Module guarantee_ladder 

Guarantee Ladder with Explicit Semantics (Task 2)

This module provides three guarantee modes with well-defined correctness contracts:

1. Fast Approximate (Approximate): Top-k under proxy score

   • Fastest, ignores quantization error
   • No recall guarantees

2. Calibrated High-Recall (Calibrated): Probabilistic guarantees

   • Uses quantile-bounded error envelopes
   • P(recall ≥ ρ) ≥ 1-δ

3. Certified (Certified): Deterministic exact via LB/UB envelopes

   • Guaranteed correct results
   • Uses rerank to verify all candidates

Math/Algorithm

Let true score be s(x), proxy be ŝ(x) = s(x) + ε(x).

• Mode 1: ε ignored (ranking by ŝ)
• Mode 2: ε bounded in probability (use quantiles)
• Mode 3: ε bounded deterministically (use LB/UB comparisons)

Structs

ScoreEnvelope

Score with error bounds for certified/calibrated modes

SearchContract

Complete search contract specifying guarantees

StopDecision

Decision about whether to stop probing

StoppingEvaluator

Evaluator for stopping rules

Enums

GuaranteeMode

Guarantee mode for search correctness

StopReason

Reason for stopping decision

StoppingRule

Stopping rule that matches guarantee mode semantics