feat: expand --reload to watch frontend file types (#3028)

src/fastmcp/cli/run.py

@@ -25,6 +25,57 @@ logger = get_logger("cli.run")
 TransportType = Literal["stdio", "http", "sse", "streamable-http"]
 LogLevelType = Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]
 
+# File extensions to watch for reload
+WATCHED_EXTENSIONS: set[str] = {
+    # Python
+    ".py",
+    # JavaScript/TypeScript
+    ".js",
+    ".ts",
+    ".jsx",
+    ".tsx",
+    # Markup/Content
+    ".html",
+    ".md",
+    ".mdx",
+    ".txt",
+    ".xml",
+    # Styles
+    ".css",
+    ".scss",
+    ".sass",
+    ".less",
+    # Data/Config
+    ".json",
+    ".yaml",
+    ".yml",
+    ".toml",
+    # Framework-specific
+    ".vue",
+    ".svelte",
+    # GraphQL
+    ".graphql",
+    ".gql",
+    # Images
+    ".svg",
+    ".png",
+    ".jpg",
+    ".jpeg",
+    ".gif",
+    ".ico",
+    ".webp",
+    # Media
+    ".mp3",
+    ".mp4",
+    ".wav",
+    ".webm",
+    # Fonts
+    ".woff",
+    ".woff2",
+    ".ttf",
+    ".eot",
+}
+
 
 def is_url(path: str) -> bool:
     """Check if a string is a URL."""
@@ -231,9 +282,9 @@ async def run_v1_server_async(
             await server.run_sse_async()
 
 
-def _python_file_filter(change: Change, path: str) -> bool:
-    """Filter for Python files only."""
-    return path.endswith(".py")
+def _watch_filter(_change: Change, path: str) -> bool:
+    """Filter for files that should trigger reload."""
+    return any(path.endswith(ext) for ext in WATCHED_EXTENSIONS)
 
 
 async def _terminate_process(process: asyncio.subprocess.Process) -> None:
@@ -300,7 +351,7 @@ async def run_with_reload(
 
             # Watch for either: file changes OR process death
             watch_task = asyncio.create_task(
-                anext(aiter(awatch(*watch_paths, watch_filter=_python_file_filter)))
+                anext(aiter(awatch(*watch_paths, watch_filter=_watch_filter)))
             )
             wait_task = asyncio.create_task(process.wait())
             shutdown_task = asyncio.create_task(shutdown_event.wait())
@@ -331,7 +382,7 @@ async def run_with_reload(
 
                 # Wait for file change or shutdown (avoid hot loop on crash)
                 watch_task = asyncio.create_task(
-                    anext(aiter(awatch(*watch_paths, watch_filter=_python_file_filter)))
+                    anext(aiter(awatch(*watch_paths, watch_filter=_watch_filter)))
                 )
                 shutdown_task = asyncio.create_task(shutdown_event.wait())
                 done, pending = await asyncio.wait(

tests/cli/test_run.py

@@ -605,24 +605,93 @@ mcp = fastmcp.FastMCP("TestServer")
 class TestReloadFunctionality:
     """Test reload functionality."""
 
-    def test_python_file_filter_accepts_py_files(self):
-        """Test that Python file filter accepts .py files."""
+    def test_watch_filter_accepts_watched_extensions(self):
+        """Test that watch filter accepts common source file extensions."""
         from watchfiles import Change
 
-        from fastmcp.cli.run import _python_file_filter
+        from fastmcp.cli.run import _watch_filter
 
-        assert _python_file_filter(Change.modified, "/path/to/file.py") is True
-        assert _python_file_filter(Change.added, "server.py") is True
-        assert _python_file_filter(Change.deleted, "/some/dir/module.py") is True
+        # Python
+        assert _watch_filter(Change.modified, "/path/to/file.py") is True
+        assert _watch_filter(Change.added, "server.py") is True
+        # JavaScript/TypeScript
+        assert _watch_filter(Change.modified, "/path/to/file.js") is True
+        assert _watch_filter(Change.modified, "/path/to/file.ts") is True
+        assert _watch_filter(Change.modified, "/path/to/file.jsx") is True
+        assert _watch_filter(Change.modified, "/path/to/file.tsx") is True
+        # Markup/Content
+        assert _watch_filter(Change.modified, "/path/to/file.html") is True
+        assert _watch_filter(Change.modified, "/path/to/file.md") is True
+        assert _watch_filter(Change.modified, "/path/to/file.txt") is True
+        # Styles
+        assert _watch_filter(Change.modified, "/path/to/file.css") is True
+        assert _watch_filter(Change.modified, "/path/to/file.scss") is True
+        # Data/Config
+        assert _watch_filter(Change.modified, "/path/to/file.json") is True
+        assert _watch_filter(Change.modified, "/path/to/file.yaml") is True
+        # Images
+        assert _watch_filter(Change.modified, "/path/to/file.png") is True
+        assert _watch_filter(Change.modified, "/path/to/file.svg") is True
 
-    def test_python_file_filter_rejects_non_py_files(self):
-        """Test that Python file filter rejects non-.py files."""
+    def test_watch_filter_rejects_unwatched_extensions(self):
+        """Test that watch filter rejects files not in the watched set."""
         from watchfiles import Change
 
-        from fastmcp.cli.run import _python_file_filter
+        from fastmcp.cli.run import _watch_filter
 
-        assert _python_file_filter(Change.modified, "/path/to/file.txt") is False
-        assert _python_file_filter(Change.modified, "/path/to/file.js") is False
-        assert _python_file_filter(Change.modified, "/path/to/file.pyc") is False
-        assert _python_file_filter(Change.modified, "/path/to/.py") is True  # Edge case
-        assert _python_file_filter(Change.modified, "Dockerfile") is False
+        assert _watch_filter(Change.modified, "/path/to/file.pyc") is False
+        assert _watch_filter(Change.modified, "/path/to/file.pyo") is False
+        assert _watch_filter(Change.modified, "Dockerfile") is False
+        assert _watch_filter(Change.modified, "/path/to/file.lock") is False
+        assert _watch_filter(Change.modified, "/path/to/.gitignore") is False
+
+    def test_all_watched_extensions_are_accepted(self):
+        """Test that every extension in WATCHED_EXTENSIONS is accepted."""
+        from watchfiles import Change
+
+        from fastmcp.cli.run import WATCHED_EXTENSIONS, _watch_filter
+
+        for ext in WATCHED_EXTENSIONS:
+            path = f"/path/to/file{ext}"
+            assert _watch_filter(Change.modified, path) is True, (
+                f"Expected {ext} to be watched"
+            )
+
+    def test_watched_extensions_includes_frontend_types(self):
+        """Verify WATCHED_EXTENSIONS contains the expected frontend file types."""
+        from fastmcp.cli.run import WATCHED_EXTENSIONS
+
+        # Core frontend extensions that must be present
+        expected = {
+            # Python
+            ".py",
+            # JavaScript/TypeScript
+            ".js",
+            ".ts",
+            ".jsx",
+            ".tsx",
+            # Markup
+            ".html",
+            ".md",
+            ".mdx",
+            ".xml",
+            # Styles
+            ".css",
+            ".scss",
+            ".sass",
+            ".less",
+            # Data/Config
+            ".json",
+            ".yaml",
+            ".yml",
+            ".toml",
+            # Images
+            ".png",
+            ".jpg",
+            ".svg",
+            # Media
+            ".mp4",
+            ".mp3",
+        }
+        for ext in expected:
+            assert ext in WATCHED_EXTENSIONS, f"Expected {ext} in WATCHED_EXTENSIONS"