Source: https://guthlabs.ai/docs/instruments/currency-adjusted-salary-comparator-cost-of-living/implementation/

instrument implementation / implementation-contract

# Currency-Adjusted Salary Comparator (Cost of Living) implementation

A source-bound implementation contract for Currency-Adjusted Salary Comparator (Cost of Living); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t7-124

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero current-city index produces division by zero and must be rejected. The specification does not state validation behavior for zero or nonpositive indices, so an implementation that passes such values to the formula can return an error, infinity, or an invalid numeric result.

## 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": {
    "current_salary": 60000,
    "currency": "USD",
    "base_city": "Reference City",
    "base_index": 100,
    "target_city": "Reference City",
    "target_index": 100
  },
  "expected_outputs": {
    "equivalent_salary": 60000,
    "percent_difference": 0
  },
  "reference_data": {
    "base_city_index": {
      "city": "Reference City",
      "year": 2024,
      "index": 100
    },
    "target_city_index": {
      "city": "Reference City",
      "year": 2024,
      "index": 100
    },
    "source_convention": "Widely tabulated standard relative-index convention: reference city = 100; exact value is a normalization convention, not a universal city dataset entry."
  },
  "working": "equivalent_salary = 60,000 × (100 ÷ 100) = 60,000 × 1 = 60,000 USD.\npercent_difference = ((60,000 - 60,000) ÷ 60,000) × 100 = 0%."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/currency-adjusted-salary-comparator-cost-of-living/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/currency-adjusted-salary-comparator-cost-of-living/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/currency-adjusted-salary-comparator-cost-of-living/qualification/>)

## 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`