feat(tradein): ppm2-tier segmentation of asking->sold ratio pool, flag-gated (#928)
Add ppm2-tier (low/mid/high) asking->sold ratio lookup behind
tier_aware_ratio_enabled feature flag (default OFF). Flag-OFF path
remains byte-identical to pre-#928 behavior.
Migration 098 (additive, idempotent):
- asking_to_sold_tier_bounds: 33.33/66.67 pct ppm2 bounds per rooms_bucket
- asking_to_sold_ratios_tiered: per-tier ratio + 'all' aggregates + global -1
Parallel table to avoid fetchone() regression on asking_to_sold_ratios.
Task (asking_to_sold_ratio.py):
- Extends recompute_asking_to_sold_ratios with tiered DELETE + re-derive
in same transaction (atomic with old table refresh).
- Two new counters: tiered_rows_written, tier_bounds_written.
Config (config.py):
- tier_aware_ratio_enabled: bool = False (feature flag, ENV: TIER_AWARE_RATIO_ENABLED)
- tier_ratio_shrink_k: int = 150 (empirical-Bayes shrink K, ENV: TIER_RATIO_SHRINK_K)
Estimator (estimator.py):
- _get_asking_sold_ratio gains anchor_ppm2 param (default None, backward-compat).
- Cache key changed from int to tuple[int, str|None] (bucket, tier).
- Flag-ON path: bounds lookup -> tier assign -> shrunk ratio w/ Bayes shrink.
- Fallback chain: tier -> 'all' -> global_all -> (None, None).
Tests:
- tests/services/test_asking_sold_tier_ratio.py: 8 new unit tests.
- tests/test_asking_to_sold_ratio.py: updated FakeDB (8 execute calls) + counter assertions.
Refs #928
bot-backend
46db7ebcba