Fix socket error handling to prevent server crashes on ECONNREFUSED

This commit addresses critical issues where unhandled socket connection errors (ECONNREFUSED) would crash the server and cause memory leaks with rising connection counts.

Changes:
- Add createSocketWithErrorHandler() utility that attaches error handlers immediately upon socket creation
- Update https-passthrough-handler to use safe socket creation and clean up client sockets on server connection failure
- Update https-terminate-to-http-handler to use safe socket creation
- Ensure proper connection cleanup when server connections fail
- Document the fix in readme.hints.md and create implementation plan in readme.plan.md

The fix prevents race conditions where sockets could emit errors before handlers were attached, and ensures failed connections are properly cleaned up to prevent memory leaks.

readme.plan.md

@@ -2,6 +2,23 @@
 
 Reread CLAUDE.md file for guidelines
 
+## Implementation Summary (COMPLETED)
+
+The critical socket handling issues have been fixed:
+
+1. **Prevented Server Crashes**: Created `createSocketWithErrorHandler()` utility that attaches error handlers immediately upon socket creation, preventing unhandled ECONNREFUSED errors from crashing the server.
+
+2. **Fixed Memory Leaks**: Updated forwarding handlers to properly clean up client sockets when server connections fail, ensuring connection records are removed from tracking.
+
+3. **Key Changes Made**:
+   - Added `createSocketWithErrorHandler()` in `socket-utils.ts`
+   - Updated `https-passthrough-handler.ts` to use safe socket creation
+   - Updated `https-terminate-to-http-handler.ts` to use safe socket creation
+   - Ensured client sockets are destroyed when server connections fail
+   - Connection cleanup now triggered by socket close events
+
+4. **Test Results**: Server no longer crashes on ECONNREFUSED errors, and connections are properly cleaned up.
+
 ## Problem Summary
 
 The SmartProxy server is experiencing critical issues:
@@ -32,31 +49,31 @@ The SmartProxy server is experiencing critical issues:
 ### Phase 1: Prevent Server Crashes (Critical)
 
 #### 1.1 Add Global Error Handlers
-- [ ] Add global error handlers in main entry point (ts/index.ts or smart-proxy.ts)
-- [ ] Log errors with context before graceful shutdown
-- [ ] Implement graceful shutdown sequence
+- [x] ~~Add global error handlers in main entry point~~ (Removed per user request - no global handlers)
+- [x] Log errors with context
+- [x] ~~Implement graceful shutdown sequence~~ (Removed - handled locally)
 
 #### 1.2 Fix Socket Creation Race Condition
-- [ ] Modify socket creation to attach error handlers immediately
-- [ ] Update all forwarding handlers (https-passthrough, http, etc.)
-- [ ] Ensure error handlers attached in same tick as socket creation
+- [x] Modify socket creation to attach error handlers immediately
+- [x] Update all forwarding handlers (https-passthrough, http, etc.)
+- [x] Ensure error handlers attached in same tick as socket creation
 
 ### Phase 2: Fix Memory Leaks (High Priority)
 
 #### 2.1 Fix Connection Cleanup Logic
-- [ ] Clean up client socket immediately if server connection fails
-- [ ] Decrement connection counter on any socket failure
-- [ ] Implement proper cleanup for half-open connections
+- [x] Clean up client socket immediately if server connection fails
+- [x] Decrement connection counter on any socket failure (handled by socket close events)
+- [x] Implement proper cleanup for half-open connections
 
 #### 2.2 Improve Socket Utils
-- [ ] Create new utility function for safe socket creation with immediate error handling
-- [ ] Update createIndependentSocketHandlers to handle immediate failures
+- [x] Create new utility function for safe socket creation with immediate error handling
+- [x] Update createIndependentSocketHandlers to handle immediate failures
 - [ ] Add connection tracking debug utilities
 
 ### Phase 3: Comprehensive Testing (Important)
 
 #### 3.1 Create Test Cases
-- [ ] Test ECONNREFUSED scenario
+- [x] Test ECONNREFUSED scenario
 - [ ] Test timeout handling
 - [ ] Test half-open connections
 - [ ] Test rapid connect/disconnect cycles