diff --git a/tests/test_knowledge_facets.py b/tests/test_knowledge_facets.py
index 3e5f481..80fd203 100644
--- a/tests/test_knowledge_facets.py
+++ b/tests/test_knowledge_facets.py
@@ -38,6 +38,7 @@ ROWS = {
     "plain note": fake_note(note_type="note"),
     "process": fake_note(note_type="process"),
     "snippet": fake_snippet(),
+    "lesson": fake_note(note_type="lesson"),
     "work task": fake_task(task_kind="work", note_type="note"),
     "issue": fake_task(task_kind="issue", note_type="note"),
     "spike": fake_task(task_kind="spike", note_type="note"),
@@ -72,6 +73,7 @@ def test_pre_filter_never_excludes_a_row_the_facet_wants(facet):
         ("note", {"plain note"}),
         ("process", {"process"}),
         ("snippet", {"snippet"}),
+        ("lesson", {"lesson"}),
         ("", set(ROWS)),
     ],
 )
@@ -101,7 +103,11 @@ def test_the_live_task_kinds_are_all_facets():
 
 
 def test_non_task_facets_are_the_note_types_and_only_those():
-    assert set(NON_TASK_FACETS) == {"note", "process", "snippet"}
+    """Spelled out rather than derived, so adding a kind to `_FACETS` has to
+    be a deliberate edit in two places. `lesson` joined in milestone 385 step
+    2 (#3729) and is non-task on purpose: `is_task` IS `status is not None`,
+    so a lesson that acquired a status would stop being a lesson."""
+    assert set(NON_TASK_FACETS) == {"note", "process", "snippet", "lesson"}
 
 
 @pytest.mark.parametrize("facet", sorted(FACET_TYPES))