# Deterministic Evaluator Prep — PREP-POLICY-ENGINE-20-002-BUILD-DETERMINISTIC

Status: Draft (2025-11-20)
Owners: Policy Guild
Scope: Capture contract and constraints for deterministic policy evaluator before implementation.

## Requirements
- Deterministic execution: no wall-clock, no RNG, no network; inputs must be content-addressed.
- Ordering: lexical rule ordering; first-match semantics; stable reduction order over inputs.
- Safe value types: disallow floats where not needed; prefer decimal with fixed scale.
- Timestamps: if required, use supplied `context.now` injected value, not system clock.

## Deliverables
- Document evaluator contract and constraints in `docs/modules/policy/design/deterministic-evaluator.md`.
- Provide sample config and test vectors under `docs/modules/policy/samples/deterministic-evaluator/` (hashes recorded in the design doc).

## Handoff
Use this doc as the prep artefact for PREP-POLICY-ENGINE-20-002-BUILD-DETERMINISTIC. Once constraints and samples are frozen, mark the sprint task DONE and unblock POLICY-ENGINE-20-002.