# SVS WIfI threatened limb grades

WIfI

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/wifi`
HTML: https://magentlab.com/docs/wifi
Markdown: https://magentlab.com/docs/wifi.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Apply Mills 2014 SVS WIfI grades and return the three independent grades (wound 0-3, ischemia 0-3, foot_infection 0-3) plus a wifi label like W0-I0-fI0.

## When to use

When an agent already has caller-assigned Mills 2014 wound, ischemia, and foot infection grades for a threatened lower extremity and needs the published WIfI label. magent does not inspect wounds or measure ABI, ankle pressure, or toe pressure.

## When not to use

- Not a medical device.
- Not an amputation or revascularization order. This tool does not report clinical stage 1-4 or Delphi amputation-risk or revascularization-benefit tables.
- magent does not inspect wounds. Wound grade is caller-assigned.
- magent does not measure ABI, ankle pressure, or toe pressure. Ischemia grade is caller-assigned; this tool does not compute ischemia from pressures.
- The three grades are independent. This tool does not return a summed WIfI total. Not PEDIS.

## Formula

```
WIfI is three independent Mills 2014 SVS grades, not a summed total: wound 0-3 (0 no ulcer and no gangrene; 1 small shallow distal ulcer without gangrene; 2 deeper ulcer with exposed bone, joint, or tendon, or gangrene limited to digits; 3 extensive deep ulcer or extensive gangrene); ischemia 0-3 as assigned by the caller (0 none; 1 mild; 2 moderate; 3 severe); foot_infection 0-3 (0 none; 1 skin and subcutaneous only; 2 deeper than skin without SIRS; 3 infection with SIRS). Label is W{wound}-I{ischemia}-fI{foot_infection}
```

## Citation

[The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI).](https://doi.org/10.1016/j.jvs.2013.08.003)
Mills JL, Conte MS, Armstrong DG, et al.
J Vasc Surg. 2014;59(1):220-234.e1-2
DOI: [10.1016/j.jvs.2013.08.003](https://doi.org/10.1016/j.jvs.2013.08.003)

## Worked example

### All three grades 0

Given: `foot_infection=0, ischemia=0, wound=0`

1. wound 0, ischemia 0, foot_infection 0
2. Each axis is the published grade-0 band
3. wifi label is W0-I0-fI0; grades are not summed


### All three grades 3

Given: `foot_infection=3, ischemia=3, wound=3`

1. wound 3, ischemia 3, foot_infection 3
2. Each axis is the published grade-3 band
3. wifi label is W3-I3-fI3; grades are not summed


## Also searched as

- WIfI classification
- SVS WIfI
- Mills WIfI
- wound ischemia foot infection
- threatened limb classification
- WIfI grades
- Society for Vascular Surgery WIfI
- WIfI 2014

## Parameters

- `wound` (integer, required): Wound grade 0-3 as assigned by the caller (Mills 2014): 0 no ulcer and no gangrene; 1 small, shallow ulcer(s) on the distal leg or foot without gangrene; 2 deeper ulcer with exposed bone, joint, or tendon, or gangrene limited to digits; 3 extensive deep ulcer involving forefoot and/or midfoot, full-thickness heel ulcer, or extensive gangrene. magent does not inspect wounds.
- `ischemia` (integer, required): Ischemia grade 0-3 as assigned by the caller (Mills 2014): 0 none; 1 mild; 2 moderate; 3 severe. magent does not measure ABI, ankle pressure, or toe pressure and does not compute this grade from pressures.
- `foot_infection` (integer, required): Foot infection grade 0-3 as assigned by the caller (Mills 2014): 0 no signs of infection; 1 infection involving only skin and subcutaneous tissue; 2 infection deeper than skin (abscess, osteomyelitis, septic arthritis, fasciitis) without SIRS; 3 infection with SIRS. magent does not diagnose infection.

## Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/wifi`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "foot_infection": "0",
      "ischemia": "0",
      "wound": "0"
    },
    {
      "foot_infection": "0",
      "ischemia": "0",
      "wound": "0"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/wifi

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/wifi",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Mills JL, Conte MS, Armstrong DG, et al.",
        "doi": "10.1016/j.jvs.2013.08.003",
        "id": "mills-2014",
        "pmid": "24126108",
        "source": "J Vasc Surg. 2014;59(1):220-234.e1-2",
        "title": "The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI)."
      },
      "formula": "wifi",
      "formula_expression": "WIfI is three independent Mills 2014 SVS grades, not a summed total: wound 0-3 (0 no ulcer and no gangrene; 1 small shallow distal ulcer without gangrene; 2 deeper ulcer with exposed bone, joint, or tendon, or gangrene limited to digits; 3 extensive deep ulcer or extensive gangrene); ischemia 0-3 as assigned by the caller (0 none; 1 mild; 2 moderate; 3 severe); foot_infection 0-3 (0 none; 1 skin and subcutaneous only; 2 deeper than skin without SIRS; 3 infection with SIRS). Label is W{wound}-I{ischemia}-fI{foot_infection}",
      "criteria": [
        {
          "value": 0,
          "factor": "wound",
          "met": true
        },
        {
          "value": 0,
          "factor": "ischemia",
          "met": true
        },
        {
          "value": 0,
          "factor": "foot_infection",
          "met": true
        }
      ],
      "wound": 0,
      "foot_infection": 0,
      "ischemia": 0,
      "wifi": "W0-I0-fI0"
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Mills JL, Conte MS, Armstrong DG, et al.",
        "doi": "10.1016/j.jvs.2013.08.003",
        "id": "mills-2014",
        "pmid": "24126108",
        "source": "J Vasc Surg. 2014;59(1):220-234.e1-2",
        "title": "The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI)."
      },
      "formula": "wifi",
      "formula_expression": "WIfI is three independent Mills 2014 SVS grades, not a summed total: wound 0-3 (0 no ulcer and no gangrene; 1 small shallow distal ulcer without gangrene; 2 deeper ulcer with exposed bone, joint, or tendon, or gangrene limited to digits; 3 extensive deep ulcer or extensive gangrene); ischemia 0-3 as assigned by the caller (0 none; 1 mild; 2 moderate; 3 severe); foot_infection 0-3 (0 none; 1 skin and subcutaneous only; 2 deeper than skin without SIRS; 3 infection with SIRS). Label is W{wound}-I{ischemia}-fI{foot_infection}",
      "criteria": [
        {
          "value": 0,
          "factor": "wound",
          "met": true
        },
        {
          "value": 0,
          "factor": "ischemia",
          "met": true
        },
        {
          "value": 0,
          "factor": "foot_infection",
          "met": true
        }
      ],
      "wound": 0,
      "foot_infection": 0,
      "ischemia": 0,
      "wifi": "W0-I0-fI0"
    }
  ]
}
```

## Response fields

- `formula` (string): wifi
- `formula_expression` (string): Three independent Mills 2014 SVS WIfI grades, not a summed total
- `wound` (integer): Caller-assigned wound grade 0-3
- `ischemia` (integer): Caller-assigned ischemia grade 0-3
- `foot_infection` (integer): Caller-assigned foot infection grade 0-3
- `wifi` (string): W{wound}-I{ischemia}-fI{foot_infection} label, for example W0-I0-fI0
- `criteria` (array): Per-axis rows with factor, met, and value for the three WIfI grades
- `citation` (object): Mills 2014 J Vasc Surg citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Mills JL, Conte MS, Armstrong DG, et al.",
    "doi": "10.1016/j.jvs.2013.08.003",
    "id": "mills-2014",
    "pmid": "24126108",
    "source": "J Vasc Surg. 2014;59(1):220-234.e1-2",
    "title": "The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI)."
  },
  "formula": "wifi",
  "formula_expression": "WIfI is three independent Mills 2014 SVS grades, not a summed total: wound 0-3 (0 no ulcer and no gangrene; 1 small shallow distal ulcer without gangrene; 2 deeper ulcer with exposed bone, joint, or tendon, or gangrene limited to digits; 3 extensive deep ulcer or extensive gangrene); ischemia 0-3 as assigned by the caller (0 none; 1 mild; 2 moderate; 3 severe); foot_infection 0-3 (0 none; 1 skin and subcutaneous only; 2 deeper than skin without SIRS; 3 infection with SIRS). Label is W{wound}-I{ischemia}-fI{foot_infection}",
  "criteria": [
    {
      "value": 0,
      "factor": "wound",
      "met": true
    },
    {
      "value": 0,
      "factor": "ischemia",
      "met": true
    },
    {
      "value": 0,
      "factor": "foot_infection",
      "met": true
    }
  ],
  "wound": 0,
  "foot_infection": 0,
  "ischemia": 0,
  "wifi": "W0-I0-fI0"
}
```

## Errors

- HTTP 400 `invalid_wifi`: wound, ischemia, and foot_infection must be integers 0-3 (Mills 2014 SVS WIfI caller-assigned grades). Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [PEDIS](https://magentlab.com/docs/pedis) — Apply Schaper 2004 IWGDF PEDIS research grades and return the five independent grades (perfusion 1-3, extent 1-3, depth 1-3, infection 1-4, sensation 1-2) plus a pedis label like 1-1-1-1-1.

## Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## Guarantees

- HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
- exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
- HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.