The ceiling at its off end stands with the default critical line

forgectrl pin 368fd0c: the critical-line cross-check binds only while the
ceiling is a gate. cooling.critical-tier pins that a POST setting the
ceiling to its off end is accepted with the default line (the unit fake
mirrors the exemption); CAMPAIGN-LOG records the gate-off failure on dev
image 20260822165832 that found it, and the critical-tier pass.

forgetest/forgetest/suite/cooling.py

@@ -422,6 +422,14 @@ def critical_tier(ctx):
     after = fc.settings()
     ctx.check(all(after.get(k, "") == orig[k] for k in CRIT_KEYS),
               "the refused POST changed a setting: %s", {k: after.get(k) for k in CRIT_KEYS})
+    # A ceiling at its off end is no ceiling: the default line stands
+    # alone, and the POST that turns the ceiling off is accepted.
+    st, body = fc.post("/settings", params={"cool_temp_max": str(ceil.get("hi"))})
+    ev["ceiling_off_accepted"] = st
+    if st == 200:
+        fc.post("/settings", params=orig)
+    ctx.check(st == 200, "the ceiling at its off end %s was refused against the critical line: %s %s",
+              ceil.get("hi"), st, body)
 
     restored = False
     with ctx.grbl() as grbl:

forgetest/tests/test_cooling_suite.py

@@ -448,7 +448,8 @@ class CriticalTierTests(unittest.TestCase):
             merged.update(form)
             tmax = float(merged.get("cool_temp_max") or 33.0)
             tcrit = float(merged.get("cool_temp_critical_c") or 38.0)
-            if tcrit <= tmax:
+            ceiling_off = tmax >= self.ROWS["cool_temp_max"][3]
+            if not ceiling_off and tcrit <= tmax:
                 return (400, {"error": "cool_temp_critical_c must be above cool_temp_max"})
         self.fc.state["settings"].update(form)
         self._describe()
@@ -508,8 +509,11 @@ class CriticalTierTests(unittest.TestCase):
         self.assertEqual(run.evidence["critical_after"]["verdict"], "OVERTEMP")
         self.assertEqual(run.evidence["critical_off"]["gates_off"], ["coolant_critical"])
         self.assertEqual(run.evidence["restored"]["verdict"], "OK")
+        self.assertEqual(run.evidence["ceiling_off_accepted"], 200)
         posts = self.settings_posts()
-        self.assertEqual(posts[1], {"cool_temp_max": "6.0", "cool_temp_resume": "5.0",
+        # refused cross-check, the ceiling at its off end (accepted), its undo, then the low leg
+        self.assertEqual(posts[1], {"cool_temp_max": "60.0"})
+        self.assertEqual(posts[3], {"cool_temp_max": "6.0", "cool_temp_resume": "5.0",
                                     "cool_temp_critical_c": "7.0"})
         self.assertEqual(posts[-1], {"cool_temp_max": "", "cool_temp_resume": "", "cool_temp_critical_c": ""})
         self.assertEqual(self.grbl.commands.count("M8"), 3)