Dev Server Launcher

A helper to run the package-provided in-memory development server with hot reload for a LangGraph project.

Capabilities

Hot-reloading startup

• Launches the dev server against the provided config file and port, enabling hot reload so edits under the project directory restart the server automatically. @test

Debugger handoff

• When a debugger port is supplied with a wait flag, startup pauses until a debugger attaches and then continues serving. @test

Tunnel exposure

• When tunneling is requested, startup prints the externally reachable URL returned by the package after the server is ready. @test

Browser toggle

• Defaults to opening the dev UI in a browser; when disabled, no browser is launched while the server still starts normally. @test

Implementation

@generates

API

def launch_dev_server(
    config_path: str,
    port: int = 8123,
    *,
    open_browser: bool = True,
    tunnel: bool = False,
    debugger_port: int | None = None,
    wait_for_debugger: bool = False,
) -> None:
    """
    Start the package's dev server with hot reload for the project defined in config_path.
    Blocks until the server process exits.

    Raises:
        FileNotFoundError: if config_path does not exist.
        RuntimeError: if startup fails (e.g., invalid config or port already in use).
    """

Dependencies { .dependencies }

langgraph-cli { .dependency }

Provides the dev server command with hot reload, debugging, tunneling, and browser control options.