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Conversation Memory Buffer Class
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Conversation Memory Buffer Class

MediumPython

Problem

Implement a simple memory buffer class in Python that retains the last N turns of a conversation but prioritizes keeping system prompts and critical metadata intact.

A turn is a dictionary. Preserve turns whose role is system or whose type is metadata and critical is True; evict the oldest unprotected turns first. Implement MemoryBuffer(capacity), add(turn), and get_turns(), returning retained turns in original order. If protected turns exceed the capacity, retain all protected turns.

Constraints

  • 0 <= capacity <= 10^4
  • 0 <= len(turns) <= 10^4
  • Each turn is a dictionary
  • A protected turn has role equal to system, or type equal to metadata and critical equal to True
  • The relative order of retained turns must not change

Function Signature

def retain_turns(turns, capacity):
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