Source: https://guthlabs.ai/docs/instruments/physical-constants-reference/implementation/

instrument implementation / implementation-contract

# Physical Constants Reference implementation

A source-bound implementation contract for Physical Constants Reference; 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**: t7-021

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification does not define empty-query handling, numeric coercion of search text, exact versus substring matching, or whether electron charge means positive elementary-charge magnitude or signed electron charge. These omissions permit rejected, overflowed, ambiguous, or sign-inverted outputs for valid-looking probes.

## 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": {
    "constant_name": "speed of light in vacuum",
    "lookup_alias": "c"
  },
  "expected_outputs": {
    "value": 299792458,
    "units": "m/s",
    "uncertainty": 0,
    "uncertainty_note": "exact by SI definition"
  },
  "reference_data": {
    "constant_name": "c",
    "value": 299792458,
    "units": "m/s",
    "standard_uncertainty": 0,
    "source_convention": "CODATA 2022; exact SI-defined value"
  },
  "working": "1. Normalize the search term 'speed of light in vacuum' to the canonical key c.\n2. Look up the CODATA 2022 row: c = 299792458 m/s.\n3. The value is exact by SI definition, so uncertainty = 0."
}
````

## Other records

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