---
title: "Deterministic BFS reachability trace (Forward Networks-style)"
method: POST
path: "/api/digital-twin/deterministic-trace"
tags: ["Digital Twin"]
---

# Deterministic BFS reachability trace (Forward Networks-style)

`POST /api/digital-twin/deterministic-trace`

## Request

- Base URL: `https://api.fiber.ac` (the document declares no server; this is the origin it was published from)
- URL: `https://api.fiber.ac/api/digital-twin/deterministic-trace`
- Auth: none declared

Pure SQL/graph reachability proof — given a list of failed links, walk the topology BFS from spines outward and emit each hop. Output is byte-identical for the same (topology snapshot, failed_links) input — no probability, no LLM.

Use cases:
  · Audit / compliance — show *why* a leaf became unreachable.
  · Diff against Monte Carlo — deterministic baseline vs probabilistic spread.
  · Root-cause closure — capture the exact spine→leaf path that broke.

Reference: Forward Networks 'deterministic network query' (2026 Forward AI launch).

## Request body

- object

## Response `200`

hop-by-hop BFS trace + reachable/unreachable leaf sets + input hash

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/fiber-ac/apis/fiber-api.md) · [All operations](https://skmtc.dev/fiber-ac/apis/fiber-api/llms.txt) · [OpenAPI document](https://skmtc.dev/fiber-ac/apis/fiber-api/revisions/58267250d793?raw)