diff --git a/tests/test_time_semantic_characterization.py b/tests/test_time_semantic_characterization.py
new file mode 100644
index 00000000..49d96369
--- /dev/null
+++ b/tests/test_time_semantic_characterization.py
@@ -0,0 +1,368 @@
+import numpy as np
+import polars as pl
+import pytest
+
+import rtichoke.performance_table as performance_table_module
+from rtichoke import (
+    create_calibration_curve_times,
+    create_decision_curve_times,
+    create_gains_curve_times,
+    create_lift_curve_times,
+    create_precision_recall_curve_times,
+    create_roc_curve_times,
+    prepare_performance_data_times,
+)
+from rtichoke.processing.plotly_helper_functions import (
+    _check_if_multiple_populations_are_being_validated_times,
+)
+from rtichoke.processing.time_reference_lines import _replace_reference_data_times
+
+HORIZONS = [5.0, 10.0]
+HEURISTICS = [
+    {
+        "censoring_heuristic": "adjusted",
+        "competing_heuristic": "adjusted_as_negative",
+    }
+]
+COLORS = ["#111111", "#222222"]
+
+PROBS_A = np.array([0.05, 0.15, 0.35, 0.55, 0.75, 0.95])
+PROBS_B = np.array([0.10, 0.25, 0.45, 0.65, 0.80, 0.90])
+REALS_SHARED = np.array([1, 0, 1, 0, 1, 0])
+TIMES_SHARED = np.array([3.0, 12.0, 8.0, 13.0, 14.0, 15.0])
+
+
+def _performance(probs, reals, times):
+    return prepare_performance_data_times(
+        probs=probs,
+        reals=reals,
+        times=times,
+        fixed_time_horizons=HORIZONS,
+        heuristics_sets=HEURISTICS,
+        by=0.25,
+    )
+
+
+def _series_keys(performance_data):
+    return set(
+        performance_data.select("reference_group", "fixed_time_horizon")
+        .unique()
+        .iter_rows()
+    )
+
+
+def _references(performance_data, curve):
+    curve_list = {
+        "fixed_time_horizons": HORIZONS,
+        "reference_data": pl.DataFrame(),
+    }
+    return _replace_reference_data_times(
+        curve_list,
+        performance_data,
+        curve=curve,
+        min_p_threshold=0.1,
+        max_p_threshold=0.9,
+    )["reference_data"]
+
+
+def _reference_names_by_horizon(reference_data):
+    return {
+        horizon: set(
+            reference_data.filter(pl.col("fixed_time_horizon") == horizon)[
+                "reference_group"
+            ].unique()
+        )
+        for horizon in HORIZONS
+    }
+
+
+def _shared_reference_names():
+    return {
+        "roc": {"random_guess"},
+        "precision recall": {"random_guess"},
+        "gains": {"random_guess", "perfect_model"},
+        "lift": {"random_guess", "perfect_model"},
+        "decision": {"treat_none", "treat_all"},
+        "interventions avoided": {"treat_all", "treat_none"},
+    }
+
+
+def _population_reference_names(populations):
+    return {
+        "roc": {"random_guess"},
+        "precision recall": {
+            f"random_guess_{population}" for population in populations
+        },
+        "gains": {"random_guess"}
+        | {f"perfect_model_{population}" for population in populations},
+        "lift": {"random_guess"}
+        | {f"perfect_model_{population}" for population in populations},
+        "decision": {"treat_none"}
+        | {f"treat_all_{population}" for population in populations},
+        "interventions avoided": {"treat_all"}
+        | {f"treat_none_{population}" for population in populations},
+    }
+
+
+def test_one_model_one_population_is_one_series_per_horizon():
+    performance_data = _performance({"model": PROBS_A}, REALS_SHARED, TIMES_SHARED)
+
+    assert _series_keys(performance_data) == {
+        ("model", 5.0),
+        ("model", 10.0),
+    }
+
+
+@pytest.mark.parametrize(
+    "creator",
+    [
+        create_roc_curve_times,
+        create_precision_recall_curve_times,
+        create_gains_curve_times,
+        create_lift_curve_times,
+        create_decision_curve_times,
+    ],
+)
+def test_multiple_models_keep_series_labels_colors_and_legends_across_horizons(
+    creator,
+):
+    fig = creator(
+        probs={"Model A": PROBS_A, "Model B": PROBS_B},
+        reals=REALS_SHARED,
+        times=TIMES_SHARED,
+        fixed_time_horizons=HORIZONS,
+        heuristics_sets=HEURISTICS,
+        by=0.25,
+        color_values=COLORS,
+    )
+
+    for model, color in zip(("Model A", "Model B"), COLORS):
+        series = [
+            trace
+            for trace in fig.data
+            if trace.name == model and trace.mode == "markers+lines"
+        ]
+        assert len(series) == len(HORIZONS)
+        assert {trace.line.color for trace in series} == {color}
+        assert all(trace.showlegend is True for trace in series)
+        assert sum(trace.visible is True for trace in series) == 1
+
+        cutoff_markers = [
+            trace for trace in fig.data if trace.name == f"{model} @ cutoff"
+        ]
+        assert len(cutoff_markers) == len(HORIZONS)
+        assert all(trace.showlegend is False for trace in cutoff_markers)
+
+
+def test_interventions_avoided_keeps_series_semantics_across_horizons():
+    fig = create_decision_curve_times(
+        probs={"Model A": PROBS_A, "Model B": PROBS_B},
+        reals=REALS_SHARED,
+        times=TIMES_SHARED,
+        fixed_time_horizons=HORIZONS,
+        heuristics_sets=HEURISTICS,
+        decision_type="interventions avoided",
+        by=0.25,
+        color_values=COLORS,
+    )
+
+    for model, color in zip(("Model A", "Model B"), COLORS):
+        series = [
+            trace
+            for trace in fig.data
+            if trace.name == model and trace.mode == "markers+lines"
+        ]
+        assert len(series) == len(HORIZONS)
+        assert {trace.line.color for trace in series} == {color}
+
+
+def test_multiple_models_share_reference_context_at_each_horizon():
+    performance_data = _performance(
+        {"Model A": PROBS_A, "Model B": PROBS_B},
+        REALS_SHARED,
+        TIMES_SHARED,
+    )
+
+    aj = (
+        performance_data.filter(pl.col("chosen_cutoff") == 0)
+        .select("reference_group", "fixed_time_horizon", "real_positives", "n")
+        .unique()
+        .with_columns((pl.col("real_positives") / pl.col("n")).alias("aj_estimate"))
+    )
+    assert not _check_if_multiple_populations_are_being_validated_times(aj)
+
+    for curve, names in _shared_reference_names().items():
+        assert _reference_names_by_horizon(_references(performance_data, curve)) == {
+            5.0: names,
+            10.0: names,
+        }
+
+
+def test_different_prevalence_populations_own_references_at_each_horizon():
+    populations = ("Population low", "Population high")
+    probs = {populations[0]: PROBS_A, populations[1]: PROBS_B}
+    reals = {
+        populations[0]: np.array([1, 0, 0, 0, 0, 0]),
+        populations[1]: np.array([1, 1, 1, 0, 0, 0]),
+    }
+    times = {
+        populations[0]: np.array([3.0, 12.0, 13.0, 14.0, 15.0, 16.0]),
+        populations[1]: np.array([2.0, 4.0, 9.0, 12.0, 13.0, 14.0]),
+    }
+    performance_data = _performance(probs, reals, times)
+
+    assert _series_keys(performance_data) == {
+        (populations[0], 5.0),
+        (populations[1], 5.0),
+        (populations[0], 10.0),
+        (populations[1], 10.0),
+    }
+
+    for curve, names in _population_reference_names(populations).items():
+        assert _reference_names_by_horizon(_references(performance_data, curve)) == {
+            5.0: names,
+            10.0: names,
+        }
+
+
+def test_equal_prevalence_populations_remain_series_but_references_collapse():
+    probs = {"Population A": PROBS_A, "Population B": PROBS_B}
+    reals = {
+        "Population A": np.array([1, 1, 0, 0, 0, 0]),
+        "Population B": np.array([1, 1, 0, 0, 0, 0]),
+    }
+    times = {
+        "Population A": np.array([3.0, 8.0, 12.0, 13.0, 14.0, 15.0]),
+        "Population B": np.array([4.0, 9.0, 12.0, 13.0, 14.0, 15.0]),
+    }
+    performance_data = _performance(probs, reals, times)
+
+    assert _series_keys(performance_data) == {
+        ("Population A", 5.0),
+        ("Population B", 5.0),
+        ("Population A", 10.0),
+        ("Population B", 10.0),
+    }
+
+    for curve, names in _shared_reference_names().items():
+        assert _reference_names_by_horizon(_references(performance_data, curve)) == {
+            5.0: names,
+            10.0: names,
+        }
+
+
+def test_reference_scope_can_switch_when_prevalence_diverges_by_horizon():
+    populations = ("Population low", "Population high")
+    performance_data = _performance(
+        {populations[0]: PROBS_A, populations[1]: PROBS_B},
+        {
+            populations[0]: np.array([1, 0, 0, 0, 0, 0]),
+            populations[1]: np.array([1, 1, 1, 0, 0, 0]),
+        },
+        {
+            populations[0]: np.array([3.0, 12.0, 13.0, 14.0, 15.0, 16.0]),
+            populations[1]: np.array([2.0, 7.0, 9.0, 12.0, 13.0, 14.0]),
+        },
+    )
+
+    references = _reference_names_by_horizon(
+        _references(performance_data, "precision recall")
+    )
+    assert references[5.0] == {"random_guess"}
+    assert references[10.0] == {
+        "random_guess_Population low",
+        "random_guess_Population high",
+    }
+
+
+def test_paired_model_population_inputs_are_generic_series_per_horizon():
+    pair_names = ["Model A @ Population A", "Model B @ Population B"]
+    probs = dict(zip(pair_names, (PROBS_A, PROBS_B)))
+    reals = {
+        pair_names[0]: np.array([1, 0, 0, 0, 0, 0]),
+        pair_names[1]: np.array([1, 1, 1, 0, 0, 0]),
+    }
+    times = {
+        pair_names[0]: np.array([3.0, 12.0, 13.0, 14.0, 15.0, 16.0]),
+        pair_names[1]: np.array([2.0, 4.0, 9.0, 12.0, 13.0, 14.0]),
+    }
+    performance_data = _performance(probs, reals, times)
+
+    assert _series_keys(performance_data) == {
+        (pair_names[0], 5.0),
+        (pair_names[1], 5.0),
+        (pair_names[0], 10.0),
+        (pair_names[1], 10.0),
+    }
+    assert "model" not in performance_data.columns
+    assert "population" not in performance_data.columns
+
+
+def test_time_calibration_has_one_identity_line_per_horizon_and_group_series():
+    fig = create_calibration_curve_times(
+        probs={"Population A": PROBS_A, "Population B": PROBS_B},
+        reals={
+            "Population A": np.array([1, 1, 0, 0, 0, 0]),
+            "Population B": np.array([1, 1, 0, 0, 0, 0]),
+        },
+        times={
+            "Population A": np.array([3.0, 8.0, 12.0, 13.0, 14.0, 15.0]),
+            "Population B": np.array([4.0, 9.0, 12.0, 13.0, 14.0, 15.0]),
+        },
+        fixed_time_horizons=HORIZONS,
+        heuristics_sets=HEURISTICS,
+        calibration_type="discrete",
+        color_values=COLORS,
+    )
+
+    identity = [trace for trace in fig.data if trace.name == "Perfectly Calibrated"]
+    assert len(identity) == len(HORIZONS)
+    assert sum(trace.visible is True for trace in identity) == 1
+
+    for group, color in zip(("Population A", "Population B"), COLORS):
+        traces = [trace for trace in fig.data if trace.name == group]
+        curve_traces = [trace for trace in traces if trace.type == "scatter"]
+        histogram_traces = [trace for trace in traces if trace.type == "bar"]
+        assert len(curve_traces) == len(HORIZONS)
+        assert len(histogram_traces) == len(HORIZONS)
+        assert {trace.marker.color for trace in curve_traces} == {color}
+
+
+def test_time_performance_data_preserves_group_and_horizon_dimensions():
+    performance_data = _performance(
+        {"Model A": PROBS_A, "Model B": PROBS_B},
+        REALS_SHARED,
+        TIMES_SHARED,
+    )
+
+    assert {"reference_group", "fixed_time_horizon"}.issubset(performance_data.columns)
+    assert _series_keys(performance_data) == {
+        ("Model A", 5.0),
+        ("Model B", 5.0),
+        ("Model A", 10.0),
+        ("Model B", 10.0),
+    }
+
+
+def test_time_performance_table_preserves_group_and_horizon_dimensions(monkeypatch):
+    monkeypatch.setattr(
+        performance_table_module,
+        "render_performance_table",
+        lambda performance_data, **kwargs: performance_data,
+    )
+
+    table_data = performance_table_module.create_performance_table_times(
+        probs={"Model A": PROBS_A, "Model B": PROBS_B},
+        reals=REALS_SHARED,
+        times=TIMES_SHARED,
+        fixed_time_horizons=HORIZONS,
+        heuristics_sets=HEURISTICS,
+        by=0.25,
+    )
+
+    assert _series_keys(table_data) == {
+        ("Model A", 5.0),
+        ("Model B", 5.0),
+        ("Model A", 10.0),
+        ("Model B", 10.0),
+    }