wai-quantum 0.3.38

//! Signed-byte pins for every receipt in this crate that seals `joules_micro`.
//!
//! These receipts carried their energy figure with no acquisition class
//! before they were given an optional one. A receipt sealed without a class
//! must keep exactly the signed bytes it had before, or every receipt
//! already issued stops verifying. Each test builds one
//! fixed, unlabelled receipt with a non-zero figure and pins, as computed by
//! the code *before* the class was added:
//!
//! - `receipt_hash()`, which covers the whole signing payload and the
//!   signature;
//! - a BLAKE3 hash of `to_json()`, so the rendered form is byte-identical too.
//!
//! The hex values must never be edited to make a test pass. A failure here
//! means legacy receipts broke.

use ed25519_dalek::SigningKey;

#[allow(dead_code)]
fn key(s: u8) -> SigningKey {
    SigningKey::from_bytes(&[s; 32])
}

#[allow(dead_code)]
fn hx(b: &[u8]) -> String {
    b.iter().map(|x| format!("{x:02x}")).collect()
}

#[allow(dead_code)]
fn json_hash(j: &str) -> String {
    hx(blake3::hash(j.as_bytes()).as_bytes())
}

#[cfg(feature = "quantum_receipt")]
#[test]
fn quantum_circuit_legacy_bytes() {
    use crate::quantum::{Circuit, Measure};
    use crate::quantum_receipt::QuantumReceipt;
    let mut c = Circuit::new(3);
    c.h(0).cx(0, 1).cx(1, 2);
    let r = QuantumReceipt::seal(&key(1), "did:key:pin", &c, Some(Measure { seed: 7, shots: 1024 }), 117_000, Some([0x21; 32]))
        .unwrap();
    assert!(r.verify());
    assert_eq!(hx(&r.receipt_hash()), "5f841f94b57ce254bea9e79cbc55cb48117c88c202a916659e4e8db5fae1fba1");
    assert_eq!(json_hash(&r.to_json()), "bc19d790962cecf2efea9d275f1b9494eb5a44bc1948e1f1bbaf2134f222b37d");
}

#[cfg(feature = "quantum_ops")]
mod ops {
    use super::*;
    use crate::quantum_ops::*;

    fn grant(cap: &str) -> GrantRef {
        GrantRef { grant_hash: content_hash(b"pin-grant"), capability: cap.into(), joule_ceiling_micro: 5_000_000, funds_ceiling: Some(100) }
    }

    fn evid() -> Vec<Evidence> {
        vec![Evidence { kind: "randomized_benchmarking".into(), blob_hash: content_hash(b"<rb>"), summary: "1q RB 0.9992".into() }]
    }

    #[test]
    fn calibration_legacy_bytes() {
        let r = CalibrationReceipt::seal(
            &key(1), "did:key:pin", "example:lab3-device", "q3", content_hash(b"cfg"), evid(),
            4_200_000, grant("quantum.calibrate"), None,
        );
        assert!(r.verify());
        // Recomputed 2026-09-30 when the device id became the neutral
        // "example:lab3-device": this receipt sealed by the code at 1c2af088 (the
        // commit before the acquisition class, d009db90), with that literal. The same
        // code with the previous literal reproduced the previous pins exactly.
        assert_eq!(hx(&r.receipt_hash()), "43326592236b428cb98124d94987b7c59c7ab09b2984ad3a4f622384992c2d03");
        assert_eq!(json_hash(&r.to_json()), "6803e8c6b38d2ce866f88a34313bd551272ad247646e0f258fa61142e87ee9f5");
    }

    #[test]
    fn job_legacy_bytes() {
        let r = JobReceipt::seal(
            &key(1), "did:key:pin", "wai.quantum.circuit", content_hash(b"c"), content_hash(b"r"),
            Some([0x31; 32]), 1000, 250, grant("quantum.job.run"), Some([0x32; 32]),
        );
        assert!(r.verify());
        assert_eq!(hx(&r.receipt_hash()), "52a38a0f7d6c9c58a67948b7ae12a92bfcb7a8a51507b50ec623adb13b05a42b");
        assert_eq!(json_hash(&r.to_json()), "9e8d951ad82084deb6f7ac3e48a049bb305de06adc5d77175bf3ce432abc786b");
    }

    #[test]
    fn mitigation_legacy_bytes() {
        let r = MitigationReceipt::seal(
            &key(1), "did:key:pin", "wai.quantum.circuit", "zne.richardson", "ZZ",
            content_hash(b"raw"), Some(content_hash(b"model")), 744_178, 912_680, 20_971, 48_000,
            900_000, grant("quantum.mitigate"), None,
        );
        assert!(r.verify());
        assert_eq!(hx(&r.receipt_hash()), "df0427389afeb3e7943ab15f7318ab22d5828c2623f5ef7dd6607ce1c1415247");
        assert_eq!(json_hash(&r.to_json()), "99379161a41ecbfb63ecf2cd1217d6589a7566e0dfc923e6fc35b561a4a6dc08");
    }

    #[test]
    fn decode_legacy_bytes() {
        let r = DecodeReceipt::seal(
            &key(1), "did:key:pin", "toric:L7", "relay-bp.min-sum",
            content_hash(b"H"), content_hash(b"s"), content_hash(b"c"),
            true, 3, 46_656, 900_000, grant("quantum.decode"), None,
        );
        assert!(r.verify());
        assert_eq!(hx(&r.receipt_hash()), "27eecec2c2b92d4e4e6e1a6e5025199e000c51ad691b0c3d195a29965a9e17a2");
        assert_eq!(json_hash(&r.to_json()), "6c9a015980792a3baf33a230d009eb00fc2eda65e121edfc788659ee603387d7");
    }

    #[test]
    fn compile_legacy_bytes() {
        let r = CompileReceipt::seal(
            &key(1), "did:key:pin", "clifford-tableau",
            content_hash(b"s"), content_hash(b"t"), content_hash(b"cpl"),
            true, 3, 4096, 300_000, grant("quantum.compile"), None,
        );
        assert!(r.verify());
        assert_eq!(hx(&r.receipt_hash()), "79ba47b4b329b1d0e53967a8c84e95756266e3c47f5366bcdc99836307adcc0f");
        assert_eq!(json_hash(&r.to_json()), "eee5a71d7cdd318841f771fe5d5b435ee0252e70a71cc2bd54f50225d729c0a0");
    }

    #[test]
    fn rearrange_legacy_bytes() {
        let r = RearrangeReceipt::seal(
            &key(1), "did:key:pin", "hungarian-lsap",
            content_hash(b"i"), content_hash(b"t"), content_hash(b"p"),
            true, 41, 318, 450_000, grant("quantum.rearrange"), None,
        );
        assert!(r.verify());
        assert_eq!(hx(&r.receipt_hash()), "a77758a5de40f9684ea0b9618d42417cc318f88ab812020cbc09618095c51efc");
        assert_eq!(json_hash(&r.to_json()), "2f980e1ec6c3cb1eaebfb3a457ad0184b3a040637a398f02bf2a31850f1741fe");
    }
}

#[cfg(feature = "quantum_phasor_meter")]
#[test]
fn phasor_legacy_bytes() {
    use crate::quantum_phasor_meter::{computation_id, result_fingerprint, PhasorReceipt, PhasorWork};
    let work = PhasorWork { n_features: 200, input_dim: 2, n_samples: 300 };
    let r = PhasorReceipt::seal(
        &key(1), "did:key:pin", "wai.quantum.kernel",
        computation_id("wai.quantum.kernel", &[0.5, 1.25]), result_fingerprint(&[0.1, 0.2, 0.3]),
        work, 117_000, None,
    );
    assert!(r.verify());
    assert_eq!(hx(&r.receipt_hash()), "b18e364f7793943873c9070c6755709014d2cf6014bfc9610283b20eca9478e8");
    assert_eq!(json_hash(&r.to_json()), "0d74576475bb5d0a9629eac5954ae81d06947b24bb62527fb9789cbcdb9e1cb1");
}

#[cfg(feature = "quantum_qbom")]
#[test]
fn qbom_legacy_bytes() {
    use crate::quantum_qbom::QbomBuilder;
    let q = QbomBuilder::new("job-pin", [0x51; 32], "sim:device")
        .stage("compile", [0x52; 32], 120_000)
        .stage("execute", [0x53; 32], 90_000)
        .seal(&key(1), "did:key:pin");
    assert!(q.verify());
    assert_eq!(hx(&q.receipt_hash()), "fe651bcfa059621f4c237fd7163ec4ceb76a41a66dd55980937c6f7715276901");
    assert_eq!(json_hash(&q.to_json()), "9f16b7b0e72a8d6a0a712de3808d819bc6cdf1712ecbddc10125def0b0168986");
}

// ---------------------------------------------------------------------------
// The optional label (`crate::quantum_energy`), exercised identically on every
// receipt type.
// ---------------------------------------------------------------------------

#[allow(dead_code)]
fn chip(ppm: u32) -> crate::quantum_energy::EnergyClass {
    use crate::quantum_energy::{CounterFiltering, EnergyClass, Uncertainty};
    EnergyClass::OnChipCounter { uncertainty: Uncertainty { relative_ppm: ppm, window_us: 2_977_104 }, filtering: CounterFiltering::Unknown }
}

#[allow(dead_code)]
fn check_label_ok<R: crate::quantum_energy::Labellable>(l: &crate::quantum_energy::Labelled<R>) -> bool {
    crate::quantum_energy::check_label(l.receipt.figure(), &l.energy_class).is_ok()
}

/// Everything the label must do, on one pinned unlabelled receipt sealed by
/// `signer`. `figure` gives mutable access to its `joules_micro`.
#[allow(dead_code)]
fn exercise<R, F>(legacy: R, signer: &SigningKey, figure: F, verify: fn(&R) -> bool)
where
    R: crate::quantum_energy::Labellable,
    F: Fn(&mut R) -> &mut u64,
{
    use crate::quantum_energy::{ClassError, CounterFiltering, EnergyClass, Labelled, MaybeLabelled, Uncertainty};
    assert!(verify(&legacy));
    let legacy_json = legacy.unlabelled_json();

    let l = Labelled::seal(legacy.clone(), chip(15_403), signer).expect("a valid label");
    assert!(l.verify(), "a labelled receipt verifies");
    assert!(!verify(&l.receipt), "the unlabelled verify() refuses a labelled receipt: it fails closed");

    // Inside the signature: not strippable, restatable or promotable.
    let mut restated = l.clone();
    restated.energy_class = chip(15_404);
    assert!(check_label_ok(&restated), "the control: the restated label is itself valid");
    assert!(!restated.verify(), "so only the signature refuses it");
    let mut promoted = l.clone();
    promoted.energy_class = EnergyClass::CalibratedInstrument {
        uncertainty: Uncertainty { relative_ppm: 15_403, window_us: 2_977_104 },
        calibration_ref: "cert".into(),
    };
    assert!(!promoted.verify());
    let mut demoted = l.clone();
    demoted.energy_class = EnergyClass::ModelBased;
    assert!(!demoted.verify());

    // Refusals.
    assert_eq!(Labelled::seal(legacy.clone(), chip(15_403), &key(8)).unwrap_err(), ClassError::SignerMismatch);
    assert_eq!(Labelled::seal(legacy.clone(), chip(0), signer).unwrap_err(), ClassError::NoUncertainty);
    let mut zero = legacy.clone();
    *figure(&mut zero) = 0;
    assert_eq!(Labelled::seal(zero, chip(15_403), signer).unwrap_err(), ClassError::NoFigure);
    // verify() refuses a correctly signed label beside a zero figure.
    let mut zero = l.clone();
    *figure(&mut zero.receipt) = 0;
    let resigned = Labelled::seal(zero.receipt.clone(), EnergyClass::Estimator, signer);
    assert_eq!(resigned.unwrap_err(), ClassError::NoFigure);
    let undeclared = EnergyClass::OnChipCounter {
        uncertainty: Uncertainty { relative_ppm: 0, window_us: 1 },
        filtering: CounterFiltering::Unknown,
    };
    let mut bad = l.clone();
    bad.energy_class = undeclared.clone();
    assert!(!bad.verify());

    // And verify() refuses a label that breaks the rules even when the
    // signature over it is valid: the rule is checked, not just the bytes.
    let signed_over = |mut r: R, class: &EnergyClass| {
        use ed25519_dalek::Signer;
        let sig = signer.sign(&r.labelled_payload(Some(class))).to_bytes();
        r.set_signature(sig);
        Labelled { receipt: r, energy_class: class.clone() }
    };
    assert!(signed_over(legacy.clone(), &chip(15_403)).verify(), "the control: a valid label, signed, verifies");
    assert!(!signed_over(legacy.clone(), &undeclared).verify(), "a refined class without its uncertainty");
    let mut zero = legacy.clone();
    *figure(&mut zero) = 0;
    assert!(!signed_over(zero, &EnergyClass::Estimator).verify(), "a class beside a zero figure");

    // A declaration below the 0.5/√3 µJ the figure's rounding adds is refused,
    // sealed or signed over: `joules_micro × relative_ppm` must reach 288 676.
    let fig = {
        let mut probe = legacy.clone();
        *figure(&mut probe)
    };
    let least = crate::quantum_energy::RESOLUTION_FLOOR_UJ_PPM.div_ceil(fig);
    assert!(signed_over(legacy.clone(), &chip(least as u32)).verify(), "the control: exactly at the floor");
    if least > 1 {
        let below = chip((least - 1) as u32);
        assert_eq!(Labelled::seal(legacy.clone(), below.clone(), signer).unwrap_err(), ClassError::BelowResolution);
        assert!(!signed_over(legacy.clone(), &below).verify(), "a declaration below the figure's resolution");
    }

    // JSON: the unlabelled form is untouched; the labelled form carries the
    // class and the labelled identity, and round-trips.
    assert!(!legacy_json.contains("energy_provenance"));
    let j = l.to_json();
    let v: serde_json::Value = serde_json::from_str(&j).unwrap();
    assert_eq!(v["energy_provenance"], "OnChipCounter");
    assert_eq!(v["receipt_hash"], serde_json::Value::from(hx(&l.receipt_hash())));
    let back = Labelled::<R>::from_json(&j).expect("parse");
    assert_eq!(back, l);
    assert!(back.verify());
    assert!(Labelled::<R>::from_json(&legacy_json).is_none(), "no class, no labelled parse");

    // Either form through the one entry point a verifier uses: the form comes
    // from the JSON, and each verifies by its own rules.
    let any = MaybeLabelled::<R>::from_json(&legacy_json).expect("the unlabelled form parses");
    assert!(matches!(any, MaybeLabelled::Unlabelled(_)) && any.verify() && any.energy_class().is_none());
    assert_eq!(any.receipt_hash(), legacy.unlabelled_receipt_hash());
    assert_eq!(any.to_json(), legacy_json);
    let any = MaybeLabelled::<R>::from_json(&j).expect("the labelled form parses");
    assert!(matches!(any, MaybeLabelled::Labelled(_)) && any.verify());
    assert_eq!(any.energy_class(), Some(&chip(15_403)));
    assert_eq!(any.receipt_hash(), l.receipt_hash());
    assert_eq!(any.to_json(), j);
    // A label whose evidence is malformed, or evidence whose class was
    // stripped, is refused — never read as an unlabelled receipt.
    let mut broken = v.clone();
    broken["energy_uncertainty"] = serde_json::Value::Null;
    assert!(MaybeLabelled::<R>::from_json(&broken.to_string()).is_none());
    let mut stripped = v.clone();
    stripped.as_object_mut().unwrap().remove("energy_provenance");
    assert!(MaybeLabelled::<R>::from_json(&stripped.to_string()).is_none());
    // A restated label parses and is refused by verify().
    let mut restated_json = v.clone();
    restated_json["energy_uncertainty"]["relative_ppm"] = serde_json::Value::from(15_404);
    let any = MaybeLabelled::<R>::from_json(&restated_json.to_string()).expect("a well-formed label parses");
    assert!(!any.verify());
    assert_ne!(l.receipt_hash(), {
        let mut h = blake3::Hasher::new();
        h.update(legacy_json.as_bytes());
        *h.finalize().as_bytes()
    });
}

#[cfg(feature = "quantum_receipt")]
#[test]
fn quantum_circuit_label() {
    use crate::quantum::{Circuit, Measure};
    use crate::quantum_energy::Labelled;
    use crate::quantum_receipt::QuantumReceipt;
    let mut c = Circuit::new(3);
    c.h(0).cx(0, 1).cx(1, 2);
    let r = QuantumReceipt::seal(&key(1), "did:key:pin", &c, Some(Measure { seed: 7, shots: 1024 }), 117_000, Some([0x21; 32])).unwrap();
    exercise(r.clone(), &key(1), |r| &mut r.joules_micro, QuantumReceipt::verify);
    let l = Labelled::seal(r, chip(15_403), &key(1)).unwrap();
    assert!(l.verify_reconstruction(&c));
    let mut other = Circuit::new(3);
    other.h(0);
    assert!(!l.verify_reconstruction(&other));
}

#[cfg(feature = "quantum_ops")]
mod ops_labels {
    use super::*;
    use crate::quantum_ops::*;

    fn grant(cap: &str) -> GrantRef {
        GrantRef { grant_hash: content_hash(b"pin-grant"), capability: cap.into(), joule_ceiling_micro: 5_000_000, funds_ceiling: Some(100) }
    }

    #[test]
    fn calibration_label() {
        let r = CalibrationReceipt::seal(
            &key(1), "did:key:pin", "example:lab3-device", "q3", content_hash(b"cfg"),
            vec![Evidence { kind: "rb".into(), blob_hash: content_hash(b"<rb>"), summary: "s".into() }],
            4_200_000, grant("quantum.calibrate"), None,
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, CalibrationReceipt::verify);
    }

    #[test]
    fn job_label() {
        let r = JobReceipt::seal(
            &key(1), "did:key:pin", "wai.quantum.circuit", content_hash(b"c"), content_hash(b"r"),
            Some([0x31; 32]), 1000, 250, grant("quantum.job.run"), Some([0x32; 32]),
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, JobReceipt::verify);
    }

    #[test]
    fn mitigation_label() {
        let r = MitigationReceipt::seal(
            &key(1), "did:key:pin", "wai.quantum.circuit", "zne.richardson", "ZZ",
            content_hash(b"raw"), Some(content_hash(b"model")), 744_178, 912_680, 20_971, 48_000,
            900_000, grant("quantum.mitigate"), None,
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, MitigationReceipt::verify);
    }

    #[test]
    fn decode_label() {
        let r = DecodeReceipt::seal(
            &key(1), "did:key:pin", "toric:L7", "relay-bp.min-sum",
            content_hash(b"H"), content_hash(b"s"), content_hash(b"c"),
            true, 3, 46_656, 900_000, grant("quantum.decode"), None,
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, DecodeReceipt::verify);
    }

    #[test]
    fn compile_label() {
        let r = CompileReceipt::seal(
            &key(1), "did:key:pin", "clifford-tableau",
            content_hash(b"s"), content_hash(b"t"), content_hash(b"cpl"),
            true, 3, 4096, 300_000, grant("quantum.compile"), None,
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, CompileReceipt::verify);
    }

    #[test]
    fn rearrange_label() {
        let r = RearrangeReceipt::seal(
            &key(1), "did:key:pin", "hungarian-lsap",
            content_hash(b"i"), content_hash(b"t"), content_hash(b"p"),
            true, 41, 318, 450_000, grant("quantum.rearrange"), None,
        );
        exercise(r, &key(1), |r| &mut r.joules_micro, RearrangeReceipt::verify);
    }

    #[test]
    fn a_job_cross_links_to_a_calibration_in_either_form() {
        use crate::quantum_energy::{Labelled, MaybeLabelled};
        let cal = CalibrationReceipt::seal(
            &key(1), "did:key:pin", "example:lab3-device", "q3", content_hash(b"cfg"),
            vec![Evidence { kind: "rb".into(), blob_hash: content_hash(b"<rb>"), summary: "s".into() }],
            4_200_000, grant("quantum.calibrate"), None,
        );
        let cal_l = Labelled::seal(cal.clone(), chip(15_403), &key(1)).unwrap();
        let job_under = |cal_id: [u8; 32]| {
            JobReceipt::seal(
                &key(1), "did:key:pin", "wai.quantum.circuit", content_hash(b"c"), content_hash(b"r"),
                Some(cal_id), 1000, 250, grant("quantum.job.run"), None,
            )
        };

        // Both unlabelled: the legacy check and the either-form check agree.
        let j0 = job_under(cal.receipt_hash());
        assert!(j0.verify_against_calibration(&cal));
        assert!(MaybeLabelled::Unlabelled(j0.clone()).verify_against_calibration(&MaybeLabelled::Unlabelled(cal.clone())));

        // A job run under a labelled calibration names its labelled identity.
        // The unlabelled check cannot see that calibration at all; the
        // either-form check binds it, and only it.
        let j1 = job_under(cal_l.receipt_hash());
        assert!(!j1.verify_against_calibration(&cal_l.receipt));
        assert!(MaybeLabelled::Unlabelled(j1.clone()).verify_against_calibration(&cal_l.clone().into()));
        assert!(!MaybeLabelled::Unlabelled(j1.clone()).verify_against_calibration(&MaybeLabelled::Unlabelled(cal.clone())), "not the unlabelled calibration");

        // Labelled jobs, under either form of calibration.
        let j2 = Labelled::seal(j1.clone(), chip(20_000), &key(1)).unwrap();
        assert!(MaybeLabelled::from(j2.clone()).verify_against_calibration(&cal_l.clone().into()));
        let j3 = Labelled::seal(j0.clone(), chip(20_000), &key(1)).unwrap();
        assert!(MaybeLabelled::from(j3).verify_against_calibration(&MaybeLabelled::Unlabelled(cal.clone())));

        // A calibration whose label was restated no longer verifies, so the
        // link fails.
        let mut restated = cal_l.clone();
        restated.energy_class = chip(15_404);
        assert!(!MaybeLabelled::Unlabelled(j1).verify_against_calibration(&restated.into()));

        // From JSON, as a verifier receives them.
        let cal_any = MaybeLabelled::<CalibrationReceipt>::from_json(&cal_l.to_json()).unwrap();
        let job_any = MaybeLabelled::<JobReceipt>::from_json(&j2.to_json()).unwrap();
        assert!(job_any.verify_against_calibration(&cal_any));
    }

    #[test]
    fn a_labelled_receipt_still_honours_its_grant() {
        // The label does not bypass the receipt's own checks: an over-budget
        // run stays invalid when labelled.
        use crate::quantum_energy::Labelled;
        let tight = GrantRef { grant_hash: [0u8; 32], capability: "quantum.decode".into(), joule_ceiling_micro: 10, funds_ceiling: None };
        let r = DecodeReceipt::seal(
            &key(1), "m", "toric:L5", "relay-bp.min-sum",
            content_hash(b"H"), content_hash(b"s"), content_hash(b"c"),
            true, 1, 100, 900_000, tight, None,
        );
        let l = Labelled::seal(r, chip(15_403), &key(1)).unwrap();
        assert!(!l.verify(), "a run that blew its grant must not verify, labelled or not");
    }
}

#[cfg(feature = "quantum_phasor_meter")]
#[test]
fn phasor_label() {
    use crate::quantum_phasor_meter::{computation_id, result_fingerprint, PhasorReceipt, PhasorWork};
    let work = PhasorWork { n_features: 200, input_dim: 2, n_samples: 300 };
    let r = PhasorReceipt::seal(
        &key(1), "did:key:pin", "wai.quantum.kernel",
        computation_id("wai.quantum.kernel", &[0.5, 1.25]), result_fingerprint(&[0.1, 0.2, 0.3]),
        work, 117_000, None,
    );
    exercise(r, &key(1), |r| &mut r.joules_micro, PhasorReceipt::verify);
}

#[cfg(feature = "quantum_qbom")]
#[test]
fn qbom_entry_labels() {
    use crate::quantum_energy::{ClassError, EnergyClass, LabelledQbom};
    use crate::quantum_qbom::{Qbom, QbomBuilder};
    let q = QbomBuilder::new("job-pin", [0x51; 32], "sim:device")
        .stage("compile", [0x52; 32], 120_000)
        .stage("execute", [0x53; 32], 90_000)
        .seal(&key(1), "did:key:pin");
    let classes = vec![Some(chip(15_403)), None];
    let l = LabelledQbom::seal(q.clone(), classes.clone(), &key(1)).unwrap();
    assert!(l.verify());
    assert!(!l.qbom.verify(), "the unlabelled verify() refuses a labelled bill");
    assert_ne!(l.provenance_root(), q.provenance_root());
    assert_ne!(l.receipt_hash(), q.receipt_hash());

    // Stripping, moving or restating an entry label breaks the bill.
    let mut moved = l.clone();
    moved.classes = vec![None, Some(chip(15_403))];
    assert!(!moved.verify());
    let mut restated = l.clone();
    restated.classes[0] = Some(chip(15_404));
    assert!(!restated.verify());
    // An entry declaring less than its figure's resolution is refused:
    // 120,000 µJ needs at least 3 ppm.
    assert_eq!(
        LabelledQbom::seal(q.clone(), vec![Some(chip(2)), None], &key(1)).unwrap_err(),
        ClassError::BelowResolution
    );
    assert!(LabelledQbom::seal(q.clone(), vec![Some(chip(3)), None], &key(1)).unwrap().verify());

    // Refusals: slot count, nothing labelled, zero figure, wrong signer.
    assert_eq!(LabelledQbom::seal(q.clone(), vec![Some(chip(1))], &key(1)).unwrap_err(), ClassError::EntryMismatch);
    assert_eq!(LabelledQbom::seal(q.clone(), vec![None, None], &key(1)).unwrap_err(), ClassError::EntryMismatch);
    assert_eq!(LabelledQbom::seal(q.clone(), classes.clone(), &key(2)).unwrap_err(), ClassError::SignerMismatch);
    let zero = QbomBuilder::new("j", [0; 32], "d").stage("compile", [1; 32], 0).seal(&key(1), "id");
    assert_eq!(LabelledQbom::seal(zero, vec![Some(EnergyClass::ModelBased)], &key(1)).unwrap_err(), ClassError::NoFigure);

    // verify() checks the rules, not just the signature: a bill signed over
    // classes that break them is refused.
    let signed_over = |q: &Qbom, classes: Vec<Option<EnergyClass>>| {
        use ed25519_dalek::Signer;
        let mut q = q.clone();
        q.sig = key(1).sign(&q.labelled_signing_payload(&classes)).to_bytes();
        LabelledQbom { qbom: q, classes }
    };
    assert!(signed_over(&q, classes.clone()).verify(), "the control verifies");
    assert!(!signed_over(&q, vec![None, None]).verify(), "a labelled bill that labels nothing");
    let zero = QbomBuilder::new("j", [0; 32], "d").stage("compile", [1; 32], 0).seal(&key(1), "id");
    assert!(!signed_over(&zero, vec![Some(EnergyClass::ModelBased)]).verify(), "a class beside a zero figure");

    // Binding checks each entry's class against its stage receipt's class.
    assert!(l.binds(&[([0x52; 32], true, Some(&chip(15_403))), ([0x53; 32], true, None)]));
    assert!(!l.binds(&[([0x52; 32], true, None), ([0x53; 32], true, None)]), "a stage whose class differs breaks the bill");

    // JSON round trip; the unlabelled bill parses as no labelled bill.
    let j = l.to_json();
    let v: serde_json::Value = serde_json::from_str(&j).unwrap();
    assert_eq!(v["entries"][0]["energy_provenance"], "OnChipCounter");
    assert!(v["entries"][1].get("energy_provenance").is_none());
    assert_eq!(v["receipt_hash"], serde_json::Value::from(hx(&l.receipt_hash())));
    let back = LabelledQbom::from_json(&j).expect("parse");
    assert_eq!(back, l);
    assert!(back.verify());
    assert!(LabelledQbom::from_json(&q.to_json()).is_none());
    let _: Option<Qbom> = Qbom::from_json(&q.to_json());
}