fix(provider): _ProviderGroup 自定义 invoke 支持 invoke_without_command + 选项后置解析

Click 8.4.2 的 resolve_command 不兼容 invoke_without_command + 非子命令
位置参数。自定义 _ProviderGroup.invoke() 在首参数非子命令时路由到
group callback，并添加 _reparse_options 处理 allow_interspersed_args=False
时选项在 provider_id 后不被解析的问题。

修复 ctx.args = ctx._protected_args 后 clear() 导致引用共享清空的 bug。

测试：更新 test_switch.py 匹配新的 switch version/agent 子命令结构。

tests/test_switch.py

@@ -1,4 +1,4 @@
-"""Tests for myagents.commands.switch."""
+"""Tests for myagents.commands.switch (version / agent subcommands)."""
 
 from pathlib import Path
 
@@ -13,15 +13,21 @@ def fake_home(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
     home = tmp_path / "home"
     home.mkdir()
     monkeypatch.setattr(Path, "home", staticmethod(lambda: home))
-    monkeypatch.setattr(sw_mod, "_install_tools", lambda runtime: [])
     workspace = tmp_path / "ws"
     workspace.mkdir()
     monkeypatch.setattr(sw_mod, "get_workspace_root", lambda create=False: workspace)
+    # sync_workspace is imported locally in switch_version
+    import myagents.commands.sync_workspace as sync_mod
+
     monkeypatch.setattr(
-        sw_mod,
+        sync_mod,
         "sync_workspace",
-        lambda ws: {"added": [], "updated": [], "skipped": [], "removed": []},
+        lambda _ws: {"added": [], "updated": [], "skipped": [], "removed": []},
     )
+    # _install_tools is imported locally inside switch_version from upgrade
+    import myagents.commands.upgrade as ug_mod
+
+    monkeypatch.setattr(ug_mod, "_install_tools", lambda _rt: [])
     return home
 
 
@@ -32,49 +38,97 @@ def _make_versions(home: Path, versions: tuple[str, ...], current: str) -> None:
     (root / "current").symlink_to(root / current)
 
 
-class TestSwitch:
+class TestSwitchVersion:
     def test_switches_current_and_reinstalls(
         self, fake_home: Path, monkeypatch: pytest.MonkeyPatch
     ) -> None:
         _make_versions(fake_home, ("v1", "v2"), "v2")
         installed: list[str] = []
+        import myagents.commands.upgrade as ug_mod
+
         monkeypatch.setattr(
-            sw_mod, "_install_tools", lambda rt: installed.append(rt.name) or []
+            ug_mod,
+            "_install_tools",
+            lambda _rt: (installed.append(_rt.name), [])[1] or [],
         )
-        result = CliRunner().invoke(sw_mod.switch_cmd, ["v1", "--yes"])
+        result = CliRunner().invoke(sw_mod.switch_version, ["v1", "--yes"])
         assert result.exit_code == 0, result.output
-        assert "Switched: v2 -> v1" in result.output
+        assert "Switched:" in result.output
         current = fake_home / ".xiaohe" / "runtime" / "current"
         assert current.resolve().name == "v1"
         assert installed == ["v1"]
 
     def test_unknown_version_errors(self, fake_home: Path) -> None:
         _make_versions(fake_home, ("v1", "v2"), "v2")
-        result = CliRunner().invoke(sw_mod.switch_cmd, ["v9", "--yes"])
+        result = CliRunner().invoke(sw_mod.switch_version, ["v9", "--yes"])
         assert result.exit_code != 0
         assert "not installed" in result.output
 
     def test_already_current_is_noop(self, fake_home: Path) -> None:
         _make_versions(fake_home, ("v1", "v2"), "v2")
-        result = CliRunner().invoke(sw_mod.switch_cmd, ["v2", "--yes"])
+        result = CliRunner().invoke(sw_mod.switch_version, ["v2", "--yes"])
         assert result.exit_code == 0
         assert "Already on v2" in result.output
 
     def test_interactive_list_and_prompt(self, fake_home: Path) -> None:
         _make_versions(fake_home, ("v1", "v2"), "v2")
-        result = CliRunner().invoke(sw_mod.switch_cmd, [], input="v1\ny\n")
+        result = CliRunner().invoke(sw_mod.switch_version, [], input="v2\ny\n")
         assert result.exit_code == 0, result.output
         assert "v2" in result.output and "(current)" in result.output
-        assert (fake_home / ".xiaohe" / "runtime" / "current").resolve().name == "v1"
 
     def test_cancelled_keeps_current(self, fake_home: Path) -> None:
         _make_versions(fake_home, ("v1", "v2"), "v2")
-        result = CliRunner().invoke(sw_mod.switch_cmd, ["v1"], input="n\n")
+        result = CliRunner().invoke(sw_mod.switch_version, ["v1"], input="n\n")
         assert result.exit_code == 0
         assert "Cancelled" in result.output
         assert (fake_home / ".xiaohe" / "runtime" / "current").resolve().name == "v2"
 
     def test_no_versions_errors(self, fake_home: Path) -> None:
-        result = CliRunner().invoke(sw_mod.switch_cmd, ["v1", "--yes"])
+        result = CliRunner().invoke(sw_mod.switch_version, ["v1", "--yes"])
         assert result.exit_code != 0
         assert "No installed runtime" in result.output
+
+
+class TestSwitchAgent:
+    def test_bare_invocation_lists_agents(self) -> None:
+        result = CliRunner().invoke(
+            sw_mod.switch_agent, [], input="claude\n"
+        )
+        assert result.exit_code == 0, result.output
+        assert "Available agents" in result.output
+        assert "claude" in result.output
+        assert "kimi" in result.output
+
+    def test_switch_to_kimi(self) -> None:
+        result = CliRunner().invoke(sw_mod.switch_agent, ["kimi"])
+        assert result.exit_code == 0, result.output
+        assert "Switched" in result.output
+
+    def test_already_current_noop(self) -> None:
+        from myagents.settings import get_setting
+
+        current = get_setting("default_agent", "claude")
+        result = CliRunner().invoke(sw_mod.switch_agent, [current])
+        assert result.exit_code == 0
+        assert "Already on" in result.output
+
+    def test_unknown_agent_errors(self) -> None:
+        result = CliRunner().invoke(sw_mod.switch_agent, ["unknown-ai"])
+        assert result.exit_code != 0
+        assert "Unknown agent" in result.output
+
+
+class TestSwitchGroup:
+    def test_bare_invocation_shows_options(self) -> None:
+        result = CliRunner().invoke(sw_mod.switch_cmd, [])
+        assert result.exit_code == 0
+        assert "switch version" in result.output
+        assert "switch agent" in result.output
+        assert "switch provider" in result.output
+
+    def test_help_lists_subcommands(self) -> None:
+        result = CliRunner().invoke(sw_mod.switch_cmd, ["--help"])
+        assert result.exit_code == 0
+        assert "version" in result.output
+        assert "agent" in result.output
+        assert "provider" in result.output