cuopt_mcp: add cuopt_solve_vrp / cuopt_vrp_result (VRP/PDP support)

[ramakrishnap-nv]

Closes #1939. Stacked on #1819 (base is feat/cuopt-mcp-server, not main) so the diff here is only the VRP work.

Adds cuopt_solve_vrp / cuopt_vrp_result, covering every setter in routing.DataModel's deferred-build surface (cost/transit-time matrices, vehicle and order time windows, capacity dimensions, pickup-delivery pairs, uniform and per-vehicle breaks, vehicle/order matching, precedence, multi-objective, initial solutions) — not just a core subset.

• problem is plain JSON arrays mirroring RoutingProblem in cuopt_routing.proto field for field. Every array-like value is converted to numpy before reaching a setter: validate_matrix/validate_time_windows reject plain Python lists, unlike the gRPC serialization layer underneath.
• cuopt_status/cuopt_cancel/cuopt_delete are reused as-is for VRP job_ids — LP/MIP/VRP jobs share one server-side registry (confirmed against grpc_job_management.cpp), so these were already category-agnostic. Only submit and result needed new tools.
• Result shaping caps inline stops the same way cuopt_result caps variables, writing the full route table to a file past the limit.
• A submitted model never touches the GPU on this host — routing.DataModel records setter calls and only builds the device model on an actual local solve, which this path never does.

Testing

101 tests pass locally: unit suite (stubbed client, no GPU — including a full-feature-set model exercising every mapped setter, cross-checked via problem_summary()) plus the live end-to-end suite. Verified end to end against a real cuopt_grpc_server: single/multi-vehicle routing, capacity dimensions, time windows, and multi-objective weighting all produced correct optimal solutions.

Known gaps

• No cuopt_list_settings coverage for VRP — its settings surface (time_limit/verbose_mode/error_logging) isn't in the codegen registry the LP/MILP catalogue is generated from, and is small enough to just document in cuopt_solve_vrp's docstring.
• Same CUDA/packaging gaps as cuopt_mcp: add cuopt_health, package it like the other Python modules #1819/cuopt_mcp: add an MCP server for LP/MILP solving over gRPC #1916 (Package libcuopt_client separately so the gRPC client installs without CUDA #1872).

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📝 Walkthrough

Walkthrough

Changes

The MCP server adds VRP model construction, asynchronous routing submission, result retrieval, shared job lifecycle support, route-file cleanup, documentation, and GPU-independent tests.

VRP support

Layer / File(s)	Summary
Routing model construction python/cuopt_mcp/cuopt_mcp/routing.py, python/cuopt_mcp/tests/test_routing.py	Validates VRP JSON input and maps costs, vehicles, orders, constraints, objectives, breaks, and initial solutions into a routing model.
Routing client and job results python/cuopt_mcp/cuopt_mcp/client.py, python/cuopt_mcp/cuopt_mcp/routing.py, python/cuopt_mcp/tests/test_routing.py	Adds cached routing-client access, asynchronous submission, status handling, route shaping, output limits, and full-route sidecar files.
Server tools and lifecycle integration python/cuopt_mcp/cuopt_mcp/server.py, python/cuopt_mcp/cuopt_mcp/tools.py	Adds VRP submission and result tools and extends status, cancellation, deletion, and artifact cleanup documentation and behavior.
VRP tool documentation python/cuopt_mcp/README.md	Documents VRP tools, limited VRP settings, and remote serialization of routing data models.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Feature

Merge Risk: 🔵 Low · up to 5269c

The VRP feature is mergeable with small fixes to input diagnostics, test gating, and settings documentation.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 37.21% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 43 functions across 5 files. (1 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the two new VRP/PDP tools and accurately summarizes the main change.
Description check	✅ Passed	The description is directly related to the changeset and explains the new VRP tools, supported routing features, result handling, testing, and known gaps.
Linked Issues check	✅ Passed	The PR satisfies the coding objectives in [#1939]. routing.py maps structured JSON to routing.DataModel setters for fleet data, matrices, time windows, capacities, pickup-delivery pairs, breaks, m…
Out of Scope Changes check	✅ Passed	The changed files support the [#1939] VRP objective. They add the routing client lifecycle, JSON model construction, VRP submission and result tools, shared job cleanup, documentation, and automated t…

Full details: Docstring Coverage

Explanation

Docstring coverage is 37.21% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 43 functions across 5 files. (1 skipped: 1 unsupported.)

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Inline comments:
In `@python/cuopt_mcp/cuopt_mcp/routing.py`:
- Around line 136-144: Wrap the routing model mapping performed by
_build_routing_model_from_json so nested KeyError exceptions are caught and
converted into CuOptMCPError messages naming the missing key, while preserving
the existing ValueError behavior for shape validation. Move the current mapping
body into a helper such as _map_problem_to_model and have the public builder
translate only KeyError failures into the user-actionable error format.

In `@python/cuopt_mcp/README.md`:
- Around line 160-161: Update the parameter documentation for cuopt_solve_vrp to
list both accepted spellings, verbose_mode and verbose, while preserving the
existing descriptions and behavior for the other options.

In `@python/cuopt_mcp/tests/test_routing.py`:
- Around line 17-20: Replace the module-level cuopt.routing import skip with a
pytest fixture named cuopt_routing that calls pytest.importorskip. Add this
fixture parameter to every test_build_model_* test and
test_submit_passes_settings_through, while leaving the result tests unguarded so
they can run with the fake client.

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📒 Files selected for processing (6)

• python/cuopt_mcp/README.md
• python/cuopt_mcp/cuopt_mcp/client.py
• python/cuopt_mcp/cuopt_mcp/routing.py
• python/cuopt_mcp/cuopt_mcp/server.py
• python/cuopt_mcp/cuopt_mcp/tools.py
• python/cuopt_mcp/tests/test_routing.py

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