Source: https://guthlabs.ai/docs/instruments/gc-content-sequence-composition-analyzer/implementation/

instrument implementation / implementation-contract

# GC Content & Sequence Composition Analyzer implementation

A source-bound implementation contract for GC Content & Sequence Composition Analyzer; 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**: t5-141

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification does not define behavior for an empty sequence, causing GC% and AT% to require division by zero. It also does not define RNA U handling or the denominator policy for ambiguous symbols such as N, so different reasonable implementations can produce different outputs.

## 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": {
    "sequence": "ATGC"
  },
  "expected_outputs": {
    "gc_percent": 50,
    "at_percent": 50,
    "base_counts": {
      "A": 1,
      "T": 1,
      "G": 1,
      "C": 1
    },
    "length": 4
  },
  "working": "Count A=1, T=1, G=1, C=1, so total=1+1+1+1=4. GC count=G+C=1+1=2. GC%=2/4×100=50%. AT count=A+T=1+1=2. AT%=2/4×100=50%. Length=4."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/gc-content-sequence-composition-analyzer/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/gc-content-sequence-composition-analyzer/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/gc-content-sequence-composition-analyzer/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`