cuopt service correct definition for status value in lp result spec (#671)

The openapi spec for the status value in lp/mip results says "int" but it is actually a string.  This change corrects that.

Unfortunately, the enums defining the values cannot be directly imported because the import causes early cuda initialization which leads to rmm errors.

So, this change uses local copies and then adds a unit test to make sure they don't drift.



## Summary by CodeRabbit

## Release Notes

* **New Features**
  * Termination status values in API responses are now human-readable strings (e.g., "Optimal", "Infeasible") instead of numeric codes.
  * Added validation to ensure termination status values are valid.

* **Tests**
  * Added verification test for termination status enumerations synchronization.

<sub>✏️ Tip: You can customize this high-level summary in your review settings.</sub>

Authors:
  - Trevor McKay (https://github.com/tmckayus)

Approvers:
  - Ramakrishnap (https://github.com/rgsl888prabhu)

URL: #671

Author: tmckayus

python/cuopt_server/cuopt_server/tests/test_lp.py

@@ -211,3 +211,31 @@ def test_barrier_solver_options(
         res.json()["response"]["solver_response"],
         LPTerminationStatus.Optimal.name,
     )
+
+
+def test_termination_status_enum_sync():
+    """
+    Ensure local status values in data_definition.py stay in sync
+    with actual LPTerminationStatus and MILPTerminationStatus enums.
+
+    The data_definition module cannot import these enums directly
+    because it triggers CUDA/RMM initialization before the server
+    has configured memory management. So we maintain local copies
+    and this test ensures they stay in sync.
+    """
+    from cuopt_server.utils.linear_programming.data_definition import (
+        LP_STATUS_NAMES,
+        MILP_STATUS_NAMES,
+    )
+
+    expected_lp = {e.name for e in LPTerminationStatus}
+    expected_milp = {e.name for e in MILPTerminationStatus}
+
+    assert LP_STATUS_NAMES == expected_lp, (
+        f"LP_STATUS_NAMES out of sync with LPTerminationStatus enum. "
+        f"Expected: {expected_lp}, Got: {LP_STATUS_NAMES}"
+    )
+    assert MILP_STATUS_NAMES == expected_milp, (
+        f"MILP_STATUS_NAMES out of sync with MILPTerminationStatus enum. "
+        f"Expected: {expected_milp}, Got: {MILP_STATUS_NAMES}"
+    )

python/cuopt_server/cuopt_server/utils/linear_programming/data_definition.py

@@ -810,27 +810,77 @@ class SolutionData(StrictModel):
     )
 
 
+# LP termination status values
+# NOTE: These must match LPTerminationStatus from
+# cuopt.linear_programming.solver.solver_wrapper
+# We cannot import them directly because it triggers CUDA/RMM initialization
+# before the server has configured memory management.
+# See test_termination_status_enum_sync() in test_lp.py to ensure these stay in sync.
+LP_STATUS_NAMES = frozenset(
+    {
+        "NoTermination",
+        "NumericalError",
+        "Optimal",
+        "PrimalInfeasible",
+        "DualInfeasible",
+        "IterationLimit",
+        "TimeLimit",
+        "PrimalFeasible",
+    }
+)
+
+# MILP termination status values
+# NOTE: These must match MILPTerminationStatus from
+# cuopt.linear_programming.solver.solver_wrapper
+MILP_STATUS_NAMES = frozenset(
+    {
+        "NoTermination",
+        "Optimal",
+        "FeasibleFound",
+        "Infeasible",
+        "Unbounded",
+        "TimeLimit",
+    }
+)
+
+# Combined set of all valid status names
+ALL_STATUS_NAMES = LP_STATUS_NAMES | MILP_STATUS_NAMES
+
+
+def validate_termination_status(v):
+    """Validate that status is a valid LP or MILP termination status name."""
+    if v not in ALL_STATUS_NAMES:
+        raise ValueError(
+            f"status must be one of {sorted(ALL_STATUS_NAMES)}, got '{v}'"
+        )
+    return v
+
+
 class SolutionResultData(StrictModel):
-    status: int = Field(
-        default=0,
-        examples=[1],
-        description=(
-            "In case of LP : \n\n"
-            "0 - No Termination \n\n"
-            "1 - Optimal solution is available \n\n"
-            "2 - Primal Infeasible solution \n\n"
-            "3 - Dual Infeasible solution \n\n"
-            "4 - Iteration Limit reached \n\n"
-            "5 - TimeLimit reached \n\n"
-            "6 - Primal Feasible \n\n"
-            "---------------------- \n\n"
-            "In case of MILP/IP : \n\n"
-            "0 - No Termination \n\n"
-            "1 - Optimal solution is available \n\n"
-            "2 - Feasible solution is available \n\n"
-            "3 - Infeasible \n\n"
-            "4 - Unbounded\n\n"
-        ),
+    status: Annotated[str, PlainValidator(validate_termination_status)] = (
+        Field(
+            default="NoTermination",
+            examples=["Optimal"],
+            description=(
+                "In case of LP : \n\n"
+                "NoTermination - No Termination \n\n"
+                "NumericalError - Numerical Error \n\n"
+                "Optimal - Optimal solution is available \n\n"
+                "PrimalInfeasible - Primal Infeasible solution \n\n"
+                "DualInfeasible - Dual Infeasible solution \n\n"
+                "IterationLimit - Iteration Limit reached \n\n"
+                "TimeLimit - TimeLimit reached \n\n"
+                "PrimalFeasible - Primal Feasible \n\n"
+                "---------------------- \n\n"
+                "In case of MILP/IP : \n\n"
+                "NoTermination - No Termination \n\n"
+                "Optimal - Optimal solution is available \n\n"
+                "FeasibleFound - Feasible solution is available \n\n"
+                "Infeasible - Infeasible \n\n"
+                "Unbounded - Unbounded \n\n"
+                "TimeLimit - TimeLimit reached \n\n"
+            ),
+        )
     )
     solution: SolutionData = Field(
         default=SolutionData(), description=("Solution of the LP problem")
@@ -896,7 +946,7 @@ class IncumbentSolution(StrictModel):
     "value": {
         "response": {
             "solver_response": {
-                "status": 1,
+                "status": "Optimal",
                 "solution": {
                     "problem_category": 0,
                     "primal_solution": [0.0, 0.0],
@@ -925,7 +975,7 @@ class IncumbentSolution(StrictModel):
     "value": {
         "response": {
             "solver_response": {
-                "status": 2,
+                "status": "FeasibleFound",
                 "solution": {
                     "problem_category": 1,
                     "primal_solution": [0.0, 0.0],
@@ -956,7 +1006,7 @@ class IncumbentSolution(StrictModel):
     "value": {
         "response": {
             "solver_response": {
-                "status": 2,
+                "status": "FeasibleFound",
                 "solution": {
                     "problem_category": 1,
                     "primal_solution": [0.0, 0.0],