v0.4.0: Streamable HTTP transport — single POST /message endpoint, no SSE

- New streamable_http.py module: simpler HTTP transport without SSE
- New CLI commands: serve-http-streamable / demo-http-streamable (port 8001)
- New library API: run_http_streamable()
- Batch message support (JSON-RPC arrays)
- 13 new tests; 34 total, all passing

Author: Coding-Dev-Tools

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 All notable changes to click-to-mcp will be documented in this file.
 
+## [0.4.0] — 2026-05-15
+
+### Added
+
+- **Streamable HTTP transport** — New transport mode using a single POST `/message` endpoint. No SSE (Server-Sent Events) required, compatible with more MCP clients.
+  - `click-to-mcp serve-http-streamable <name>` — Serve any discovered CLI
+  - `click-to-mcp demo-http-streamable` — Run the built-in demo
+  - `run_http_streamable()` — Library API (from `click_to_mcp` import)
+  - `serve_http_streamable()` — Low-level API (from `click_to_mcp.streamable_http`)
+  - Default port 8001 (different from HTTP+SSE's 8000)
+- **Batch message support** — Streamable HTTP transport accepts both single JSON-RPC messages and arrays (batch).
+- 13 new tests covering Streamable HTTP transport (health, initialize, tools/list, tools/call, notifications, batch, edge cases)
+
+### Changed
+
+- Version bumped to 0.4.0
+- `initialize` response now includes `"streamableHttp": {}` capability
+
 ## [0.2.1] — 2026-05-15
 
 ### Added

click_to_mcp/__init__.py

@@ -22,7 +22,7 @@
 from .server import serve_stdio
 from .discover import scan_entry_points, load_cli, find_our_clis, DiscoveredCLI
 
-__version__ = "0.3.0"
+__version__ = "0.4.0"
 
 
 def run(app: Any, prefix: str = "", name: str = "") -> None:
@@ -95,7 +95,48 @@ def run_http(app: Any, prefix: str = "", name: str = "",
     )
 
 
+def run_http_streamable(app: Any, prefix: str = "", name: str = "",
+                        host: str = "127.0.0.1", port: int = 8001) -> None:
+    """High-level entry point: serve a Click/typer app as an MCP Streamable HTTP server.
+
+    Uses a single POST /message endpoint — no SSE required. Simpler than the
+    HTTP+SSE transport, compatible with more MCP clients.
+
+    Requires optional dependencies: pip install 'click-to-mcp[http]'
+
+    Args:
+        app: A click.Group or typer.Typer instance.
+        prefix: Optional tool name prefix.
+        name: Optional server name (defaults to app name or 'cli').
+        host: Host to bind (default: 127.0.0.1).
+        port: Port to bind (default: 8001).
+    """
+    from .streamable_http import serve_http_streamable
+
+    if not name:
+        name = getattr(app, "name", None) or "cli"
+    desc = ""
+    if hasattr(app, "info"):
+        info_desc = getattr(app.info, "help", None)
+        if info_desc and "DefaultPlaceholder" not in str(type(info_desc)):
+            desc = str(info_desc)
+    if not desc:
+        desc = getattr(app, "help", None) or ""
+    if not isinstance(desc, str):
+        desc = str(desc) if desc else ""
+
+    serve_http_streamable(
+        app,
+        name=name,
+        description=desc,
+        prefix=prefix,
+        host=host,
+        port=port,
+    )
+
+
 __all__ = [
     "cli_to_mcp_tools", "CliToolDef", "serve_stdio", "run", "run_http",
+    "run_http_streamable",
     "scan_entry_points", "load_cli", "find_our_clis", "DiscoveredCLI",
 ]

click_to_mcp/cli.py

@@ -160,6 +160,69 @@ def demo_http(host: str, port: int):
     _serve_http(demo_cli, name="click-to-mcp-demo", host=host, port=port)
 
 
+@cli.command("serve-http-streamable")
+@click.argument("name", required=False, default=None)
+@click.option("--host", default="127.0.0.1", help="Host to bind (default: 127.0.0.1)")
+@click.option("--port", default=8001, type=int, help="Port to bind (default: 8001)")
+@click.option("--all", "serve_all", is_flag=True, help="Serve all discoverable CLIs")
+def serve_http_streamable(name: Optional[str], host: str, port: int, serve_all: bool):
+    """Serve a CLI as an MCP server over Streamable HTTP (no SSE).
+
+    Uses a single POST /message endpoint — simpler than HTTP+SSE, compatible
+    with more MCP clients. Default port is 8001 (different from serve-http).
+    Requires: pip install 'click-to-mcp[http]'
+    """
+    if not name and not serve_all:
+        click.echo("Error: Specify a CLI name or --all", err=True)
+        sys.exit(1)
+
+    try:
+        from .streamable_http import serve_http_streamable as _serve
+    except ImportError as e:
+        click.echo(f"Error: {e}", err=True)
+        sys.exit(1)
+
+    if serve_all:
+        clis = scan_entry_points()
+        if not clis:
+            click.echo("No CLIs found to serve.", err=True)
+            sys.exit(1)
+        click.echo(f"Multiple CLIs found. Serving the first one: {clis[0].name}", err=True)
+        target_cli = load_cli(clis[0].name)
+        if target_cli is None:
+            click.echo(f"Error: Could not load CLI '{clis[0].name}'", err=True)
+            sys.exit(1)
+        _serve(target_cli, name=clis[0].name, host=host, port=port)
+        return
+
+    target_cli = load_cli(name)
+    if target_cli is None:
+        click.echo(f"Error: CLI '{name}' not found.", err=True)
+        click.echo("Run 'click-to-mcp discover' to see available CLIs.", err=True)
+        sys.exit(1)
+
+    _serve(target_cli, name=name, host=host, port=port)
+
+
+@cli.command("demo-http-streamable")
+@click.option("--host", default="127.0.0.1", help="Host to bind (default: 127.0.0.1)")
+@click.option("--port", default=8001, type=int, help="Port to bind (default: 8001)")
+def demo_http_streamable(host: str, port: int):
+    """Run the built-in demo CLI as a Streamable HTTP MCP server (no SSE).
+
+    Requires: pip install 'click-to-mcp[http]'
+    """
+    try:
+        from .streamable_http import serve_http_streamable as _serve
+    except ImportError as e:
+        click.echo(f"Error: {e}", err=True)
+        sys.exit(1)
+
+    from .demo import cli as demo_cli
+
+    _serve(demo_cli, name="click-to-mcp-demo", host=host, port=port)
+
+
 def main():
     """Entry point for the click-to-mcp CLI."""
     cli()