- session_memory/core/retention.py: RetentionConfig + sweep() with backstop,
budget (oldest-analyzed-first, never touches un-analyzed), and hard-cap
overflow (analyze-now then reported last-resort data_loss); EvictionReport
- tests/test_retention.py covers all four branches
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>