diff --git a/tests/orchestration/test_modelling_goal_band_floor.py b/tests/orchestration/test_modelling_goal_band_floor.py
new file mode 100644
index 000000000..3238fa477
--- /dev/null
+++ b/tests/orchestration/test_modelling_goal_band_floor.py
@@ -0,0 +1,42 @@
+"""The Optimiser judges "already at the goal band" on the *published* rating.
+
+A dwelling is in a band by the rating published on its EPC — the continuous SAP
+rounded half up. The Optimiser works in continuous SAP, so a goal of "reach band
+X" has to be met at the point the published rating enters band X (the integer
+floor less half a point), not at the integer floor itself. Comparing a
+continuous score against the integer floor makes a dwelling that already
+publishes in the band read as a fraction short, and the Optimiser buys the
+cheapest measure to close a gap that does not exist (#1652 / #1654 — 630 homes
+in portfolio 796 published at SAP 69 / band C, each sold ~1 marginal SAP point
+of works toward a band they had already reached).
+
+End-to-end through ``run_modelling`` (no database) with the real calculator,
+against Elmhurst certs that sit in the boundary window.
+"""
+
+from __future__ import annotations
+
+from datatypes.epc.domain.epc_property_data import EpcPropertyData
+from domain.modelling.plan import Plan
+from harness.console import run_modelling
+from tests.domain.modelling._elmhurst_recommendation import (
+    parse_recommendation_summary,
+)
+
+
+def _dwelling(fixture: str) -> EpcPropertyData:
+    return parse_recommendation_summary(fixture)
+
+
+def test_dwelling_published_at_the_goal_band_is_sold_no_works() -> None:
+    # Arrange — cert 001431 with a flat roof scores a continuous 54.575, which
+    # publishes as SAP 55: exactly the band D floor, so the dwelling already IS
+    # band D. Against an integer floor of 55 it reads as 0.425 short.
+    already_band_d = _dwelling("flat_roof_001431_before.pdf")
+
+    # Act — ask for the band it is already in.
+    plan: Plan = run_modelling(already_band_d, goal_band="D", print_table=False)
+
+    # Assert — nothing to buy: the goal is already met.
+    assert plan.measures == ()
+    assert plan.cost_of_works == 0.0