{
  "protocol": {
    "name": "CVP",
    "version": "1.0.0-proposed",
    "revision": "2026-09-13",
    "spec_sha256": "f62725968356c92930531cd6085db76e216da06e95be53d636b0d2cf3218b148",
    "spec": "https://www.calculatorx.com/developers/cvp/spec/1.0"
  },
  "document_status": "proposed",
  "calculator": {
    "id": "subtraction",
    "version": "1.0.1",
    "title": "Subtraction Calculator",
    "formula_family": "subtraction",
    "capability_id": "math.subtraction",
    "verification_revision": "2026-09-16.sources-no-wolfram"
  },
  "profile": "core",
  "status": "VERIFIED",
  "verification_status": "VERIFIED",
  "production_freshness": "CURRENT",
  "overall_trust": "VERIFIED",
  "runner": {
    "name": "cvp-runner",
    "version": "1.0.0"
  },
  "environment": {
    "runtime": "node",
    "runtime_version": "20.19.2",
    "numeric_model": "IEEE-754 binary64",
    "os": "darwin"
  },
  "suite": {
    "id": "subtraction",
    "version": "1.0.1",
    "uri": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1.json",
    "verification_revision": "2026-09-16.sources-no-wolfram"
  },
  "obligation_set": [
    "CVP-PROV-01",
    "CVP-MODEL-01",
    "CVP-SCOPE-01",
    "CVP-UNIT-01",
    "CVP-REF-01",
    "CVP-GOLD-01",
    "CVP-BND-01",
    "CVP-INV-01",
    "CVP-NUM-01",
    "CVP-COV-01",
    "CVP-CONTRACT-01",
    "CVP-DEP-01",
    "CVP-ART-01",
    "CVP-PROD-01",
    "CVP-PROP-01",
    "CVP-META-01",
    "CVP-ROUND-01",
    "CVP-IFACE-01"
  ],
  "provenance": {
    "mode": "direct",
    "sources": [
      {
        "label": "OpenStax Prealgebra 2e — Subtract Whole Numbers",
        "kind": "other",
        "reference": "1.3 Minuend − subtrahend = difference",
        "url": "https://openstax.org/books/prealgebra-2e/pages/1-3-subtract-whole-numbers"
      },
      {
        "label": "CalculatorX mathematical conventions",
        "kind": "other",
        "reference": "Long subtraction with regrouping"
      }
    ]
  },
  "reference": {
    "items": [
      {
        "class": "O1",
        "reference_scope": "model",
        "scope": "model",
        "label": "Subtraction as inverse of addition"
      },
      {
        "class": "O2",
        "reference_scope": "expected_values",
        "scope": "expected_values",
        "label": "Separate-module subtraction oracle — independent difference / solve-for / long-domain",
        "engine": {
          "name": "subtraction-reference",
          "precision_bits": 53,
          "independent_of_iut": true
        }
      },
      {
        "class": "O2",
        "reference_scope": "numerical_behavior",
        "scope": "numerical_behavior",
        "label": "Same O2 module backs ≤2 ULP value comparison vs IUT",
        "engine": {
          "name": "subtraction-reference",
          "precision_bits": 53,
          "independent_of_iut": true
        }
      }
    ],
    "notes": "Golden expected values use a separate O2 module (not IUT transcription). O2 shares Node/V8 binary64 with the IUT unless noted otherwise. Long-mode goldens compare the numeric difference, not regrouping text."
  },
  "controls": {
    "CVP-PROV-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "Sources present on evidence"
    },
    "CVP-MODEL-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "a − b = d"
    },
    "CVP-SCOPE-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "Declared partitions are difference, solve-for-minuend, solve-for-subtrahend, long-normal, long-negative-result, invalid-domain — aligned with published capability modes. O2 checks numeric values and long-mode domain; column-work strings are not an independent numerical claim."
    },
    "CVP-UNIT-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "dimensionless"
    },
    "CVP-REF-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "O1 model + O2 expected_values / numerical_behavior (O2 shares V8 binary64 with the IUT)"
    },
    "CVP-GOLD-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "6/6 legacy golden; 5/5 oracle-backed numeric"
    },
    "CVP-BND-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "1/1 CVP boundary · 1/1 legacy Evidence boundary"
    },
    "CVP-INV-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "1 Evidence illegal-input + 2/2 oracle-backed error-code (exact_error_match, not ULP)"
    },
    "CVP-NUM-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "≤2 ULP on the numeric value for difference, solve-for-minuend, solve-for-subtrahend, and long-mode difference. Column-work strings and regrouping steps are not an O2 numerical claim. Legacy Evidence `tol` is not this policy."
    },
    "CVP-COV-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "6/6 declared partitions (difference, solve-for-minuend, solve-for-subtrahend, long-normal, long-negative-result, invalid-domain) · 6 legacy golden / 1 CVP boundary unique cases · 1 Evidence invalid-input (may overlap boundary)"
    },
    "CVP-CONTRACT-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "1/1 CVP contract"
    },
    "CVP-DEP-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "engine subtraction; Node binary64"
    },
    "CVP-ART-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "release_integrity.status=verified · digests: artifact_evidence_sha256=Evidence core (Trust freshness) · cvp_evidence_digest=artifacts.evidence_digest (fingerprint v2) · evidence_bundle_sha256=legacy Evidence JSON bytes · evidence_catalog_digest=attested_catalog_sha256 · production_sha256=bound production report · see artifacts.digest_registry"
    },
    "CVP-PROD-01": {
      "result": "PASS",
      "applicability": "required",
      "notes": "this calculator CURRENT · bound snapshot pass @ 2026-09-16T06:43:50.908Z · live site-wide report stale @ 2026-09-16T06:44:05.018Z (3 other capabilities) · local checks pass · attestation_id=9864b02dd59e627629179439ae27934aea8c6fd24193702e66c56019c5e3e050 · This calculator CURRENT · This calculator is not affected · Bound attestation PASS @ 2026-09-16T06:43:50.908Z · Live production status STALE (3 capabilities; 161 remain CURRENT) @ 2026-09-16T06:44:05.018Z · Public schema 1.0.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓ · schema_const=1.0.1 · report output-const=pass · evidence-sha256=pass · semantic-contract=pass · capability-html-public-origin-agree=pass · cvp-manifest-public-origin-agree=pass · cvp-latest-alias-agrees=pass · cvp-immutable-manifest-fetch=pass · cvp-immutable-manifest-sha256=pass · cvp-latest-alias-matches-immutable=pass · calculator-html-cvp-projection=pass · evidence-html-cvp-projection=pass · attested_evidence_sha256=31e075dd2788e7c13520557df716a4e118f4844aca3908f8b06acf4a41fad0cc · verified_at=2026-09-16T06:43:08.441Z · evidence_attested_at=2026-09-16T06:43:08.441Z · last_confirmed_current_at=2026-09-16T06:43:50.908Z · rendered_at=2026-09-16T06:44:05.057Z · binds=cvp_core_sha256",
      "check_result": "PASS",
      "production_state": "CURRENT",
      "binding_current": true
    },
    "CVP-DIM-01": {
      "result": "SKIP",
      "applicability": "not_applicable",
      "notes": "Unitless core calculator — no physical dimension algebra"
    },
    "CVP-PROP-01": {
      "result": "PASS",
      "applicability": "applicable",
      "notes": "2/2 property"
    },
    "CVP-META-01": {
      "result": "PASS",
      "applicability": "applicable",
      "notes": "1/1 metamorphic"
    },
    "CVP-ROUND-01": {
      "result": "PASS",
      "applicability": "applicable",
      "notes": "2/2 round-trips"
    },
    "CVP-XCAL-01": {
      "result": "SKIP",
      "applicability": "not_applicable",
      "notes": "No related calculator in the same formula family / no related-identity peers declared — control not in obligation set"
    },
    "CVP-IFACE-01": {
      "result": "PASS",
      "applicability": "applicable",
      "notes": "UI (SSR) · REST · MCP equivalent (MCP uses calc API handler). ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only."
    },
    "CVP-ORACLE-01": {
      "result": "SKIP",
      "applicability": "higher_assurance",
      "notes": "O2 present; O3 not required this wave"
    },
    "CVP-EXP-01": {
      "result": "SKIP",
      "applicability": "optional",
      "notes": "named expert review not performed"
    }
  },
  "tests": {
    "golden": {
      "passed": 5,
      "total": 5,
      "failed": 0,
      "case_ids": [
        "g-sub-245-147",
        "g-sub-solve-minuend",
        "g-sub-solve-subtrahend",
        "g-sub-long-245-147",
        "g-sub-long-45-123"
      ]
    },
    "boundary": {
      "passed": 1,
      "total": 1,
      "failed": 0,
      "case_ids": [
        "boundary-sub-one-term"
      ]
    },
    "invalid": {
      "passed": 3,
      "total": 3,
      "failed": 0,
      "case_ids": [
        "boundary-sub-one-term",
        "g-inv-missing",
        "g-inv-long-negative"
      ],
      "comparison": "exact_error_match",
      "records": [
        {
          "id": "g-inv-missing",
          "comparison": "exact_error_match",
          "expected": {
            "code": "MISSING_REQUIRED_INPUT"
          },
          "actual": {
            "code": "MISSING_REQUIRED_INPUT"
          },
          "match": true
        },
        {
          "id": "g-inv-long-negative",
          "comparison": "exact_error_match",
          "expected": {
            "code": "VALUE_MUST_BE_NON_NEGATIVE"
          },
          "actual": {
            "code": "VALUE_MUST_BE_NON_NEGATIVE"
          },
          "match": true
        }
      ]
    },
    "property": {
      "passed": 2,
      "total": 2,
      "failed": 0,
      "case_ids": [
        "prop-minus-self",
        "prop-minus-zero"
      ],
      "definition_ids": [
        "a-minus-a",
        "a-minus-zero"
      ]
    },
    "round_trip": {
      "passed": 2,
      "total": 2,
      "failed": 0,
      "case_ids": [
        "rt-diff-then-minuend",
        "rt-diff-then-sub"
      ]
    },
    "metamorphic": {
      "passed": 1,
      "total": 1,
      "failed": 0,
      "case_ids": [
        "meta-add-same"
      ],
      "definition_ids": [
        "shift-both"
      ]
    },
    "contract": {
      "passed": 1,
      "total": 1,
      "failed": 0
    },
    "cross_interface": {
      "passed": 5,
      "total": 5,
      "failed": 0,
      "case_ids": [
        "iface-sub",
        "iface-solve-minuend",
        "iface-long",
        "iface-long-neg",
        "iface-err-long-neg"
      ]
    }
  },
  "coverage": {
    "partitions": [
      {
        "id": "difference",
        "description": "Difference mode: minuend and subtrahend given, solve a − b",
        "exercised": true,
        "case_count": 10
      },
      {
        "id": "solve-for-minuend",
        "description": "Difference mode: solve minuend from subtrahend and difference",
        "exercised": true,
        "case_count": 2
      },
      {
        "id": "solve-for-subtrahend",
        "description": "Difference mode: solve subtrahend from minuend and difference",
        "exercised": true,
        "case_count": 1
      },
      {
        "id": "long-normal",
        "description": "Long subtraction with non-negative inputs and minuend ≥ subtrahend",
        "exercised": true,
        "case_count": 1
      },
      {
        "id": "long-negative-result",
        "description": "Long subtraction with minuend on top when minuend < subtrahend (negative difference)",
        "exercised": true,
        "case_count": 2
      },
      {
        "id": "invalid-domain",
        "description": "Missing terms, long-mode negatives / scientific notation, invalid mode",
        "exercised": true,
        "case_count": 3
      }
    ]
  },
  "numerical": {
    "representation": "IEEE-754 binary64 a − b",
    "tolerance": {
      "type": "ulp",
      "value": 2,
      "rationale": "Independent minuend−subtrahend vs IUT; ≤2 ULP on value. Declared a priori.",
      "declared_before_evaluation": true
    },
    "claim_scope": "≤2 ULP on the numeric value for difference, solve-for-minuend, solve-for-subtrahend, and long-mode difference. Column-work strings and regrouping steps are not an O2 numerical claim.",
    "max_error_observed": 0,
    "records": [
      {
        "id": "g-sub-245-147",
        "reference": {
          "solve_for": "difference",
          "value": 98,
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98
        },
        "actual": {
          "mode": "difference",
          "solve_for": "difference",
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98,
          "value": 98,
          "formula": "a − b = d",
          "display": {
            "minuend": "245",
            "subtrahend": "147",
            "difference": "98",
            "value": "98"
          },
          "work": "Difference: 245 − 147 = 98\nCheck: 245 − 147 = 98",
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "golden"
      },
      {
        "id": "g-sub-solve-minuend",
        "reference": {
          "solve_for": "minuend",
          "value": 15,
          "minuend": 15,
          "subtrahend": 6,
          "difference": 9
        },
        "actual": {
          "mode": "difference",
          "solve_for": "minuend",
          "minuend": 15,
          "subtrahend": 6,
          "difference": 9,
          "value": 15,
          "formula": "a − b = d",
          "display": {
            "minuend": "15",
            "subtrahend": "6",
            "difference": "9",
            "value": "15"
          },
          "work": "Solve minuend: d + b = 9 + 6 = 15\nCheck: 15 − 6 = 9",
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "golden"
      },
      {
        "id": "g-sub-solve-subtrahend",
        "reference": {
          "solve_for": "subtrahend",
          "value": 6,
          "minuend": 15,
          "subtrahend": 6,
          "difference": 9
        },
        "actual": {
          "mode": "difference",
          "solve_for": "subtrahend",
          "minuend": 15,
          "subtrahend": 6,
          "difference": 9,
          "value": 6,
          "formula": "a − b = d",
          "display": {
            "minuend": "15",
            "subtrahend": "6",
            "difference": "9",
            "value": "6"
          },
          "work": "Solve subtrahend: a − d = 15 − 9 = 6\nCheck: 15 − 6 = 9",
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "golden"
      },
      {
        "id": "g-sub-long-245-147",
        "reference": {
          "solve_for": "difference",
          "value": 98,
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98
        },
        "actual": {
          "mode": "long",
          "solve_for": "difference",
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98,
          "value": 98,
          "formula": "a − b = d",
          "display": {
            "minuend": "245",
            "subtrahend": "147",
            "difference": "98",
            "value": "98"
          },
          "work": "Long subtraction (align place values, subtract right → left):\n\n    245\n− 147\n  -----\n     98\n\nColumn work (with regrouping / borrowing):\n  hundreds: 1 − 1 = 0\n  tens: 3 < 4 → borrow from hundreds; becomes 13, then 13 − 4 = 9\n  ones: 5 < 7 → borrow from tens; becomes 15, then 15 − 7 = 8",
          "steps": [
            {
              "column": "ones",
              "operation": "borrow",
              "top": 5,
              "bottom": 7,
              "expression": "15 − 7",
              "result": 8,
              "borrow_from": "tens"
            },
            {
              "column": "tens",
              "operation": "borrow",
              "top": 3,
              "bottom": 4,
              "expression": "13 − 4",
              "result": 9,
              "borrow_from": "hundreds"
            },
            {
              "column": "hundreds",
              "operation": "subtract",
              "top": 1,
              "bottom": 1,
              "expression": "1 − 1",
              "result": 0
            }
          ],
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "golden"
      },
      {
        "id": "g-sub-long-45-123",
        "reference": {
          "solve_for": "difference",
          "value": -78,
          "minuend": 45,
          "subtrahend": 123,
          "difference": -78
        },
        "actual": {
          "mode": "long",
          "solve_for": "difference",
          "minuend": 45,
          "subtrahend": 123,
          "difference": -78,
          "value": -78,
          "formula": "a − b = d",
          "display": {
            "minuend": "45",
            "subtrahend": "123",
            "difference": "-78",
            "value": "-78"
          },
          "work": "Long subtraction (align place values, subtract right → left):\n\n     45\n− 123\n  -----\n    -78\n\nIf minuend < subtrahend, the result is negative. Column work subtracts the smaller magnitude from the larger, then applies the sign.\n\nColumn work (with regrouping / borrowing):\n  hundreds: 0 − 0 = 0\n  tens: 1 < 4 → borrow from hundreds; becomes 11, then 11 − 4 = 7\n  ones: 3 < 5 → borrow from tens; becomes 13, then 13 − 5 = 8",
          "steps": [
            {
              "column": "sign",
              "operation": "sign",
              "expression": "minuend < subtrahend → −(larger − smaller)",
              "result": -78
            },
            {
              "column": "ones",
              "operation": "borrow",
              "top": 3,
              "bottom": 5,
              "expression": "13 − 5",
              "result": 8,
              "borrow_from": "tens"
            },
            {
              "column": "tens",
              "operation": "borrow",
              "top": 1,
              "bottom": 4,
              "expression": "11 − 4",
              "result": 7,
              "borrow_from": "hundreds"
            },
            {
              "column": "hundreds",
              "operation": "subtract",
              "top": 0,
              "bottom": 0,
              "expression": "0 − 0",
              "result": 0
            }
          ],
          "swapped": true,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "golden"
      },
      {
        "id": "rt-diff-then-minuend",
        "reference": {
          "solve_for": "difference",
          "value": 98,
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98
        },
        "actual": {
          "mode": "difference",
          "solve_for": "difference",
          "minuend": 245,
          "subtrahend": 147,
          "difference": 98,
          "value": 98,
          "formula": "a − b = d",
          "display": {
            "minuend": "245",
            "subtrahend": "147",
            "difference": "98",
            "value": "98"
          },
          "work": "Difference: 245 − 147 = 98\nCheck: 245 − 147 = 98",
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "round-trip",
        "hops": {
          "forward": {
            "reference": {
              "solve_for": "difference",
              "value": 98,
              "minuend": 245,
              "subtrahend": 147,
              "difference": 98
            },
            "actual": {
              "mode": "difference",
              "solve_for": "difference",
              "minuend": 245,
              "subtrahend": 147,
              "difference": 98,
              "value": 98,
              "formula": "a − b = d",
              "display": {
                "minuend": "245",
                "subtrahend": "147",
                "difference": "98",
                "value": "98"
              },
              "work": "Difference: 245 − 147 = 98\nCheck: 245 − 147 = 98",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          },
          "reverse": {
            "reference": 245,
            "actual": {
              "mode": "difference",
              "solve_for": "minuend",
              "minuend": 245,
              "subtrahend": 147,
              "difference": 98,
              "value": 245,
              "formula": "a − b = d",
              "display": {
                "minuend": "245",
                "subtrahend": "147",
                "difference": "98",
                "value": "245"
              },
              "work": "Solve minuend: d + b = 98 + 147 = 245\nCheck: 245 − 147 = 98",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          }
        }
      },
      {
        "id": "rt-diff-then-sub",
        "reference": {
          "solve_for": "difference",
          "value": 42,
          "minuend": 50,
          "subtrahend": 8,
          "difference": 42
        },
        "actual": {
          "mode": "difference",
          "solve_for": "difference",
          "minuend": 50,
          "subtrahend": 8,
          "difference": 42,
          "value": 42,
          "formula": "a − b = d",
          "display": {
            "minuend": "50",
            "subtrahend": "8",
            "difference": "42",
            "value": "42"
          },
          "work": "Difference: 50 − 8 = 42\nCheck: 50 − 8 = 42",
          "swapped": false,
          "calculation_version": "1.0.1"
        },
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "round-trip",
        "hops": {
          "forward": {
            "reference": {
              "solve_for": "difference",
              "value": 42,
              "minuend": 50,
              "subtrahend": 8,
              "difference": 42
            },
            "actual": {
              "mode": "difference",
              "solve_for": "difference",
              "minuend": 50,
              "subtrahend": 8,
              "difference": 42,
              "value": 42,
              "formula": "a − b = d",
              "display": {
                "minuend": "50",
                "subtrahend": "8",
                "difference": "42",
                "value": "42"
              },
              "work": "Difference: 50 − 8 = 42\nCheck: 50 − 8 = 42",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          },
          "reverse": {
            "reference": 8,
            "actual": {
              "mode": "difference",
              "solve_for": "subtrahend",
              "minuend": 50,
              "subtrahend": 8,
              "difference": 42,
              "value": 8,
              "formula": "a − b = d",
              "display": {
                "minuend": "50",
                "subtrahend": "8",
                "difference": "42",
                "value": "8"
              },
              "work": "Solve subtrahend: a − d = 50 − 42 = 8\nCheck: 50 − 8 = 42",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          }
        }
      },
      {
        "id": "meta-add-same",
        "reference": 1,
        "actual": 1,
        "error_ulp": 0,
        "threshold_ulp": 2,
        "suite": "metamorphic",
        "hops": {
          "base": {
            "reference": {
              "solve_for": "difference",
              "value": 98,
              "minuend": 245,
              "subtrahend": 147,
              "difference": 98
            },
            "actual": {
              "mode": "difference",
              "solve_for": "difference",
              "minuend": 245,
              "subtrahend": 147,
              "difference": 98,
              "value": 98,
              "formula": "a − b = d",
              "display": {
                "minuend": "245",
                "subtrahend": "147",
                "difference": "98",
                "value": "98"
              },
              "work": "Difference: 245 − 147 = 98\nCheck: 245 − 147 = 98",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          },
          "follow": {
            "reference": {
              "solve_for": "difference",
              "value": 98,
              "minuend": 255,
              "subtrahend": 157,
              "difference": 98
            },
            "actual": {
              "mode": "difference",
              "solve_for": "difference",
              "minuend": 255,
              "subtrahend": 157,
              "difference": 98,
              "value": 98,
              "formula": "a − b = d",
              "display": {
                "minuend": "255",
                "subtrahend": "157",
                "difference": "98",
                "value": "98"
              },
              "work": "Difference: 255 − 157 = 98\nCheck: 255 − 157 = 98",
              "swapped": false,
              "calculation_version": "1.0.1"
            },
            "error_ulp": 0
          },
          "relation": {
            "reference": 1,
            "actual": 1,
            "error_ulp": 0
          }
        }
      }
    ]
  },
  "interfaces": {
    "compared": [
      "ui-ssr",
      "rest",
      "mcp"
    ],
    "result": "PASS",
    "notes": "UI (SSR) · REST · MCP equivalent (MCP uses calc API handler). ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only."
  },
  "artifacts": {
    "evidence_bundle_sha256": "5a30a584901f6fb4c1bce7e77419bda7669212ea7dc3285981503d3df6eb7be2",
    "evidence_digest": "c11ae651671e7ad05ffeb3d5e220eb11864dfc60cb37e0d3d235f93ace6d5b97",
    "production_sha256": "31e075dd2788e7c13520557df716a4e118f4844aca3908f8b06acf4a41fad0cc",
    "attested_catalog_sha256": "f89399c8dda78af9b2d784bf34d77b786cf749392d54e5e00bd3707c3fcdd13e",
    "production_checks": [
      {
        "id": "math.subtraction:output-const",
        "status": "pass",
        "detail": "output const 1.0.1 vs capability 1.0.1",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:evidence-sha256",
        "status": "pass",
        "detail": "a47f93519391",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:semantic-contract",
        "status": "pass",
        "detail": "7/7",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:capability-html-public-origin-agree",
        "status": "pass",
        "detail": "public 1.0.1 vs origin 1.0.1",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:cvp-manifest-public-origin-agree",
        "status": "pass",
        "detail": "math.subtraction/1.0.1/2026-09-16.sources-no-wolfram/core/c11ae651671e",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z",
        "projection_compared": false
      },
      {
        "id": "math.subtraction:cvp-latest-alias-agrees",
        "status": "pass",
        "detail": "math.subtraction/1.0.1/2026-09-16.sources-no-wolfram/core/c11ae651671e",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z",
        "projection_compared": false
      },
      {
        "id": "math.subtraction:cvp-immutable-manifest-fetch",
        "status": "pass",
        "detail": "public=200 origin=200",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:cvp-immutable-manifest-sha256",
        "status": "pass",
        "detail": "c11ae651671e",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:cvp-latest-alias-matches-immutable",
        "status": "pass",
        "detail": "math.subtraction/1.0.1/2026-09-16.sources-no-wolfram/core/c11ae651671e",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z",
        "projection_compared": false
      },
      {
        "id": "math.subtraction:calculator-html-cvp-projection",
        "status": "pass",
        "detail": "matches Trust display",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      },
      {
        "id": "math.subtraction:evidence-html-cvp-projection",
        "status": "pass",
        "detail": "matches Trust display",
        "scope": "last_attestation_snapshot",
        "current": true,
        "attestation_binding_current": true,
        "attested_at": "2026-09-16T06:43:08.441Z"
      }
    ],
    "digest_registry": {
      "digest_algorithm": "sha256",
      "canonicalization": "json-sorted-keys-utf8",
      "entries": [
        {
          "name": "cvp_core_sha256",
          "field": "artifacts.cvp_core_sha256",
          "digest_scope": "cvp_verification_fingerprint_v2",
          "value": "c11ae651671e7ad05ffeb3d5e220eb11864dfc60cb37e0d3d235f93ace6d5b97",
          "note": "Immutable verification core; excludes attestation/live-status and Evidence contract counts"
        },
        {
          "name": "cvp_evidence_digest",
          "field": "artifacts.evidence_digest",
          "digest_scope": "cvp_verification_fingerprint_v2",
          "value": "c11ae651671e7ad05ffeb3d5e220eb11864dfc60cb37e0d3d235f93ace6d5b97",
          "note": "Alias of cvp_core_sha256 (historical field name)"
        },
        {
          "name": "artifact_evidence_sha256",
          "field": "release_integrity.digests.evidence_core_sha256",
          "digest_scope": "evidence_artifact_core",
          "value": "a47f935193913f0199c2618c3cfc47c175a013a180b542b60fb0bfab824d2c47",
          "note": "Published Evidence JSON core — Trust freshness / production bind subject"
        },
        {
          "name": "evidence_catalog_digest",
          "field": "artifacts.attested_catalog_sha256",
          "digest_scope": "capability_catalog",
          "value": "f89399c8dda78af9b2d784bf34d77b786cf749392d54e5e00bd3707c3fcdd13e",
          "note": "Capability catalog integrity; site-wide, not per-suite fingerprint"
        }
      ]
    },
    "cvp_core_sha256": "c11ae651671e7ad05ffeb3d5e220eb11864dfc60cb37e0d3d235f93ace6d5b97"
  },
  "dependencies": [
    {
      "name": "subtraction-engine",
      "version": "1.0.1"
    },
    {
      "name": "subtraction-reference-oracle",
      "version": "1.0.0"
    },
    {
      "name": "node",
      "version": "20.19.2"
    }
  ],
  "attestation": {
    "status": "CURRENT",
    "href": "/.well-known/calculatorx-production-attestation.json",
    "id": "9864b02dd59e627629179439ae27934aea8c6fd24193702e66c56019c5e3e050",
    "attested_at": "2026-09-16T06:43:08.441Z",
    "last_confirmed_current_at": "2026-09-16T06:43:50.908Z",
    "site_attestation_current": false,
    "capability_attestation_current": true,
    "bound_snapshot_status": "pass",
    "live_report_status": "stale",
    "bound_attested_at": "2026-09-16T06:43:50.908Z",
    "live_updated_at": "2026-09-16T06:44:05.018Z",
    "bound_snapshot": {
      "status": "pass",
      "attested_at": "2026-09-16T06:43:50.908Z",
      "site_stale_count": 3
    },
    "live_site_status": {
      "href": "/.well-known/calculatorx-production-attestation.json"
    },
    "bound_snapshot_site_stale_count": 3,
    "site_stale_capability_count": 3,
    "evidence_attested_at": "2026-09-16T06:43:08.441Z"
  },
  "domain_review": {
    "status": "ABSENT",
    "spec_version": "1.0.1",
    "external_third_party": false,
    "note": "Named expert review not performed"
  },
  "timestamps": {
    "verified_at": "2026-09-16T06:43:08.441Z",
    "generated_at": "2026-09-16T06:43:08.441Z",
    "rendered_at": "2026-09-16T06:44:05.057Z",
    "notes": "verified_at/generated_at mark the first publication of this cvp_core_sha256 (artifacts.evidence_digest alias) for suite verification. evidence_attested_at/attested_at is the first production bind of that core digest. last_confirmed_current_at is the latest site-wide report that still confirms CURRENT. rendered_at is this JSON serialization and is not part of cvp_core_sha256 / evidence_digest. Production attestation binds cvp_core_sha256 (binds evidence_digest). Causal order: verified_at ≤ evidence_attested_at ≤ last_confirmed_current_at. attestation.bound_snapshot.site_stale_count is the site-wide stale capability count at Manifest bind time — not a live value. Fetch attestation.live_site_status.href for the current site report."
  },
  "links": {
    "legacy_evidence": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1.json",
    "evidence_page": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1",
    "calculator": "https://www.calculatorx.com/calc/math/subtraction",
    "schema": "https://www.calculatorx.com/developers/cvp/schema/cvp-evidence-1.0.json",
    "protocol": "https://www.calculatorx.com/developers/cvp/spec/1.0",
    "manifest": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1.cvp.json",
    "manifest_immutable": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1/2026-09-16.sources-no-wolfram.cvp.json",
    "manifest_core": "https://www.calculatorx.com/evidence/math.subtraction/1.0.1/2026-09-16.sources-no-wolfram.c11ae651671e.cvp.json"
  }
}