{
  "capability_id": "math.linear_algebra",
  "tool_id": "linear-system",
  "engine": "linear-algebra",
  "calculation_version": "1.12.0",
  "generated_at": "2026-09-22T07:25:48.832Z",
  "engine_build": "2026-09-22",
  "test_count": 54,
  "passed": 54,
  "failed": 0,
  "tests_summary": {
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      "passed": 27
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    "boundary": {
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      "passed": 6
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      "passed": 21
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  "expert_reviewed": false,
  "internally_reviewed": false,
  "review_kind": null,
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  "reviewer_role": null,
  "last_reviewed": null,
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    "scope": [
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      "input semantics",
      "assumptions",
      "limitations",
      "sources",
      "tests"
    ],
    "note": "Domain expert review is optional under CVP (CVP-EXP-01). Absence does not block CVP Verified. See Review policy for supplemental domain assurance."
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  "internal_review": {
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    "reviewer": null
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  "api": "https://www.calculatorx.com/api/v1/calc/linear-system",
  "schema_input": "https://www.calculatorx.com/schemas/math.linear_algebra.input.json",
  "schema_output": "https://www.calculatorx.com/schemas/math.linear_algebra.output.json",
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    "Order ≤ 4 square for solve/det/inverse/factorizations",
    "lstsq also A ∈ R^{m×n} with m,n ∈ [2,4]",
    "Planar ℝ² figure when 2×2; other shapes omit it",
    "Not a CAS"
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    "Singular inverse → SINGULAR_MATRIX",
    "lstsq accepts rectangular m×n with m,n ∈ [2,4]; other modes stay square",
    "Cholesky is SPD only (NOT_SYMMETRIC / NOT_POSITIVE_DEFINITE)",
    "Not Statistics regression / large-matrix server compute",
    "Not 2-norm κ₂ as a product / CAS / Jordan form"
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  "boundary_conditions": [
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    "asymmetric Cholesky → NOT_SYMMETRIC; nonpositive pivot → NOT_POSITIVE_DEFINITE",
    "unknown mode (including jordan-form) → INVALID_MODE"
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      "title": "ISO 80000-2:2019 Quantities and units — Mathematics",
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      "kind": "standard",
      "reference_scope": "all"
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    {
      "title": "CRC / Strang — Ax=b, LU/QR/SVD, four fundamental subspaces",
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            "kind": "real"
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    {
      "id": "golden-rref-rank1",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "rref",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expect": {
        "rank": 1,
        "rref": [
          [
            1,
            2
          ],
          [
            0,
            0
          ]
        ],
        "pivot_columns": [
          1
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "rref",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            2,
            4
          ]
        ],
        "rref": [
          [
            1,
            2
          ],
          [
            0,
            0
          ]
        ],
        "rank": 1,
        "pivot_columns": [
          1
        ],
        "det": 0,
        "formula": "Gauss–Jordan → RREF",
        "algorithm": "gauss_jordan_rref",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": null,
        "warnings": []
      },
      "tol": 1e-12
    },
    {
      "id": "golden-rref-full",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "rref",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 3,
        "a22": 4
      },
      "expect": {
        "rank": 2,
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "rref",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            3,
            4
          ]
        ],
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "rank": 2,
        "pivot_columns": [
          1,
          2
        ],
        "det": -2,
        "formula": "Gauss–Jordan → RREF",
        "algorithm": "gauss_jordan_rref",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": 21,
        "warnings": []
      },
      "tol": 1e-12
    },
    {
      "id": "golden-condition-diag",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "condition",
        "order": 2,
        "a11": 2,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expect": {
        "condition_number": 2,
        "infinite": false,
        "status": "finite"
      },
      "expectWarning": null,
      "actual": {
        "mode": "condition",
        "order": 2,
        "A": [
          [
            2,
            0
          ],
          [
            0,
            1
          ]
        ],
        "condition_number": 2,
        "infinite": false,
        "status": "finite",
        "norm": "1",
        "det": 2,
        "formula": "κ₁(A) = ‖A‖₁ ‖A⁻¹‖₁",
        "algorithm": "one_norm_inverse",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "warnings": []
      },
      "tol": 1e-12
    },
    {
      "id": "golden-condition-singular",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "condition",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expect": {
        "condition_number": null,
        "infinite": true,
        "status": "singular"
      },
      "expectWarning": null,
      "actual": {
        "mode": "condition",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            2,
            4
          ]
        ],
        "condition_number": null,
        "infinite": true,
        "status": "singular",
        "norm": "1",
        "det": 0,
        "formula": "κ₁(A) = ‖A‖₁ ‖A⁻¹‖₁",
        "algorithm": "one_norm_inverse",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-nullspace-rank1",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "nullspace",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expect": {
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "basis": [
          [
            -2,
            1
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "nullspace",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            2,
            4
          ]
        ],
        "basis": [
          [
            -2,
            1
          ]
        ],
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "residual_max": 0,
        "free_columns": [
          2
        ],
        "pivot_columns": [
          1
        ],
        "rref": [
          [
            1,
            2
          ],
          [
            0,
            0
          ]
        ],
        "det": 0,
        "formula": "dim ker A = n − rank A",
        "algorithm": "gauss_jordan_rref + free_variables",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": null,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-nullspace-full",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "nullspace",
        "order": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expect": {
        "dimension": 0,
        "trivial": true,
        "basis": []
      },
      "expectWarning": null,
      "actual": {
        "mode": "nullspace",
        "order": 2,
        "A": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "basis": [],
        "dimension": 0,
        "rank": 2,
        "trivial": true,
        "residual_max": 0,
        "free_columns": [],
        "pivot_columns": [
          1,
          2
        ],
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "det": 1,
        "formula": "dim ker A = n − rank A",
        "algorithm": "gauss_jordan_rref + free_variables",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": 1,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-colspace-rank1",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "columnspace",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expect": {
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "basis": [
          [
            1,
            2
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "columnspace",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            2,
            4
          ]
        ],
        "basis": [
          [
            1,
            2
          ]
        ],
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "residual_max": 0,
        "pivot_columns": [
          1
        ],
        "rref": [
          [
            1,
            2
          ],
          [
            0,
            0
          ]
        ],
        "det": 0,
        "formula": "dim im A = rank A",
        "algorithm": "gauss_jordan_rref + pivot_columns",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": null,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-colspace-full",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "columnspace",
        "order": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expect": {
        "dimension": 2,
        "trivial": false,
        "basis": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "columnspace",
        "order": 2,
        "A": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "basis": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "dimension": 2,
        "rank": 2,
        "trivial": false,
        "residual_max": 0,
        "pivot_columns": [
          1,
          2
        ],
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "det": 1,
        "formula": "dim im A = rank A",
        "algorithm": "gauss_jordan_rref + pivot_columns",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": 1,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-rowspace-rank1",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "rowspace",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expect": {
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "basis": [
          [
            1,
            2
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "rowspace",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            2,
            4
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        ],
        "basis": [
          [
            1,
            2
          ]
        ],
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "residual_max": 0,
        "pivot_columns": [
          1
        ],
        "rref": [
          [
            1,
            2
          ],
          [
            0,
            0
          ]
        ],
        "det": 0,
        "formula": "dim row A = rank A",
        "algorithm": "gauss_jordan_rref + nonzero_rows",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": null,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-rowspace-full",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "rowspace",
        "order": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expect": {
        "dimension": 2,
        "trivial": false,
        "basis": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "rowspace",
        "order": 2,
        "A": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "basis": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "dimension": 2,
        "rank": 2,
        "trivial": false,
        "residual_max": 0,
        "pivot_columns": [
          1,
          2
        ],
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "det": 1,
        "formula": "dim row A = rank A",
        "algorithm": "gauss_jordan_rref + nonzero_rows",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": 1,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-leftnullspace-rank1",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "leftnullspace",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 3,
        "a22": 6
      },
      "expect": {
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "basis": [
          [
            -3,
            1
          ]
        ]
      },
      "expectWarning": null,
      "actual": {
        "mode": "leftnullspace",
        "order": 2,
        "A": [
          [
            1,
            2
          ],
          [
            3,
            6
          ]
        ],
        "basis": [
          [
            -3,
            1
          ]
        ],
        "dimension": 1,
        "rank": 1,
        "trivial": false,
        "residual_max": 0,
        "free_columns": [
          2
        ],
        "pivot_columns": [
          1
        ],
        "rref": [
          [
            1,
            3
          ],
          [
            0,
            0
          ]
        ],
        "det": 0,
        "formula": "dim ker Aᵀ = n − rank A",
        "algorithm": "gauss_jordan_rref + transpose + free_variables",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": null,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "golden-leftnullspace-full",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "mode": "leftnullspace",
        "order": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expect": {
        "dimension": 0,
        "trivial": true,
        "basis": []
      },
      "expectWarning": null,
      "actual": {
        "mode": "leftnullspace",
        "order": 2,
        "A": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "basis": [],
        "dimension": 0,
        "rank": 2,
        "trivial": true,
        "residual_max": 0,
        "free_columns": [],
        "pivot_columns": [
          1,
          2
        ],
        "rref": [
          [
            1,
            0
          ],
          [
            0,
            1
          ]
        ],
        "det": 1,
        "formula": "dim ker Aᵀ = n − rank A",
        "algorithm": "gauss_jordan_rref + transpose + free_variables",
        "numeric_backend": "float64",
        "singularity_threshold": 1e-15,
        "condition_number": 1,
        "warnings": []
      },
      "tol": null
    },
    {
      "id": "boundary-singular",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "inverse",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 2,
        "a22": 4
      },
      "expectError": "SINGULAR_MATRIX",
      "code": "SINGULAR_MATRIX",
      "error": "Matrix is singular; inverse does not exist."
    },
    {
      "id": "boundary-jordan-form",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "jordan-form",
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1
      },
      "expectError": "INVALID_MODE",
      "code": "INVALID_MODE",
      "error": "mode must be solve, det, inverse, rank, multiply, transpose, eigen, lu, chol, qr, svd, lstsq, rref, condition, nullspace, columnspace, rowspace, or leftnullspace."
    },
    {
      "id": "boundary-lstsq-rows",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "lstsq",
        "rows": 5,
        "cols": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": 1,
        "b1": 1,
        "b2": 0
      },
      "expectError": "INVALID_INPUT",
      "code": "INVALID_INPUT",
      "error": "rows must be an integer 2–4."
    },
    {
      "id": "boundary-rect-solve",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "solve",
        "rows": 3,
        "cols": 2,
        "a11": 1,
        "a12": 1,
        "a21": 1,
        "a22": 2,
        "a31": 1,
        "a32": 3,
        "b1": 1,
        "b2": 2,
        "b3": 2
      },
      "expectError": "INVALID_INPUT",
      "code": "INVALID_INPUT",
      "error": "solve/det/inverse/factorizations need a square matrix. Rectangular A is lstsq-only."
    },
    {
      "id": "boundary-chol-nonsym",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "chol",
        "order": 2,
        "a11": 1,
        "a12": 2,
        "a21": 0,
        "a22": 1
      },
      "expectError": "NOT_SYMMETRIC",
      "code": "NOT_SYMMETRIC",
      "error": "Cholesky needs a symmetric matrix. Asymmetric A is NOT_SYMMETRIC."
    },
    {
      "id": "boundary-chol-indef",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "chol",
        "order": 2,
        "a11": 1,
        "a12": 0,
        "a21": 0,
        "a22": -1
      },
      "expectError": "NOT_POSITIVE_DEFINITE",
      "code": "NOT_POSITIVE_DEFINITE",
      "error": "Cholesky needs a positive-definite matrix. Nonpositive pivot is NOT_POSITIVE_DEFINITE."
    },
    {
      "id": "property-la-solve",
      "ok": true,
      "kind": "property",
      "detail": "2x+y=5",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-det",
      "ok": true,
      "kind": "property",
      "detail": "det",
      "expect": -2,
      "actual": -2
    },
    {
      "id": "property-la-inv",
      "ok": true,
      "kind": "property",
      "detail": "diag inverse",
      "expect": 0.5,
      "actual": 0.5
    },
    {
      "id": "property-la-rank",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 singular",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-t",
      "ok": true,
      "kind": "property",
      "detail": "transpose",
      "expect": 3,
      "actual": 3
    },
    {
      "id": "property-la-qr",
      "ok": true,
      "kind": "property",
      "detail": "QR residual",
      "expect": 0,
      "actual": 0
    },
    {
      "id": "property-la-lu",
      "ok": true,
      "kind": "property",
      "detail": "LU residual",
      "expect": 0,
      "actual": 0
    },
    {
      "id": "property-la-chol",
      "ok": true,
      "kind": "property",
      "detail": "Cholesky LLᵀ",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-eigen",
      "ok": true,
      "kind": "property",
      "detail": "diag eigen",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-svd",
      "ok": true,
      "kind": "property",
      "detail": "diag SVD",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-svd-sym",
      "ok": true,
      "kind": "property",
      "detail": "sym SVD residual",
      "expect": 0,
      "actual": 0
    },
    {
      "id": "property-la-lstsq",
      "ok": true,
      "kind": "property",
      "detail": "lstsq QR unique",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-lstsq-pinv",
      "ok": true,
      "kind": "property",
      "detail": "lstsq SVD min-norm",
      "expect": 0.04,
      "actual": 0.04
    },
    {
      "id": "property-la-lstsq-rect",
      "ok": true,
      "kind": "property",
      "detail": "rectangular 3×2 QR",
      "expect": 0.6666666666666666,
      "actual": 0.666666666667
    },
    {
      "id": "property-la-rref",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 RREF",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-condition",
      "ok": true,
      "kind": "property",
      "detail": "κ₁ diag 2,1",
      "expect": 2,
      "actual": 2
    },
    {
      "id": "property-la-nullspace",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 kernel",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-colspace",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 image",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-rowspace",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 rowspace",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-leftnullspace",
      "ok": true,
      "kind": "property",
      "detail": "rank-1 left kernel ≠ right kernel",
      "expect": 1,
      "actual": 1
    },
    {
      "id": "property-la-id3",
      "ok": true,
      "kind": "property",
      "detail": "I₃ solve",
      "expect": 9,
      "actual": 9
    }
  ],
  "tier": "engine_tested",
  "verification": {
    "tests": {
      "passed": 54,
      "total": 54,
      "golden": 27,
      "boundary": 6,
      "property": 21
    },
    "contract_checks": {
      "passed": 5,
      "total": 5
    }
  },
  "evidence_core_generated_at": "2026-09-22T07:23:03.591Z",
  "rendered_at": "2026-09-22T07:25:48.832Z",
  "release_integrity": {
    "status": "verified",
    "scope": "workspace",
    "production_attestation_required": true,
    "calculation_version": "1.12.0",
    "artifacts": {
      "engine": "1.12.0",
      "page": "1.12.0",
      "capability": "1.12.0",
      "evidence": "1.12.0",
      "input_schema": "1.12.0",
      "output_schema": "1.12.0",
      "mcp_contract": "1.12.0"
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    },
    "contract_checks": {
      "total": 5,
      "passed": 5,
      "failed": 0,
      "items": [
        {
          "id": "release-artifacts-aligned",
          "status": "pass",
          "detail": "1.12.0"
        },
        {
          "id": "schema-output-required-declared",
          "status": "pass"
        },
        {
          "id": "schema-valid-input-executes",
          "status": "pass"
        },
        {
          "id": "engine-success-output-validates-schema",
          "status": "pass"
        },
        {
          "id": "rest-success-payload-validates-schema",
          "status": "pass"
        }
      ]
    },
    "report": "https://www.calculatorx.com/.well-known/calculatorx-release-integrity.json"
  }
}
