feat(adr-118/p3.2): identity_risk score + GateAction enum — 72/72 GREEN
Iter 10. Lands the stateless half of ADR-121 §2.2–§2.4: the
multiplicative risk-score formula and the 4-band gate classifier.
Hysteresis + 5s debounce (stateful CoherenceGate) land in iter 11.
Added (no_std-compatible):
- src/identity_risk.rs:
* score(sep, stab, consist, conf) -> f32
Each input clamped to [0,1]; NaN → 0 (conservative). Multiplicative
combination: any near-zero factor collapses the score → privacy-biased.
* Threshold constants: PREDICT_ONLY_THRESHOLD=0.5, REJECT_THRESHOLD=0.7,
RECALIBRATE_THRESHOLD=0.9
* GateAction enum: Accept | PredictOnly | Reject | Recalibrate
* GateAction::from_score(f32) -> Self — band-based classification with
inclusive lower edges (0.7 maps to Reject, 0.9 maps to Recalibrate)
* GateAction::allows_publish() / drops_event() / requires_recalibrate()
- pub use identity_risk_score (the function) and GateAction from lib.rs
tests/identity_risk_score.rs (12 named tests, all green):
all_ones_yields_one
any_zero_factor_collapses_score_to_zero (4 single-factor variants)
score_is_monotonic_non_decreasing_in_single_factor
out_of_range_inputs_are_clamped_to_unit_interval
nan_inputs_treated_as_zero (verifies privacy-conservative NaN handling)
known_score_matches_hand_calculation (0.8*0.9*0.85*0.95 to 1e-6)
from_score_classifies_each_band (8 boundary-condition checks)
threshold_constants_match_documented_values
nan_score_maps_to_accept_conservatively
allows_publish_partitions_actions_correctly
drops_event_inverts_allows_publish (parameterized over all 4 actions)
requires_recalibrate_is_unique_to_recalibrate
ACs progressed:
- ADR-121 AC2 partial — `score` formula structurally enforces non-negativity,
upper bound 1.0, and conservative behavior under uncertainty (NaN, negative
input, single near-zero factor).
- ADR-121 AC7 partial — score function is pure / deterministic; identical
inputs always produce identical outputs (asserted by the known-value test).
Test config:
- cargo test --no-default-features → 43 passed (31 + 12)
- cargo test → 72 passed (60 + 12)
Out of scope (next iter target):
- CoherenceGate stateful struct: ±0.05 hysteresis + 5-second debounce
(ADR-121 §2.5) so the gate doesn't oscillate near band boundaries.
- SoulMatchOracle stub trait (ADR-121 §2.6) — the Recalibrate exemption
hook for `--features soul-signature` deployments.
Co-Authored-By: claude-flow <ruv@ruv.net>
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