{
  "tool_id": "art-693-isa530-audit-sampling-mus",
  "tool_version": "1.0.0",
  "display_name": "ISA 530 Audit Sampling + MUS",
  "mcp_name": "compute_isa530_audit_sampling_mus",
  "mandate_type": "compliance_control",
  "wave": 113,
  "gpu": false,
  "url": "https://ainumbers.co/chaingraph/art-693-isa530-audit-sampling-mus.html",
  "description": "Deterministic audit-sampling arithmetic in three caller-declared functions dispatched on method. monetary_unit_sampling sizes a MUS engagement: n = ceil(book_value * confidence_factor / (performance_materiality - expected_misstatement)) and sampling interval = round(book_value / n), failing closed whenever expected_misstatement >= performance_materiality. misstatement_projection applies the tainting method to caller-supplied sampled items (taint = (book - audited) / book, projected misstatement = sum of taint * interval) and adds the basic-precision figure confidence_factor * interval. benford_screen compares the observed first-significant-digit distribution of caller-supplied positive amounts against the Benford expected proportions with a chi-square deviation flag at the 5% level (8 degrees of freedom, critical value 15.507). The method's source standard is ISA 530 (iaasb.org): this node computes the arithmetic of the method and never certifies compliance with any standard, never opines on audit sufficiency, and never selects sample items. No randomness of any kind: the tool performs no selection logic, and any selection start point a caller uses is a caller-declared input, never generated here. Absent, non-numeric, or out-of-domain inputs resolve to INPUT_REJECTED with the field named, never guessed or defaulted.",
  "input_schema_ref": "chaingraph/art-693-isa530-audit-sampling-mus.html#manifest",
  "consumes": [],
  "feeds": [],
  "status": "live",
  "conformance_fixtures": true,
  "compute_capability": "server",
  "compute_images": [
    {"system":"sha256-source","image_id":"sha256:e92c7887ebf4004dfc6cc8f68bdea0bc5ae6ac9b7b90356275ea4b1a5ee3cd8c","valid_from":"2026-09-26"},
    {"system":"risc0","image_id":"sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6","valid_from":"2026-09-26"}
  ],
  "export_capability": ["json"],
  "standards_basis": "not_applicable",
  "cited_clause_digest": [],
  "compute_proof_ready": "ready",
  "compute_proof": {
    "type": "ZkVmReceipt",
    "system": "risc0",
    "receiptFormat": "groth16-bn254",
    "imageId": "sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6",
    "seal": "H3T4r6np1A35IEKSc8ckqeF3EUND3wF7uz1OvWNQ8cMGjrY1MT5YKKn2L3g82/ctGHwUyeleBNdVj6w8apnHhCclQTzbPcBAmkPeGbklNqmaeeRlKcJFmYJGOqg5PeSTJTLDZLpWase3fa56XSQjUP4s5xVUpJMiZJSYlCRj/MMSfP/uv6E9d6GHPQ/VgcAxi80CGv9Hcaj6peNOXcSNHy+d7xO7xirqeG0jmKPvo6vBsD71tftA4F8fp8TTd89DJkmCyJy55ZrFXX0U+gxb2PzxsTfyfzqKwMselbifjzYWz2VTo1Nlvvli6UISw6UofnK40YLmNOHw6jP99+Vw/g==",
    "journal": {
      "chaingraph_version": "0.4.0",
      "kernel_digest": "sha256:e92c7887ebf4004dfc6cc8f68bdea0bc5ae6ac9b7b90356275ea4b1a5ee3cd8c",
      "output": {
        "overall": "SAMPLE_COMPUTED",
        "sample_size": 75,
        "sampling_interval": 66667,
        "tolerable_misstatement": 250000,
        "trace": "5000000 * 3 / 200000 = 75; interval = round(5000000 / 75) = 66667"
      }
    }
  }
}