[Rafael-SOWNet]

The power rule wrote a constant exponent as its evaluated value, so an exponent that is not rational became a decimal: x^pi differentiated to 3.14159... * x^2.14159.... l'Hôpital's rule then answered limits whose value is pi with a hundred-digit decimal, and limits that needed the decimal read as pi again were left unevaluated.

The value is kept where it is rational, and the exponent is written as it is otherwise.

Input	2.6.0 and master	This PR
x^pi differentiated	3.14159... * x ^ 2.14159...	pi * x ^ (pi - 1)
(x^pi - 1) / (x - 1) at 1	3.14159...	pi
(x^sqrt(2) - 1) / ln(x) at 1	1.41421...	sqrt(2)
(x^ln(2) - 1) / (x - 1) at 1	0.69314...	ln(2)
x^pi / log(x, 2) - 2 at 0 from the right	unevaluated	-2
x^(abs(x)^arctan(2)) at 0 from each side	unevaluated	1

x^(abs(x)^arctan(2)) at 0 from the left is 1: the exponent t tends to 0 and t ln(x) = t (ln|x| + i pi) tends to 0. Two-sided it stays NaN on every build, which is the convention for a complex branch on one side and is not changed here.

x^pi / log(x, 2) - 2 now answers, but takes about 12 s, because l'Hôpital's rule differentiates that quotient about ten times. That is a separate defect.

The new ADerivativeKeepsAnIrrationalExponentExactTest fails on master in 7 of its 8 rows; the eighth pins a rational exponent, which is unchanged. Entry in BREAKING-CHANGES.md.

Measured

• Suite, wrappers, AOT and the harnesses are green; canoncheck and confluence match their baselines.
• limitcheck at DEPTH=3, across 42 seeds against master: only the x^(abs(x)^arctan(2)) rows move, from unevaluated to 1.

Found by limitcheck; no issue was filed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.79%. Comparing base (5f620b1) to head (c723a6d).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2393      +/-   ##
==========================================
- Coverage   86.80%   86.79%   -0.02%     
==========================================
  Files         312      312              
  Lines       69223    69224       +1     
  Branches    20186    20186              
==========================================
- Hits        60090    60083       -7     
- Misses       4917     4925       +8     
  Partials     4216     4216              

Flag	Coverage Δ
cpp	37.77% <ø> (ø)
csharp	87.33% <100.00%> (-0.02%)	⬇️
fsharp	32.97% <ø> (ø)
interactive	40.72% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ngouriMath/Functions/Continuous/Differentiation.cs	89.57% <100.00%> (+0.06%)	⬆️

... and 5 files with indirect coverage changes

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