Source: https://guthlabs.ai/docs/instruments/age-calculator/implementation/

instrument implementation / implementation-contract

# Age Calculator implementation

A source-bound implementation contract for Age Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_WITH_ERRATA**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-with-binding-errata

**Evidence ID**: t5-007

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification leaves two important hazards unresolved: invalid calendar dates must be rejected, and the leap-day birthday rule is unspecified. A permissive parser could normalize 2024-02-30 incorrectly, while Feb-29 birthdays produce different ages and countdowns under the February-28 and March-1 conventions. Future birth dates also have an unspecified signed-versus-reject behavior.

## Required corrections

````
[
  {
    "vector": 2,
    "field": "days_until_next_birthday",
    "wrong": 1461,
    "correct": 0,
    "cause": "convention contradiction with her own v4 (same-day birthday counts as 0)"
  }
]
````

## Inspectable interface fixture

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

````
{
  "inputs": {
    "birth_date": "1990-04-15",
    "reference_date": "2025-06-20"
  },
  "expected_outputs": {
    "age_years": 35,
    "age_months": 2,
    "age_days": 5,
    "days_until_next_birthday": 299
  },
  "working": "Age: 1990-04-15 + 35 years = 2025-04-15; + 2 months = 2025-06-15; + 5 days = 2025-06-20, so age = 35 years, 2 months, 5 days. Next birthday = 2026-04-15. Days remaining in 2025 after 2025-06-20 = 10 (June) + 31 (July) + 31 (August) + 30 (September) + 31 (October) + 30 (November) + 31 (December) = 194. Days from 2026-01-01 through 2026-04-15 = 31 + 28 + 31 + 15 = 105. Total = 194 + 105 = 299 days."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/age-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/age-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/age-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`

- `tranche errata record`