fix(tests): migration round-trip tests leave core_api_test at head (T-14)

Every round-trip test across test_book_migration.py, test_scribe_migration.py
and test_tenants_migration.py re-upgraded to its own revision on the way back
up rather than to head, so a full suite run left core_api_test one or two
migrations behind (008, with 009/010 released since). Each now ends on
`upgrade head`; a new TestSchemaEndsAtHeadAfterTheMigrationSuite class checks
the final state directly with no upgrade of its own, as a regression guard.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -17,6 +17,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   documented ways to reach either database; none of them print a password or a
   credential-bearing URL.
 
+### Fixed
+
+- **Migration round-trip tests leave `core_api_test` at head** (core-api T-14) — every
+  round-trip test in `tests/test_book_migration.py`, `tests/test_scribe_migration.py` and
+  `tests/test_tenants_migration.py` now ends on `upgrade head` rather than its own
+  revision, so a full suite run leaves the test database at head instead of one or two
+  migrations behind it.
+
 ## [1.15.0] - 2026-10-19
 
 ### Added

tests/test_book_migration.py

@@ -65,8 +65,8 @@ class TestMigration005RoundTrip:
         assert not await _table_exists(test_database_url, "book_events")
         assert not await _table_exists(test_database_url, "book_tenant_counters")
 
-        # Leave the schema at head for the rest of the suite.
-        up = run_alembic(test_database_url, "upgrade", "005")
+        # Leave the schema at head for the rest of the suite (core-api T-14).
+        up = run_alembic(test_database_url, "upgrade", "head")
         assert up.returncode == 0, up.stderr
         assert await _table_exists(test_database_url, "book_records")
         assert await _table_exists(test_database_url, "book_events")

tests/test_scribe_migration.py

@@ -120,8 +120,8 @@ class TestMigration006RoundTrip:
         # a downgrade of 006 — proves 006 only touches its own tables.
         assert await _table_exists(test_database_url, "book_records")
 
-        # Leave the schema at head for the rest of the suite.
-        up = run_alembic(test_database_url, "upgrade", "006")
+        # Leave the schema at head for the rest of the suite (core-api T-14).
+        up = run_alembic(test_database_url, "upgrade", "head")
         assert up.returncode == 0, up.stderr
         assert await _table_exists(test_database_url, "scribe_addresses")
         assert await _table_exists(test_database_url, "scribe_messages")

tests/test_tenants_migration.py

@@ -67,8 +67,8 @@ class TestMigration007RoundTrip:
         assert await _table_exists(test_database_url, "book_records")
         assert await _table_exists(test_database_url, "scribe_addresses")
 
-        # Leave the schema at head for the rest of the suite.
-        up = run_alembic(test_database_url, "upgrade", "007")
+        # Leave the schema at head for the rest of the suite (core-api T-14).
+        up = run_alembic(test_database_url, "upgrade", "head")
         assert up.returncode == 0, up.stderr
         assert await _table_exists(test_database_url, "tenants")
         assert await _table_exists(test_database_url, "tenant_consumers")
@@ -224,8 +224,8 @@ class TestMigration008RoundTrip:
         assert await _table_exists(test_database_url, "tenant_consumers")
         assert await _table_exists(test_database_url, "tenants")
 
-        # Leave the schema at head for the rest of the suite.
-        up = run_alembic(test_database_url, "upgrade", "008")
+        # Leave the schema at head for the rest of the suite (core-api T-14).
+        up = run_alembic(test_database_url, "upgrade", "head")
         assert up.returncode == 0, up.stderr
         found = await _scalar(
             test_database_url,
@@ -312,7 +312,10 @@ class TestMigration008DataStep:
         down = run_alembic(test_database_url, "downgrade", "007")
         assert down.returncode == 0, down.stderr
 
-        up = run_alembic(test_database_url, "upgrade", "008")
+        # Upgrade through to head (core-api T-14) — migrations 009/010 touch
+        # neither this table nor this column, so the assertion below still
+        # proves 008's data step alone.
+        up = run_alembic(test_database_url, "upgrade", "head")
         assert up.returncode == 0, up.stderr
         found = await _scalar(
             test_database_url,
@@ -356,7 +359,9 @@ class TestMigration008DataStep:
                     )
                 )
 
-            up = run_alembic(test_database_url, "upgrade", "008")
+            # Upgrade through to head (core-api T-14) — same reasoning as
+            # test_is_a_noop_when_claude_ai_is_absent above.
+            up = run_alembic(test_database_url, "upgrade", "head")
             assert up.returncode == 0, up.stderr
 
             found = await _scalar(
@@ -380,3 +385,22 @@ class TestMigration008DataStep:
                     )
                 )
             await engine.dispose()
+
+
+class TestSchemaEndsAtHeadAfterTheMigrationSuite:
+    """core-api T-14 regression guard: every round-trip test above (and in
+    test_book_migration.py / test_scribe_migration.py, which this file's
+    alphabetically-later collection runs after) must leave `core_api_test`
+    at head, not on its own revision. This class is the last one defined in
+    the last-collected migration test file, and its check is a bare
+    `current` — no `upgrade head` of its own — so a round-trip test that
+    regresses to ending on its own revision again shows up here as "not
+    head" rather than being silently repaired by this very check."""
+
+    @pytest.mark.asyncio
+    async def test_schema_is_at_head(self, test_database_url):
+        result = run_alembic(test_database_url, "current")
+        assert result.returncode == 0, result.stderr
+        assert "(head)" in result.stdout, (
+            f"core_api_test is not at head after the migration suite: {result.stdout!r}"
+        )