test(appstate): address CodeRabbit — restore slots on teardown, really re-import

Two real findings on #833, both fixed:

(1) `isolated_server` closed server's DB connections but left `appstate.meta_db`
    and `appstate.audio_effect_mappings` published and pointing at the closed
    handles -- a live-looking, dead singleton for any later test. Teardown now
    snapshots and restores both slots.

(2) `test_reimporting_server_republishes_the_fresh_singletons` never performed a
    second import: it only re-asserted what `test_server_wires_the_seam` already
    covers, so it could not detect the very staleness it names. (I introduced
    that regression while fixing Codex's CONFIG_DIR isolation finding.) It now
    pops `server`, re-imports under a SECOND CONFIG_DIR, and asserts the seam
    republishes -- `second_server.meta_db is not first_db` and
    `appstate.meta_db is second_server.meta_db`.

Negative-checked both directions: simulating an appstate-OWNED singleton
(configure() only-first-wins) now fails the re-import test, and dropping
server's configure() call still fails exactly the two wiring tests.

NB CodeRabbit's committable suggestion inserted the snapshot above the
fixture docstring, which would have demoted it from __doc__; written by hand
instead.

pytest 2348 passed; the full suite leaves the real ~/.local/share/feedback
untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_appstate.py

@@ -16,6 +16,16 @@ import pytest
 import appstate
 
 
+def _close_server_dbs(mod):
+    conn = getattr(getattr(mod, "meta_db", None), "conn", None)
+    if conn is not None:
+        getattr(mod, "_join_background_db_threads", lambda: None)()
+        conn.close()
+    ae_conn = getattr(getattr(mod, "audio_effect_mappings", None), "conn", None)
+    if ae_conn is not None:
+        ae_conn.close()
+
+
 @pytest.fixture()
 def isolated_server(tmp_path, monkeypatch):
     """A freshly imported `server` bound to a throwaway CONFIG_DIR.
@@ -25,20 +35,20 @@ def isolated_server(tmp_path, monkeypatch):
     unguarded `import server` would create/mutate the developer's real
     `~/.local/share/feedback` databases. Same idiom as the other ~49
     server-importing suites.
+
+    Teardown restores the appstate slots as well as closing the connections:
+    leaving `appstate.meta_db` published but pointing at a closed sqlite handle
+    would hand a later test (or router) a live-looking, dead singleton.
     """
+    previous = (appstate.meta_db, appstate.audio_effect_mappings)
     monkeypatch.setenv("CONFIG_DIR", str(tmp_path))
     sys.modules.pop("server", None)
     mod = importlib.import_module("server")
     yield mod
-    conn = getattr(getattr(mod, "meta_db", None), "conn", None)
-    if conn is not None:
-        getattr(mod, "_join_background_db_threads", lambda: None)()
-        conn.close()
-    ae_conn = getattr(getattr(mod, "audio_effect_mappings", None), "conn", None)
-    if ae_conn is not None:
-        ae_conn.close()
+    _close_server_dbs(mod)
     # Leave no half-torn-down `server` behind: the next fixture re-imports it.
     sys.modules.pop("server", None)
+    appstate.configure(meta_db=previous[0], audio_effect_mappings=previous[1])
 
 
 def test_import_is_side_effect_free():
@@ -114,9 +124,30 @@ def test_server_wires_the_seam(isolated_server):
     assert appstate.meta_db is not None
 
 
-def test_reimporting_server_republishes_the_fresh_singletons(isolated_server, tmp_path):
-    """The 49-fixture contract: re-importing server under a new CONFIG_DIR must
-    leave the seam pointing at the NEW meta_db, without those fixtures having to
-    know appstate exists."""
-    assert appstate.meta_db is isolated_server.meta_db
-    assert str(tmp_path) in isolated_server.meta_db.db_path
+def test_reimporting_server_republishes_the_fresh_singletons(
+    isolated_server, tmp_path, monkeypatch
+):
+    """The 49-fixture contract, exercised end to end.
+
+    Those fixtures `sys.modules.pop("server")` + re-import to rebuild `meta_db`
+    under a new CONFIG_DIR, and know nothing about appstate. So the seam must
+    re-publish on that second import. This is the test that would fail if
+    `appstate` ever *owned* the singletons: a module-level `meta_db` there
+    survives the pop and the assertions below would still see the FIRST DB.
+    """
+    first_db = isolated_server.meta_db
+    assert appstate.meta_db is first_db
+    assert str(tmp_path) in first_db.db_path
+
+    second_config = tmp_path / "second"
+    monkeypatch.setenv("CONFIG_DIR", str(second_config))
+    sys.modules.pop("server", None)
+    second_server = importlib.import_module("server")
+    try:
+        assert second_server.meta_db is not first_db          # genuinely rebuilt
+        assert str(second_config) in second_server.meta_db.db_path
+        assert appstate.meta_db is second_server.meta_db      # ...and re-published
+        assert appstate.audio_effect_mappings is second_server.audio_effect_mappings
+    finally:
+        _close_server_dbs(second_server)
+        sys.modules.pop("server", None)