# IVT Class III Harm contraindications

IVT contraindications

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

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

## What it computes

Apply Powers 2018 Table 6 Class III: Harm caller flags and return whether intravenous alteplase (IVT) is contraindicated. contraindicated is true iff any of the 15 published Harm flags is true.

## When to use

When an agent already has caller-assigned Powers 2018 Table 6 Class III Harm flags and needs the published any-flag combination. magent does not read CT, assay coagulation, or examine the patient. Not Class I eligibility, not a time window, and not a dose.

## When not to use

- Not a medical device and not a treatment order.
- Encodes Powers 2018 Table 6 Class III: Harm rows only. Does not encode Class III No Benefit rows (unclear/wake-up onset windows, extensive CT hypoattenuation), Class I eligibility, 0-3h vs 3-4.5h windows, or a dose.
- magent does not read CT, assay coagulation, or examine the patient. Each flag is caller-assigned.
- Not eligibility for tenecteplase. Intravenous alteplase (IVT) Harm flags only.
- Coagulopathy is one caller-assigned flag (platelets <100000/mm3 or INR >1.7 or aPTT >40 s or PT >15 s as in Table 6). magent does not assay labs.
- DOAC not cleared is caller-assigned from that Table 6 row (direct thrombin or factor Xa inhibitor AND labs not documented normal AND last dose not >48 h with normal renal function).

## Formula

```
contraindicated iff ct_ich or ischemic_stroke_within_3_mo or severe_head_trauma_within_3_mo or posttraumatic_infarction_in_hospital or intracranial_spinal_surgery_within_3_mo or history_ich or sah_presentation or gi_malignancy_or_gi_bleed_21d or coagulopathy or lmwh_treatment_dose_within_24h or doac_not_cleared or gp2b3a_concurrent or infective_endocarditis or aortic_arch_dissection or intra_axial_neoplasm (Powers 2018 Table 6 Class III: Harm). Not Class III No Benefit (unclear/wake-up onset windows, extensive CT hypoattenuation). Not Class I eligibility. Not 0-3h vs 3-4.5h. Not a dose. magent does not read CT, assay coagulation, or examine the patient. Not a treatment order
```

## Citation

[2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association](https://doi.org/10.1161/STR.0000000000000158)
Powers WJ, Rabinstein AA, Ackerson T, et al.
Stroke. 2018;49(3):e46-e110
DOI: [10.1161/STR.0000000000000158](https://doi.org/10.1161/STR.0000000000000158)

## Worked example

### All 15 Class III Harm flags false is not contraindicated

Given: `aortic_arch_dissection=false, coagulopathy=false, ct_ich=false, doac_not_cleared=false, gi_malignancy_or_gi_bleed_21d=false, gp2b3a_concurrent=false, history_ich=false, infective_endocarditis=false, intra_axial_neoplasm=false, intracranial_spinal_surgery_within_3_mo=false, ischemic_stroke_within_3_mo=false, lmwh_treatment_dose_within_24h=false, posttraumatic_infarction_in_hospital=false, sah_presentation=false, severe_head_trauma_within_3_mo=false`

1. each Powers 2018 Table 6 Class III: Harm flag is false
2. no Harm row is met
3. contraindicated false


### CT acute intracranial hemorrhage is contraindicated

Given: `aortic_arch_dissection=false, coagulopathy=false, ct_ich=true, doac_not_cleared=false, gi_malignancy_or_gi_bleed_21d=false, gp2b3a_concurrent=false, history_ich=false, infective_endocarditis=false, intra_axial_neoplasm=false, intracranial_spinal_surgery_within_3_mo=false, ischemic_stroke_within_3_mo=false, lmwh_treatment_dose_within_24h=false, posttraumatic_infarction_in_hospital=false, sah_presentation=false, severe_head_trauma_within_3_mo=false`

1. ct_ich true
2. the other 14 Class III Harm flags are false
3. any Harm flag is enough
4. contraindicated true


## Also searched as

- IVT contraindications
- intravenous alteplase contraindications
- Powers 2018 Table 6
- Class III Harm IVT
- IV alteplase exclusion criteria
- acute ischemic stroke IVT Harm rows
- Powers 2018 IVT contraindications

## Parameters

- `ct_ich` (boolean, required): CT reveals acute intracranial hemorrhage as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read CT.
- `ischemic_stroke_within_3_mo` (boolean, required): Prior ischemic stroke within 3 months as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not date prior strokes.
- `severe_head_trauma_within_3_mo` (boolean, required): Recent severe head trauma within 3 months as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `posttraumatic_infarction_in_hospital` (boolean, required): Posttraumatic infarction in the acute in-hospital phase as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `intracranial_spinal_surgery_within_3_mo` (boolean, required): Intracranial or spinal surgery within 3 months as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read an operative note.
- `history_ich` (boolean, required): History of intracranial hemorrhage as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read prior imaging.
- `sah_presentation` (boolean, required): Presentation most consistent with subarachnoid hemorrhage as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `gi_malignancy_or_gi_bleed_21d` (boolean, required): Structural GI malignancy or GI bleed within 21 days as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `coagulopathy` (boolean, required): Caller-assigned coagulopathy as in Table 6 (platelets <100000/mm3 or INR >1.7 or aPTT >40 s or PT >15 s). One flag. true or false. magent does not assay labs.
- `lmwh_treatment_dose_within_24h` (boolean, required): Treatment-dose LMWH within the previous 24 h as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read a medication list.
- `doac_not_cleared` (boolean, required): Taking a direct thrombin or factor Xa inhibitor AND labs not documented normal AND last dose not >48 h with normal renal function, as assigned by the caller from that Table 6 row. true or false. magent does not assay labs.
- `gp2b3a_concurrent` (boolean, required): Concurrent GP IIb/IIIa inhibitor as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read a medication list.
- `infective_endocarditis` (boolean, required): Symptoms consistent with infective endocarditis as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `aortic_arch_dissection` (boolean, required): Known or suspected aortic arch dissection as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not examine the patient.
- `intra_axial_neoplasm` (boolean, required): Intra-axial intracranial neoplasm as assigned by the caller (Powers 2018 Table 6 Class III: Harm). true or false. magent does not read imaging.

## 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/ivt_contraindications`
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": [
    {
      "aortic_arch_dissection": "false",
      "coagulopathy": "false",
      "ct_ich": "false",
      "doac_not_cleared": "false",
      "gi_malignancy_or_gi_bleed_21d": "false",
      "gp2b3a_concurrent": "false",
      "history_ich": "false",
      "infective_endocarditis": "false",
      "intra_axial_neoplasm": "false",
      "intracranial_spinal_surgery_within_3_mo": "false",
      "ischemic_stroke_within_3_mo": "false",
      "lmwh_treatment_dose_within_24h": "false",
      "posttraumatic_infarction_in_hospital": "false",
      "sah_presentation": "false",
      "severe_head_trauma_within_3_mo": "false"
    },
    {
      "aortic_arch_dissection": "false",
      "coagulopathy": "false",
      "ct_ich": "false",
      "doac_not_cleared": "false",
      "gi_malignancy_or_gi_bleed_21d": "false",
      "gp2b3a_concurrent": "false",
      "history_ich": "false",
      "infective_endocarditis": "false",
      "intra_axial_neoplasm": "false",
      "intracranial_spinal_surgery_within_3_mo": "false",
      "ischemic_stroke_within_3_mo": "false",
      "lmwh_treatment_dose_within_24h": "false",
      "posttraumatic_infarction_in_hospital": "false",
      "sah_presentation": "false",
      "severe_head_trauma_within_3_mo": "false"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/ivt_contraindications",
  "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": "Powers WJ, Rabinstein AA, Ackerson T, et al.",
        "doi": "10.1161/STR.0000000000000158",
        "id": "powers-2018",
        "pmid": "29133354",
        "source": "Stroke. 2018;49(3):e46-e110",
        "title": "2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association"
      },
      "formula": "ivt_contraindications",
      "formula_expression": "contraindicated iff ct_ich or ischemic_stroke_within_3_mo or severe_head_trauma_within_3_mo or posttraumatic_infarction_in_hospital or intracranial_spinal_surgery_within_3_mo or history_ich or sah_presentation or gi_malignancy_or_gi_bleed_21d or coagulopathy or lmwh_treatment_dose_within_24h or doac_not_cleared or gp2b3a_concurrent or infective_endocarditis or aortic_arch_dissection or intra_axial_neoplasm (Powers 2018 Table 6 Class III: Harm). Not Class III No Benefit (unclear/wake-up onset windows, extensive CT hypoattenuation). Not Class I eligibility. Not 0-3h vs 3-4.5h. Not a dose. magent does not read CT, assay coagulation, or examine the patient. Not a treatment order",
      "criteria": [
        {
          "factor": "ct_ich",
          "met": false
        },
        {
          "factor": "ischemic_stroke_within_3_mo",
          "met": false
        },
        {
          "factor": "severe_head_trauma_within_3_mo",
          "met": false
        },
        {
          "factor": "posttraumatic_infarction_in_hospital",
          "met": false
        },
        {
          "factor": "intracranial_spinal_surgery_within_3_mo",
          "met": false
        },
        {
          "factor": "history_ich",
          "met": false
        },
        {
          "factor": "sah_presentation",
          "met": false
        },
        {
          "factor": "gi_malignancy_or_gi_bleed_21d",
          "met": false
        },
        {
          "factor": "coagulopathy",
          "met": false
        },
        {
          "factor": "lmwh_treatment_dose_within_24h",
          "met": false
        },
        {
          "factor": "doac_not_cleared",
          "met": false
        },
        {
          "factor": "gp2b3a_concurrent",
          "met": false
        },
        {
          "factor": "infective_endocarditis",
          "met": false
        },
        {
          "factor": "aortic_arch_dissection",
          "met": false
        },
        {
          "factor": "intra_axial_neoplasm",
          "met": false
        },
        {
          "factor": "contraindicated",
          "met": false
        }
      ],
      "aortic_arch_dissection": false,
      "coagulopathy": false,
      "contraindicated": false,
      "ct_ich": false,
      "doac_not_cleared": false,
      "gi_malignancy_or_gi_bleed_21d": false,
      "gp2b3a_concurrent": false,
      "history_ich": false,
      "infective_endocarditis": false,
      "intra_axial_neoplasm": false,
      "intracranial_spinal_surgery_within_3_mo": false,
      "ischemic_stroke_within_3_mo": false,
      "lmwh_treatment_dose_within_24h": false,
      "posttraumatic_infarction_in_hospital": false,
      "sah_presentation": false,
      "severe_head_trauma_within_3_mo": false
    },
    {
      "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": "Powers WJ, Rabinstein AA, Ackerson T, et al.",
        "doi": "10.1161/STR.0000000000000158",
        "id": "powers-2018",
        "pmid": "29133354",
        "source": "Stroke. 2018;49(3):e46-e110",
        "title": "2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association"
      },
      "formula": "ivt_contraindications",
      "formula_expression": "contraindicated iff ct_ich or ischemic_stroke_within_3_mo or severe_head_trauma_within_3_mo or posttraumatic_infarction_in_hospital or intracranial_spinal_surgery_within_3_mo or history_ich or sah_presentation or gi_malignancy_or_gi_bleed_21d or coagulopathy or lmwh_treatment_dose_within_24h or doac_not_cleared or gp2b3a_concurrent or infective_endocarditis or aortic_arch_dissection or intra_axial_neoplasm (Powers 2018 Table 6 Class III: Harm). Not Class III No Benefit (unclear/wake-up onset windows, extensive CT hypoattenuation). Not Class I eligibility. Not 0-3h vs 3-4.5h. Not a dose. magent does not read CT, assay coagulation, or examine the patient. Not a treatment order",
      "criteria": [
        {
          "factor": "ct_ich",
          "met": false
        },
        {
          "factor": "ischemic_stroke_within_3_mo",
          "met": false
        },
        {
          "factor": "severe_head_trauma_within_3_mo",
          "met": false
        },
        {
          "factor": "posttraumatic_infarction_in_hospital",
          "met": false
        },
        {
          "factor": "intracranial_spinal_surgery_within_3_mo",
          "met": false
        },
        {
          "factor": "history_ich",
          "met": false
        },
        {
          "factor": "sah_presentation",
          "met": false
        },
        {
          "factor": "gi_malignancy_or_gi_bleed_21d",
          "met": false
        },
        {
          "factor": "coagulopathy",
          "met": false
        },
        {
          "factor": "lmwh_treatment_dose_within_24h",
          "met": false
        },
        {
          "factor": "doac_not_cleared",
          "met": false
        },
        {
          "factor": "gp2b3a_concurrent",
          "met": false
        },
        {
          "factor": "infective_endocarditis",
          "met": false
        },
        {
          "factor": "aortic_arch_dissection",
          "met": false
        },
        {
          "factor": "intra_axial_neoplasm",
          "met": false
        },
        {
          "factor": "contraindicated",
          "met": false
        }
      ],
      "aortic_arch_dissection": false,
      "coagulopathy": false,
      "contraindicated": false,
      "ct_ich": false,
      "doac_not_cleared": false,
      "gi_malignancy_or_gi_bleed_21d": false,
      "gp2b3a_concurrent": false,
      "history_ich": false,
      "infective_endocarditis": false,
      "intra_axial_neoplasm": false,
      "intracranial_spinal_surgery_within_3_mo": false,
      "ischemic_stroke_within_3_mo": false,
      "lmwh_treatment_dose_within_24h": false,
      "posttraumatic_infarction_in_hospital": false,
      "sah_presentation": false,
      "severe_head_trauma_within_3_mo": false
    }
  ]
}
```

## Response fields

- `formula` (string): ivt_contraindications
- `formula_expression` (string): Powers 2018 Table 6 Class III: Harm any-flag combination
- `ct_ich` (boolean): Caller-assigned ct_ich flag used
- `ischemic_stroke_within_3_mo` (boolean): Caller-assigned ischemic_stroke_within_3_mo flag used
- `severe_head_trauma_within_3_mo` (boolean): Caller-assigned severe_head_trauma_within_3_mo flag used
- `posttraumatic_infarction_in_hospital` (boolean): Caller-assigned posttraumatic_infarction_in_hospital flag used
- `intracranial_spinal_surgery_within_3_mo` (boolean): Caller-assigned intracranial_spinal_surgery_within_3_mo flag used
- `history_ich` (boolean): Caller-assigned history_ich flag used
- `sah_presentation` (boolean): Caller-assigned sah_presentation flag used
- `gi_malignancy_or_gi_bleed_21d` (boolean): Caller-assigned gi_malignancy_or_gi_bleed_21d flag used
- `coagulopathy` (boolean): Caller-assigned coagulopathy flag used
- `lmwh_treatment_dose_within_24h` (boolean): Caller-assigned lmwh_treatment_dose_within_24h flag used
- `doac_not_cleared` (boolean): Caller-assigned doac_not_cleared flag used
- `gp2b3a_concurrent` (boolean): Caller-assigned gp2b3a_concurrent flag used
- `infective_endocarditis` (boolean): Caller-assigned infective_endocarditis flag used
- `aortic_arch_dissection` (boolean): Caller-assigned aortic_arch_dissection flag used
- `intra_axial_neoplasm` (boolean): Caller-assigned intra_axial_neoplasm flag used
- `contraindicated` (boolean): true iff any Powers 2018 Table 6 Class III: Harm caller flag is true. Not a treatment order. Not Class I eligibility. Not a dose.
- `criteria` (array): Rows for each caller flag and contraindicated with factor and met
- `citation` (object): Powers 2018 Stroke AHA/ASA acute ischemic stroke guideline 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": "Powers WJ, Rabinstein AA, Ackerson T, et al.",
    "doi": "10.1161/STR.0000000000000158",
    "id": "powers-2018",
    "pmid": "29133354",
    "source": "Stroke. 2018;49(3):e46-e110",
    "title": "2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association"
  },
  "formula": "ivt_contraindications",
  "formula_expression": "contraindicated iff ct_ich or ischemic_stroke_within_3_mo or severe_head_trauma_within_3_mo or posttraumatic_infarction_in_hospital or intracranial_spinal_surgery_within_3_mo or history_ich or sah_presentation or gi_malignancy_or_gi_bleed_21d or coagulopathy or lmwh_treatment_dose_within_24h or doac_not_cleared or gp2b3a_concurrent or infective_endocarditis or aortic_arch_dissection or intra_axial_neoplasm (Powers 2018 Table 6 Class III: Harm). Not Class III No Benefit (unclear/wake-up onset windows, extensive CT hypoattenuation). Not Class I eligibility. Not 0-3h vs 3-4.5h. Not a dose. magent does not read CT, assay coagulation, or examine the patient. Not a treatment order",
  "criteria": [
    {
      "factor": "ct_ich",
      "met": false
    },
    {
      "factor": "ischemic_stroke_within_3_mo",
      "met": false
    },
    {
      "factor": "severe_head_trauma_within_3_mo",
      "met": false
    },
    {
      "factor": "posttraumatic_infarction_in_hospital",
      "met": false
    },
    {
      "factor": "intracranial_spinal_surgery_within_3_mo",
      "met": false
    },
    {
      "factor": "history_ich",
      "met": false
    },
    {
      "factor": "sah_presentation",
      "met": false
    },
    {
      "factor": "gi_malignancy_or_gi_bleed_21d",
      "met": false
    },
    {
      "factor": "coagulopathy",
      "met": false
    },
    {
      "factor": "lmwh_treatment_dose_within_24h",
      "met": false
    },
    {
      "factor": "doac_not_cleared",
      "met": false
    },
    {
      "factor": "gp2b3a_concurrent",
      "met": false
    },
    {
      "factor": "infective_endocarditis",
      "met": false
    },
    {
      "factor": "aortic_arch_dissection",
      "met": false
    },
    {
      "factor": "intra_axial_neoplasm",
      "met": false
    },
    {
      "factor": "contraindicated",
      "met": false
    }
  ],
  "aortic_arch_dissection": false,
  "coagulopathy": false,
  "contraindicated": false,
  "ct_ich": false,
  "doac_not_cleared": false,
  "gi_malignancy_or_gi_bleed_21d": false,
  "gp2b3a_concurrent": false,
  "history_ich": false,
  "infective_endocarditis": false,
  "intra_axial_neoplasm": false,
  "intracranial_spinal_surgery_within_3_mo": false,
  "ischemic_stroke_within_3_mo": false,
  "lmwh_treatment_dose_within_24h": false,
  "posttraumatic_infarction_in_hospital": false,
  "sah_presentation": false,
  "severe_head_trauma_within_3_mo": false
}
```

## Errors

- HTTP 400 `invalid_ivt`: IVT contraindication flags must each be true or false as published in Powers 2018 Table 6 Class III Harm rows. 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

- [Alteplase stroke dose](https://magentlab.com/docs/alteplase-stroke) — Compute NINDS 1995 intravenous alteplase milligrams from weight: 0.9 mg/kg capped at 90 mg, with 10% as a bolus and the remainder over 60 minutes.
- [NIHSS](https://magentlab.com/docs/nihss) — Sum Brott 1989 NIH stroke scale points from 15 caller-assigned examination integers, including pupillary response and plantar reflex. Weaker-limb motor arm and leg. Does not apply later total-score severity bands.

## 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.