feat(rules)!: retire rulebook subscriptions and per-project suppressions (#4052)

A rule's home is its scope now: a rule in a rulebook topic is global, a rule on
a project applies to that project, and retrieval reads that directly (#4074).
A subscription had stopped changing anything a session received; a suppression
muted rules from a subscription. Operator, 2026-09-15: "we have global and
project scoped rules, we don't need the subscriptions now."

What goes, whole (rule 22):
- Migration 0101 drops project_rulebook_subscriptions, project_rule_suppressions
  and project_topic_suppressions, and strips subscribe_rulebooks (and 394's
  leftover exclude_always_on_rulebooks) from stored inception choices.
- Service, MCP and REST: subscribe/unsubscribe and the four suppress/unsuppress
  operations. The Subscribers checklist, the subscribe chips, the skip buttons
  and the Suppressed section in the rules UI.
- Inception asks two questions (design system, seed Systems). create_project and
  decide_project_inception lose subscribe_rulebooks.
- Backup v15 stops exporting the three sections; older archives still restore,
  the keys simply unread. Trash no longer hard-deletes suppression rows.

What changes meaning:
- get_applicable_rules is a project's LISTING: its own rules, plus the global
  rules tagged to an area it works in. Untagged global rules apply everywhere
  and arrive by retrieval, so they are not listed. A co_surfaces partner on a
  different project is not dragged in.
- list_rules(project_id) lists that project's own rules.
- rules_payload drops subscribed_rulebooks and suppressed_*; the handshake's
  brief form is project_rules alone.
- using-scribe's "Where a new rule goes" and inception sections, tool
  docstrings and docs say global vs project. Plugin 2026.09.15.1620.

Milestone 414 step 2.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

tests/test_services_rulebooks.py

@@ -172,23 +172,7 @@ async def test_get_rule_returns_none_when_not_owner():
     assert result is None
 
 
-# ── Subscriptions + applicable_rules ────────────────────────────────────
-
-@pytest.mark.asyncio
-async def test_subscribe_project_requires_owned_rulebook():
-    """subscribe_project raises if user doesn't own the rulebook."""
-    mock_session = make_mock_session()
-    mock_result = MagicMock()
-    mock_result.scalar_one_or_none.return_value = None
-    mock_session.execute = AsyncMock(return_value=mock_result)
-    with patch("scribe.services.rulebooks.async_session") as mock_cls:
-        mock_cls.return_value = mock_session
-        from scribe.services.rulebooks import subscribe_project
-        with pytest.raises(ValueError, match="not found"):
-            await subscribe_project(
-                project_id=1, rulebook_id=999, user_id=7,
-            )
-
+# ── applicable_rules ────────────────────────────────────────────────────
 
 def _empty():
     """A MagicMock result whose .all() returns [] (or .scalars().all() returns [])."""
@@ -217,13 +201,18 @@ def _no_edges():
     )
 
 
+def _areas(*canonical_ids):
+    """The project-areas query's result: `.scalars().all()` of canonical ids."""
+    r = MagicMock()
+    r.scalars.return_value.all.return_value = list(canonical_ids)
+    return r
+
+
 @pytest.mark.asyncio
 async def test_get_applicable_rules_returns_shape():
-    """get_applicable_rules returns the full projection — including the
-    new suppression fields and rulebook/topic IDs on each rule."""
+    """The listing is a project's own rules plus the global rules tagged to its
+    areas (milestone 414) — no subscriptions or suppressions in the shape."""
     mock_session = make_mock_session()
-    sub_result = MagicMock()
-    sub_result.all.return_value = [(1, "FabledSword family")]
     rules_result = MagicMock()
     rules_result.all.return_value = [
         # The query selects the ENTITY plus three labels, so rule_brief stays
@@ -232,10 +221,9 @@ async def test_get_applicable_rules_returns_shape():
          "git-workflow", 1, "FabledSword family")
         for i in range(50)
     ]
-    # Execute order: sub_q, suppressed_rules_q, suppressed_topics_q,
-    # project-areas_q (milestone 307), rules_q, proj_rules_q
+    # Execute order: project-areas_q, rules_q (only with areas), proj_rules_q
     mock_session.execute = AsyncMock(side_effect=[
-        sub_result, _empty(), _empty(), _empty(), rules_result, _empty(),
+        _areas(4), rules_result, _empty(),
     ])
 
     _p1, _p2, _p3 = _no_edges()
@@ -244,19 +232,11 @@ async def test_get_applicable_rules_returns_shape():
         from scribe.services.rulebooks import get_applicable_rules
         result = await get_applicable_rules(project_id=3, user_id=7, limit=50)
 
-    assert "rules" in result
-    assert "project_rules" in result
-    assert "suppressed_rules" in result
-    assert "suppressed_topics" in result
-    assert "truncated" in result
-    assert "subscribed_rulebooks" in result
-    assert result["subscribed_rulebooks"] == [{"id": 1, "title": "FabledSword family"}]
+    assert set(result) == {"rules", "project_rules", "truncated"}
     assert len(result["rules"]) == 50
     assert result["rules"][0]["topic_id"] == 2
     assert result["rules"][0]["rulebook_id"] == 1
     assert result["project_rules"] == []
-    assert result["suppressed_rules"] == []
-    assert result["suppressed_topics"] == []
     assert result["truncated"] is False
 
 
@@ -264,14 +244,12 @@ async def test_get_applicable_rules_returns_shape():
 async def test_get_applicable_rules_truncates_when_over_limit():
     """When limit+1 rows are returned, truncated=True and only `limit` returned."""
     mock_session = make_mock_session()
-    sub_result = MagicMock()
-    sub_result.all.return_value = []
     rules_result = MagicMock()
     rules_result.all.return_value = [
         (fake_rule(id=i, title=f"r{i}"), "topic", 1, "rb") for i in range(51)
     ]
     mock_session.execute = AsyncMock(side_effect=[
-        sub_result, _empty(), _empty(), _empty(), rules_result, _empty(),
+        _areas(4), rules_result, _empty(),
     ])
 
     _p1, _p2, _p3 = _no_edges()
@@ -284,6 +262,24 @@ async def test_get_applicable_rules_truncates_when_over_limit():
     assert len(result["rules"]) == 50
 
 
+@pytest.mark.asyncio
+async def test_a_project_with_no_areas_lists_no_global_rules():
+    """Untagged global rules apply everywhere and arrive by retrieval; the
+    listing only names the ones bound by area, so no areas means none — and
+    the global-rules query is not run at all."""
+    mock_session = make_mock_session()
+    mock_session.execute = AsyncMock(side_effect=[_areas(), _empty()])
+
+    _p1, _p2, _p3 = _no_edges()
+    with patch("scribe.services.rulebooks.async_session") as mock_cls, _p1, _p2, _p3:
+        mock_cls.return_value = mock_session
+        from scribe.services.rulebooks import get_applicable_rules
+        result = await get_applicable_rules(project_id=3, user_id=7)
+
+    assert result["rules"] == []
+    assert mock_session.execute.await_count == 2
+
+
 @pytest.mark.asyncio
 async def test_get_applicable_rules_includes_project_scoped_rules():
     """Project-scoped rules surface in the project_rules field."""
@@ -295,9 +291,7 @@ async def test_get_applicable_rules_includes_project_scoped_rules():
         (fake_rule(id=101, topic_id=None, project_id=3, title="PR-bound",
                    statement="Land schema changes in their own PR."),),
     ]
-    mock_session.execute = AsyncMock(side_effect=[
-        _empty(), _empty(), _empty(), _empty(), _empty(), proj_rules_result,
-    ])
+    mock_session.execute = AsyncMock(side_effect=[_areas(), proj_rules_result])
 
     _p1, _p2, _p3 = _no_edges()
     with patch("scribe.services.rulebooks.async_session") as mock_cls, _p1, _p2, _p3:
@@ -311,38 +305,28 @@ async def test_get_applicable_rules_includes_project_scoped_rules():
 
 
 @pytest.mark.asyncio
-async def test_get_applicable_rules_surfaces_suppressed_with_context():
-    """Suppressed rules and topics come back with full title + rulebook context
-    so the UI can render them without an extra round-trip."""
+async def test_a_co_surfaces_partner_on_another_project_is_not_dragged_in():
+    """An edge is not a way into a project: a partner that is global or on this
+    project arrives; one on a different project does not."""
     mock_session = make_mock_session()
-    suppressed_rules_result = MagicMock()
-    suppressed_rules_result.all.return_value = [
-        # (rule_id, title, topic_id, topic_title, rulebook_id, rulebook_title)
-        (17, "Old rule", 5, "old-topic", 1, "FabledSword family"),
+    proj_rules_result = MagicMock()
+    proj_rules_result.all.return_value = [(fake_rule(id=100, topic_id=None, project_id=3),)]
+    mock_session.execute = AsyncMock(side_effect=[_areas(), proj_rules_result])
+    partners = [
+        fake_rule(id=200, topic_id=9, project_id=None, title="global partner"),
+        fake_rule(id=201, topic_id=None, project_id=3, title="same-project partner"),
+        fake_rule(id=202, topic_id=None, project_id=8, title="other-project partner"),
     ]
-    suppressed_topics_result = MagicMock()
-    suppressed_topics_result.all.return_value = [
-        # (topic_id, topic_title, rulebook_id, rulebook_title)
-        (22, "design-system", 1, "FabledSword family"),
-    ]
-    mock_session.execute = AsyncMock(side_effect=[
-        # sub_q, suppressed_rules_q, suppressed_topics_q, project-areas_q,
-        # rules_q, proj_rules_q
-        _empty(), suppressed_rules_result, suppressed_topics_result,
-        _empty(), _empty(), _empty(),
-    ])
 
-    _p1, _p2, _p3 = _no_edges()
-    with patch("scribe.services.rulebooks.async_session") as mock_cls, _p1, _p2, _p3:
+    with patch("scribe.services.rulebooks.async_session") as mock_cls, \
+         patch("scribe.services.rulebooks.co_surfaced_partners", AsyncMock(return_value=partners)), \
+         patch("scribe.services.rulebooks.list_rule_relations", AsyncMock(return_value={})), \
+         patch("scribe.services.rulebooks.list_rule_systems", AsyncMock(return_value={})):
         mock_cls.return_value = mock_session
         from scribe.services.rulebooks import get_applicable_rules
         result = await get_applicable_rules(project_id=3, user_id=7)
 
-    assert len(result["suppressed_rules"]) == 1
-    assert result["suppressed_rules"][0]["id"] == 17
-    assert result["suppressed_rules"][0]["rulebook_title"] == "FabledSword family"
-    assert len(result["suppressed_topics"]) == 1
-    assert result["suppressed_topics"][0]["title"] == "design-system"
+    assert [r["id"] for r in result["rules"]] == [200, 201]
 
 
 # ── rule_brief (milestone 307) ──────────────────────────────────────────