test(harness): isolate imports and stabilize browser and DNS fixtures

tests/test_fenced_invoke_no_raw_xml.py

@@ -3,41 +3,7 @@ can't be converted (e.g. a hyphenated/namespaced tool name that _XML_INVOKE_RE's
 \\w+ won't match, or an unknown tool) must NOT fall through and ship the raw XML
 to the code executor as if it were python/bash.
 """
-import sys
-from unittest.mock import MagicMock
-
-# This module needs the real agent-tool stack; importing it pulls in heavy
-# DB/auth deps, so we stub those just long enough to import, then restore them.
-# We deliberately do NOT pop src.tool_execution: popping and re-importing it
-# rebinds the `src` package's `tool_execution` attribute, so a later
-# `import src.tool_execution as te` resolves to a different module object than
-# the one its functions live in - which silently breaks tests that monkeypatch
-# it (e.g. test_edit_file's admin gate) and breaks request-scoped ContextVars.
-_ABSENT = object()
-_AGENT_MODULES = ["src.agent_tools", "src.tool_parsing", "src.tool_schemas"]
-_STUBBED = [
-    "sqlalchemy", "sqlalchemy.orm", "sqlalchemy.ext", "sqlalchemy.ext.declarative",
-    "sqlalchemy.ext.hybrid", "sqlalchemy.sql", "sqlalchemy.sql.expression",
-    "src.database", "core.models", "core.database", "core.auth",
-]
-_saved_stubs = {name: sys.modules.get(name, _ABSENT) for name in _STUBBED}
-
-for _mod in _AGENT_MODULES:
-    sys.modules.pop(_mod, None)
-for _mod in _STUBBED:
-    if _mod not in sys.modules:
-        sys.modules[_mod] = MagicMock()
-
-import src.agent_tools  # noqa: E402, F401
-from src.tool_parsing import parse_tool_blocks  # noqa: E402
-
-# Drop the stubs we installed so they do not leak into later tests.
-for _name, _original in _saved_stubs.items():
-    if _original is _ABSENT:
-        sys.modules.pop(_name, None)
-    else:
-        sys.modules[_name] = _original
-
+from src.tool_parsing import parse_tool_blocks
 
 def test_unconvertible_invoke_in_fence_is_not_executed_as_code():
     text = '```python\n<invoke name="foo-bar">\n<parameter name="x">1</parameter>\n</invoke>\n```'