Four hardcoded constants in the selector and feedback tracker are now
user-tunable via [router.bandit]:
- quality_alpha (EMA smoothing, default 0.3)
- min_observations (samples before observed overrides heuristic, default 3)
- observed_weight (observed/heuristic blend ratio, default 0.7)
- strength_bonus (quality bonus for Strengths-tagged arms, default 0.15)
Each field treats 0 as 'use default', so an empty TOML block is
byte-identical to pre-config behaviour. BanditParams is plumbed via
router.Config{Bandit: ...} and resolveBanditParams() centralises the
fallback so every call site shares the same defaults.
QualityTracker, scoreArm, bestScored, and selectBest signatures now
take the configured values directly rather than reaching for package-
level constants. Tests updated to pass BanditParams{} (defaults) or
explicit overrides where they validate the new tuning paths.
Tracks item #3 from the 'Bandit selector — design decisions deferred'
TODO entry — ships independently of the EMA vs SLM strategic decision.
vikingowl
eea26a262e