Fix MCP server reliability issues #4299
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Replace SIGHUP with SIGTERM for proper graceful shutdown of MCP server processes. SIGTERM is the standard signal for requesting process termination and allows processes to clean up properly.
Implement locking mechanism to prevent race conditions when multiple instances of MCPHypervisor or MCPCompatibilityLayer are created simultaneously. This ensures only one instance is created even under concurrent access.
Clear timeout handlers after connection succeeds or fails to prevent memory leaks. Add proper cleanup in both success and error paths when using Promise.race with timeout.
…4017 Mintplex-Labs#3854 GUI applications on macOS and Linux don't inherit login shell environment. Load shell environment to ensure PATH and other variables are available for MCP server processes, fixing 'spawn npx ENOENT' errors.
Add explicit support for type='http' in transport configuration. Route HTTP streaming servers to StreamableHTTPClientTransport instead of incorrectly falling back to SSE transport.
Implement fallback JSON stringification with circular reference detection to prevent crashes when MCP tool results contain circular object references. Use WeakSet to track visited objects and replace circular references with '[Circular]' markers.
Get fresh MCP instance reference on each tool call to avoid using stale connections when MCP servers are restarted. Add validation to ensure MCP server is running before attempting tool execution.
Add try-catch blocks around all MCP async operations including ping(), listTools(), and tool execution. Gracefully handle connection failures and provide fallback behavior when MCP servers become unavailable.
- Replace hasOwnProperty calls with Object.prototype.hasOwnProperty.call() - Add eslint-disable-line for intentionally unused parameter
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Summary
Fix multiple reliability issues in MCP server management including process termination, memory leaks, race conditions, and transport compatibility.
Test plan
These changes address real issues reported in #4017 and #3854 regarding MCP server failures in desktop environments.