ddims #1013) on Triangle with FutureWarning shims pointing to origin and development.
• Update internal usage across core modules, estimators, adjustments, and tails to prevent internal deprecation warnings.
• Preserve legacy pickle compatibility in Triangle.__setstate__ to migrate legacy pickled instances cleanly.
• Add test coverage for 4-axis descriptor validation, edge cases, deprecation warnings, and pickle round-trips.

Related GitHub Issue(s)

Closes #1012, closes #1013, closes #1053 , #1454, refs #601, refs #1216, refs #1466

Additional Context for Reviewers

• Existing code reading or setting odims and ddims continues to work with deprecation warnings for backward compatibility.
• Incorporates the centralized axis descriptor work previously staged in [FEAT] Centralize axis descriptors #1454 so all four dimensions (0..3) follow the TriangleAxis pattern established in feat(core): deprecate vdims (#1011) and kdims (#1010) #1303.

Checklist

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

---

Note

Medium Risk
This is a wide refactor of Triangle’s four-axis model and pickle migration; backward-compatible shims limit user breakage, but incorrect axis assignment could still affect reserving and development logic.

Overview
Origin and development are now first-class TriangleAxis descriptors (axes 2 and 3), with raw storage in _axes and get/set logic moved to chainladder.core.axis. Public origin / development replace direct use of internal date arrays; odims and ddims remain as FutureWarning shims that delegate to the new properties.

Internal code across core, development, methods, tails, and adjustments now reads/writes _axes[2] / _axes[3] or the public properties instead of odims/ddims. Slicing, concat, arithmetic alignment, and is_val_tri checks follow the same model (e.g. bootstrap/incremental use X.is_val_tri instead of inspecting ddims type). Triangle.__setstate__ migrates legacy pickles that still carry odims/ddims (and related keys) into _axes.

Axis helpers are shared via utility_functions / typing, and DevelopmentConstant pattern detection no longer treats arbitrary DataFrames with origin/development columns as Triangles. Tests cover descriptor edge cases, deprecation warnings, pickle round-trips, and a few new validation paths (valuation triangles on bootstrap/incremental, predict age limits).

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[codecov]

Codecov Report

❌ Patch coverage is 94.61078% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.58%. Comparing base (cf665f3) to head (94a86a1).

Files with missing lines	Patch %	Lines
chainladder/core/axis.py	85.26%	6 Missing and 8 partials ⚠️
chainladder/core/triangle.py	94.66%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1304      +/-   ##
==========================================
+ Coverage   94.36%   94.58%   +0.22%     
==========================================
  Files          97       97              
  Lines        6188     6313     +125     
  Branches      798      826      +28     
==========================================
+ Hits         5839     5971     +132     
+ Misses        225      214      -11     
- Partials      124      128       +4     

Flag	Coverage Δ
unittests	94.58% <94.61%> (+0.22%)	⬆️

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[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 15.7% of exported symbols fully typed (241 / 1536)

	Known	Ambiguous	Unknown	Total
Project (head)	241	106	1189	1536

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: 348
• Functions without default param: 0
• Classes without docstring: 8

Patch (exported symbols added or changed by this PR): 12.5% fully typed (2 / 16)

	Known	Ambiguous	Unknown	Total
Patch	2	0	14	16

Patch symbol details

Symbol	Status	Change
chainladder.adjustments.tests.test_bootstrap.test_bootstrap_odp_val_triangle_error	❌ unknown	new
chainladder.core.tests.test_triangle.test_centralized_axis_edge_cases	❌ unknown	new
chainladder.core.tests.test_triangle.test_ddims_deprecation_warning	❌ unknown	new
chainladder.core.tests.test_triangle.test_odims_deprecation_warning	❌ unknown	new
chainladder.core.tests.test_triangle.test_set_axis	❌ unknown	new
chainladder.core.triangle.Triangle.ddims	❌ unknown	changed (was ✅ known)
chainladder.core.triangle.Triangle.development	✅ known	changed (was ❌ unknown)
chainladder.core.triangle.Triangle.odims	❌ unknown	changed (was ✅ known)
chainladder.core.triangle.Triangle.origin	✅ known	changed (was ❌ unknown)
chainladder.development.tests.test_constant.test_constant_dataframe_with_origin_development_columns	❌ unknown	new
chainladder.development.tests.test_constant.test_constant_incr_cumulative_none	❌ unknown	new
chainladder.development.tests.test_incremental.test_incremental_additive_val_triangle_error	❌ unknown	new
chainladder.development.tests.test_munich.test_munich_properties	❌ unknown	new
chainladder.methods.tests.test_predict.test_predict_age_exceeds_model	❌ unknown	new
chainladder.tails.tests.test_constant.test_constant_attachment_age	❌ unknown	new
chainladder.tails.tests.test_exponential.test_tail_curve_attachment_age	❌ unknown	new

[cursor]

Stale Bugbot comment from a previous run.

[cursor]

Stale Bugbot comment from a previous run.

[priyam0k]

I wasn't sure if this was ready for review, so I figure I'd chime in just in case. Let's follow the general strategy we took in #1303:

• _ddims will become develoment and be initialized via TriangleAxis
• _odims will become origin and be initialized via TriangleAxis

Folded the descriptor commits into this branch per your note. origin and development are now wired through TriangleAxis (axis 2 and 3) with _set_origin and _set_development in axis.py, and _axes stores all four dimensions (0..3).

Since bringing the descriptors and call-site updates together touches around 40 files, we can either review it in one go to get the full dimension stack in, or split it up if you'd rather review in smaller chunks.

[genedan]

I can review it one go, let's get the ddims and odims replaced with development and origin, respectively.

[priyam0k]

I can review it one go, let's get the ddims and odims replaced with development and origin, respectively.

Works for me. The swap to origin and development is in place, so all set for review.

[genedan]

I'm still seeing a lot of references to _odims and _ddims. Can you remove their references, definitions, and replace them with origin and development?

[cursor]

Stale Bugbot comment from a previous run.

[priyam0k]

Can you remove their references, definitions, and replace them with origin and development?

Sorry about that, the changes were stashed locally while I was testing, and I mistakenly thought they had already been pushed when I replied.
The commit is now pushed with all references and definitions removed across the codebase. Ready for review whenever have time.

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[cursor]

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[cursor]

G_ list ages fail length check

Low Severity

Passing a Python list of ages to G_() now raises a length-mismatch error. The list is wrapped as a 2-D array, so len(age) is 1, while _G broadcasts values along the last axis. Assigning that array to development then fails the new _len_check against values.shape[3].

Additional Locations (1)

• chainladder/core/axis.py#L229-L232

 

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