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

instrument implementation / implementation-contract

# Paint Coverage Calculator implementation

A source-bound implementation contract for Paint Coverage 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**: t3-007

**Effect**: Computation or source lookup only

## Input and validation requirements

The zero-coverage input produces an undefined division and must be rejected. The specification also does not explicitly define whether openings are always nonnegative magnitudes, creating a sign-convention hazard that can change the computed volume.

## 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": {
    "wall_segments": [
      {
        "width_ft": 12,
        "height_ft": 8
      },
      {
        "width_ft": 10,
        "height_ft": 8
      }
    ],
    "openings_sq_ft": 20,
    "coats": 2,
    "coverage_rate_sq_ft_per_gallon": 350
  },
  "expected_outputs": {
    "paintable_area_sq_ft": 156,
    "paint_gallons": 0.8914285714,
    "paint_liters": 3.3744226286
  },
  "working": "Wall area = (12 × 8) + (10 × 8) = 96 + 80 = 176 sq ft. Paintable area = 176 − 20 = 156 sq ft. Gallons = (156 ÷ 350) × 2 = 312 ÷ 350 = 0.8914285714 US gal. Liters = 0.8914285714 × 3.78541 = 3.3744226286 L."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/paint-coverage-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/paint-coverage-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/paint-coverage-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-tranche3/tranche3-results.json`