Squash Odysseus development history

tests/test_history_routes_shim.py

@@ -0,0 +1,43 @@
+"""Regression test for the history route shim (slice 2d, #4082/#4071).
+
+The backward-compat shim at ``routes/history_routes.py`` uses ``sys.modules``
+replacement so the legacy import path and the canonical ``routes.history.*``
+path resolve to the *same* module object. This is required because
+``test_history_compact_tool_calls.py`` and ``test_fork_session_metadata.py``
+do ``import routes.history_routes as history_routes`` followed by
+``monkeypatch.setattr(history_routes, "_verify_session_owner", ...)`` — for
+those patches to take effect at runtime, the legacy module object and the
+canonical one must be identical. This test pins that contract.
+"""
+
+import importlib
+
+import routes.history_routes as _shim_history  # noqa: F401
+
+
+def test_legacy_and_canonical_history_module_are_same_object():
+    """``import routes.history_routes`` must alias the canonical module."""
+    legacy = importlib.import_module("routes.history_routes")
+    canonical = importlib.import_module("routes.history.history_routes")
+    assert legacy is canonical, (
+        "routes.history_routes shim must resolve to the canonical "
+        "routes.history.history_routes module object"
+    )
+
+
+def test_monkeypatch_via_legacy_alias_reaches_canonical(monkeypatch):
+    """Patching through the legacy alias must reach the canonical module.
+
+    Several history tests do ``import routes.history_routes as history_routes``
+    followed by ``monkeypatch.setattr(history_routes, "_verify_session_owner",
+    ...)``. For that to take effect at runtime, the legacy module object and the
+    canonical one must be identical.
+    """
+    legacy = importlib.import_module("routes.history_routes")
+    canonical = importlib.import_module("routes.history.history_routes")
+
+    sentinel = object()
+    monkeypatch.setattr(legacy, "setup_history_routes", sentinel)
+    assert canonical.setup_history_routes is sentinel, (
+        "monkeypatch via legacy alias did not reach the canonical module"
+    )