Add OwnerApprovalHook (Profile A) — human spending-approval gate via off-chain owner signature

[with0utwhy]

OwnerApprovalHook — Profile A (Simple Policy)

A policy hook that blocks fund() until a designated owner has approved the
job's budget, where approval is an off-chain EIP-712 signature presented in the
fund optParams. No token custody.

Use case

An AI agent's human operator wants to gate the agent's spending: the agent can
create and run jobs, but money only moves once the human signs off on the
budget. This adds a human-in-the-loop oversight lane to ERC-8183 without a
trusted intermediary — useful for spend controls and regulatory human-oversight
requirements.

Flow

1. setBudget optParams carry abi.encode(owner). The hook records the owner
   from optParams; if none is supplied the job stays owner-less and cannot be
   funded (fail-closed). Once an owner is set, it emits
   ApprovalRequested(jobId, owner, client, budget) for an off-chain notifier.
2. The owner signs EIP-712 typed data — Approval(uint256 jobId,uint256 budget, uint256 deadline) under this contract's EIP712("OwnerApprovalHook","1")
   domain — gasless, in a wallet. The wallet shows the named fields, not an
   opaque hash.
3. fund optParams carry abi.encode(signature, deadline). _preFund validates
   the signature against the recorded owner — an EOA (ECDSA) or a smart-contract
   wallet (ERC-1271), via OpenZeppelin SignatureChecker — and requires the
   deadline to be in the future and within a bounded window. A missing or invalid
   signature reverts, blocking the funding.

requiredSelectors() returns [setBudget, fund] because the owner is captured
at setBudget and consumed at fund.

Trust model / assumptions

• Trustless: the hook holds no approval state and exposes no mutating functions
  outside the ERC-8183 callbacks. Only a valid signature from the recorded owner
  (EOA or ERC-1271 wallet) can unblock funding. No admin, no upgradeability.
• The owner is locked on first setBudget (no later swap). The budget is bound
  into the signed payload, so raising the budget invalidates a prior approval
  (no escalation). The EIP-712 domain binds the signature to this hook on this
  chain, and jobId binds it to one job (no cross-job/chain/hook replay). The job
  is flagged funded in _postFund, so the same approval can't be replayed even if
  the core ever permitted a second fund() (no same-job replay).
• The deadline is bounded both ways: in the future and no more than
  MAX_APPROVAL_WINDOW (30 days) ahead, so an approval cannot accidentally be
  made effectively non-expiring.
• Denial needs no transaction: an unsigned job can never be funded.
• No token custody (Profile A); reentrancy is not applicable.

Off-chain integration

The hook is intentionally thin: it emits ApprovalRequested and verifies a
signature. The owner-facing pieces live off-chain and follow a simple pattern any
integrator can implement:

1. Watch ApprovalRequested(jobId, owner, client, budget); notify the owner.
2. Have the owner sign the EIP-712 Approval payload (wallet shows the fields).
3. Relay the signature to the funder, who passes abi.encode(signature, deadline)
   as fund optParams.

A minimal integration is just two off-chain steps — no relay infrastructure required:

// 1) Owner approves: sign the job terms (EIP-712, gasless — no transaction).
const domain = { name: "OwnerApprovalHook", version: "1", chainId, verifyingContract: hook };
const types  = { Approval: [
  { name: "jobId",    type: "uint256" },
  { name: "budget",   type: "uint256" },
  { name: "deadline", type: "uint256" },
]};
const signature = await ownerWallet.signTypedData(domain, types, { jobId, budget, deadline });

// 2) Funder funds: pass (signature, deadline) as the fund optParams.
const optParams = AbiCoder.defaultAbiCoder().encode(["bytes", "uint256"], [signature, deadline]);
await core.fund(jobId, amount, optParams); // _preFund verifies the signature on-chain

A reference implementation of this layer — an event listener with
Telegram / ntfy / web-push notifications and a one-click owner approval UI — is
hosted at https://humantaste.app/gatekeeper, so integrators don't have to build
the notification + signature-relay plumbing themselves.

Conformance checklist

• Inherits BaseERC8183Hook + IERC8183HookMetadata; supportsInterface advertises both
• Implements requiredSelectors(); overrides only _postSetBudget, _preFund, and _postFund
• No external mutating functions outside callbacks; immutable, no proxy
• Zero-address dependency reverts in the constructor (via BaseERC8183Hook)
• EIP-712 typed-data approval; signature via OZ SignatureChecker (EOA + ERC-1271); deadline lower- and upper-bounded
• Replay-safe: EIP-712 domain (chain + verifyingContract) + jobId + budget in the payload — no cross-job/chain/hook reuse, no escalation; _funded guard in _postFund blocks same-job replay
• Single .sol, ^0.8.20, SPDX MIT, named imports, vendor-neutral, no test files
• NatSpec USE CASE / FLOW / TRUST MODEL; MultiHookRouter-safe (inherited onlyERC8183 guard)

Deployed + exercised end-to-end (setBudget → off-chain owner signature → fund) on
Base Sepolia; mainnet instance at 0xB2d871a9cE05ABE8B4A4Ea2BBbD666bE4aF4CBbF.