Thank you very much @danilpavlov!!! You saved my day with your PR. I hope it will be merged soon.

Nice!

Just wanted to add that using this alongside langchain's adapters that use the /mcp/sse prefix made the /mcp to get repeated. I had to change it a bit to fix it. Worked on:

• http://localhost:8000/sse
• http://localhost:8000/mcp/sse
• http://localhost:8000/myversion/mcp/sse
• http://localhost:8000/myversion/sse

Please note that I also had to change the urljoin

url_parsed = urlparse(url)

base_path = re.search(
    r"https?://[^/]+/(.+?)(?:/mcp)?/sse$", url
)
base_path = (
    base_path.group(1) if base_path else ""
)
endpoint_url = urljoin(
    url_parsed.scheme + "://" + url_parsed.netloc,
    base_path + sse.data
)
logger.info(
    f"Received endpoint URL: {endpoint_url}"
)

Please see danilpavlov#1 @danilpavlov

Nice!

Just wanted to add that using this alongside langchain's adapters that use the /mcp/sse prefix made the /mcp to get repeated. I had to change it a bit to fix it. Worked on:

• http://localhost:8000/sse
• http://localhost:8000/mcp/sse
• http://localhost:8000/myversion/mcp/sse
• http://localhost:8000/myversion/sse

Please note that I also had to change the urljoin

url_parsed = urlparse(url)

base_path = re.search(
    r"https?://[^/]+/(.+?)(?:/mcp)?/sse$", url
)
base_path = (
    base_path.group(1) if base_path else ""
)
endpoint_url = urljoin(
    url_parsed.scheme + "://" + url_parsed.netloc,
    base_path + sse.data
)
logger.info(
    f"Received endpoint URL: {endpoint_url}"
)

Thank you @jonathanglima so much for that feature!

@dsp-ant Can you please check this PR. Forget to mark as reviewer :/

Be good to get this merged and released

Thanks a lot for the great PR!

I have a suggestion regarding the current implementation.

Right now, the SSE client dynamically extracts the base path using regex to reconstruct the endpoint URL. While this works, it places too much responsibility on the client to figure out the correct path structure. This can lead to edge cases and inconsistent behavior—especially in environments with path-based routing like Kubernetes.

A more reliable and maintainable approach would be to have the server explicitly provide the full and correct session_uri to the client. For example, in src/mcp/server/sse.py, there's this snippet:

session_id = uuid4()

# === mount_prefix ===
request_path = scope["path"]  # e.g., "/test/sse"
match = re.match(r"^/([^/]+(?:/mcp)?)/sse$", request_path)
mount_prefix = match.group(1) if match else ""

session_uri = f"/{quote(mount_prefix)}{quote(self._endpoint)}?session_id={session_id.hex}"

If the server constructs the session_uri correctly and returns it to the client, the client doesn't need to guess or reconstruct the path—it can just use what's provided.

In short, I believe the server should own the responsibility of defining the correct mount path or prefix. That way, the client logic remains simpler and more robust.

That's nice @sebin1213 . I wasn't aware that the server could actually provide the session uri to the client. Responsibility-wise, that's much better

Yeah, @sebin1213 that's a really good point -- the server seem to be a better place for that feature. Great job! Thank you for joining us