Fix sensor output for disconnected measured components

[appleweiping]

Summary

• Return null sensor output when a measured source, shunt, load, or generator is disabled, or when the measured terminal of a branch or branch3 is disconnected.
• Preserve the topology-group check for grids that are not connected to a source, and apply the same terminal-status semantics to power and current sensors.
• Preserve reduced main-core component-container compatibility with compile-time guards for component types that a container omits.
• Re-enable the existing symmetric/asymmetric batch regression cases, add focused C++ coverage, and document how sensor-output energized is derived at the measured terminal.

Root cause

Sensor output only checked whether the measured object had a connected mathematical topology group. Status-only updates for shunts, loads, and generators do not rebuild that topology, so a disabled appliance could still produce energized == 1 and non-zero residuals. A partially disconnected branch or branch3 also retains a mathematical group through its connected terminals, so the group alone does not describe whether the terminal measured by a sensor is connected.

The output path now keeps the topology check and additionally reads the actual status of the measured appliance or measured branch terminal. Power and current sensors share the same terminal-status mapping.

Because the measured terminal is selected at runtime, all lookup branches are instantiated at compile time. Compile-time type guards preserve support for reduced component containers that omit unused measured-object types.

Validation

• uv run --frozen pytest — 1778 passed, 4 skipped, 13 xfailed; 97.13% coverage, using the newly built C++ core.
• Release power_grid_model_c build — passed, including production model.cpp template instantiation and DLL linking.
• Focused C++ main-core build and CTest selection — 9/9 passed, including symmetric/asymmetric power and current sensor cases.
• The two affected dataset fixture families — 9/9 passed.
• uv run --frozen ruff check ., uv run --frozen reuse lint, clang-format dry-run, and git diff --check — passed.
• The old behavior returns energized output for a sensor on a disconnected terminal of a partially connected branch/branch3; the new regression cases require null output with zero residuals.

The temporary Python migration reference was removed after the maintainer resolved the C++ test-migration thread.

No public API, schema, or generated file is changed.

Closes #1464

Assisted-by: OpenAI Codex

[Copilot]

Pull request overview

This PR fixes state-estimation power-sensor outputs so that sensors measuring disabled appliances (source, shunt, load, generator) return a null output (energized = 0 and zero residuals), while preserving topology-governed energized semantics for branch/branch3 power sensors and leaving current-sensor behavior unchanged.

Changes:

• Update main-core power-sensor output logic to additionally gate energized output on the measured appliance’s status() (for appliance terminal types).
• Re-enable previously xfailed regression datasets by updating expected outputs to reflect null residuals when measured appliances are disabled.
• Add C++ unit tests for energized/null-output behavior across appliance-vs-branch topology semantics and document the energized derivation in the user manual.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/data/state_estimation/dummy-test-line-into-itself/params.json	Removes xfail now that appliance-disabled behavior is fixed.
tests/data/state_estimation/dummy-test-line-into-itself/asym_output_batch.json	Updates expected residuals to zeros for null (energized=0) outputs.
tests/data/state_estimation/dummy-test-line-into-itself-minimal/sym_output_batch.json	Updates expected null-output residuals to zero for disabled measured appliance.
tests/data/state_estimation/dummy-test-line-into-itself-minimal/params.json	Removes xfail now that appliance-disabled behavior is fixed.
tests/cpp_unit_tests/main_core/test_main_core_output.cpp	Adds focused unit tests for power/current sensor energized semantics.
power_grid_model_c/power_grid_model/include/power_grid_model/main_core/output.hpp	Implements measured-object status gating for appliance-measured power sensors.
docs/user_manual/components.md	Documents how energized is derived and that null outputs have zero residuals.

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[mgovers]

Hi @appleweiping, Something seems to have gone wrong with the base branch. I had to change the base branch due to some blocking things in the root, but the base branch was not automatically updated. Can you please re-open the PR and point the base branch to PowerGridModel:main?

[nitbharambe]

I see this PR got closed because underlying branch was deleted. That branch and PR is now merged.
@appleweiping would you please create a new PR where we can continue with the contribution?

[nitbharambe]

Nevermind, resolved! We will continue with review here.

[mgovers]

Hi @appleweiping,

It looks like compilation is failing for MSVC and clang-tidy for unreachable code and misc-include-cleaner reasons, respectively. If you need any help, please let us know and we'll have a look.

[TonyXiang8787]

Hi @appleweiping,

Thank you again for your contribution. The PR is in good shape and will be added to the merge queue if CI succeeds.

[TonyXiang8787]

Hi @appleweiping,

The code is now breaking due to another change in #1546 causing the code not compatible anymore. Please have a look and adjust accordingly.

[appleweiping]

Thanks, Tony. I adapted the current-sensor output test state to the Edge topology base introduced by #1546 in commit 91cc2ff, while retaining Branch because the sensor object sequence is still branch-relative.

I verified the change against a fresh snapshot of the merged head with GCC 14 / C++23: the main-core target builds and all 9 test cases (266 assertions) pass. clang-format --dry-run --Werror also passes. The full CI has been triggered again.