Implementing Selective Preservation

Lecture 7.2

• When sliding window is too lossy: keep messages that matter regardless of age
• Three categories worth preserving: structural anchors, decisions and goals, recent exchanges
• Heuristic tagging: role and content patterns (first user message, mutating tool calls)
• Explicit tagging: setting `important: True` at known checkpoints
• Combining heuristics, explicit tags, and pair integrity in a single function
• The limits of classification — what compaction handles that selection cannot

Additional Resources

• Lecture slides
• selective_preservation.py (Python demo)