Resolve attribute chains through the four leaf sub-packages too

Every package init in the SDK resolves its submodules on attribute
access except four docstring-only leaves - mcp.os.posix, mcp.os.win32,
mcp.server.auth.handlers and mcp.server.auth.middleware - so a chain like
`import mcp; mcp.server.auth.handlers.token` stopped resolving even though
`mcp.client.stdio` and friends do. Give them the same lazy fallback, so
"attribute chains still resolve" is true without a footnote (explicit
imports remain the supported form), and pin one chain through each in the
ratchet.

Author: maxisbey

src/mcp/os/posix/__init__.py

@@ -1 +1,11 @@
 """POSIX-specific utilities for MCP."""
+
+from typing import TYPE_CHECKING
+
+from mcp.shared._lazy import lazy_module_attrs as _lazy_module_attrs
+
+# `mcp.os.posix.utilities` resolves by attribute access even before it was
+# imported explicitly, like the other packages. Runtime only, so a type
+# checker still flags a typo.
+if not TYPE_CHECKING:
+    __getattr__, __dir__ = _lazy_module_attrs(__name__, globals())

src/mcp/os/win32/__init__.py

@@ -1 +1,11 @@
 """Windows-specific utilities for MCP."""
+
+from typing import TYPE_CHECKING
+
+from mcp.shared._lazy import lazy_module_attrs as _lazy_module_attrs
+
+# `mcp.os.win32.utilities` resolves by attribute access even before it was
+# imported explicitly, like the other packages. Runtime only, so a type
+# checker still flags a typo.
+if not TYPE_CHECKING:
+    __getattr__, __dir__ = _lazy_module_attrs(__name__, globals())

src/mcp/server/auth/handlers/__init__.py

@@ -1 +1,11 @@
 """Request handlers for MCP authorization endpoints."""
+
+from typing import TYPE_CHECKING
+
+from mcp.shared._lazy import lazy_module_attrs as _lazy_module_attrs
+
+# `mcp.server.auth.handlers.<handler>` resolves by attribute access even
+# before that submodule was imported explicitly, like the other packages.
+# Runtime only, so a type checker still flags a typo.
+if not TYPE_CHECKING:
+    __getattr__, __dir__ = _lazy_module_attrs(__name__, globals())

src/mcp/server/auth/middleware/__init__.py

@@ -1 +1,11 @@
 """Middleware for MCP authorization."""
+
+from typing import TYPE_CHECKING
+
+from mcp.shared._lazy import lazy_module_attrs as _lazy_module_attrs
+
+# `mcp.server.auth.middleware.<module>` resolves by attribute access even
+# before that submodule was imported explicitly, like the other packages.
+# Runtime only, so a type checker still flags a typo.
+if not TYPE_CHECKING:
+    __getattr__, __dir__ = _lazy_module_attrs(__name__, globals())

tests/shared/test_lazy.py

@@ -65,11 +65,14 @@ def test_bare_import_mcp_still_resolves_deep_submodule_chains():
     probe = (
         "import mcp\n"
         "print([mcp.client.stdio.stdio_client.__name__, mcp.server.stdio.stdio_server.__name__,\n"
-        "       mcp.shared.memory.__name__, mcp.os.posix.__name__,\n"
+        "       mcp.shared.memory.__name__, mcp.os.posix.utilities.__name__,\n"
+        "       mcp.os.win32.utilities.__name__, mcp.server.auth.handlers.token.__name__,\n"
+        "       mcp.server.auth.middleware.auth_context.__name__,\n"
         "       'stdio' in dir(mcp.client), 'stdio' in dir(mcp.server), 'exceptions' in dir(mcp.shared)])\n"
     )
     result = subprocess.run([sys.executable, "-c", probe], capture_output=True, text=True, check=False, timeout=20)
     assert result.returncode == 0, result.stderr
-    assert result.stdout == snapshot(
-        "['stdio_client', 'stdio_server', 'mcp.shared.memory', 'mcp.os.posix', True, True, True]\n"
-    )
+    assert result.stdout == snapshot("""\
+['stdio_client', 'stdio_server', 'mcp.shared.memory', 'mcp.os.posix.utilities', 'mcp.os.win32.utilities', \
+'mcp.server.auth.handlers.token', 'mcp.server.auth.middleware.auth_context', True, True, True]
+""")