Spend Mandates

A spend mandate is a signed, scope-limited, expiring authorization for one wallet. It is the x402-native equivalent of an AP2 mandate: it answers which actor, what scope, what limits and under what conditions, and it is bound by an EIP-191 signature.

Creating, reading, revoking and auditing a mandate is free and requires no account — the signature is the authorization, exactly as the x402 payment is the authentication everywhere else in this API.

Why

A funded agent wallet has one limit: its balance. A retry loop, a prompt injection, or a mis-parsed instruction can turn that into a 15,500 USDC company formation, and on-chain settlement is final. A mandate puts a ceiling and a scope between the agent’s intent and the payment challenge.

Create one

POST /v1/mandates
Content-Type: application/json

{
  "controller_address": "0xA11ce…",
  "spender_address": "0xA11ce…",
  "per_call_cap_usdc": 5.0,
  "daily_cap_usdc": 25.0,
  "monthly_cap_usdc": 200.0,
  "total_cap_usdc": null,
  "allowed_paths": ["/v1/fax", "/v1/letters", "/v1/invoices"],
  "nonce": "7c1e9b04…",
  "not_before": "2026-08-10T09:00:00",
  "expires_at": "2026-09-09T09:00:00",
  "controller_signature": "0x…"
}

Any cap left null is unlimited. An empty allowed_paths permits every priced endpoint.

The signature

The mandate_id is keccak256 of a canonical seed, and the controller signs a plain-text message containing it:

seed    = "{chain}:{controller}:{spender}:{per_call}:{daily}:{monthly}:{total}:{paths_csv}:{not_before}:{expires_at}:{nonce}"
message = "AgentBureau Mandate: {mandate_id}"

• Caps render as "*" when unlimited, otherwise with six decimals ("5.000000").
• paths_csv is the allowlist, trailing slashes stripped, sorted, comma-joined.
• Timestamps are naive UTC to second precision (2026-08-10T09:00:00).
• Addresses are lowercased.
• chain is decided by the mount you POST to (/v1/… = mainnet, /dev/v1/… = testnet), not by the request body. A testnet mandate can never authorize mainnet spend.

The server recomputes the id from your fields and recovers the signer. A mismatch anywhere in the seed surfaces as 403 controller_signature does not recover to controller_address.

Re-POSTing an identical mandate is idempotent and returns "created": false.

Delegation

When spender_address differs from controller_address, the request must also carry spender_signature over the same message. Without it the request is rejected — otherwise anyone could name a stranger’s wallet as spender and read its spend totals and ledger.

Use it

Send the id on every priced call:

curl -X POST https://agentbureau-api.datafortress.cloud/v1/invoices \
  -H "X-MANDATE-ID: 0x5881…" \
  -H "Content-Type: application/json" \
  -d '{"recipient_name":"…","recipient_email":"…","amount":100,"description":"…"}'

If the call fits the mandate you get the normal 402 challenge and pay as usual. If it would breach a cap you get 403 with an X-POLICY-DENIED header — before any payment challenge exists, so nothing is spent. See Policy Denied for the response shape.

Caution

Without the header, the gateway cannot know which wallet is calling until the payment is verified. Caps are still enforced at that point, but the funds have already moved — the call is refused and the payment is queued for refund. Always send the header.

Check the remaining budget

GET /v1/mandates/{mandate_id}/status

{
  "spent_today_usdc": 9.0,
  "spent_month_usdc": 41.0,
  "spent_total_usdc": 41.0,
  "remaining_today_usdc": 16.0,
  "remaining_month_usdc": 159.0,
  "calls": 12,
  "active": true,
  "daily_reset_at": "2026-08-11T00:00:00"
}

Windows are the UTC calendar day and calendar month, not rolling — a daily cap resets at 00:00 UTC.

This endpoint is also exposed over MCP as the read-only tool check_spend_budget, so an agent can consult its own budget mid-run without leaving the protocol.

Revoke

POST /v1/mandates/{mandate_id}/revoke
{ "signature": "0x…" }   // over "AgentBureau Mandate Revoke: {mandate_id}"

Either the controller or the spender may revoke. The next call under the mandate is denied.

Export the ledger

GET /v1/mandates/{mandate_id}/audit?format=csv&deadline={unix}&signature=0x…

Signed by the spender wallet over AgentBureau Mandate Audit: {mandate_id}:{deadline}, with the deadline at most one hour in the future — the same deadline-bound signature pattern the arbiter endpoints use.

Each row carries the task id, timestamp, service type, amount_usdc, status, on-chain transaction hash, intent id and chain. Request payloads are never included, so customer PII stays out of the audit path.

Limits

• Caps apply to calls made from the moment mandates shipped; calls recorded before then carry no amount and are excluded from the sums.
• A mandate governs spend on AgentBureau. It cannot restrict what the wallet does elsewhere on Base.
• AgentBureau implements the AP2 mandate model on the x402 rail. It does not yet accept AP2 mandates issued on card or bank rails.