fix(tests): stop poisoning sys.modules session-wide with a bare MagicMock

Three test files (test_llm_scoping, test_fix_meshcore_save_and_llm_test,
test_config_partial_save_merge) did `sys.modules.setdefault(_mod, MagicMock())`
to stub an optional import. `setdefault` installs the MagicMock into
sys.modules for the ENTIRE pytest session even when the real package is
present — so any LATER test that does `await <that module>.<coro>(...)`
(e.g. `await aiosqlite.connect(...)`) fails with
"object MagicMock can't be used in 'await' expression" / "Event loop is closed".

This is what made test_fire_tracker_phase4::test_natural_language_fire_
question_routes_to_llm pass in isolation but fail in full-suite order — the
leak came from an earlier file, not the victim. #140 hardened the victim's
own config/history isolation but couldn't fix an external sys.modules poison.

Fix: only fall back to the MagicMock when the real module genuinely fails to
import (guarded assignment), so a present package is never replaced. Root-cause
fix in the polluters, not a skip on the victim.

Suite: 2422 passed, 0 failed, 72 skipped — fully green (was 6 failed before
#140, then 1 order-dependent failure after). Confirmed deterministic across
repeated full runs.

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

work/tests/test_config_partial_save_merge.py

@@ -32,6 +32,7 @@ omitted keys keep their live values while explicitly-sent keys still apply.
 """
 from __future__ import annotations
 
+import importlib
 import sys
 from unittest.mock import MagicMock
 
@@ -41,8 +42,22 @@ from fastapi import FastAPI
 from fastapi.testclient import TestClient
 
 # Stub heavy optional deps so config_routes imports without them.
+#
+# Try the real import first -- sys.modules.setdefault() alone is only a
+# no-op "in production where the real packages are installed" if some
+# earlier-run test has already imported the real module. When this file
+# collects first (test order is alphabetical, not guaranteed), setdefault()
+# permanently replaces a genuinely-installed module (e.g. aiosqlite) with a
+# bare MagicMock for the rest of the pytest session -- every later test's
+# `await aiosqlite.connect(...)` then breaks with "MagicMock can't be used
+# in 'await' expression". Only fall back to the mock when the real package
+# truly isn't importable.
 for _mod in ("openai", "aiosqlite", "anthropic", "google", "google.genai"):
-    sys.modules.setdefault(_mod, MagicMock())
+    if _mod not in sys.modules:
+        try:
+            importlib.import_module(_mod)
+        except ImportError:
+            sys.modules[_mod] = MagicMock()
 
 from meshai.config import (  # noqa: E402
     Config,

work/tests/test_fix_meshcore_save_and_llm_test.py

@@ -12,6 +12,7 @@ Bug 2 — POST /api/config/test-llm "string indices must be integers, not 'str'"
 """
 from __future__ import annotations
 
+import importlib
 import sys
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock, patch
@@ -20,9 +21,23 @@ import pytest
 
 # -----------------------------------------------------------------------
 # Stub heavy optional deps so config_routes can be imported without them.
+#
+# Try the real import first -- sys.modules.setdefault() alone is only a
+# no-op "in production where the real packages are installed" if some
+# earlier-run test has already imported the real module. When this file
+# collects first (test order is alphabetical, not guaranteed), setdefault()
+# permanently replaces a genuinely-installed module (e.g. aiosqlite) with a
+# bare MagicMock for the rest of the pytest session -- every later test's
+# `await aiosqlite.connect(...)` then breaks with "MagicMock can't be used
+# in 'await' expression". Only fall back to the mock when the real package
+# truly isn't importable.
 # -----------------------------------------------------------------------
 for _mod in ("openai", "aiosqlite", "anthropic", "google", "google.genai"):
-    sys.modules.setdefault(_mod, MagicMock())
+    if _mod not in sys.modules:
+        try:
+            importlib.import_module(_mod)
+        except ImportError:
+            sys.modules[_mod] = MagicMock()
 
 
 # ==========================================================================

work/tests/test_llm_scoping.py

@@ -7,6 +7,7 @@ Covers:
   (d) ContextConfig.max_age default is 14 days (1_209_600 seconds)
 """
 
+import importlib
 import sys
 from unittest.mock import MagicMock
 
@@ -14,11 +15,23 @@ import pytest
 
 # ---------------------------------------------------------------------------
 # Stub optional heavy deps so meshai.router can be imported in this env.
-# These stubs are set before any meshai.router import in this process;
-# they are no-ops in production where the real packages are installed.
+#
+# Try the real import first -- sys.modules.setdefault() alone is only a
+# no-op "in production where the real packages are installed" if some
+# earlier-run test has already imported the real module. When this file
+# collects first (test order is alphabetical, not guaranteed), setdefault()
+# permanently replaces a genuinely-installed module (e.g. aiosqlite) with a
+# bare MagicMock for the rest of the pytest session -- every later test's
+# `await aiosqlite.connect(...)` then breaks with "MagicMock can't be used
+# in 'await' expression". Only fall back to the mock when the real package
+# truly isn't importable.
 # ---------------------------------------------------------------------------
 for _mod in ("openai", "aiosqlite", "anthropic", "google", "google.genai"):
-    sys.modules.setdefault(_mod, MagicMock())
+    if _mod not in sys.modules:
+        try:
+            importlib.import_module(_mod)
+        except ImportError:
+            sys.modules[_mod] = MagicMock()
 
 from meshai.config import (  # noqa: E402
     BotConfig,