fix(routing): penalize missing required breaks in route cost

[np96]

Description

Routes that miss a required break were reported as feasible (status=0) because the per-dimension break cost max(0, breaks - num_breaks) only penalizes excess. After eject_until_feasible removes break nodes, the dimension reports zero infeasibility and the solver returns the break-less route as success.

Fix: in route_t::view_t::compute_cost, after the per-dim loop, count breaks whose break_latest <= route_arrival_at_depot and add max(0, required - breaks_present) to the BREAK infeasibility cost. Routes missing a required break now correctly report status=1 (INFEASIBLE).

Issue

#1195 — problem A

Checklist

• I am familiar with the Contributing Guidelines.
• Testing
  • New or existing tests cover these changes
  • Added tests
• Documentation
  • NA

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: a0821d04-db4c-433f-b7f6-1c3da3e8fb71

📥 Commits

Reviewing files that changed from the base of the PR and between a146585 and 49831a5.

📒 Files selected for processing (2)

• cpp/src/routing/route/route.cuh
• python/cuopt/cuopt/tests/routing/test_vehicle_properties.py

🚧 Files skipped from review as they are similar to previous changes (1)

• python/cuopt/cuopt/tests/routing/test_vehicle_properties.py

---

📝 Walkthrough

Walkthrough

This PR adds logic in route cost computation to penalize missing required breaks when both BREAK and TIME dimensions are enabled, and adds a unit test that asserts a routing instance with an unreachable required break is infeasible.

Changes

Required Break Infeasibility Penalty

Layer / File(s)	Summary
Break Cost Penalty Logic cpp/src/routing/route/route.cuh	When both BREAK and TIME dimensions are active, compute_cost estimates depot arrival, counts required breaks whose break_latest ≤ arrival, reads route-present breaks (breaks_forward[*n_nodes]), and adds positive shortfall to infeasibility_cost[0][dim_t::BREAK].
Test Validation python/cuopt/cuopt/tests/routing/test_vehicle_properties.py	Adds test_required_break_unreachable_is_infeasible, which builds a 3-node scenario with a required break in an infeasible time window, solves, and asserts the solver returns infeasible status.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	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 accurately summarizes the main change: adding a penalty for missing required breaks in route cost computation.
Description check	✅ Passed	The description is directly related to the changeset, explaining the bug, the fix, and referencing issue #1195 with test coverage details.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}