Does drift run the transaction?

No. It compares and decodes only. It never signs or moves funds.

Is a match a guarantee?

No. OpenAPI states a match is not a guarantee.

What typed data can it decode without intent?

Permit, Permit2, DAI, CoW, Seaport, or EIP-7702. Unknown primaryType is UNDECODED_CAUTION.

What happens on an oversize body?

Oversize drift or simulate body is HTTP 400 before payment.

Docs / Intent drift check

How do I detect parameter drift in an unsigned agent transaction?

Meridian by MioDio's POST /v1/drift compares optional intent to an unsigned tx or EIP-712 payload and answers match, drift, or cannot_verify for $0.005 USDC on Base. Without intent it decodes common typed-data patterns and gives back risk_flags; a match is not a guarantee.

With intent vs decode-only

With intent: compares security-relevant decoded fields to the intent you send. Verdict is match, drift, or cannot_verify.
Without intent: decodes Permit, Permit2, DAI, CoW, Seaport, or EIP-7702 and gives back risk_flags. It does not compare or verdict. Unknown primaryType is UNDECODED_CAUTION.

Request body shape

JSON body required. anyOf requires one of tx, typed_data, or eip7702_authorization.

Properties: chain (base or ethereum), optional intent, tx, typed_data, eip7702_authorization (object or array).

Decoder caps (OpenAPI): body at most 20480 chars; tx.data at most 8192 bytes; typed JSON depth at most 8, nodes at most 200, object keys at most 32, array length at most 16; type/field/primaryType names at most 64 chars; array suffix depth at most 4; wei at most 2^256-1; eip7702_authorization length at most 16.

Call it (curl + free demo)

curl -s "https://meridian.miodiollc.com/v1/demo/drift"

curl -i -X POST "https://meridian.miodiollc.com/v1/drift" \
  -H 'content-type: application/json' \
  -d '{
    "chain": "base",
    "intent": {
      "action": "transfer",
      "recipient": "0x0000000000000000000000000000000000000001",
      "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "amount": "1000000",
      "expected_contract": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
    },
    "tx": {
      "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "value": "0x0",
      "data": "0xa9059cbb000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000f4240",
      "chainId": 8453
    }
  }'

Unpaid -> HTTP 402 + PAYMENT-REQUIRED. Oversize body -> 400 before payment.

Price

$0.005 USDC on Base (~5000 atomic). Network eip155:8453. Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913. payTo 0x4DA1ED782BD61BaE9AdD5a5CaBbCf32f767f8d7F.

Caps and errors

See decoder caps above. Oversize drift body is 400 before payment. Invalid input after a payment header is 400 and not settled.

Response (demo, trimmed)

{
  "card": "parameter_drift",
  "status": "ok",
  "chain": "base",
  "verdict": "drift",
  "diffs": [
    {
      "field": "recipient",
      "intended": "0x0000000000000000000000000000000000000001",
      "actual": "0x0000000000000000000000000000000000000002",
      "severity": "high"
    }
  ],
  "decoded": {
    "selector": "0xa9059cbb",
    "function": "transfer",
    "kind": "erc20_transfer",
    "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "recipient": "0x0000000000000000000000000000000000000002",
    "amount": "1000000",
    "unlimited": false
  },
  "flags": ["recipient_differs"],
  "risk_flags": []
}

verdict is the answer. diffs lists each field that disagrees. A paid answer may also carry a signed Meridian-Receipt header.

What it does NOT do

Meridian by MioDio never holds keys, does not sign user transactions, and does not move funds.
Not financial, legal, or compliance advice. Screens, drift, and simulation are informational and point-in-time where that applies.
Not a substitute for a compliance program.
No MCP server and no SDK are available today.

Unpaid calls return HTTP 402 with PAYMENT-REQUIRED. Retry with PAYMENT-SIGNATURE.

FAQ

Does drift run the transaction?: No. It compares and decodes only. It never signs or moves funds.
Is a match a guarantee?: No. OpenAPI states a match is not a guarantee.
What typed data can it decode without intent?: Permit, Permit2, DAI, CoW, Seaport, or EIP-7702. Unknown primaryType is UNDECODED_CAUTION.
What happens on an oversize body?: Oversize drift or simulate body is HTTP 400 before payment.