Source: https://guthlabs.ai/docs/instruments/smoking-pack-year-calculator/implementation/

instrument implementation / implementation-contract

# Smoking Pack-Year Calculator implementation

A source-bound implementation contract for Smoking Pack-Year Calculator; 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**: t5-068

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification does not define the cigarettes-per-pack conversion, so the same cigarette history can produce different totals. Extreme finite inputs also overflow ordinary JavaScript arithmetic to Infinity, which requires validation or rejection.

## 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": {
    "cigarettes_per_day": 20,
    "years_smoked": 15,
    "assumed_cigarettes_per_pack": 20
  },
  "expected_outputs": {
    "total_pack_years": 15
  },
  "working": "packs/day = 20 cigarettes/day ÷ 20 cigarettes/pack = 1 pack/day; pack-years = 1 × 15 years = 15 pack-years."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/smoking-pack-year-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/smoking-pack-year-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/smoking-pack-year-calculator/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-tranche5/tranche5-results.json`