Inflation Adjuster (CPI) implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-017

Effect

Computation or source lookup only

Input and validation requirements

An invalid or missing base-year lookup can produce CPI_base = 0 or an undefined CPI value; calculating instead of rejecting causes division by zero or an undefined result. The direction of the amount conversion is also convention-sensitive unless the interface clearly states that the amount is denominated in the base year and converted to the target year.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "amount_usd": 100,
    "base_year": 1983,
    "target_year": 2023
  },
  "expected_outputs": {
    "inflation_adjusted_amount_usd": 304.702,
    "cumulative_inflation_percent": 204.702
  },
  "reference_data": {
    "cpi_u_annual_average_1983": 100,
    "cpi_u_annual_average_2023": 304.702,
    "source_convention": "Official BLS CPI-U annual-average historical table; U.S. city average, all items, 1982-84=100"
  },
  "working": "CPI ratio = 304.702 / 100.000 = 3.04702. Inflation-adjusted amount = $100.00 × 3.04702 = $304.702. Cumulative inflation = (3.04702 - 1) × 100% = 204.702%."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json