[DEPR] Deprecation warning for inplace=True

[henrydingliu]

Summary of Changes

Related GitHub Issue(s)

AI/LLM Usage

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---

Note

Low Risk
Documentation and type hints only; no change to conversion logic or inplace return behavior yet.

Overview
Documents an upcoming API alignment for Triangle.incr_to_cum and Triangle.cum_to_incr: when inplace=True, returning self is deprecated as of 0.11 and 2.0 is expected to return None (pandas-style inplace).

incr_to_cum also gets explicit typing (inplace: bool = False, return type Self) and imports Self from typing. Runtime behavior is unchanged—both methods still mutate and return self when inplace=True.

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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 (228 / 1456)

	Known	Ambiguous	Unknown	Total
Project (head)	228	108	1120	1456

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: 326
• Functions without default param: 0
• Classes without docstring: 8

Patch (exported symbols added or changed by this PR): 100.0% fully typed (1 / 1)

	Known	Ambiguous	Unknown	Total
Patch	1	0	0	1

Patch symbol details

Symbol	Status	Change
chainladder.core.triangle.Triangle.incr_to_cum	✅ known	changed (was ❌ unknown)

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.14%. Comparing base (d046ca3) to head (c070945).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1468   +/-   ##
=======================================
  Coverage   94.14%   94.14%           
=======================================
  Files          96       96           
  Lines        5843     5843           
  Branches      739      739           
=======================================
  Hits         5501     5501           
  Misses        221      221           
  Partials      121      121           

Flag	Coverage Δ
unittests	94.14% <100.00%> (ø)

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