Source: https://guthlabs.ai/docs/instruments/two-s-complement-calculator/implementation/

instrument implementation / implementation-contract

# Two's Complement Calculator implementation

A source-bound implementation contract for Two's Complement 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**: t2-004

**Effect**: Computation or source lookup only

## Input and validation requirements

A pure-JavaScript implementation that parses large decimal inputs as Number can round -9223372036854775809 to -9223372036854775808, incorrectly accepting an out-of-range value and producing a valid-looking bit pattern. The signed-versus-unsigned interpretation of bit patterns is also a user-facing convention hazard.

## 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": {
    "operation": "encode",
    "decimal_value": 5,
    "bit_width": 8
  },
  "expected_outputs": {
    "binary_bit_pattern": "00000101",
    "decimal_value": 5,
    "overflow_flag": false
  },
  "working": "Range for 8 bits: [-2^(8-1), 2^(8-1)-1] = [-128, 127]. 5 is in range, so overflow = false. 5 in 8-bit binary is 00000101. Therefore bit pattern = 00000101 and decoded decimal value = 5."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/two-s-complement-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/two-s-complement-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/two-s-complement-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-tranche2/tranche2-results.json`