diff --git a/tests/test_homogeneity_additional.py b/tests/test_homogeneity_additional.py
new file mode 100644
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+++ b/tests/test_homogeneity_additional.py
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+"""Focused tests for ``iav.interval_analysis_core._homogeneity``."""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from iav.analysis_enums import IntervallicHeadlineMode
+from iav.interval_analysis_core._homogeneity import (
+    cluster_compactness,
+    dominance,
+    dominance_weighted,
+    entropy_evenness,
+    entropy_evenness_supportbounded,
+    entropy_evenness_supportbounded_weighted,
+    homogeneity_score,
+    intervallic_concentration,
+    proximity_weighted_distance_counts,
+    type_concentration,
+)
+
+
+def test_cluster_compactness_single_note_fallback():
+    notes = [("C", 0.0, 4)]
+    compactness, span_cents, avg_distance = cluster_compactness(notes, bin_cents=100)
+    assert compactness == 1.0
+    assert span_cents == 0
+    assert avg_distance == 0.0
+
+
+def test_cluster_compactness_identical_pitches_zero_span():
+    notes = [("C", 0.0, 4), ("C", 0.0, 4)]
+    compactness, span_cents, avg_distance = cluster_compactness(notes, bin_cents=100)
+    assert compactness == 1.0
+    assert span_cents == 0
+    assert avg_distance == 0.0
+
+
+def test_cluster_compactness_nonzero_span():
+    notes = [("C", 0.0, 4), ("E", 0.0, 4), ("G", 0.0, 4)]
+    compactness, span_cents, avg_distance = cluster_compactness(notes, bin_cents=100)
+    assert compactness == pytest.approx(1.0 / 3.0)
+    assert span_cents == 700
+    assert avg_distance == pytest.approx(1400.0 / 3.0)
+
+
+def test_type_concentration_empty_returns_zero():
+    assert type_concentration({}) == 0.0
+
+
+def test_type_concentration_total_at_most_one_returns_one():
+    assert type_concentration({"M3": 1}) == 1.0
+
+
+def test_type_concentration_single_type_multiple_counts_is_maximal():
+    assert type_concentration({"P5": 5}) == 1.0
+
+
+def test_type_concentration_multiple_types_lower_than_maximal():
+    assert type_concentration({"M3": 2, "P5": 2}) == pytest.approx(2.0 / 3.0)
+
+
+def test_entropy_evenness_empty_returns_zero():
+    assert entropy_evenness({}) == 0.0
+
+
+def test_entropy_evenness_single_category_returns_zero():
+    assert entropy_evenness({"M3": 4}) == 0.0
+
+
+def test_entropy_evenness_balanced_higher_than_concentrated():
+    balanced = entropy_evenness({"M3": 2, "P5": 2})
+    concentrated = entropy_evenness({"M3": 10, "P5": 1})
+    assert balanced == pytest.approx(1.0)
+    assert concentrated < balanced
+
+
+def test_dominance_empty_returns_zero():
+    assert dominance({}) == 0.0
+
+
+def test_dominance_non_empty_share_of_largest_count():
+    assert dominance({7: 3, 4: 1}) == pytest.approx(0.75)
+
+
+def test_dominance_zero_total_returns_zero():
+    assert dominance({7: 0, 4: 0}) == 0.0
+
+
+def test_dominance_weighted_empty_returns_zero():
+    assert dominance_weighted({}) == 0.0
+
+
+def test_dominance_weighted_non_empty_share_of_largest_weight():
+    assert dominance_weighted({7: 3.0, 4: 1.0}) == pytest.approx(0.75)
+
+
+def test_dominance_weighted_zero_total_returns_zero():
+    assert dominance_weighted({7: 0.0, 4: 0.0}) == 0.0
+
+
+def test_entropy_evenness_supportbounded_empty_returns_zero():
+    assert entropy_evenness_supportbounded({}, support_bins=5) == 0.0
+
+
+def test_entropy_evenness_supportbounded_non_positive_total_returns_zero():
+    assert entropy_evenness_supportbounded({1: 0, 2: 0}, support_bins=5) == 0.0
+
+
+def test_entropy_evenness_supportbounded_support_bins_at_most_one_returns_zero():
+    assert entropy_evenness_supportbounded({1: 2, 2: 1}, support_bins=1) == 0.0
+    assert entropy_evenness_supportbounded({1: 2, 2: 1}, support_bins=0) == 0.0
+
+
+def test_entropy_evenness_supportbounded_balanced_higher_than_concentrated():
+    balanced = entropy_evenness_supportbounded({1: 1, 2: 1, 3: 1}, support_bins=3)
+    concentrated = entropy_evenness_supportbounded({1: 9, 2: 1}, support_bins=3)
+    assert balanced == pytest.approx(1.0)
+    assert concentrated < balanced
+
+
+def test_entropy_evenness_supportbounded_weighted_empty_returns_zero():
+    assert entropy_evenness_supportbounded_weighted({}, support_bins=5) == 0.0
+
+
+def test_entropy_evenness_supportbounded_weighted_non_positive_total_returns_zero():
+    assert entropy_evenness_supportbounded_weighted({1: 0.0}, support_bins=5) == 0.0
+
+
+def test_entropy_evenness_supportbounded_weighted_support_bins_at_most_one_returns_zero():
+    assert entropy_evenness_supportbounded_weighted({1: 1.0, 2: 1.0}, support_bins=1) == 0.0
+
+
+def test_entropy_evenness_supportbounded_weighted_balanced_higher_than_concentrated():
+    balanced = entropy_evenness_supportbounded_weighted(
+        {1: 1.0, 2: 1.0, 3: 1.0}, support_bins=3
+    )
+    concentrated = entropy_evenness_supportbounded_weighted(
+        {1: 100.0, 2: 1.0}, support_bins=3
+    )
+    assert balanced == pytest.approx(math.log(3) / math.log(3))
+    assert concentrated < balanced
+
+
+def test_intervallic_concentration_weighted_dominance_path():
+    counts = proximity_weighted_distance_counts(
+        [("C", 0.0, 4), ("E", 0.0, 4), ("G", 0.0, 4)],
+        bin_cents=100,
+        inverse_power=1,
+    )
+    assert intervallic_concentration(counts, "dominance", support_bins=5) == pytest.approx(
+        dominance_weighted(counts)
+    )
+
+
+def test_intervallic_concentration_weighted_entropy_path():
+    counts = proximity_weighted_distance_counts(
+        [("C", 0.0, 4), ("E", 0.0, 4), ("G", 0.0, 4)],
+        bin_cents=100,
+        inverse_power=2,
+    )
+    expected = 1.0 - entropy_evenness_supportbounded_weighted(counts, 5)
+    assert intervallic_concentration(counts, "entropy", support_bins=5) == pytest.approx(
+        expected
+    )
+
+
+@pytest.mark.parametrize("alpha", [-0.01, 1.01])
+def test_homogeneity_score_rejects_alpha_out_of_range(alpha: float):
+    notes = [("C", 0.0, 4), ("E", 0.0, 4)]
+    with pytest.raises(ValueError, match="alpha must be between 0 and 1"):
+        homogeneity_score(notes, alpha=alpha)
+
+
+def test_homogeneity_score_rejects_invalid_method():
+    notes = [("C", 0.0, 4), ("E", 0.0, 4)]
+    with pytest.raises(ValueError, match="method must be 'dominance' or 'entropy'"):
+        homogeneity_score(notes, alpha=0.5, method="variance")
+
+
+def test_homogeneity_score_dominance_method_dyad():
+    notes = [("C", 0.0, 4), ("G", 0.0, 4)]
+    h, chain, pair, *_ = homogeneity_score(notes, alpha=0.5, method="dominance")
+    assert pair == 1.0
+    assert chain == 1.0
+    assert h == 1.0
+
+
+def test_homogeneity_score_entropy_method_dyad():
+    notes = [("C", 0.0, 4), ("G", 0.0, 4)]
+    h, chain, pair, *_ = homogeneity_score(notes, alpha=0.5, method="entropy")
+    assert pair == 1.0
+    assert chain == 1.0
+    assert h == 1.0
+
+
+def test_homogeneity_score_adjacent_headline_mode():
+    notes = [("C", 0.0, 4), ("C", 1.0, 4), ("D", 0.0, 4)]
+    h, chain, pair, *_ = homogeneity_score(
+        notes,
+        alpha=0.5,
+        method="entropy",
+        headline_mode=IntervallicHeadlineMode.ADJACENT,
+    )
+    assert h == chain