Conversation
…vs light-gateway mcp rotuer
There was a problem hiding this comment.
Pull request overview
This PR implements gateway-managed MCP sessions in light-pingora so the gateway can issue its own frontend mcp-session-id, map it to backend MCP session IDs per target, and properly tear down backend sessions—addressing the session-id mismatch between calling an MCP server directly vs via the light-gateway MCP router (fixes #118).
Changes:
- Added an in-memory frontend session store with a 30-minute idle timeout, validation on non-
initializemethods, andDELETE /mcpsession teardown. - Implemented backend MCP session initialization (
initialize+notifications/initialized), per-frontend/per-target backend session reuse, and backend session termination on purge/delete. - Updated MCP router design docs and expanded tests to cover session requirements, backend session mapping/reuse, and teardown.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| frameworks/light-pingora/src/mcp.rs | Adds frontend session issuance/validation, backend MCP session mapping & lazy initialization, DELETE teardown, idle expiry purge, and expanded test coverage. |
| docs/src/design/mcp-router.md | Updates the design/status to reflect the implemented in-memory session store, lazy expiry purge, and backend session mapping/teardown behavior. |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
Contributor
Author
|
Reviewed PR #119 comments. There are two Copilot comments, and both were valid, so I patched them locally. In light-fabric/frameworks/light-pingora/src/mcp.rs:1242, backend MCP session teardown now sends both mcp-session-id and mcp-protocol-version. In light-fabric/frameworks/light-pingora/src/mcp.rs:1892, 405 Method Not Allowed now advertises Allow: POST, DELETE since DELETE /mcp is supported. I also updated the existing tests to assert both behaviors. |
Contributor
Author
|
What changed in light-fabric/frameworks/light-pingora/src/mcp.rs:23:
|
Contributor
Author
|
Comment on lines
+2019
to
+2025
| let mut outbound = outbound_headers(headers)?; | ||
| if !outbound.contains_key(ACCEPT) { | ||
| outbound.insert( | ||
| ACCEPT, | ||
| HeaderValue::from_static("application/json, text/event-stream"), | ||
| ); | ||
| } |
Comment on lines
+752
to
+755
| let client_sessions = sessions | ||
| .values() | ||
| .filter(|session| session.client_key == client_key) | ||
| .count(); |
Contributor
Author
|
Comment on lines
+1451
to
+1467
| async fn terminate_backend_session(&self, backend_session: McpBackendSession) { | ||
| let Some(session_id) = backend_session.session_id.as_deref() else { | ||
| return; | ||
| }; | ||
| let mut headers = HeaderMap::new(); | ||
| let Ok(value) = HeaderValue::from_str(session_id) else { | ||
| return; | ||
| }; | ||
| headers.insert(HeaderName::from_static(MCP_SESSION_ID_HEADER), value); | ||
| if let Ok(value) = HeaderValue::from_str(backend_session.protocol_version.as_str()) { | ||
| headers.insert(HeaderName::from_static(MCP_PROTOCOL_VERSION_HEADER), value); | ||
| } | ||
| if let Err(error) = self | ||
| .client | ||
| .delete(backend_session.target_url.as_str()) | ||
| .headers(headers) | ||
| .send() |
Comment on lines
+2087
to
+2090
| } else if !outbound.contains_key(MCP_PROTOCOL_VERSION_HEADER) { | ||
| let value = HeaderValue::from_static(DEFAULT_PROTOCOL_VERSION); | ||
| outbound.insert(HeaderName::from_static(MCP_PROTOCOL_VERSION_HEADER), value); | ||
| } |
Contributor
Author
|
Contributor
Author
|
Change made: aliased Tokio’s mutex as AsyncMutex in frameworks/light-pingora/src/mcp.rs, then updated the runtime session fields and constructor initializers. The test module can keep |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
…vs light-gateway mcp rotuer