diff --git a/pyproject.toml b/pyproject.toml
index 16863cf..b5d14f2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,10 @@ classifiers = [
     "Programming Language :: Python :: 3.9",
     "Topic :: Software Development :: Libraries :: Application Frameworks",
 ]
-dependencies = ["graphlib_backport >= 1.0.0; python_version < '3.9'"]
+dependencies = [
+    "graphlib_backport >= 1.0.0; python_version < '3.9'",
+    "typing-extensions>=4.13.2",
+]
 description = "Lightweight, type-safe DAG task scheduler with multi-strategy execution."
 keywords = ["async", "dag", "scheduler", "task", "workflow"]
 license = { text = "MIT" }
@@ -22,9 +25,9 @@ version = "0.2.3"
 [project.scripts]
 autofmt     = "pyflowx.cli.autofmt:main"
 bumpversion = "pyflowx.cli.bumpversion:main"
-clr         = "pyflowx.cli.clearscreen:main"
+cls         = "pyflowx.cli.clearscreen:main"
 emlman      = "pyflowx.cli.emlmanager:main"
-envlinux    = "pyflowx.cli.envlinux:main"
+envdev      = "pyflowx.cli.envdev:main"
 envpy       = "pyflowx.cli.envpy:main"
 envqt       = "pyflowx.cli.envqt:main"
 envrs       = "pyflowx.cli.envrs:main"
@@ -146,6 +149,6 @@ select = [
 "**/tests/**" = ["ARG001", "ARG002"]
 
 [tool.pyrefly]
-preset           = "basic"
+preset           = "strict"
 project-includes = ["**/*.ipynb", "**/*.py*"]
 python-version   = "3.8"
diff --git a/src/pyflowx/cli/__init__.py b/src/pyflowx/cli/__init__.py
index 278ad14..e69de29 100644
--- a/src/pyflowx/cli/__init__.py
+++ b/src/pyflowx/cli/__init__.py
@@ -1,78 +0,0 @@
-"""CLI 工具模块.
-
-提供各种命令行工具的入口点.
-"""
-
-from __future__ import annotations
-
-# 自动格式化工具
-from pyflowx.cli.autofmt import main as autofmt_main
-from pyflowx.cli.bumpversion import main as bumpversion_main
-from pyflowx.cli.clearscreen import main as clearscreen_main
-
-# EML 邮件管理工具
-from pyflowx.cli.emlmanager import main as emlmanager_main
-
-# EML 邮件管理工具
-from pyflowx.cli.emlmanager import main as emlmanager_web_main
-from pyflowx.cli.envpy import main as envpy_main
-from pyflowx.cli.envqt import main as envqt_main
-from pyflowx.cli.envrs import main as envrs_main
-
-# 文件工具
-from pyflowx.cli.filedate import main as filedate_main
-from pyflowx.cli.filelevel import main as filelevel_main
-from pyflowx.cli.folderback import main as folderback_main
-from pyflowx.cli.folderzip import main as folderzip_main
-
-# Git 工具
-from pyflowx.cli.gittool import main as gittool_main
-
-# 仿真工具
-from pyflowx.cli.lscalc import main as lscalc_main
-
-# 打包工具
-from pyflowx.cli.packtool import main as packtool_main
-
-# PDF 工具
-from pyflowx.cli.pdftool import main as pdftool_main
-
-# 开发工具
-from pyflowx.cli.piptool import main as piptool_main
-from pyflowx.cli.pymake import main as pymake_main
-from pyflowx.cli.screenshot import main as screenshot_main
-from pyflowx.cli.sshcopyid import main as sshcopyid_main
-
-__all__ = [
-    # 自动格式化工具
-    "autofmt_main",
-    "bumpversion_main",
-    "clearscreen_main",
-    # EML 邮件管理工具
-    "emlmanager_main",
-    "emlmanager_web_main",
-    "envpy_main",
-    "envqt_main",
-    "envrs_main",
-    # 文件工具
-    "filedate_main",
-    "filelevel_main",
-    "folderback_main",
-    "folderzip_main",
-    # Git 工具
-    "gittool_main",
-    # 仿真工具
-    "lscalc_main",
-    # 打包工具
-    "packtool_main",
-    # PDF 工具
-    "pdftool_main",
-    # 开发工具
-    "piptool_main",
-    "pymake_main",
-    "screenshot_main",
-    "sshcopyid_main",
-    # 系统工具
-    "taskkill_main",
-    "which_main",
-]
diff --git a/src/pyflowx/cli/autofmt.py b/src/pyflowx/cli/autofmt.py
index c249de2..4deb81d 100644
--- a/src/pyflowx/cli/autofmt.py
+++ b/src/pyflowx/cli/autofmt.py
@@ -268,13 +268,13 @@ def main() -> None:
             cmd.extend(["--fix", "--unsafe-fixes"])
         graph = px.Graph.from_specs([px.TaskSpec("ruff_check", cmd=cmd, verbose=True)])
     elif args.command == "doc":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("auto_docstring", fn=auto_add_docstrings, args=(Path(args.root_dir),), verbose=True)]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("auto_docstring", fn=auto_add_docstrings, args=(Path(args.root_dir),), verbose=True)
+        ])
     elif args.command == "sync":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("sync_config", fn=sync_pyproject_config, args=(Path(args.root_dir),), verbose=True)]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("sync_config", fn=sync_pyproject_config, args=(Path(args.root_dir),), verbose=True)
+        ])
     else:
         parser.print_help()
         return
diff --git a/src/pyflowx/cli/bumpversion.py b/src/pyflowx/cli/bumpversion.py
index 05118c8..e7521eb 100644
--- a/src/pyflowx/cli/bumpversion.py
+++ b/src/pyflowx/cli/bumpversion.py
@@ -212,16 +212,14 @@ def main() -> None:
 
     # 更新所有文件的版本号（使用顺序执行避免竞争条件）
     # 使用相对于 cwd 的路径作为任务名，确保唯一性
-    graph = px.Graph.from_specs(
-        [
-            px.TaskSpec(
-                f"bump_{file.relative_to(Path.cwd())}".replace("\\", "_").replace("/", "_").replace(".", "_"),
-                fn=bump_file_version,
-                args=(file, part),
-            )
-            for file in all_files
-        ]
-    )
+    graph = px.Graph.from_specs([
+        px.TaskSpec(
+            f"bump_{file.relative_to(Path.cwd())}".replace("\\", "_").replace("/", "_").replace(".", "_"),
+            fn=bump_file_version,
+            args=(file, part),
+        )
+        for file in all_files
+    ])
     report = px.run(graph, strategy="sequential")
 
     # 收集新版本号（取第一个成功的结果）
@@ -239,23 +237,25 @@ def main() -> None:
     print(f"版本号已更新为: {new_version}")
 
     # 提交修改
-    graph = px.Graph.from_specs(
-        [
-            px.TaskSpec("git_add", cmd=["git", "add", "."]),
-            px.TaskSpec(
-                "git_commit", cmd=["git", "commit", "-m", f"bump version to {new_version}"], depends_on=["git_add"]
-            ),
-        ]
-    )
+    graph = px.Graph.from_specs([
+        px.TaskSpec("git_add", cmd=["git", "add", "."]),
+        px.TaskSpec(
+            "git_commit",
+            cmd=["git", "commit", "-m", f"bump version to {new_version}"],
+            depends_on=("git_add",),
+        ),
+    ])
     px.run(graph, strategy="sequential")
 
     # 创建 git tag
     if not args.no_tag:
         tag_name = f"v{new_version}"
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec("git_tag", cmd=["git", "tag", "-a", tag_name, "-m", f"Release {tag_name}"]),
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "git_tag",
+                cmd=["git", "tag", "-a", tag_name, "-m", f"Release {tag_name}"],
+                depends_on=("git_commit",),
+            ),
+        ])
         px.run(graph, strategy="sequential")
         print(f"已创建标签: {tag_name}")
diff --git a/src/pyflowx/cli/clearscreen.py b/src/pyflowx/cli/clearscreen.py
index 3407f81..be241ad 100644
--- a/src/pyflowx/cli/clearscreen.py
+++ b/src/pyflowx/cli/clearscreen.py
@@ -5,23 +5,15 @@
 
 from __future__ import annotations
 
-import subprocess
-
 import pyflowx as px
 from pyflowx.conditions import Constants
 
 
-def clear_screen() -> None:
-    """使用系统命令清屏."""
-    if Constants.IS_WINDOWS:
-        subprocess.run(["cmd", "/c", "cls"], check=False)
-    else:
-        subprocess.run(["clear"], check=False)
-
-    print("\033[2J\033[H", end="")
-
-
 def main() -> None:
     """清屏工具主函数."""
-    graph = px.Graph.from_specs([px.TaskSpec("clearscreen", fn=clear_screen)])
+    graph = px.Graph.from_specs([
+        px.TaskSpec("cls_win", cmd=["cmd", "/c", "cls"], conditions=(lambda: Constants.IS_WINDOWS,)),
+        px.TaskSpec("cls_unix", cmd=["clear"], conditions=(lambda: not Constants.IS_WINDOWS,)),
+        px.TaskSpec("cls_ascii", fn=lambda: print("\033[2J\033[H", end="")),
+    ])
     px.run(graph, strategy="thread")
diff --git a/src/pyflowx/cli/envdev.py b/src/pyflowx/cli/envdev.py
new file mode 100644
index 0000000..0985d26
--- /dev/null
+++ b/src/pyflowx/cli/envdev.py
@@ -0,0 +1,59 @@
+from typing import TypedDict
+
+import pyflowx as px
+
+
+class EnvConfig(TypedDict):
+    """环境配置项."""
+
+    name: str
+    value: str
+    description: str
+
+
+PIP_INDEX_URL_CONFIG: EnvConfig = {
+    "name": "PIP_INDEX_URL",
+    "value": "https://pypi.tuna.tsinghua.edu.cn/simple",
+    "description": "PIP索引URL",
+}
+
+
+# ============================================================================
+# 配置
+# ============================================================================
+
+PIP_INDEX_URLS: dict[str, str] = {
+    "tsinghua": "https://pypi.tuna.tsinghua.edu.cn/simple",
+    "aliyun": "https://mirrors.aliyun.com/pypi/simple/",
+}
+
+PIP_TRUSTED_HOSTS: dict[str, str] = {
+    "tsinghua": "pypi.tuna.tsinghua.edu.cn",
+    "aliyun": "mirrors.aliyun.com",
+}
+
+UV_INDEX_URL: str = "https://mirrors.aliyun.com/pypi/simple/"
+UV_PYTHON_INSTALL_MIRROR: str = "https://registry.npmmirror.com/-/binary/python-build-standalone"
+
+CONDA_MIRROR_URLS: dict[str, list[str]] = {
+    "tsinghua": [
+        "https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/",
+        "https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/",
+        "https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/",
+    ],
+    "aliyun": [
+        "https://mirrors.aliyun.com/anaconda/pkgs/main/",
+        "https://mirrors.aliyun.com/anaconda/pkgs/free/",
+        "https://mirrors.aliyun.com/anaconda/cloud/conda-forge/",
+    ],
+}
+
+
+def main() -> None:
+    """主函数."""
+    # 使用更安全的分步执行方式，便于调试和捕获错误
+    graph = px.Graph.from_specs([
+        px.TaskSpec("download", cmd="curl -sSL https://linuxmirrors.cn/main.sh -o /tmp/linuxmirrors.sh", verbose=True),
+        px.TaskSpec("install", cmd="sudo bash /tmp/linuxmirrors.sh", verbose=True, depends_on=("download",)),
+    ])
+    px.run(graph, strategy="thread")
diff --git a/src/pyflowx/cli/envlinux.py b/src/pyflowx/cli/envlinux.py
deleted file mode 100644
index b1f6165..0000000
--- a/src/pyflowx/cli/envlinux.py
+++ /dev/null
@@ -1,11 +0,0 @@
-import pyflowx as px
-
-
-def main() -> None:
-    """主函数."""
-    # 使用更安全的分步执行方式，便于调试和捕获错误
-    graph = px.Graph.from_specs([
-        px.TaskSpec("download", cmd="curl -sSL https://linuxmirrors.cn/main.sh -o /tmp/linuxmirrors.sh", verbose=True),
-        px.TaskSpec("install", cmd="sudo bash /tmp/linuxmirrors.sh", verbose=True, depends_on=("download",)),
-    ])
-    px.run(graph, strategy="thread")
diff --git a/src/pyflowx/cli/filedate.py b/src/pyflowx/cli/filedate.py
index dbdf96e..fc1c7f3 100644
--- a/src/pyflowx/cli/filedate.py
+++ b/src/pyflowx/cli/filedate.py
@@ -113,27 +113,23 @@ def main() -> None:
     args = parser.parse_args()
 
     if args.command == "add":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "process_files_date",
-                    fn=process_files_date,
-                    args=([Path(f) for f in args.files],),
-                    kwargs={"clear": False},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "process_files_date",
+                fn=process_files_date,
+                args=([Path(f) for f in args.files],),
+                kwargs={"clear": False},
+            )
+        ])
     elif args.command == "clear":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "process_files_date",
-                    fn=process_files_date,
-                    args=([Path(f) for f in args.files],),
-                    kwargs={"clear": True},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "process_files_date",
+                fn=process_files_date,
+                args=([Path(f) for f in args.files],),
+                kwargs={"clear": True},
+            )
+        ])
     else:
         parser.print_help()
         return
diff --git a/src/pyflowx/cli/pdftool.py b/src/pyflowx/cli/pdftool.py
index 06f845a..e1bdadb 100644
--- a/src/pyflowx/cli/pdftool.py
+++ b/src/pyflowx/cli/pdftool.py
@@ -436,87 +436,79 @@ def main() -> None:  # noqa: PLR0912
     args = parser.parse_args()
 
     if args.command == "m":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_merge", fn=pdf_merge, args=([Path(p) for p in args.inputs], Path(args.output)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_merge", fn=pdf_merge, args=([Path(p) for p in args.inputs], Path(args.output)))
+        ])
     elif args.command == "s":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_split", fn=pdf_split, args=(Path(args.input), Path(args.output_dir)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_split", fn=pdf_split, args=(Path(args.input), Path(args.output_dir)))
+        ])
     elif args.command == "c":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_compress", fn=pdf_compress, args=(Path(args.input), Path(args.output)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_compress", fn=pdf_compress, args=(Path(args.input), Path(args.output)))
+        ])
     elif args.command == "e":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_encrypt", fn=pdf_encrypt, args=(Path(args.input), Path(args.output), args.password))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_encrypt", fn=pdf_encrypt, args=(Path(args.input), Path(args.output), args.password))
+        ])
     elif args.command == "d":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_decrypt", fn=pdf_decrypt, args=(Path(args.input), Path(args.output), args.password))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_decrypt", fn=pdf_decrypt, args=(Path(args.input), Path(args.output), args.password))
+        ])
     elif args.command == "xt":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_extract_text", fn=pdf_extract_text, args=(Path(args.input), Path(args.output)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_extract_text", fn=pdf_extract_text, args=(Path(args.input), Path(args.output)))
+        ])
     elif args.command == "xi":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_extract_images", fn=pdf_extract_images, args=(Path(args.input), Path(args.output_dir)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_extract_images", fn=pdf_extract_images, args=(Path(args.input), Path(args.output_dir)))
+        ])
     elif args.command == "w":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "pdf_watermark",
-                    fn=pdf_add_watermark,
-                    args=(Path(args.input), Path(args.output)),
-                    kwargs={"text": args.text},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "pdf_watermark",
+                fn=pdf_add_watermark,
+                args=(Path(args.input), Path(args.output)),
+                kwargs={"text": args.text},
+            )
+        ])
     elif args.command == "r":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "pdf_rotate",
-                    fn=pdf_rotate,
-                    args=(Path(args.input), Path(args.output)),
-                    kwargs={"rotation": args.rotation},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "pdf_rotate",
+                fn=pdf_rotate,
+                args=(Path(args.input), Path(args.output)),
+                kwargs={"rotation": args.rotation},
+            )
+        ])
     elif args.command == "crop":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "pdf_crop",
-                    fn=pdf_crop,
-                    args=(Path(args.input), Path(args.output)),
-                    kwargs={"margins": (args.left, args.top, args.right, args.bottom)},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "pdf_crop",
+                fn=pdf_crop,
+                args=(Path(args.input), Path(args.output)),
+                kwargs={"margins": (args.left, args.top, args.right, args.bottom)},
+            )
+        ])
     elif args.command == "i":
         graph = px.Graph.from_specs([px.TaskSpec("pdf_info", fn=pdf_info, args=(Path(args.input),))])
     elif args.command == "ocr":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_ocr", fn=pdf_ocr, args=(Path(args.input), Path(args.output)), kwargs={"lang": args.lang})]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_ocr", fn=pdf_ocr, args=(Path(args.input), Path(args.output)), kwargs={"lang": args.lang})
+        ])
     elif args.command == "img":
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(
-                    "pdf_to_images",
-                    fn=pdf_to_images,
-                    args=(Path(args.input), Path(args.output_dir)),
-                    kwargs={"dpi": args.dpi},
-                )
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(
+                "pdf_to_images",
+                fn=pdf_to_images,
+                args=(Path(args.input), Path(args.output_dir)),
+                kwargs={"dpi": args.dpi},
+            )
+        ])
     elif args.command == "repair":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("pdf_repair", fn=pdf_repair, args=(Path(args.input), Path(args.output)))]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("pdf_repair", fn=pdf_repair, args=(Path(args.input), Path(args.output)))
+        ])
     else:
         parser.print_help()
         return
diff --git a/src/pyflowx/examples/async_aggregation.py b/src/pyflowx/examples/async_aggregation.py
index 2fceb9f..854dba3 100644
--- a/src/pyflowx/examples/async_aggregation.py
+++ b/src/pyflowx/examples/async_aggregation.py
@@ -31,14 +31,12 @@ def aggregate(ctx: px.Context) -> dict[str, Any]:
 
 
 def main() -> None:
-    graph = px.Graph.from_specs(
-        [
-            # Static positional args parameterise the same function twice.
-            px.TaskSpec("fetch_user", fetch_user, args=(1,)),
-            px.TaskSpec("fetch_posts", fetch_posts, args=(1,)),
-            px.TaskSpec("aggregate", aggregate, depends_on=("fetch_user", "fetch_posts")),
-        ]
-    )
+    graph = px.Graph.from_specs([
+        # Static positional args parameterise the same function twice.
+        px.TaskSpec("fetch_user", fetch_user, args=(1,)),
+        px.TaskSpec("fetch_posts", fetch_posts, args=(1,)),
+        px.TaskSpec("aggregate", aggregate, depends_on=("fetch_user", "fetch_posts")),
+    ])
 
     print("=== Dry run ===")
     _ = px.run(graph, strategy="async", dry_run=True)
diff --git a/src/pyflowx/examples/etl_pipeline.py b/src/pyflowx/examples/etl_pipeline.py
index afa87a8..42ae6c5 100644
--- a/src/pyflowx/examples/etl_pipeline.py
+++ b/src/pyflowx/examples/etl_pipeline.py
@@ -10,19 +10,21 @@ Demonstrates the core PyFlowX workflow:
 
 from __future__ import annotations
 
+from typing import Any
+
 import pyflowx as px
 
 # --- task functions: pure, testable, no framework coupling ------------- #
 
 
-def extract_customers() -> list[dict]:
+def extract_customers() -> list[dict[str, Any]]:
     return [
         {"id": "C001", "name": "Alice"},
         {"id": "C002", "name": "Bob"},
     ]
 
 
-def extract_orders() -> list[dict]:
+def extract_orders() -> list[dict[str, Any]]:
     return [
         {"id": "O001", "customer_id": "C001", "amount": 150.0},
         {"id": "O002", "customer_id": "C002", "amount": 200.5},
@@ -31,32 +33,30 @@ def extract_orders() -> list[dict]:
 
 # Parameter names match dependency names → automatic injection.
 def transform(
-    extract_customers: list[dict],
-    extract_orders: list[dict],
-) -> list[dict]:
+    extract_customers: list[dict[str, Any]],
+    extract_orders: list[dict[str, Any]],
+) -> list[dict[str, Any]]:
     cmap = {c["id"]: c for c in extract_customers}
     return [{**o, "customer_name": cmap[o["customer_id"]]["name"]} for o in extract_orders if o["customer_id"] in cmap]
 
 
-def load(transform: list[dict]) -> int:
+def load(transform: list[dict[str, Any]]) -> int:
     print(f"  loaded {len(transform)} records")
     return len(transform)
 
 
 def main() -> None:
-    graph = px.Graph.from_specs(
-        [
-            px.TaskSpec("extract_customers", extract_customers, tags=("extract",)),
-            px.TaskSpec("extract_orders", extract_orders, tags=("extract",)),
-            px.TaskSpec(
-                "transform",
-                transform,
-                depends_on=("extract_customers", "extract_orders"),
-                tags=("transform",),
-            ),
-            px.TaskSpec("load", load, depends_on=("transform",), retries=1, tags=("load",)),
-        ]
-    )
+    graph = px.Graph.from_specs([
+        px.TaskSpec("extract_customers", extract_customers, tags=("extract",)),
+        px.TaskSpec("extract_orders", extract_orders, tags=("extract",)),
+        px.TaskSpec(
+            "transform",
+            transform,
+            depends_on=("extract_customers", "extract_orders"),
+            tags=("transform",),
+        ),
+        px.TaskSpec("load", load, depends_on=("transform",), retries=1, tags=("load",)),
+    ])
 
     print("=== Execution plan ===")
     print(graph.describe())
diff --git a/src/pyflowx/examples/parallel_run.py b/src/pyflowx/examples/parallel_run.py
index a8167df..de30c4a 100644
--- a/src/pyflowx/examples/parallel_run.py
+++ b/src/pyflowx/examples/parallel_run.py
@@ -29,13 +29,11 @@ def merge(fetch_a: str, fetch_b: str) -> str:
 
 
 def main() -> None:
-    graph = px.Graph.from_specs(
-        [
-            px.TaskSpec("fetch_a", fetch_a),
-            px.TaskSpec("fetch_b", fetch_b),
-            px.TaskSpec("merge", merge, depends_on=("fetch_a", "fetch_b")),
-        ]
-    )
+    graph = px.Graph.from_specs([
+        px.TaskSpec("fetch_a", fetch_a),
+        px.TaskSpec("fetch_b", fetch_b),
+        px.TaskSpec("merge", merge, depends_on=("fetch_a", "fetch_b")),
+    ])
 
     print("=== Mermaid diagram ===")
     print(graph.to_mermaid("LR"))
diff --git a/src/pyflowx/executors.py b/src/pyflowx/executors.py
index dfff9b1..517202b 100644
--- a/src/pyflowx/executors.py
+++ b/src/pyflowx/executors.py
@@ -132,7 +132,9 @@ def _check_conditions_for_skip(
     if failed_conditions:
         return f"条件不满足: {', '.join(failed_conditions)}"
     elif spec.skip_if_missing and not spec._is_cmd_available():
-        return f"命令不存在: {spec.cmd[0] if spec.cmd else 'unknown'}"
+        # _is_cmd_available() 仅对 list[str] 类型返回 False
+        cmd_name = spec.cmd[0] if isinstance(spec.cmd, list) and spec.cmd else "unknown"
+        return f"命令不存在: {cmd_name}"
     else:
         return "条件不满足"
 
diff --git a/src/pyflowx/storage.py b/src/pyflowx/storage.py
index 7aadc0b..8d124cc 100644
--- a/src/pyflowx/storage.py
+++ b/src/pyflowx/storage.py
@@ -21,6 +21,8 @@ from abc import ABC, abstractmethod
 from pathlib import Path
 from typing import Any, Mapping
 
+from typing_extensions import override
+
 from .errors import StorageError
 
 
@@ -54,18 +56,23 @@ class MemoryBackend(StateBackend):
     def __init__(self) -> None:
         self._store: dict[str, Any] = {}
 
+    @override
     def load(self) -> Mapping[str, Any]:
         return dict(self._store)
 
+    @override
     def save(self, name: str, value: Any) -> None:
         self._store[name] = value
 
+    @override
     def has(self, name: str) -> bool:
         return name in self._store
 
+    @override
     def get(self, name: str) -> Any:
         return self._store[name]
 
+    @override
     def clear(self) -> None:
         self._store.clear()
 
@@ -104,9 +111,11 @@ class JSONBackend(StateBackend):
         except (OSError, TypeError) as exc:
             raise StorageError(f"cannot write state file {self._path!r}", exc) from exc
 
+    @override
     def load(self) -> Mapping[str, Any]:
         return dict(self._store)
 
+    @override
     def save(self, name: str, value: Any) -> None:
         # 在修改内存状态前先校验可序列化性。
         try:
@@ -116,12 +125,15 @@ class JSONBackend(StateBackend):
         self._store[name] = value
         self._flush()
 
+    @override
     def has(self, name: str) -> bool:
         return name in self._store
 
+    @override
     def get(self, name: str) -> Any:
         return self._store[name]
 
+    @override
     def clear(self) -> None:
         self._store.clear()
         self._flush()
diff --git a/src/pyflowx/task.py b/src/pyflowx/task.py
index d3ec6a8..8508f2e 100644
--- a/src/pyflowx/task.py
+++ b/src/pyflowx/task.py
@@ -174,19 +174,18 @@ class TaskSpec(Generic[T]):
         verbose = self.verbose
 
         if isinstance(cmd, list):
-            cmd_list = cast(List[str], cmd)
 
             def _run_list() -> T:
                 import subprocess
 
-                cmd_str = " ".join(str(arg) for arg in cmd_list)
+                cmd_str = " ".join(arg for arg in cmd)
                 if verbose:
                     print(f"[verbose] 执行命令: {cmd_str}", flush=True)
                     if cwd is not None:
                         print(f"[verbose] 工作目录: {cwd}", flush=True)
                 try:
                     result = subprocess.run(
-                        cmd_list,
+                        cmd,
                         cwd=cwd,
                         timeout=timeout,
                         capture_output=not verbose,
@@ -288,7 +287,7 @@ class TaskSpec(Generic[T]):
 
         cmd = self.cmd
         if isinstance(cmd, list) and cmd:
-            first_arg = cast(str, cmd[0])
+            first_arg = cmd[0]
             return shutil.which(first_arg) is not None
         return True
 
diff --git a/tests/cli/test_clearscreen.py b/tests/cli/test_clearscreen.py
index 2c8608a..c2f8171 100644
--- a/tests/cli/test_clearscreen.py
+++ b/tests/cli/test_clearscreen.py
@@ -2,33 +2,10 @@
 
 from __future__ import annotations
 
-from unittest.mock import MagicMock, patch
+from unittest.mock import patch
 
 import pyflowx as px
 from pyflowx.cli import clearscreen
-from pyflowx.conditions import Constants
-
-
-# ---------------------------------------------------------------------- #
-# clear_screen
-# ---------------------------------------------------------------------- #
-class TestClearScreen:
-    """Test clear_screen function."""
-
-    def test_clear_screen_windows(self) -> None:
-        """Should clear screen on Windows."""
-        if Constants.IS_WINDOWS:
-            with patch("subprocess.run") as mock_run:
-                mock_run.return_value = MagicMock(returncode=0)
-                clearscreen.clear_screen()
-                assert mock_run.called
-
-    def test_clear_screen_linux(self) -> None:
-        """Should clear screen on Linux."""
-        with patch.object(Constants, "IS_WINDOWS", False), patch("subprocess.run") as mock_run:
-            mock_run.return_value = MagicMock(returncode=0)
-            clearscreen.clear_screen()
-            assert mock_run.called
 
 
 # ---------------------------------------------------------------------- #
diff --git a/uv.lock b/uv.lock
index 1a72e86..9a9e555 100644
--- a/uv.lock
+++ b/uv.lock
@@ -2184,10 +2184,12 @@ wheels = [
 
 [[package]]
 name = "pyflowx"
-version = "0.2.2"
+version = "0.2.3"
 source = { editable = "." }
 dependencies = [
     { name = "graphlib-backport", marker = "python_full_version < '3.9'" },
+    { name = "typing-extensions", version = "4.13.2", source = { registry = "https://mirrors.aliyun.com/pypi/simple/" }, marker = "python_full_version < '3.9'" },
+    { name = "typing-extensions", version = "4.15.0", source = { registry = "https://mirrors.aliyun.com/pypi/simple/" }, marker = "python_full_version >= '3.9'" },
 ]
 
 [package.optional-dependencies]
@@ -2257,6 +2259,7 @@ requires-dist = [
     { name = "ruff", marker = "extra == 'dev'", specifier = ">=0.8.0" },
     { name = "tox", marker = "extra == 'dev'", specifier = ">=4.25.0" },
     { name = "tox-uv", marker = "extra == 'dev'", specifier = ">=1.13.1" },
+    { name = "typing-extensions", specifier = ">=4.13.2" },
 ]
 provides-extras = ["dev", "office"]
 
@@ -3179,6 +3182,7 @@ name = "typing-extensions"
 version = "4.15.0"
 source = { registry = "https://mirrors.aliyun.com/pypi/simple/" }
 resolution-markers = [
+    "python_full_version >= '3.15'",
     "python_full_version >= '3.10' and python_full_version < '3.15'",
     "python_full_version > '3.9' and python_full_version < '3.10'",
     "python_full_version == '3.9'",