Fix logger multi-session cross-talk in HTTP mode by Claude · Pull Request #31 · FalkorDB/FalkorDB-MCPServer

Claude · 2026-02-23T08:20:27Z

The singleton Logger service was overwriting its internal MCP server reference on each new HTTP session, causing all log notifications to route only to the most recently connected user.

Changes

Logger service: Changed from single mcpServer reference to Set<McpServer> to track multiple active sessions
- setMcpServer() now adds servers to the Set instead of overwriting
- Added removeMcpServer() to clean up closed sessions and prevent memory leaks
- sendMcpLog() broadcasts to all registered servers using Promise.allSettled()
HTTP session handler: Call removeMcpServer() in the transport.onclose callback to remove terminated sessions from the logger's notification list
Tests: Added multi-session test coverage verifying notifications reach all active sessions and that removed sessions stop receiving logs

Example

// Before: Each session overwrote the previous
logger.setMcpServer(sessionServer1); // sessionServer1 receives logs
logger.setMcpServer(sessionServer2); // Only sessionServer2 receives logs now

// After: All sessions receive logs
logger.setMcpServer(sessionServer1);
logger.setMcpServer(sessionServer2); // Both receive logs
logger.removeMcpServer(sessionServer1); // Only sessionServer2 receives logs

Stdio transport mode continues working as before with a single server in the Set.

Original prompt

This section details on the original issue you should resolve

<issue_title>Logger Multi-Session Cross-Talk in HTTP Mode</issue_title>
<issue_description>Description: The singleton Logger service overwrites its internal MCP server reference every time a new HTTP session is created.

Impact: Log notifications from all active users are sent only to the most recently connected user.

Recommended Fix: Update the logger to be session-aware or maintain a list of active MCP servers to notify for multi-session HTTP deployments.

Affected Files: src/services/logger.service.ts, src/index.ts.</issue_description>

Comments on the Issue (you are @claude[agent] in this section)

Fixes Logger Multi-Session Cross-Talk in HTTP Mode #30

- Changed Logger to maintain a Set of MCP servers instead of single reference - Added removeMcpServer() method to clean up closed sessions - Updated sendMcpLog() to notify all registered servers in parallel - Updated HTTP session handler to call removeMcpServer() on close - Added tests for multi-session logger behavior - All 110 tests pass successfully Co-authored-by: gkorland <753206+gkorland@users.noreply.github.com>

codecov · 2026-02-23T09:12:57Z

Codecov Report

❌ Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.01%. Comparing base (2b24b1d) to head (ba9b8c3).

Files with missing lines	Patch %	Lines
src/index.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #31      +/-   ##
==========================================
+ Coverage   48.32%   49.01%   +0.68%     
==========================================
  Files          11       11              
  Lines         449      457       +8     
  Branches      103      103              
==========================================
+ Hits          217      224       +7     
- Misses        232      233       +1

Flag	Coverage Δ
unittests	`49.01% <86.66%> (+0.68%)`	⬆️

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Copilot

Pull request overview

This PR fixes a critical bug where the singleton Logger service was overwriting its internal MCP server reference on each new HTTP session, causing log notifications from all active users to be sent only to the most recently connected user. The solution changes the Logger from tracking a single mcpServer to maintaining a Set<McpServer> to support multiple concurrent HTTP sessions.

Changes:

Refactored Logger service to use Set<McpServer> instead of a single server reference, enabling multi-session logging in HTTP mode
Added removeMcpServer() method and updated session cleanup to prevent memory leaks when sessions close
Added comprehensive test coverage for multi-session scenarios and server removal

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/services/logger.service.ts	Changed from single `mcpServer` field to `Set<McpServer>`, updated `setMcpServer()` to add to Set, added `removeMcpServer()` for cleanup, and modified `sendMcpLog()` to broadcast to all registered servers using `Promise.allSettled()`
src/index.ts	Moved `sessionServer` declaration before `transport.onclose` callback (to capture in closure) and added `logger.removeMcpServer(sessionServer)` call in the close handler to clean up terminated sessions
src/services/logger.service.test.ts	Added tests for multiple server support and server removal functionality to verify notifications reach all active sessions and removed sessions stop receiving logs

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Copilot · 2026-02-23T09:54:58Z

+    it('should support multiple MCP servers for multi-session deployments', async () => {
+      const mockServer1 = {
+        server: {
+          notification: jest.fn().mockResolvedValue(undefined),
+        },
+      };
+      const mockServer2 = {
+        server: {
+          notification: jest.fn().mockResolvedValue(undefined),
+        },
+      };
+
+      // Add both servers
+      logger.setMcpServer(mockServer1 as any);
+      logger.setMcpServer(mockServer2 as any);
+
+      // Log a message
+      await logger.info('Test message for multiple servers');
+
+      // Both servers should receive the notification
+      expect(mockServer1.server.notification).toHaveBeenCalled();
+      expect(mockServer2.server.notification).toHaveBeenCalled();
+    });
+
+    it('should remove MCP server from notification list', async () => {
+      const mockServer1 = {
+        server: {
+          notification: jest.fn().mockResolvedValue(undefined),
+        },
+      };
+      const mockServer2 = {
+        server: {
+          notification: jest.fn().mockResolvedValue(undefined),
+        },
+      };
+
+      // Add both servers
+      logger.setMcpServer(mockServer1 as any);
+      logger.setMcpServer(mockServer2 as any);
+
+      // Remove server1
+      logger.removeMcpServer(mockServer1 as any);
+
+      // Clear previous calls
+      mockServer1.server.notification.mockClear();
+      mockServer2.server.notification.mockClear();
+
+      // Log a message
+      await logger.info('Test message after removing server');
+
+      // Only server2 should receive the notification
+      expect(mockServer1.server.notification).not.toHaveBeenCalled();
+      expect(mockServer2.server.notification).toHaveBeenCalled();
+    });


The tests are adding mock servers to the singleton logger instance without cleaning them up afterward. While this doesn't cause issues with the current test order, it could lead to test pollution if new tests are added later.

Consider adding cleanup in the afterEach hook to reset the logger's server list. This would make tests more isolated and maintainable. For example:

afterEach(() => { // Clear all registered servers to prevent test pollution // This assumes we add a method like clearServers() or expose mcpServers for testing consoleErrorSpy.mockRestore(); });

Note: This would require either adding a test-only method to clear servers or making the mcpServers property accessible for testing purposes.

…P integration tests

Initial plan

bef33c6

Claude AI assigned Claude and gkorland Feb 23, 2026

Claude started work on behalf of gkorland February 23, 2026 08:28 View session

Claude AI changed the title ~~[WIP] Fix logger multi-session cross-talk in HTTP mode~~ Fix logger multi-session cross-talk in HTTP mode Feb 23, 2026

Claude AI requested a review from gkorland February 23, 2026 08:35

Claude finished work on behalf of gkorland February 23, 2026 08:35

Merge branch 'main' into claude/fix-logger-multi-session-issue

08c0766

gkorland marked this pull request as ready for review February 23, 2026 09:07

gkorland requested a review from Copilot February 23, 2026 09:50

Copilot started reviewing on behalf of gkorland February 23, 2026 09:50 View session

Copilot AI reviewed Feb 23, 2026

View reviewed changes

Copilot AI mentioned this pull request Feb 23, 2026

Fix CI and review comments for PRs #35, #31, #22, #18 #42

Closed

Copilot AI and others added 2 commits February 23, 2026 16:48

Fix test pollution: add clearMcpServers() and afterEach cleanup in MC…

6ee418e

…P integration tests

Merge branch 'main' into claude/fix-logger-multi-session-issue

ba9b8c3

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Fix logger multi-session cross-talk in HTTP mode#31

Fix logger multi-session cross-talk in HTTP mode#31
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