test(crew): lock the documented public import surface (regression guard)

Executes 'from smallestai.atoms.crew import AtomsCrewApp, CrewSession, ...' so the
exact ImportError a customer hit can't silently come back. Lives in tests/custom
(fernignored), runs in the SDK test CI.

Author: abhishekmishragithub

tests/custom/test_public_imports.py

@@ -0,0 +1,57 @@
+"""Guards the documented public import surface of `smallestai.atoms.crew`.
+
+A customer hit `ImportError` on `from smallestai.atoms.crew import AtomsCrewApp`
+because `crew/__init__` exported nothing (the imports there lived only in the
+docstring). Both the module docstring and the docs advertise this short path, so
+lock it here: if the package stops exporting a public symbol, this test fails in
+CI rather than in a customer's notebook.
+"""
+
+import importlib
+
+CREW_PUBLIC = [
+    "AtomsCrewApp",
+    "CrewSession",
+    "OutputCrewNode",
+    "BackgroundCrewNode",
+    "OpenAIClient",
+    "function_tool",
+    "ToolRegistry",
+]
+
+
+def test_crew_all_advertises_public_api():
+    mod = importlib.import_module("smallestai.atoms.crew")
+    assert set(CREW_PUBLIC) <= set(mod.__all__)
+
+
+def test_crew_public_symbols_resolve_from_short_path():
+    from smallestai.atoms.crew import (  # noqa: F401
+        AtomsCrewApp,
+        BackgroundCrewNode,
+        CrewSession,
+        OpenAIClient,
+        OutputCrewNode,
+        ToolRegistry,
+        function_tool,
+    )
+
+    for sym in (
+        AtomsCrewApp,
+        CrewSession,
+        OutputCrewNode,
+        BackgroundCrewNode,
+        OpenAIClient,
+        ToolRegistry,
+        function_tool,
+    ):
+        assert sym is not None
+
+
+def test_unknown_attr_raises_attributeerror():
+    mod = importlib.import_module("smallestai.atoms.crew")
+    try:
+        mod.DefinitelyNotAThing
+    except AttributeError:
+        return
+    raise AssertionError("expected AttributeError for an unknown attribute")