Please ignore this PR until reviewed by @ChrisRackauckas.

Summary

• restore the OrdinaryDiffEqDifferentiation SciMLOperators floor from 1.24.3 to 1.24.4 and bump the package from 3.4.0 to 3.4.1
• replace the obsolete InterfaceIII assertion that depended on WOperator._concrete_form with public behavioral checks
• verify that calc_W! does not invoke an operator Jacobian's update callback, while public concretization and factorization produce the current W matrix
• add SciMLOperators as a direct root test dependency so the test imports MatrixOperator from its owning package

Root cause

SciMLOperators commit d1f46ec / v1.24.4 intentionally changed in-place WOperator concretization for operator-typed Jacobians. No OrdinaryDiffEq caller maintains the internal concrete form for that case, so v1.24.3 returned the stale matrix constructed at gamma = 0; concrete linear solvers could consequently factorize an Inf matrix and silently compute incorrect implicit solutions. V1.24.4 reconstructs the public matrix representation at the current gamma.

The OrdinaryDiffEq companion commit 28e7eb52 originally required SciMLOperators 1.24.4, but the later downgrade-floor change 6b10b916 lowered the constraint to 1.24.3. The old InterfaceIII test also encoded the obsolete behavior and accessed the dependency's private _concrete_form field.

This is independent of LinearSolve 5. Untouched master reproduced with LinearSolve 4.3.0 and SciMLOperators 1.24.4.

Introducing-commit check

The same WOperator probe was run against the introducing commit and its direct parent:

57a69ab (SciMLOperators 1.24.3, parent of d1f46ec)
observed=[-Inf 0.0; 0.0 -Inf]
expected=[-3.0 0.0; 0.0 -2.0]
current=false
finite=false

d1f46ec (SciMLOperators 1.24.4)
observed=[-3.0 0.0; 0.0 -2.0]
expected=[-3.0 0.0; 0.0 -2.0]
current=true
finite=true

Validation

Untouched master at 8fc48e69d5:

GROUP=InterfaceIII julia +1.12 --project=. -e 'using Pkg; Pkg.test()'
LinearSolve v4.3.0
SciMLOperators v1.24.4
Derivative Utilities Tests: 10 passed, 2 failed

Both failures were the stale convert(AbstractMatrix, W) != concrete_W and stale-solve assertions.

This branch:

GROUP=InterfaceIII julia +1.12 --project=. -e 'using Pkg; Pkg.test()'
Derivative Utilities Tests: 11/11 passed
stats Tests: 14/14 passed
No Index Tests: 24/24 passed
Events + DAE addsteps Tests: 5/5 passed
Units Tests: 52 passed, 4 pre-existing broken
DEVerbosity Tests: 142/142 passed
Testing OrdinaryDiffEq tests passed

Whole-repository formatting:

julia +1.12 -e 'using Runic; exit(Runic.main(["--inplace", "."]))'
julia +1.12 -e 'using Runic; exit(Runic.main(["--check", "."]))'

Both Runic commands exited successfully.