{
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  "engine_build": "2026-09-19",
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  "failed": 0,
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      "passed": 4
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    "boundary": {
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      "passed": 2
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    "property": {
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  "engine_tested": true,
  "expert_reviewed": false,
  "internally_reviewed": false,
  "review_kind": null,
  "source_checked": true,
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  "reviewer_role": null,
  "last_reviewed": null,
  "expert_review": {
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    "scope": [
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      "assumptions",
      "limitations",
      "sources",
      "tests"
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    "n ≤ 1000",
    "Not Pascal / partition / n!"
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    "Integers only — no Binet float Fibonacci",
    "Engine id is sequence; never alias the add/sub engine id arithmetic",
    "n=0 on AP/GP → VALUE_MUST_BE_POSITIVE",
    "n>1000 → VALUE_ABOVE_MAX",
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  "boundary_conditions": [
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    "n=0 on AP/GP → VALUE_MUST_BE_POSITIVE",
    "n>1000 → VALUE_ABOVE_MAX"
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      "ok": true,
      "kind": "golden",
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        "a": 3,
        "r": 2,
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        "sum": 45
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        "a0": 0,
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        "exact": "55",
        "formula": "u_n = p·u_{n-1} + q·u_{n-2}",
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