Fix: Recalculate toxic stub chain after cleanup and improve documentationFix: Recalculate toxic stub chain after cleanup and improve buffer cl…

[shan786786786]

Summary

This PR addresses two TODO items in link.go that could lead to memory leaks and data loss in production environments:

1. Fixed stub chain recalculation after Cleanup() (line 223)
2. Documented buffer cleanup investigation (line 248)

Changes Made

1. Toxic Stub Chain Recalculation (Lines 219-233)

Problem: When a toxic is removed and Cleanup() closes it, the stub chain was not recalculated, leaving dangling references.

Solution:

• Reconnect previous toxic's output to the now-closed stub's output
• Remove closed stub from the stubs list
• Prevents memory leaks in long-running proxy instances

2. Buffer Cleanup Documentation (Lines 253-262)

Problem: TODO noted missing buffer cleanup when connection closes early.

Investigation:

• Added comprehensive documentation explaining why cleanup is complex
• Buffer is shared across goroutines (interrupt, Input, Output)
• Early returns in interrupt handling make defer placement non-trivial
• Left TODO with context for future improvement

Testing

✅ All tests passing:

• TestRemoveToxic - PASS
• TestRemoveToxicWithBrokenConnection - PASS
• TestNoDataDropped - PASS
• 60+ total tests in test suite

Impact

• Conservative fix - maintains backward compatibility
• No breaking changes - all existing functionality preserved
• Production-safe - prevents resource leaks in high-throughput scenarios

Author

• Signed Shopify CLA as shan786786786 (FAYAS070@GMAIL.COM)
• Tested on Windows with Go 1.25.3