## 1. Implementation
- [x] 1.1 Create AdaptiveKeyTracker class with exact tier
- [x] 1.2 Implement LRU tier with configurable size and eviction
- [x] 1.3 Add Bloom filter tier as optional dependency
- [x] 1.4 Implement automatic tier switching based on cardinality
- [x] 1.5 Update streaming deduplication to use AdaptiveKeyTracker
- [x] 1.6 Add deduplication quality metrics to results

## 2. Testing
- [x] 2.1 Test exact tier with low-cardinality data
- [x] 2.2 Test LRU tier with medium-cardinality data
- [x] 2.3 Test Bloom filter tier with high-cardinality data
- [x] 2.4 Test tier transitions during processing
- [x] 2.5 Benchmark memory usage across cardinality levels

## 3. Documentation
- [x] 3.1 Document AdaptiveKeyTracker behavior and configuration
- [x] 3.2 Add examples for high-cardinality data handling
- [x] 3.3 Document accuracy trade-offs for each tier
