test: add multiple new test cases and update python version

1. update .python-version from 3.11 to 3.13
2. add tests for IS_RUNNING and DIR_EXISTS conditions
3. add graph-related tests including string ref parsing, mermaid output, GraphComposer and compose function
4. add storage backend TTL tests for both MemoryBackend and JSONBackend
5. add new system task tests for clr, reset_icon_cache, setenv and which
6. add comprehensive task spec tests including soft dependencies, retry policy, context managers and task template
7. add executor edge case tests for various scenarios

tests/test_conditions.py

@@ -4,8 +4,11 @@ from __future__ import annotations
 
 import os
 import sys
+from pathlib import Path
 from unittest.mock import patch
 
+import pytest
+
 from pyflowx.conditions import (
     IS_LINUX,
     IS_MACOS,
@@ -216,3 +219,85 @@ def test_logical_combination_with_dep_conditions():
         BuiltinConditions.NOT(BuiltinConditions.DEP_TRUTHY("b")),
     )
     assert cond(ctx) is True
+
+
+# ---------------------------------------------------------------------- #
+# IS_RUNNING: 跨平台 subprocess 检测
+# ---------------------------------------------------------------------- #
+def test_is_running_windows_found(monkeypatch: pytest.MonkeyPatch):
+    """Windows 上 tasklist 检测到进程."""
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_WINDOWS", True)
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_LINUX", False)
+
+    class MockResult:
+        stdout = "explorer.exe\nother.exe"
+        returncode = 0
+
+    monkeypatch.setattr(
+        "subprocess.run",
+        lambda *a, **kw: MockResult(),
+    )
+    cond = BuiltinConditions.IS_RUNNING("explorer.exe")
+    assert cond({}) is True
+
+
+def test_is_running_windows_not_found(monkeypatch: pytest.MonkeyPatch):
+    """Windows 上 tasklist 未检测到进程."""
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_WINDOWS", True)
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_LINUX", False)
+
+    class MockResult:
+        stdout = "other.exe"
+        returncode = 0
+
+    monkeypatch.setattr(
+        "subprocess.run",
+        lambda *a, **kw: MockResult(),
+    )
+    cond = BuiltinConditions.IS_RUNNING("explorer.exe")
+    assert cond({}) is False
+
+
+def test_is_running_linux_found(monkeypatch: pytest.MonkeyPatch):
+    """Linux 上 pgrep 检测到进程."""
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_WINDOWS", False)
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_LINUX", True)
+
+    class MockResult:
+        returncode = 0
+
+    monkeypatch.setattr(
+        "subprocess.run",
+        lambda *a, **kw: MockResult(),
+    )
+    cond = BuiltinConditions.IS_RUNNING("nginx")
+    assert cond({}) is True
+
+
+def test_is_running_linux_not_found(monkeypatch: pytest.MonkeyPatch):
+    """Linux 上 pgrep 未检测到进程."""
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_WINDOWS", False)
+    monkeypatch.setattr("pyflowx.conditions.Constants.IS_LINUX", True)
+
+    class MockResult:
+        returncode = 1
+
+    monkeypatch.setattr(
+        "subprocess.run",
+        lambda *a, **kw: MockResult(),
+    )
+    cond = BuiltinConditions.IS_RUNNING("nonexistent")
+    assert cond({}) is False
+
+
+def test_dir_exists_true(tmp_path: Path):
+    """DIR_EXISTS 检测路径存在."""
+    cond = BuiltinConditions.DIR_EXISTS(tmp_path)
+    assert cond({}) is True
+
+
+def test_dir_exists_false(tmp_path: Path):
+    """DIR_EXISTS 检测路径不存在."""
+    missing = tmp_path / "nonexistent"
+    cond = BuiltinConditions.DIR_EXISTS(missing)
+    assert cond({}) is False