GPU/MPS-First Guard Measurement Contracts

Plain language: Accelerator-friendly guard measurements are acceptable only when their estimator settings, sampling policy, and measurement-contract hashes are recorded so later verification can replay the same contract.

Overview

Claim

Spectral and RMT guard evidence must remain reproducible without requiring full matrix decompositions on large models. The runtime therefore records bounded iterative estimator settings, sampling policy, and measurement-contract hashes for the guard evidence that invarlock verify later checks.

For operational guard usage, see Guards.

Concepts

• Accelerator-first: guard math runs on CUDA/MPS-capable paths without full SVD.
• Bounded approximation: iterative estimators and deterministic sampling replace exact decompositions for large tensors.
• Measurement contracts: estimator + sampling policy must be recorded in reports.

Runtime Contract

Guard reports must preserve enough information for later verification:

• Spectral evidence records the estimator family, bounded iteration budget, degeneracy proxies, and measurement-contract hash.
• RMT evidence records activation edge-risk scoring, sampling policy, estimator budget, and measurement-contract hash.
• CI/Release verification rejects missing measurement-contract hashes for evaluated Spectral/RMT guard evidence and requires the resolved-policy measurement contract to match the baseline evidence contract.

Contract Details

1. Single evidence mode: one canonical contract for each guard.
2. Spectral contract: track $\hat{\sigma}_{\max}$ and degeneracy proxies (stable-rank drift, row/col norm collapse).
3. RMT contract: activation edge-risk score normalized by MP edge.
4. Verification gate: reports must record the measurement contract, hash, baseline hash, and match flag.

Non-goals

• Full-spectrum or exact SVD computations.
• Accepting reports missing measurement contracts in CI/Release assurance paths.

Troubleshooting

• See Guards for operational guidance and guard configuration.

Observability

• Contract hashes appear under spectral.measurement_contract_hash and rmt.measurement_contract_hash in reports.
• Baseline comparison appears under spectral.baseline_measurement_contract_hash, rmt.baseline_measurement_contract_hash, and *.measurement_contract_match.
• Resolved-policy contracts appear under resolved_policy.spectral.measurement_contract and resolved_policy.rmt.measurement_contract.

Related Documentation

• Guards
• Guard Contracts & Primer
• Spectral False-Positive Control
• RMT ε-Rule