Hardware-safe gradient execution product (BL-47 / Axis 5)

Fail-closed no-submit default execution policy surface for hardware-adjacent gradient planning. Dry-run plans estimate shot budgets and cost-model status without provider submission; enforce refuses would-submit and over-budget paths.

Module: scpn_quantum_control.hardware_safe_execution
Complements phase.hardware_gradient_policy (preparation decisions) with a versioned public catalogue + probe product.

Rules

Rule	Behaviour
Default policy	default_no_submit with no_submit=True
Would-submit	Always refused on this product surface
Dry-run	Allowed when within shot/param budgets
Cost model	unavailable / blocked / rate_table (fixture only; no invent vendor rates)
Ticketed prep	Requires owner_allow_submit + non-empty ticket; still no live submit
Unknown/blank policy	Fail closed

The registry schema is hardware_safe_execution.v1. Catalogue order and policy identifiers are stable. Every policy defines positive per-evaluation, total, parameter, and shift-term ceilings. A policy cannot set no_submit=False without explicit owner_allow_submit=True, and the product still never submits a job.

Claim boundary:

hardware-safe execution product only; no-submit is the default; dry-run plans estimate shots/cost status without provider submission; enforce refuses would-submit and over-budget without owner-gated allow; this surface never executes QPU jobs or invents hardware results

Policy catalogue

list_execution_policy_ids() returns canonical identifiers in stable order. get_execution_policy(policy_id) trims outer whitespace and raises ValueError for blank or unknown values. iter_execution_policies(no_submit) optionally filters the immutable catalogue; omitting the filter returns all policies. default_execution_policy() resolves default_no_submit.

ExecutionPolicy validates its identifier, summary, positive budgets, total versus per-evaluation shots, cost status, rate, owner gate, and inventory date. cost_model_status has three honest states:

Status	Meaning
unavailable	No rate table is present; estimated cost is None
blocked	Cost evaluation is deliberately unavailable for this policy
rate_table	The policy carries an explicit non-negative fixture rate

A non-rate-table policy must carry a zero rate. The built-in ticketed-prep row uses a zero-cost fixture only; it is not a vendor price claim.

Dry-run planning

dry_run_execution_plan(...) estimates two-sided parameter-shift work as 2 * n_params * shift_terms evaluations and multiplies by shots per evaluation. When shots are omitted, the policy maximum is used. Non-positive parameters, shifts, or shots raise ValueError.

The returned immutable DryRunPlan records dimensions, evaluations, total shots, optional cost, submit intent, outcome, reason, and blockers. It refuses requests that exceed any policy ceiling. Submit intent also adds no-submit and owner-gate blockers. An allowed plan has no blockers; a refused or blocked plan must explain at least one blocker.

Enforcement modes

enforce_execution_request(...) accepts exactly three modes:

Mode	Decision
dry_run	Allowed only when the dry-run plan is within every budget
would_submit	Always refused because this surface never submits
ticketed_prep	Allowed for plan preparation only when the policy owner gate, non-empty ticket, and every budget pass

An allowed ticketed-prep decision is not submission authority. Ticket labels are identifiers, not credentials, and the function does not use them to contact a provider. Duplicate blocker text is removed while preserving order.

EnforceDecision includes the policy, mode, allowed/outcome state, total shots, reason, blockers, and a deterministic audit identifier. Value-object validation rejects inconsistent allowed/outcome/blocker combinations and negative totals.

Audit records and registry integrity

build_audit_record(decision) copies a decision into an immutable AuditRecord. Its JSON-ready mapping always reports contains_secrets=False; no ticket value is copied into the record.

build_hardware_safe_execution_registry() serialises the schema, claim boundary, counts, default identifier, note, and every policy. assert_hardware_safe_execution_integrity(payload=None) rejects:

• an absent, empty, or non-list policy collection;
• non-mapping, blank, duplicate, or unknown policy rows;
• a missing or submit-enabled default_no_submit row;
• non-boolean no-submit values or non-positive budgets;
• canonical policy-set drift; and
• inconsistent blank or policy counts.

The validator returns a shallow dictionary copy. It proves registry structure and safety posture, not provider availability or successful execution.

Public API

from scpn_quantum_control.hardware_safe_execution import (
    assert_hardware_safe_execution_integrity,
    build_audit_record,
    build_hardware_safe_execution_registry,
    default_execution_policy,
    dry_run_execution_plan,
    enforce_execution_request,
)

assert default_execution_policy().no_submit is True
reg = assert_hardware_safe_execution_integrity(
    build_hardware_safe_execution_registry()
)
plan = dry_run_execution_plan("default_no_submit", n_params=2, shots_per_evaluation=64)
assert plan.outcome == "allowed_plan"
assert plan.estimated_total_shots == 256

submit = enforce_execution_request(
    "default_no_submit",
    mode="would_submit",
    n_params=1,
    shots_per_evaluation=64,
)
assert submit.allowed is False
audit = build_audit_record(submit)
assert audit.to_dict()["contains_secrets"] is False

prep = enforce_execution_request(
    "owner_ticketed_prep",
    mode="ticketed_prep",
    n_params=1,
    shots_per_evaluation=64,
    live_execution_ticket="owner-ticket-reference",
)
assert prep.allowed is True

Importing the module, listing policies, planning, enforcing, building an audit record, or validating the registry does not access a network, inspect provider credentials, submit a circuit, spend funds, execute feedback control, mutate a rate table, or promote hardware readiness.

Bounded product status

Shipped: S47.0–S47.1 policy catalogue · S47.2 shot budgets · S47.3 cost status · S47.4 dry-run planner · S47.5 audit records · S47.6 enforce wrapper · docs.

Open: S47.7 BL-33/BL-09 integration · S47.8 BL-29 ticket package template · multi-file execution_policy/ package split · live rate tables (owner data).

Authored by Anulum Fortis & Arcane Sapience (protoscience@anulum.li)