Simulation Sign-off Evidence

ZapTrace combines existing DC, transient, AC, power-integrity, signal-integrity, thermal, and current-density producers into one state-bound simulation sign-off report. The report does not replace the underlying analyzers. It records which producer ran, which model it used, what the producer reported, and whether that evidence is strong enough for autonomous sign-off.

Evidence status is not engine status

Every check retains both the producer's engine_status and ZapTrace's normalized status:

Evidence method	Engine result	Normalized sign-off status
Non-degraded ngspice model	pass	pass
Degraded or low-confidence ngspice model	pass	human-review-required
hybrid, analytical, or heuristic	pass	human-review-required
Any method	skipped, missing, unsupported, or no reference	skipped, high risk, release blocking
Any method	fail or error	fail, release blocking, repair hint required

A successful calculation is therefore not automatically an autonomous engineering approval. Analytical evidence can show a useful margin while still requiring a qualified reviewer. Missing models and unsupported analyses are preserved as explicit risk rather than converted into pass results.

Model and report identity

SimulationModelEvidence records:

• model source, version, and SHA-256 identity;
• ngspice, hybrid, analytical, or heuristic method;
• family-fixture or other model binding;
• degraded status and confidence;
• assumptions and limitations;
• retained model/netlist artifact paths and netlist SHA-256;
• detected solver version for ngspice and hybrid producer results.

SimulationFamilyReport binds the resulting checks to the canonical design-state SHA-256. It retains model inputs, assumptions, metrics, raw producer results, repair hints, block/review decisions, live-simulation pass count, and its own report SHA-256. A changed report no longer matches its embedded digest and cannot be attached to a Proof Pack.

Four-family evidence corpus

The committed corpus covers four representative board families:

Family	Evidence domains	Primary gate
switching_regulator_module	transient, power integrity, thermal, current density	strict buck transient gate through ngspice
usb_c_power_sink	transient/inrush, power integrity, current density	USB-C inrush hybrid or analytical gate
lipo_charger_node	AC stability, thermal margin	governed analytical AC stability fixture
esp32_usb_sensor	SI/PI risk	analytical impedance, return-path, and decoupling evidence

The aggregate report carries the committed corpus version and policy SHA-256. The Quality workflow installs ngspice and requires at least one live solver-backed pass. The remaining analytical or degraded-family evidence stays visible as human-review-required. The corpus checks evidence production and policy behavior; it does not claim that every family is autonomously release-ready.

Proof Pack integration

attach_simulation_signoff_evidence() adds a hash-valid family report reference to ProofManifest.simulation_signoff. The Proof Pack records the report and design identity, model/check counts, live pass count, failures, skips, and review state.

• A blocked family creates blocking simulation-signoff evidence.
• A non-blocking analytical or low-confidence result creates warning evidence and a human-review requirement.
• Only non-degraded, solver-backed passing evidence can map to an autonomous pass.

The complete input models, assumptions, detailed results, pass/fail states, and repair hints remain in the referenced simulation-signoff.json artifact rather than being flattened into the manifest. For SPICE-backed families, the retained input-model.spice is the exact deterministic netlist passed to the gate and is bundled alongside its governed model JSON.

Reproduce the corpus

Run the evidence corpus without requiring a local solver:

.venv/bin/python scripts/ci_simulation_signoff.py \
  --artifact-dir simulation-signoff-artifacts \
  --output simulation-signoff-report.json \
  --markdown simulation-signoff-report.md \
  --strict

Run the same gate used in CI when ngspice is installed:

.venv/bin/python scripts/ci_simulation_signoff.py \
  --artifact-dir simulation-signoff-artifacts \
  --output simulation-signoff-report.json \
  --markdown simulation-signoff-report.md \
  --require-live-simulation \
  --strict

All output paths must remain inside --trusted-output-root (the current directory by default). Existing artifact directories are cleaned only when they contain the ZapTrace ownership marker.

Non-claims

A passing corpus run is not electrical correctness, device-model accuracy, field-solver SI/PI validation, fabrication readiness, EMC or safety compliance, manufacturer approval, physical bring-up, or qualified human engineering approval. Family fixtures are governed regression models; they are not automatically selected-device, board-extracted, or lab-correlated models.