Main merge release/26.02 3

[rgsl888prabhu]

For #825

Summary by CodeRabbit

• New Features

  • Added support for passing user data context through MIP solution callbacks.
  • Exposed solution bounds in incumbent solution callbacks and server API responses.
  • Enhanced MIP callback mechanisms to enable better integration with external solution providers.

• Improvements

  • Improved presolve variable mapping and solution recovery.
  • Better stream synchronization for GPU memory operations.

[coderabbitai]

Caution

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📝 Walkthrough

Walkthrough

Introduces MIP solution callbacks with user_data support, including C/C++ API extensions, atomic solution bound tracking, Papilo presolve integration via presolve_data_t, and corresponding Python/server updates affecting callback signatures, problem construction, and solver state management.

Changes

Cohort / File(s)	Summary
Build & CI Configuration ci/run_cuopt_*.sh, conda/recipes/libcuopt/recipe.yaml, cpp/src/mip/CMakeLists.txt	Updated copyright years, added -s flag to pytest invocations, and added presolve_data.cu to MIP_LP_NECESSARY_FILES build list.
C API Callbacks cpp/include/cuopt/linear_programming/cuopt_c.h, cpp/src/linear_programming/cuopt_c.cpp	Introduced new callback typedefs (cuOptMIPGetSolutionCallback, cuOptMIPSetSolutionCallback), public API functions for registering callbacks, and internal solver_settings_handle_t for callback lifetime management.
C++ Callback Infrastructure cpp/include/cuopt/linear_programming/utilities/internals.hpp, cpp/include/cuopt/linear_programming/utilities/callbacks_implems.hpp	Extended callback interface signatures to include solution_bound and user_data parameters; added user_data storage and accessors to base_solution_callback_t; updated callback implementations to handle additional parameters.
Solver Settings cpp/include/cuopt/linear_programming/.../solver_settings.hpp, cpp/src/.../solver_settings.cu, cpp/src/mip/solver_settings.cu	Updated set_mip_callback to accept user_data parameter; changed default mip_scaling from true to false; added user_data propagation to callback storage.
Solution Bound Tracking cpp/include/cuopt/linear_programming/mip/solver_stats.hpp, cpp/src/mip/solution/solution.cu, cpp/src/mip/solver_solution.cu	Converted solution_bound to std::atomic<f_t> with default/copy constructors, assignment operator, and explicit getter/setter methods using relaxed memory ordering.
Presolve Data Management cpp/src/mip/presolve/third_party_presolve.hpp, cpp/src/mip/presolve/third_party_presolve.cpp, cpp/src/mip/problem/presolve_data.cuh, cpp/src/mip/problem/presolve_data.cu	Introduced presolve_data_t class with pre/post-process assignment methods, Papilo integration, and variable mapping support; added accessors and mappings to third_party_presolve_result_t.
Problem Construction cpp/src/mip/problem/problem.cuh, cpp/src/mip/problem/problem.cu, cpp/src/mip/relaxed_lp/lp_state.cuh	Added new constructor overload accepting external raft::handle_t; delegated presolve operations to presolve_data; added setters for Papilo presolve data and uncrushing methods.
Solver Core Integration cpp/src/mip/solve.cu, cpp/src/mip/solver.cu, cpp/src/mip/solver_context.cuh	Integrated presolve result handling, added diversity_manager support for callbacks, implemented GET_SOLUTION callback invocation paths, added user-bound callback mechanism, and propagated diversity_manager through solver context.
Population & Diversity cpp/src/mip/diversity/population.cuh, cpp/src/mip/diversity/population.cu, cpp/src/mip/diversity/diversity_manager.cu	Added invoke_get_solution_callback helper, updated solution callback invocation logic to handle solution_bound and user_data, replaced direct assignment with setter for solution_bound.
Branch & Bound cpp/src/dual_simplex/branch_and_bound.hpp, cpp/src/dual_simplex/branch_and_bound.cpp	Added set_user_bound_callback and update_user_bound methods to propagate lower bound information via user callback during branch-and-bound execution.
Feasibility Methods cpp/src/mip/local_search/feasibility_pump.cu, cpp/src/mip/local_search/local_search.cu, cpp/src/mip/feasibility_jump/feasibility_jump.cu, cpp/src/mip/diversity/lns/rins.cu	Added diversity_manager preemption checks, updated problem initialization to use handle-based construction, and added periodic solution incorporation via diversity_manager.
C API Tests cpp/tests/linear_programming/c_api_tests/c_api_test.c, cpp/tests/linear_programming/c_api_tests/c_api_tests.cpp, cpp/tests/linear_programming/c_api_tests/c_api_tests.h	Introduced MIP callback testing framework with mip_callback_context_t, implemented test callbacks with user_data verification, and added test wrapper functions.
MIP Tests cpp/tests/mip/incumbent_callback_test.cu, cpp/tests/mip/mip_utils.cuh	Updated callback signatures to accept solution_bound and user_data; replaced device vectors with host vectors for callback data; added new test overloads for host-based solution verification.
Test Utilities cpp/tests/linear_programming/utilities/pdlp_test_utilities.cuh	Added new overload of test_objective_sanity accepting std::vector for host-side objective validation.
Python Bindings python/cuopt/cuopt/linear_programming/internals/internals.pyx, python/cuopt/cuopt/linear_programming/solver/solver.pxd, python/cuopt/cuopt/linear_programming/solver/solver_wrapper.pyx, python/cuopt/cuopt/linear_programming/solver_settings/solver_settings.py	Extended callback signatures in Cython; added PyCallback._user_data field with getter/setter; updated memory access to use ctypes; propagated user_data through MIP callback registration.
Python Tests python/cuopt/cuopt/tests/linear_programming/test_incumbent_callbacks.py, python/cuopt/cuopt/tests/linear_programming/test_python_API.py	Reworked callback tests to accept solution_bound and user_data; added parameterized test variants with/without set-solution callback; updated assertions and storage to reflect new callback signatures.
Server Data Models & Utilities python/cuopt_server/cuopt_server/utils/linear_programming/data_definition.py, python/cuopt_server/cuopt_server/utils/linear_programming/solver.py, python/cuopt_server/cuopt_server/utils/job_queue.py, python/cuopt_server/cuopt_server/utils/solver.py	Added bound field to IncumbentSolution; introduced CustomSetSolutionCallback; extended solve signatures with incumbent_set_solutions parameter; propagated bound through intermediate responses.
Server Web API python/cuopt_server/cuopt_server/webserver.py	Added incumbent_set_solutions query parameter to postrequest; updated incumbent solution response schema to include bound field; propagated flag through job constructors.
Server Tests python/cuopt_server/cuopt_server/tests/test_incumbents.py	Updated test helper to accept include_set_callback; expanded test problem to 3 variables; added assertions for bound field; created parameterized test entry points.
Client & Examples python/cuopt_self_hosted/cuopt_sh_client/cuopt_self_host_client.py, docs/cuopt/source/cuopt-python/.../incumbent_solutions_example.py, docs/cuopt/source/cuopt-server/.../incumbent_callback_example.py	Added post-polling incumbent fetch; updated example callbacks to receive and propagate solution_bound and user_data; modified callback function signatures and documentation.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

• Add C api callbacks for getting and setting solutions #779: Implements complementary MIP callback surface and C API callback wrapping with nearly identical callback registration and user_data propagation patterns across C/C++ layers.

Suggested labels

breaking, improvement, mip

Suggested reviewers

• gforsyth
• nguidotti

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