Source: https://guthlabs.ai/docs/instruments/hydration-needs-estimator/implementation/

instrument implementation / implementation-contract

# Hydration Needs Estimator implementation

A source-bound implementation contract for Hydration Needs Estimator; 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**: t4-247

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification has no explicit validation for zero or non-finite inputs, can produce Infinity for extreme magnitudes, does not define the activity-intensity branch within the 500-1000 ml/hr range, and leaves weight units and climate_add calculation ambiguous.

## 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": {
    "weight_kg": 70,
    "activity_duration_hr": 1,
    "activity_rate_ml_per_hr": 750,
    "climate_add_ml": 500
  },
  "expected_outputs": {
    "baseline_ml": 2450,
    "activity_add_ml": 750,
    "total_ml": 3700,
    "total_us_fl_oz": 125.11
  },
  "working": "baseline = 70 × 35 = 2450 ml/day; activity_add = 1 × 750 = 750 ml; total = 2450 + 750 + 500 = 3700 ml/day; US fl oz = 3700 ÷ 29.5735 = 125.112..., rounded to 125.11 fl oz."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/hydration-needs-estimator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/hydration-needs-estimator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/hydration-needs-estimator/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-tranche4/tranche4-results.json`