diff --git a/tests/test_leftover_map_report_graphic_tick_share_contract.py b/tests/test_leftover_map_report_graphic_tick_share_contract.py
new file mode 100644
index 000000000..ca71d132a
--- /dev/null
+++ b/tests/test_leftover_map_report_graphic_tick_share_contract.py
@@ -0,0 +1,29 @@
+"""Executable contract for report-graphic tick axis-share captions."""
+
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+SINGULAR_SOURCE = ROOT / "frontend" / "src" / "leftoverMapPlotAxisSingular.ts"
+
+
+def test_report_graphic_tick_keeps_axis_share_independent_of_singular() -> None:
+    """A report-graphic tick may name persisted share when singular evidence is absent."""
+    assert SINGULAR_SOURCE.exists(), "report graphic axis projection helper is missing"
+    source = SINGULAR_SOURCE.read_text(encoding="utf-8")
+
+    assert "leftoverMapPlotTickAxisBadge" in source
+    assert "leftover-map axis {axis} tick {value} {share}%" in source
+    assert "leftover-map axis {axis} tick {value} σ {singular} {share}%" in source
+
+
+def test_report_graphic_tick_never_infers_share_from_singular() -> None:
+    """Share-only, singular-only, combined, and empty states remain persisted-data decisions."""
+    assert SINGULAR_SOURCE.exists(), "report graphic axis projection helper is missing"
+    source = SINGULAR_SOURCE.read_text(encoding="utf-8")
+
+    assert "Number.isFinite" in source
+    assert "leftover_share" in source
+    assert "formatLeftoverMapPlotAxisSingular" in source
+    assert "Math.sqrt" not in source
+    assert "Math.max" not in source