Add deprecation warning

README.md

@@ -6,6 +6,14 @@
 [![image](https://img.shields.io/pypi/pyversions/ruff-lsp.svg)](https://pypi.python.org/pypi/ruff-lsp)
 [![Actions status](https://github.com/astral-sh/ruff-lsp/workflows/CI/badge.svg)](https://github.com/astral-sh/ruff-lsp/actions)
 
+> [!WARNING]
+>
+> **`ruff-lsp` is deprecated. Please switch to the native language server
+> (`ruff server`). Refer to the [migration
+> guide](https://docs.astral.sh/ruff/editors/migration/) on how to migrate the
+> settings and [setup guide](https://docs.astral.sh/ruff/editors/setup/) for
+> editor-specific setup instructions.**
+
 > [!NOTE]
 >
 > **As of Ruff v0.4.5, Ruff ships with a built-in language server written in Rust: ⚡ `ruff server` ⚡**

ruff_lsp/server.py

@@ -1570,6 +1570,15 @@ async def run_path(
 @LSP_SERVER.feature(INITIALIZE)
 def initialize(params: InitializeParams) -> None:
     """LSP handler for initialize request."""
+    show_warning(
+        "`ruff-lsp` is deprecated. Please switch to the native language server "
+        "(`ruff server`). Refer to the "
+        "[migration guide](https://docs.astral.sh/ruff/editors/migration/) on how to "
+        "migrate the settings and "
+        "[setup guide](https://docs.astral.sh/ruff/editors/setup/) for editor-specific "
+        "setup instructions."
+    )
+
     # Extract client capabilities.
     CLIENT_CAPABILITIES[CODE_ACTION_RESOLVE] = _supports_code_action_resolve(
         params.capabilities
@@ -1995,6 +2004,12 @@ def show_error(message: str) -> None:
     LSP_SERVER.show_message(message, MessageType.Error)
 
 
+def show_warning(message: str) -> None:
+    """Show a pop-up with a warning."""
+    LSP_SERVER.show_message_log(message, MessageType.Warning)
+    LSP_SERVER.show_message(message, MessageType.Warning)
+
+
 def log_warning(message: str) -> None:
     LSP_SERVER.show_message_log(message, MessageType.Warning)
     if os.getenv("LS_SHOW_NOTIFICATION", "off") in ["onWarning", "always"]: