Fix chart interpolation for rows mixing real sensors with flex-config constants

[sankalpsthakur]

Description

• Fix create_line_layer in flexmeasures/data/models/charts/belief_charts.py so that a chart row's interpolation mode (linear vs step-after) is decided only by the real sensors in that row, not by fixed-value/constant sensors sourced from flex-model / flex-context (e.g. soc-min, soc-max, capacities). Fixed-value sensors always report event_resolution == timedelta(0) by construction (they're synthetic, not backed by timed data), so a row mixing a real, non-instantaneous sensor with any such constant was incorrectly forced to linear interpolation instead of the correct step-after.
• Added changelog item in documentation/changelog.rst

Look & Feel

Before/after illustrations were supplied using representative values and the generated interpolation setting. They are illustrative renders, not screenshots of a seeded deployment.

How to test

Run the two new tests in flexmeasures/data/tests/test_belief_charts.py:

pytest flexmeasures/data/tests/test_belief_charts.py -k "test_mixed_row_with_fixed_value_sensor_keeps_step_after or test_real_instantaneous_sensor_still_uses_linear" -q

• test_mixed_row_with_fixed_value_sensor_keeps_step_after is the regression case: a real 15-min-resolution sensor sharing a row with a soc-min fixed-value constant must produce step-after. Fails on main (asserts linear == step-after → AssertionError), passes with this fix.
• test_real_instantaneous_sensor_still_uses_linear is a guard case proving a real instantaneous sensor alone still correctly gets linear.

Full chart-module check: pytest flexmeasures/data/tests/test_belief_charts.py -q (33 passed locally on the current merge). The wider local suite stopped after 130 passes when disk space ran out; a complete local suite pass is unverified.

Further Improvements

No further changes proposed here.

Related Items

Fixes #2253

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AI/LLM disclosure

• Claude Code assisted with the original change. Codex assisted with the conflict resolution, validation and this description update.

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Sign-off

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #34521892 | 📁 Comparing bcf0b79 against latest (5bac1ab)

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140 files changed · + 21 added · ± 119 modified

+ Added

• _autodoc/COUPLING.html
• _autodoc/COUPLING_COEFFICIENT.html
• _autodoc/INFLEXIBLE_CONSUMPTION.html
• _autodoc/INFLEXIBLE_PRODUCTION.html
• _autodoc/OPERATION_MODES.html
• _autosummary/flexmeasures.api.common.rate_limiting.html
• _autosummary/flexmeasures.api.v3_0.utils.html
• _autosummary/flexmeasures.data.models.automations.html
• _autosummary/flexmeasures.data.models.planning.highspy_optimization.html
• _autosummary/flexmeasures.data.models.planning.scheduling_problem.html
• and 11 more...

± Modified

• changelog.html
• configuration.html
• genindex.html
• getting-started.html
• http-routingtable.html
• index.html
• py-modindex.html
• _autodoc/CONSUMPTION_CAPACITY.html
• _autodoc/GROUP.html
• _autodoc/INFLEXIBLE_DEVICE_SENSORS.html
• and 109 more...

[Ahmad-Wahid]

@sankalpsthakur could you share some screenshots after the fixes?

[sankalpsthakur]

attached before/after — rendered straight from create_line_layer's real mark.interpolate output (linear vs step-after) using the same setup as the regression test's battery_with_interval_sensor_and_soc_min fixture, with representative sample values standing in for a live sensor since standing up a seeded deployment wasn't practical here.

before (main): soc-min forces the whole row to linear

after (this PR): real 15-min sensor correctly keeps step-after