src/scribe/mcp/tools/notes.py

@@ -69,12 +69,11 @@ async def _attach_supersession(uid: int, note_id: int, data: dict) -> None:
     permanently-empty lists. A field that always says nothing trains readers to
     skip fields, which is the lesson `consolidated_at` cost us (#2483).
     """
-    supersedes = await supersession_svc.get_supersedes(uid, note_id)
-    superseded_by = await supersession_svc.get_superseded_by(uid, note_id)
-    if supersedes:
-        data["supersedes"] = supersedes
-    if superseded_by:
-        data["superseded_by"] = superseded_by
+    rel = await supersession_svc.get_relations(uid, note_id)
+    if rel["supersedes"]:
+        data["supersedes"] = rel["supersedes"]
+    if rel["superseded_by"]:
+        data["superseded_by"] = rel["superseded_by"]
         data["superseded_note"] = (
             "A later note claims to bring this up to date — see superseded_by. "
             "Read this as what was true when written, and check the newer one "

src/scribe/routes/notes.py

@@ -36,12 +36,11 @@ async def _attach_supersession(uid: int, note_id: int, data: dict) -> None:
     Omitted when empty: a field that always says nothing trains readers to skip
     fields, which is what `consolidated_at` cost (#2483).
     """
-    supersedes = await supersession_svc.get_supersedes(uid, note_id)
-    superseded_by = await supersession_svc.get_superseded_by(uid, note_id)
-    if supersedes:
-        data["supersedes"] = supersedes
-    if superseded_by:
-        data["superseded_by"] = superseded_by
+    rel = await supersession_svc.get_relations(uid, note_id)
+    if rel["supersedes"]:
+        data["supersedes"] = rel["supersedes"]
+    if rel["superseded_by"]:
+        data["superseded_by"] = rel["superseded_by"]
 from scribe.services.note_versions import list_versions, get_version
 
 logger = logging.getLogger(__name__)

src/scribe/services/supersession.py

@@ -129,33 +129,40 @@ async def set_supersedes(
         return wanted
 
 
-async def get_supersedes(user_id: int, note_id: int) -> list[int]:
-    """Ids this note claims to supersede. Empty if the caller can't read it."""
-    if not await access.can_read_note(user_id, note_id):
-        return []
-    async with async_session() as session:
-        return [int(i) for i in (await session.execute(
-            select(NoteSupersession.superseded_id)
-            .where(NoteSupersession.superseder_id == note_id)
-            .order_by(NoteSupersession.superseded_id)
-        )).scalars().all()]
+async def get_relations(user_id: int, note_id: int) -> dict[str, list[int]]:
+    """Both directions for one note: what it supersedes, and what supersedes it.
 
+    ONE query and ONE ACL check, because this runs on every note read. Asking
+    the two questions separately doubled the round trips on the hottest path in
+    the product to save a two-line partition — the wrong trade, and one I made
+    on the first attempt.
 
-async def get_superseded_by(user_id: int, note_id: int) -> list[int]:
-    """Ids claiming to supersede this note.
+    Returns {"supersedes": [...], "superseded_by": [...]}, both sorted. Empty
+    lists when the caller cannot read the note.
 
-    The direction that matters to a READER, and the one the note itself cannot
-    know. An agent handed a stale record with no marker acts on it confidently;
-    that is worse than never surfacing it at all.
+    `superseded_by` is the direction that matters to a READER and the one the
+    note itself cannot know. An agent handed a stale record with no marker acts
+    on it confidently, which is worse than never surfacing it at all.
     """
+    empty: dict[str, list[int]] = {"supersedes": [], "superseded_by": []}
     if not await access.can_read_note(user_id, note_id):
-        return []
+        return empty
     async with async_session() as session:
-        return [int(i) for i in (await session.execute(
-            select(NoteSupersession.superseder_id)
-            .where(NoteSupersession.superseded_id == note_id)
-            .order_by(NoteSupersession.superseder_id)
-        )).scalars().all()]
+        rows = (await session.execute(
+            select(
+                NoteSupersession.superseder_id, NoteSupersession.superseded_id
+            ).where(
+                (NoteSupersession.superseder_id == note_id)
+                | (NoteSupersession.superseded_id == note_id)
+            )
+        )).all()
+    supersedes = sorted(
+        int(old) for new, old in rows if int(new) == note_id
+    )
+    superseded_by = sorted(
+        int(new) for new, old in rows if int(old) == note_id
+    )
+    return {"supersedes": supersedes, "superseded_by": superseded_by}
 
 
 async def superseded_ids(note_ids: list[int]) -> set[int]:

tests/test_mcp_tool_notes.py

@@ -17,6 +17,21 @@ def _bind_user():
     _user_id_ctx.reset(token)
 
 
+@pytest.fixture(autouse=True)
+def _no_supersession():
+    """Every note read/write now asks for its supersession relations (#278).
+
+    These are unit tests of the TOOL layer and this job has no database — the
+    same hazard the `_fake_note` comment below records for note 2109. Stubbed
+    to "no relations", which is the state of essentially every note; the
+    relation's own behaviour is covered in test_services_supersession.py, and
+    the attachment is covered explicitly below.
+    """
+    with patch("scribe.mcp.tools.notes.supersession_svc.get_relations",
+               AsyncMock(return_value={"supersedes": [], "superseded_by": []})):
+        yield
+
+
 def _fake_note(*, user_id: int = 7, **overrides) -> MagicMock:
     note = MagicMock()
     base = {"id": 1, "title": "t", "body": "b", "tags": [], "is_task": False}
@@ -123,6 +138,30 @@ async def test_get_note_returns_dict():
     assert out["title"] == "found"
     # Own record: no provenance noise.
     assert "shared" not in out
+    # No supersession relations: both keys ABSENT, not present-and-empty. A
+    # field that always says nothing trains readers to skip fields (#2483).
+    assert "supersedes" not in out
+    assert "superseded_by" not in out
+
+
+@pytest.mark.asyncio
+async def test_get_note_warns_in_words_when_a_later_note_overtook_it():
+    """The label is the point, not the ids.
+
+    A superseded record still surfaces — supersession demotes, it never hides —
+    so an agent WILL read stale material. Handing it over with only a numeric
+    field to notice would be worse than not surfacing it, because the reader
+    acts on it confidently either way.
+    """
+    fake = _fake_note(id=5, title="June's answer")
+    with patch("scribe.mcp.tools.notes.notes_svc.get_note_for_user",
+               AsyncMock(return_value=(fake, "owner"))), \
+         patch("scribe.mcp.tools.notes.supersession_svc.get_relations",
+               AsyncMock(return_value={"supersedes": [], "superseded_by": [9]})):
+        out = await get_note(note_id=5)
+    assert out["superseded_by"] == [9]
+    assert "superseded_note" in out
+    assert "before acting" in out["superseded_note"]
 
 
 @pytest.mark.asyncio

tests/test_services_supersession.py

@@ -144,5 +144,32 @@ async def test_superseded_ids_is_empty_for_an_empty_candidate_set():
 async def test_reads_are_empty_when_the_caller_cannot_read_the_note():
     with patch("scribe.services.supersession.access.can_read_note",
                AsyncMock(return_value=False)):
-        assert await supersession.get_supersedes(7, 1) == []
-        assert await supersession.get_superseded_by(7, 1) == []
+        assert await supersession.get_relations(7, 1) == {
+            "supersedes": [], "superseded_by": []
+        }
+
+
+@pytest.mark.asyncio
+async def test_get_relations_partitions_both_directions_from_one_query():
+    """ONE round trip for both directions, because this runs on every note read.
+
+    Note 5 supersedes 2 and 3, and is itself superseded by 9. All four rows come
+    back from a single OR query and are partitioned by which column holds 5.
+    """
+    session = AsyncMock()
+    session.__aenter__ = AsyncMock(return_value=session)
+    session.__aexit__ = AsyncMock(return_value=False)
+    result = MagicMock()
+    result.all.return_value = [(5, 3), (5, 2), (9, 5)]   # (superseder, superseded)
+    session.execute = AsyncMock(return_value=result)
+
+    with patch("scribe.services.supersession.access.can_read_note",
+               AsyncMock(return_value=True)), \
+         patch("scribe.services.supersession.async_session", return_value=session):
+        rel = await supersession.get_relations(7, 5)
+
+    assert rel == {"supersedes": [2, 3], "superseded_by": [9]}
+    assert session.execute.await_count == 1, (
+        "both directions must come from one query — asking separately doubles "
+        "the round trips on the hottest path in the product"
+    )