diff --git a/src/pyflowx/cli/emlmanager.py b/src/pyflowx/cli/emlmanager.py
index e1a2b9a..0c60cdf 100644
--- a/src/pyflowx/cli/emlmanager.py
+++ b/src/pyflowx/cli/emlmanager.py
@@ -88,6 +88,8 @@ class EmailDatabase:
 
     def insert_email(self, email_data: dict[str, Any]) -> bool:
         """插入邮件数据."""
+        assert self.conn, "数据库连接未初始化"
+
         try:
             with self._lock:
                 cursor = self.conn.cursor()
@@ -123,6 +125,8 @@ class EmailDatabase:
         self, keyword: str = "", field: str = "all", limit: int = 100, offset: int = 0
     ) -> list[dict[str, Any]]:
         """搜索邮件."""
+        assert self.conn, "数据库连接未初始化"
+
         with self._lock:
             cursor = self.conn.cursor()
 
@@ -154,6 +158,8 @@ class EmailDatabase:
 
     def get_grouped_emails(self) -> dict[str, list[dict[str, Any]]]:
         """获取按主题分组的邮件."""
+        assert self.conn, "数据库连接未初始化"
+
         with self._lock:
             cursor = self.conn.cursor()
             cursor.execute(f"SELECT * FROM {TABLE_NAME} ORDER BY subject, date_parsed DESC")
@@ -183,6 +189,8 @@ class EmailDatabase:
 
     def get_email_count(self) -> int:
         """获取邮件总数."""
+        assert self.conn, "数据库连接未初始化"
+
         with self._lock:
             cursor = self.conn.cursor()
             cursor.execute(f"SELECT COUNT(*) FROM {TABLE_NAME}")
@@ -190,6 +198,8 @@ class EmailDatabase:
 
     def clear_all(self) -> None:
         """清空所有邮件数据."""
+        assert self.conn, "数据库连接未初始化"
+
         with self._lock:
             cursor = self.conn.cursor()
             cursor.execute(f"DELETE FROM {TABLE_NAME}")
@@ -557,15 +567,13 @@ class EmlManagerHandler(BaseHTTPRequestHandler):
 
         emails = self.db.search_emails(keyword, field, limit, offset)
         total_count = self.db.get_email_count()
-        self._send_json_response(
-            {
-                "emails": emails,
-                "count": len(emails),
-                "total": total_count,
-                "limit": limit,
-                "offset": offset,
-            }
-        )
+        self._send_json_response({
+            "emails": emails,
+            "count": len(emails),
+            "total": total_count,
+            "limit": limit,
+            "offset": offset,
+        })
 
     def _api_get_email(self, query_params: dict[str, list[str]]) -> None:
         """API: 获取单个邮件详情."""
@@ -578,6 +586,10 @@ class EmlManagerHandler(BaseHTTPRequestHandler):
             self._send_json_response({"error": "缺少邮件ID"}, 400)
             return
 
+        if not self.db.conn:
+            self._send_json_response({"error": "数据库连接未初始化"}, 500)
+            return
+
         with self.db._lock:
             cursor = self.db.conn.cursor()
             cursor.execute(f"SELECT * FROM {TABLE_NAME} WHERE id = ?", (int(email_id),))
@@ -630,6 +642,10 @@ class EmlManagerHandler(BaseHTTPRequestHandler):
             if not eml_files:
                 return
 
+            if not self.db.conn:
+                self._send_json_response({"error": "数据库连接未初始化"}, 500)
+                return
+
             # 先批量查询所有已存在的文件
             with self.db._lock:
                 cursor = self.db.conn.cursor()
@@ -1268,6 +1284,10 @@ def main() -> None:
             if eml_files:
                 print(f"发现 {len(eml_files)} 个 EML 文件，开始导入...")
 
+                if not EmlManagerHandler.db.conn:
+                    print("数据库连接未初始化，无法导入邮件")
+                    return
+
                 # 先批量查询所有已存在的文件
                 with EmlManagerHandler.db._lock:
                     cursor = EmlManagerHandler.db.conn.cursor()
diff --git a/src/pyflowx/cli/envrs.py b/src/pyflowx/cli/envrs.py
index 4e8ecab..3a45566 100644
--- a/src/pyflowx/cli/envrs.py
+++ b/src/pyflowx/cli/envrs.py
@@ -39,7 +39,7 @@ RUSTUP_MIRRORS: dict[str, dict[str, str]] = {
 UsableRustVersion = Literal["stable", "nightly", "beta"]
 UsableMirror = Literal["aliyun", "ustc", "tsinghua"]
 
-DEFAULT_RUST_VERSION: str = "stable"
+DEFAULT_RUST_VERSION: UsableRustVersion = "stable"
 DEFAULT_MIRROR: UsableMirror = "tsinghua"
 
 
@@ -136,13 +136,13 @@ def main() -> None:
     args = parser.parse_args()
 
     if args.command == "mirror":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("set_rust_mirror", fn=set_rust_mirror, args=(args.name,), verbose=True)]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("set_rust_mirror", fn=set_rust_mirror, args=(args.name,), verbose=True)
+        ])
     elif args.command == "install":
-        graph = px.Graph.from_specs(
-            [px.TaskSpec("install_rust", cmd=["rustup", "toolchain", "install", args.version], verbose=True)]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec("install_rust", cmd=["rustup", "toolchain", "install", args.version], verbose=True)
+        ])
     else:
         parser.print_help()
         return
diff --git a/src/pyflowx/cli/gittool.py b/src/pyflowx/cli/gittool.py
index 066301a..bb45a57 100644
--- a/src/pyflowx/cli/gittool.py
+++ b/src/pyflowx/cli/gittool.py
@@ -33,20 +33,16 @@ def init_sub_dirs() -> None:
     sub_dirs = [subdir for subdir in Path.cwd().iterdir() if subdir.is_dir()]
     for subdir in sub_dirs:
         px.run(
-            px.Graph.from_specs(
-                [
-                    px.TaskSpec(
-                        "init",
-                        cmd=["git", "init"],
-                        conditions=[not_has_git_repo],
-                        cwd=str(subdir),
-                    ),
-                    px.TaskSpec("add", cmd=["git", "add", "."], depends_on=["init"], cwd=str(subdir)),
-                    px.TaskSpec(
-                        "commit", cmd=["git", "commit", "-m", "init commit"], depends_on=["add"], cwd=str(subdir)
-                    ),
-                ]
-            ),
+            px.Graph.from_specs([
+                px.TaskSpec(
+                    "init",
+                    cmd=["git", "init"],
+                    conditions=(not_has_git_repo,),
+                    cwd=subdir,
+                ),
+                px.TaskSpec("add", cmd=["git", "add", "."], depends_on=("init",)),
+                px.TaskSpec("commit", cmd=["git", "commit", "-m", "init commit"], depends_on=("add",)),
+            ]),
         )
 
 
@@ -73,29 +69,23 @@ def main() -> None:
         description="Gittool - Git 执行工具.",
         graphs={
             # 添加并提交
-            "a": px.Graph.from_specs(
-                [
-                    px.TaskSpec("add", cmd=["git", "add", "."], conditions=[has_files]),
-                    px.TaskSpec("commit", cmd=["git", "commit", "-m", "chore: update"], depends_on=["add"]),
-                ]
-            ),
+            "a": px.Graph.from_specs([
+                px.TaskSpec("add", cmd=["git", "add", "."], conditions=(has_files,)),
+                px.TaskSpec("commit", cmd=["git", "commit", "-m", "chore: update"], depends_on=("add",)),
+            ]),
             # 清理
-            "c": px.Graph.from_specs(
-                [
-                    px.TaskSpec("clean", cmd=["git", "clean", "-xfd", *EXCLUDE_CMDS]),
-                    px.TaskSpec("status", cmd=["git", "status", "--porcelain"], depends_on=["clean"]),
-                ]
-            ),
+            "c": px.Graph.from_specs([
+                px.TaskSpec("clean", cmd=["git", "clean", "-xfd", *EXCLUDE_CMDS]),
+                px.TaskSpec("status", cmd=["git", "status", "--porcelain"], depends_on=("clean",)),
+            ]),
             # 初始化、添加并提交
-            "i": px.Graph.from_specs(
-                [
-                    px.TaskSpec("init", cmd=["git", "init"], conditions=[not_has_git_repo]),
-                    px.TaskSpec("add", cmd=["git", "add", "."], depends_on=["init"], conditions=[has_files]),
-                    px.TaskSpec(
-                        "commit", cmd=["git", "commit", "-m", "init commit"], depends_on=["add"], conditions=[has_files]
-                    ),
-                ]
-            ),
+            "i": px.Graph.from_specs([
+                px.TaskSpec("init", cmd=["git", "init"], conditions=(not_has_git_repo,)),
+                px.TaskSpec("add", cmd=["git", "add", "."], depends_on=("init",), conditions=(has_files,)),
+                px.TaskSpec(
+                    "commit", cmd=["git", "commit", "-m", "init commit"], depends_on=("add",), conditions=(has_files,)
+                ),
+            ]),
             # 初始化子目录
             "isub": px.Graph.from_specs([isub]),
             # 推送
diff --git a/src/pyflowx/cli/hfdownload.py b/src/pyflowx/cli/hfdownload.py
index a3dc7bf..c5ecc70 100644
--- a/src/pyflowx/cli/hfdownload.py
+++ b/src/pyflowx/cli/hfdownload.py
@@ -37,50 +37,46 @@ def main():
     download_dir.mkdir(parents=True, exist_ok=True)
 
     if args.use_hfd:
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(name="setenvs", fn=setenvs, verbose=True),
-                px.TaskSpec(
-                    name="download_hfd",
-                    cmd=["wget", "https://hf-mirror.com/hfd/hfd.sh"],
-                    depends_on=["setenvs"],
-                    verbose=True,
-                ),
-                px.TaskSpec(
-                    name="chmod_hfd",
-                    cmd=["chmod", "a+x", "hfd.sh"],
-                    depends_on=["download_hfd"],
-                    verbose=True,
-                ),
-                px.TaskSpec(
-                    name="run_hfd",
-                    cmd=["./hfd.sh", dataset_name, args.type],
-                    depends_on=["chmod_hfd"],
-                    verbose=True,
-                ),
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(name="setenvs", fn=setenvs, verbose=True),
+            px.TaskSpec(
+                name="download_hfd",
+                cmd=["wget", "https://hf-mirror.com/hfd/hfd.sh"],
+                depends_on=("setenvs",),
+                verbose=True,
+            ),
+            px.TaskSpec(
+                name="chmod_hfd",
+                cmd=["chmod", "a+x", "hfd.sh"],
+                depends_on=("download_hfd",),
+                verbose=True,
+            ),
+            px.TaskSpec(
+                name="run_hfd",
+                cmd=["./hfd.sh", dataset_name, args.type],
+                depends_on=("chmod_hfd",),
+                verbose=True,
+            ),
+        ])
     else:
-        graph = px.Graph.from_specs(
-            [
-                px.TaskSpec(name="setenvs", fn=setenvs, verbose=True),
-                px.TaskSpec(
-                    name="download",
-                    cmd=[
-                        "uvx",
-                        "hf",
-                        "download",
-                        "--repo-type",
-                        args.type,
-                        "--force-download",
-                        dataset_name,
-                        "--local-dir",
-                        str(Path.cwd() / dataset_name),
-                    ],
-                    depends_on=["setenvs"],
-                    verbose=True,
-                ),
-            ]
-        )
+        graph = px.Graph.from_specs([
+            px.TaskSpec(name="setenvs", fn=setenvs, verbose=True),
+            px.TaskSpec(
+                name="download",
+                cmd=[
+                    "uvx",
+                    "hf",
+                    "download",
+                    "--repo-type",
+                    args.type,
+                    "--force-download",
+                    dataset_name,
+                    "--local-dir",
+                    str(Path.cwd() / dataset_name),
+                ],
+                depends_on=("setenvs",),
+                verbose=True,
+            ),
+        ])
 
     px.run(graph, strategy="thread", verbose=True)
diff --git a/src/pyflowx/cli/pdftool.py b/src/pyflowx/cli/pdftool.py
index e1bdadb..b950f51 100644
--- a/src/pyflowx/cli/pdftool.py
+++ b/src/pyflowx/cli/pdftool.py
@@ -146,7 +146,7 @@ def pdf_extract_text(input_path: Path, output_path: Path) -> None:
     doc = fitz.open(str(input_path))
     text = ""
     for page in doc:
-        text += page.get_text() + "\n\n"
+        text += str(page.get_text()) + "\n\n"
     doc.close()
 
     output_path.parent.mkdir(parents=True, exist_ok=True)
@@ -164,6 +164,7 @@ def pdf_extract_images(input_path: Path, output_dir: Path) -> None:
     output_dir.mkdir(parents=True, exist_ok=True)
 
     image_count = 0
+    # pyrefly: ignore [bad-argument-type]
     for page_num, page in enumerate(doc):
         images = page.get_images(full=True)
         for img_idx, img in enumerate(images):
@@ -249,9 +250,13 @@ def pdf_info(input_path: Path) -> None:
     doc = fitz.open(str(input_path))
     print(f"文件: {input_path}")
     print(f"页数: {doc.page_count}")
+    # pyrefly: ignore [missing-attribute]
     print(f"标题: {doc.metadata.get('title', 'N/A')}")
+    # pyrefly: ignore [missing-attribute]
     print(f"作者: {doc.metadata.get('author', 'N/A')}")
+    # pyrefly: ignore [missing-attribute]
     print(f"创建日期: {doc.metadata.get('creationDate', 'N/A')}")
+    # pyrefly: ignore [missing-attribute]
     print(f"修改日期: {doc.metadata.get('modDate', 'N/A')}")
     print(f"文件大小: {input_path.stat().st_size / 1024:.1f} KB")
     doc.close()
@@ -281,6 +286,7 @@ def pdf_ocr(input_path: Path, output_path: Path, lang: str = "chi_sim+eng") -> N
         new_page = new_doc.new_page(width=page.rect.width, height=page.rect.height)
         new_page.insert_image(new_page.rect, pixmap=pix)
         text_rect = fitz.Rect(0, 0, page.rect.width, page.rect.height)
+        # pyrefly: ignore [bad-argument-type]
         new_page.insert_textbox(text_rect, ocr_text)
 
     output_path.parent.mkdir(parents=True, exist_ok=True)
@@ -319,6 +325,7 @@ def pdf_to_images(input_path: Path, output_dir: Path, dpi: int = 300) -> None:
     doc = fitz.open(str(input_path))
     output_dir.mkdir(parents=True, exist_ok=True)
 
+    # pyrefly: ignore [bad-argument-type]
     for page_num, page in enumerate(doc):
         pix = page.get_pixmap(dpi=dpi)
         image_path = output_dir / f"{input_path.stem}_page_{page_num + 1}.png"
diff --git a/src/pyflowx/task.py b/src/pyflowx/task.py
index 8508f2e..1d1a4a5 100644
--- a/src/pyflowx/task.py
+++ b/src/pyflowx/task.py
@@ -28,12 +28,13 @@ from typing import (
     Mapping,
     Optional,
     Tuple,
-    TypeVar,
     Union,
     cast,
 )
 
-T = TypeVar("T")
+from typing_extensions import TypeVar
+
+T = TypeVar("T", default=Any)
 
 # 任务可调用对象可以是同步或异步的。显式保留联合类型，让 mypy 理解两种形态。
 TaskFn = Union[