ND Search Profiles

ND search profiles provide explicit, user-friendly quality controls without requiring ANN expertise.

Profiles map to backend parameters. Current defaults (reference runner):

• fast: low latency, lower recall
• M=8, ef_search=20
• balanced: default quality/latency tradeoff
• M=16, ef_search=50
• accurate: higher recall, higher latency
• M=32, ef_search=100

Additional knobs:

• nd_target_recall: raises ef_search to meet a recall target where possible.
• nd_latency_budget_ms: caps ef_search for latency targets. If this reduces quality, the downgrade is logged.

If a backend cannot honor these settings, it must refuse or log an explicit downgrade.