diff --git a/tests/test_lesson_usage_surface.py b/tests/test_lesson_usage_surface.py
index 2789442..0b4c3a9 100644
--- a/tests/test_lesson_usage_surface.py
+++ b/tests/test_lesson_usage_surface.py
@@ -25,6 +25,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 from scribe.mcp.tools import lessons as lesson_tools
+from scribe.services import note_usage
 from scribe.services.note_usage import empty_usage
 
 
@@ -47,7 +48,7 @@ async def test_the_mcp_listing_carries_usage_for_every_row():
                      new=AsyncMock(return_value=(_rows(), 2))),
         patch.object(lesson_tools.access_svc, "label_shared_items",
                      new=AsyncMock(side_effect=lambda _uid, items: items)),
-        patch.object(lesson_tools, "usage_for_notes",
+        patch.object(note_usage, "usage_for_notes",
                      new=AsyncMock(return_value=used)),
     ):
         out = await lesson_tools.list_lessons()
@@ -71,7 +72,7 @@ async def test_the_listing_asks_for_usage_once_for_the_whole_page():
                      new=AsyncMock(return_value=(_rows(), 2))),
         patch.object(lesson_tools.access_svc, "label_shared_items",
                      new=AsyncMock(side_effect=lambda _uid, items: items)),
-        patch.object(lesson_tools, "usage_for_notes", new=reader),
+        patch.object(note_usage, "usage_for_notes", new=reader),
     ):
         await lesson_tools.list_lessons()
 
@@ -101,7 +102,7 @@ async def test_get_lesson_reads_the_count_before_recording_its_own_pull():
         patch.object(lesson_tools, "_to_dict", return_value={"id": 7}),
         patch.object(lesson_tools.access_svc, "describe_provenance",
                      new=AsyncMock(return_value={})),
-        patch.object(lesson_tools, "usage_for_notes", new=_usage_read),
+        patch.object(note_usage, "usage_for_notes", new=_usage_read),
         patch.object(lesson_tools, "record_pulled",
                      side_effect=lambda **_kw: order.append("pull")),
     ):
@@ -116,6 +117,13 @@ async def test_get_lesson_reads_the_count_before_recording_its_own_pull():
 
 # ── the REST door, on structure (rule 167) ───────────────────────────────────
 #
+# MOVED 2026-09-21 (#4230), not weakened. These used to look for
+# `usage_for_notes(` and `empty_usage()` in the route body. Both now live in
+# ONE seam, `note_usage.attach_usage`, which seven doors share — so the
+# zero-fill and the single aggregate are pinned once, against the seam, in
+# tests/test_usage_attach_seam.py. What stays HERE is what only this route can
+# get wrong: that it calls the seam at all, once, and before it records a pull.
+#
 # Its siblings in test_lesson_rest_door.py are source guards for the same
 # reason: the route is decorated and returns a Quart response, so driving it
 # means standing up the app. What matters here is reachable from the source
@@ -136,19 +144,17 @@ def test_the_rest_listing_reads_usage_once_for_the_page():
     """A per-row lookup would be N+1 by construction — the listing's own
     comment says so, and this is what makes that comment checkable."""
     src = _route_source("list_lessons_route")
-    assert src.count("usage_for_notes(") == 1
-    # The one call is not inside the loop that assigns the rows.
-    call = src.index("usage_for_notes(")
-    assign = src.index('["usage"]')
-    assert call < assign
+    assert src.count("attach_usage(") == 1
+    assert "attach_usage(items)" in src, "the seam must get the page, not a row"
 
 
 def test_every_rest_row_carries_the_key_even_at_zero():
     """"Never surfaced" is a state the UI renders; a missing field is not."""
     src = _route_source("list_lessons_route")
-    assert "empty_usage()" in src, (
-        "a row with no recorded usage would come back without the key, and a "
-        "reader cannot tell that from a reporting failure"
+    assert "attach_usage(" in src
+    assert 'it["usage"] =' not in src, (
+        "the route re-spells the attach by hand, so a row with no recorded "
+        "usage can come back without the key again"
     )
 
 
@@ -156,7 +162,7 @@ def test_the_rest_detail_door_also_reads_before_it_records():
     """Two doors that disagree about what the number counts are worse than
     one door that is wrong, because only one of them looks wrong."""
     src = _route_source("get_lesson_route")
-    assert src.index("usage_for_notes(") < src.index("record_pulled(")
+    assert src.index("attach_usage(") < src.index("record_pulled(")
 
 
 def test_these_guards_can_fail():
@@ -181,9 +187,14 @@ def test_the_detail_view_renders_the_badge_rather_than_respelling_it():
     assert "UsageBadge" in view
     assert "usage-tag" not in view, "re-spelled the chip instead of reusing it"
 
-    key = 'dead-weight-advice="'
-    start = view.index(key) + len(key)
-    advice = view[start:view.index('"', start)]
+    # The sentence moved out of this template into the shared table (#4230,
+    # recorded on #3460). Assert BOTH halves, so the guard cannot pass by the
+    # view pointing at an entry that no longer says the right thing.
+    assert "DEAD_WEIGHT_ADVICE.lesson" in view, "the view no longer reads the lesson advice"
+    table = (Path(__file__).resolve().parents[1]
+             / "frontend/src/utils/deadWeight.ts").read_text()
+    start = table.index("  lesson:")
+    advice = table[start:table.index(",\n", start)]
     assert "when_to_apply" in advice, (
         f"the dead-weight advice does not point at the trigger: {advice!r}"
     )