fix: bb outages

[BenjPetr]

Checklist

Please check if the PR fulfills these requirements:

• PR Title follows conventional commit messages
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• All commits in this PR are DCO signed-off (see CONTRIBUTING.md)

Does this PR already have an issue describing the problem?

Fixes busbar outages:

• order issue
• list(set()) deduplication issue
• flow still on line for outaged stub -> now zero

What is the new behavior (if this is a feature change)?

Does this PR introduce a breaking change?

• Yes
• No

[Copilot]

Pull request overview

This PR fixes incorrect busbar outage handling across preprocessing and the JAX outage execution path, addressing case ordering/deduplication and ensuring physically disconnected stub subtrees yield zero monitored flow instead of residual flow. It also adds regression grids and tests to prevent reintroducing these issues.

Changes:

• Extend busbar-outage preprocessing to preserve branch order during deduplication and to track “zero-flow” branches for bridge-fed stub subtrees.
• Propagate the new busbar-outage metadata through NetworkData → convert_to_jax → HDF5 persistence → JAX outage execution, including filtering padded/always-articulation busbar slots.
• Add a dedicated node-breaker regression grid plus end-to-end tests validating DC solver results against reference loadflows for busbar contingencies.

Reviewed changes

Copilot reviewed 19 out of 20 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/interfaces_pkg/src/toop_engine_interfaces/loadflow_result_helpers_polars.py	Fix empty-return arrays to be well-formed and filled with NaN instead of relying on invalid np.full usage.
packages/importer_pkg/src/toop_engine_importer/network_graph/powsybl_station_to_graph.py	Adjust connected-component in-service mask evaluation for branches/injections.
packages/grid_helpers_pkg/tests/powsybl/test_powsybl_example_grids.py	Add convergence test for the new always-articulation busbar outage regression grid.
packages/grid_helpers_pkg/src/toop_engine_grid_helpers/powsybl/example_grids.py	Introduce create_busbar_outage_always_articulation_grid() regression grid builder.
packages/dc_solver_pkg/tests/test_example_grids.py	Add preprocessing-path test coverage for the new regression grid.
packages/dc_solver_pkg/tests/preprocessing/test_preprocess_bb_outage.py	Update tests for new return values (zero-flow branches) + add ordering and stub-compensation regression tests.
packages/dc_solver_pkg/tests/preprocessing/test_convert_to_jax.py	Assert correct N-1 case counting and persistence of new rel-busbar validity metadata.
packages/dc_solver_pkg/tests/postprocessing/test_postprocess_powsybl.py	Add reference-matching tests comparing solver busbar-outage results to Powsybl DC loadflow per contingency.
packages/dc_solver_pkg/tests/jax/test_busbar_outage.py	Add unit tests for padded-slot filtering and extend dummy rel-bb outage data with new fields.
packages/dc_solver_pkg/tests/conftest.py	Add fixtures to generate/copy the new regression grid preprocessing folder for tests.
packages/dc_solver_pkg/src/toop_engine_dc_solver/preprocess/preprocess_bb_outage.py	Refactor busbar-outage extraction: stable deduplication, connected-busbar propagation logic, and “zero-flow branch” tracking.
packages/dc_solver_pkg/src/toop_engine_dc_solver/preprocess/network_data.py	Extend OutageData/NetworkData with *_zero_flow_br_indices fields for busbar outages.
packages/dc_solver_pkg/src/toop_engine_dc_solver/preprocess/convert_to_jax.py	Convert/pad new outage metadata for JAX, compute valid busbar masks/flat indices, and carry zero-flow branch sets.
packages/dc_solver_pkg/src/toop_engine_dc_solver/jax/types.py	Add new RelBBOutageData / NonRelBBOutageData fields and update outage counts to use valid busbar indices.
packages/dc_solver_pkg/src/toop_engine_dc_solver/jax/inputs.py	Persist/load new busbar-outage datasets in HDF5 with backward-compatible defaults.
packages/dc_solver_pkg/src/toop_engine_dc_solver/jax/busbar_outage.py	Apply zero-flow forcing post-outage, improve retry outage selection, and filter valid busbar slots in rel-bb execution.
packages/dc_solver_pkg/src/toop_engine_dc_solver/jax/branch_action_set.py	Merge new rel-bb outage fields when combining action sets.
packages/dc_solver_pkg/src/toop_engine_dc_solver/example_grids.py	Provide a preprocessing-folder generator for the new always-articulation regression grid.
notebooks/example3_e2e_pipeline.ipynb	Update notebook pipeline configuration and optionally generate demo grids from helpers.
.gitignore	Ignore new notebook demo data folder.

[sonarqube-mccs]

Quality Gate passed

Issues
5 New issues
1 Fixed issue
0 Accepted issues

Measures
0 Security Hotspots
95.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[LeonHilf]

lgtm