* ⬆️ Upgrade MCP SDK to v2 and remove HTTP sessions
MCP's per-request protocol removes the need to retain HTTP sessions.
Use the v2 handler to manage each request's transport and lifecycle,
so requests can reach any server instance without session affinity
or the workaround that adopts sessions through private SDK fields.
Keep legacy SSE support and the shared plugin and Redis bridges.
Remove the shared expiry checker, including legacy SSE idle expiry;
SSE connections now remain until disconnection or server shutdown.
Verify stateless requests, token isolation, and legacy compatibility.
Resolves#11827
AI-assisted-by: gpt-6-astra
* 🔥 Remove legacy MCP SSE support
Use Streamable HTTP as the sole MCP client transport so the server no
longer needs a separate SSE connection registry or lifecycle.
Remove /sse and /messages, their nginx routes, and the server-legacy
dependency. Legacy SSE clients must switch to /mcp; older Streamable
HTTP clients remain supported. Document the migration and verify that
the removed endpoints return 404.
Resolves#11846
AI-assisted-by: gpt-6-astra
The generated /etc/nginx/overrides/server.d/mcp-locations.conf used a
plain proxy_pass target (e.g. `proxy_pass http://penpot-mcp:4402;`)
where $PENPOT_MCP_URI/$PENPOT_MCP_URI_WS are shell variables substituted
once by envsubst in nginx-entrypoint.sh at container startup, not nginx
variables. nginx resolves a literal proxy_pass hostname once when the
config loads and never re-checks it, so the existing
`resolver 127.0.0.11 valid=10s;` directive in
overrides/http.d/resolvers.conf has no effect on these three locations
- it only applies to nginx variables evaluated per-request.
In multi-container deployments where the penpot-mcp container restarts
or is recreated independently of penpot-frontend (image update, OOM,
orchestrator reschedule), it gets a new IP from Docker's/the
orchestrator's DNS, and the frontend's nginx keeps forwarding to the
old, now-dead address until penpot-frontend itself is restarted. This
surfaces to users as `wss://<host>/mcp/ws` failing to connect from the
browser after enabling the MCP plugin, with
`connect() failed (111: Connection refused)` in the frontend's nginx
logs.
Route each location through a `set $var ...; proxy_pass $var;` pair so
proxy_pass evaluates a real nginx variable, letting the pre-existing
resolver directive re-resolve penpot-mcp within its 10s TTL instead of
caching the address for the container's lifetime.
For /mcp/stream and /mcp/sse, the set value also appends
$is_args$args explicitly: when proxy_pass targets a variable AND that
variable's value includes a URI/path component, nginx does not
automatically forward the original request's query string the way it
does for a static proxy_pass target - it must be appended by hand, or
the userToken query parameter used for multi-user authentication is
silently dropped before reaching the MCP server. /mcp/ws has no path
component in its target so it isn't affected by this and needed no
such change.
Verified locally: force-recreated the penpot-mcp container onto a
different IP while leaving penpot-frontend untouched; the /mcp/ws
WebSocket upgrade kept returning 101 Switching Protocols throughout,
both immediately and after the resolver's TTL window. Separately
verified /mcp/stream: a POST with ?userToken=... now shows up
server-side as userTokenFp=<redacted first 8 chars> instead of <none>,
and an actual MCP client (Claude Code) using this proxy can now call
authenticated tools like execute_code successfully.
Signed-off-by: Jules LaPrairie <jules@lucidbox.ca>
