feat: xiaohe 命令组 + settings.json 拆分 + workspace 同步引擎

- xiaohe：默认转发 default_agent（settings.json default_agent，兼容 myclaude 拼写），
  子命令 init（首用引导 workspace 路径+骨架+sync+启动器）/ sync（runtime→workspace
  哈希三态同步：新增/覆盖/本地改动跳过；git 检出拒绝）
- settings.py：~/.xiaohe/agent/settings.json 优先，config.json settings 段兜底
- get_workspace_root：env > settings > project_root/workspace > ~/workspace
- build_cli 增 offer_install：缺二进制时交互提示安装（claude/codex 有 install_cmd）
- 测试 +11（settings/sync 引擎三态/幂等/git 拒绝）

tests/test_settings.py

@@ -0,0 +1,48 @@
+"""Tests for myagents.settings."""
+
+import json
+from pathlib import Path
+
+import pytest
+
+from myagents import settings as settings_mod
+
+
+@pytest.fixture()
+def fake_config_dir(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    config_dir = tmp_path / ".xiaohe" / "agent"
+    monkeypatch.setattr(settings_mod, "CONFIG_DIR", config_dir)
+    monkeypatch.setattr(settings_mod, "SETTINGS_PATH", config_dir / "settings.json")
+    monkeypatch.setattr(
+        settings_mod, "LEGACY_CONFIG_PATH", config_dir / "config.json"
+    )
+    return config_dir
+
+
+class TestLoadSettings:
+    def test_empty_when_no_files(self, fake_config_dir: Path) -> None:
+        assert settings_mod.load_settings() == {}
+
+    def test_settings_json_wins_over_legacy(self, fake_config_dir: Path) -> None:
+        fake_config_dir.mkdir(parents=True)
+        (fake_config_dir / "config.json").write_text(
+            json.dumps({"keys": {}, "settings": {"a": "legacy", "b": "legacy"}})
+        )
+        (fake_config_dir / "settings.json").write_text(json.dumps({"b": "new"}))
+        assert settings_mod.load_settings() == {"a": "legacy", "b": "new"}
+
+    def test_corrupt_files_yield_empty(self, fake_config_dir: Path) -> None:
+        fake_config_dir.mkdir(parents=True)
+        (fake_config_dir / "settings.json").write_text("{not json")
+        assert settings_mod.load_settings() == {}
+
+
+class TestSaveAndSet:
+    def test_set_setting_roundtrip(self, fake_config_dir: Path) -> None:
+        settings_mod.set_setting("workspace_root", "/tmp/ws")
+        assert settings_mod.get_setting("workspace_root") == "/tmp/ws"
+        on_disk = json.loads((fake_config_dir / "settings.json").read_text())
+        assert on_disk == {"workspace_root": "/tmp/ws"}
+
+    def test_get_setting_default(self, fake_config_dir: Path) -> None:
+        assert settings_mod.get_setting("missing", "dflt") == "dflt"

tests/test_sync_workspace.py

@@ -0,0 +1,87 @@
+"""Tests for myagents.commands.sync_workspace."""
+
+import json
+from pathlib import Path
+
+import click
+import pytest
+
+from myagents.commands import sync_workspace as sync_mod
+
+
+@pytest.fixture()
+def runtime(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
+    rt = tmp_path / "runtime"
+    (rt / ".agents" / "skills" / "demo").mkdir(parents=True)
+    (rt / ".agents" / "skills" / "demo" / "SKILL.md").write_text("demo v1")
+    (rt / "agents.md").write_text("agent rules v1")
+    (rt / "VERSION").write_text("v0.0.0-test\n")
+    monkeypatch.setattr(sync_mod, "get_runtime_root", lambda: rt)
+    return rt
+
+
+@pytest.fixture()
+def workspace(tmp_path: Path) -> Path:
+    ws = tmp_path / "workspace"
+    ws.mkdir()
+    return ws
+
+
+def _read_stamp(ws: Path) -> dict:
+    return json.loads((ws / sync_mod.STAMP_NAME).read_text())
+
+
+class TestSyncWorkspace:
+    def test_new_files_copied_and_symlinks_made(
+        self, runtime: Path, workspace: Path
+    ) -> None:
+        report = sync_mod.sync_workspace(workspace)
+        skill = workspace / ".agents" / "skills" / "demo" / "SKILL.md"
+        assert skill.read_text() == "demo v1"
+        assert (workspace / "agents.md").read_text() == "agent rules v1"
+        assert (workspace / "CLAUDE.md").is_symlink()
+        assert (workspace / ".claude").is_symlink()
+        assert report["added"] and not report["skipped"]
+        assert _read_stamp(workspace)["version"] == "v0.0.0-test"
+
+    def test_second_run_is_noop(self, runtime: Path, workspace: Path) -> None:
+        sync_mod.sync_workspace(workspace)
+        report = sync_mod.sync_workspace(workspace)
+        assert report == {"added": [], "updated": [], "skipped": [], "removed": []}
+
+    def test_upgrade_overwrites_untouched_file(
+        self, runtime: Path, workspace: Path
+    ) -> None:
+        sync_mod.sync_workspace(workspace)
+        (runtime / "agents.md").write_text("agent rules v2")
+        report = sync_mod.sync_workspace(workspace)
+        assert (workspace / "agents.md").read_text() == "agent rules v2"
+        assert "agents.md" in report["updated"]
+
+    def test_user_modified_file_is_skipped(
+        self, runtime: Path, workspace: Path
+    ) -> None:
+        sync_mod.sync_workspace(workspace)
+        (workspace / "agents.md").write_text("my local edits")
+        (runtime / "agents.md").write_text("agent rules v2")
+        report = sync_mod.sync_workspace(workspace)
+        assert (workspace / "agents.md").read_text() == "my local edits"
+        assert "agents.md" in report["skipped"]
+
+    def test_removed_from_runtime_is_removed_from_workspace(
+        self, runtime: Path, workspace: Path
+    ) -> None:
+        sync_mod.sync_workspace(workspace)
+        (runtime / ".agents" / "skills" / "demo" / "SKILL.md").unlink()
+        report = sync_mod.sync_workspace(workspace)
+        assert not (workspace / ".agents" / "skills" / "demo" / "SKILL.md").exists()
+        assert report["removed"]
+
+    def test_git_checkout_refused_without_force(
+        self, runtime: Path, workspace: Path
+    ) -> None:
+        (workspace / ".git").mkdir()
+        with pytest.raises(click.ClickException):
+            sync_mod.sync_workspace(workspace)
+        report = sync_mod.sync_workspace(workspace, force=True)
+        assert report["added"]