Source: https://guthlabs.ai/docs/instruments/ipv6-address-explorer/implementation/

instrument implementation / implementation-contract

# IPv6 Address Explorer implementation

A source-bound implementation contract for IPv6 Address Explorer; 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**: t3-016

**Effect**: Computation or source lookup only

## Input and validation requirements

The computational cases remain exactly representable when implemented with 128-bit arithmetic, but the link-local vector exposes an under-specified convention: a bare fe80::1 lacks the interface zone needed for many real operations. The explorer must distinguish syntactic classification from scoped operational validity. Extreme all-ones input also breaks implementations that use JavaScript Number arithmetic instead of exact 128-bit handling.

## 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": {
    "ipv6_address": "2001:4860:4860:0000:0000:0000:0000:8888",
    "prefix_length": 64
  },
  "expected_outputs": {
    "expanded_form": "2001:4860:4860:0000:0000:0000:0000:8888",
    "compressed_form": "2001:4860:4860::8888",
    "network_range": {
      "network_start": "2001:4860:4860:0000:0000:0000:0000:0000",
      "network_end": "2001:4860:4860:0000:ffff:ffff:ffff:ffff"
    },
    "address_class": "global"
  },
  "working": "Parse into hextets [2001,4860,4860,0000,0000,0000,0000,8888]. The longest zero run is hextets 4-7, so compress it: 2001:4860:4860::8888. For /64, retain the first 4 hextets and zero the last 4: network_start = 2001:4860:4860:0000:0000:0000:0000:0000. Host bits = 128-64 = 64. Maximum host value = 2^64-1 = 0xffffffffffffffff, which is four ffff hextets. Therefore network_end = 2001:4860:4860:0000:ffff:ffff:ffff:ffff. The address begins with 2000::/3 and is not in the listed special ranges, so it is global."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/ipv6-address-explorer/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/ipv6-address-explorer/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/ipv6-address-explorer/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`