Support matrix

Same contract discipline as @observer-protocol/ows-op-verify: nothing is claimed that a conformance fixture or the live-fire harness does not prove; nothing a reader would discover on their own is hidden. Where enforcement is partial or inherited, it says so.

Enforcement events

Event (viem seam)	What it is	Enforcement
signTransaction → escrow open	open(payee, token, deposit, salt, authorizedSigner) on the TempoStreamChannel contract	Chokepoint for the structured {to, data} shape ONLY. A real escrow open is not currently recognised. mppx emits an open as a batched calls[] transaction with no top-level to, which this engine does not decode: it classifies as non-escrow, resolves as a 0-value native transfer, passes any ceiling, and is not counted into velocity. Measured at zero, not theorized. Fix tracked. For the structured shape the following all apply: full vendored mandate: per-tx ceiling / maxNotionalPerOrder, counterparty (payee), temporal, velocity. deposit counted into the daily velocity counter. The channel id is derived (computeChannelId) and linked, so vouchers and top-ups bind to it. Credential fully verified (issuer pin, schema allowlist, eddsa-jcs-2022 proof, assertionMethod, revocation).
signTransaction → escrow topUp	topUp(channelId, additionalDeposit)	additionalDeposit mandate-checked (ceiling/velocity) and counted into velocity; the channel cap accumulates. Counterparty inherited from the linked channel's payee — so a counterparty mandate is enforced on top-ups too. (A top-up on a channel with no locally-known open — e.g. a cold process with no shared audit log — fails closed under a counterparty mandate.)
signTransaction → escrow close / settle	close/settle(channelId, cumulativeAmount, sig)	Benign (no new spend) and trues up velocity: refund = counted deposit − final cumulative, returned to the day's counter so unused escrow headroom is freed.
signTransaction → requestClose / withdraw	finalize / withdraw	Benign — no new spend, no cumulative. Allowed (credential still verified).
signTransaction → non-escrow	any other Tempo tx	Decoded by the core resolver and mandate-enforced like any transfer (native value / ERC-20 / EIP-3009), counted into velocity. Caveat: a real batched calls[] transaction lands in this row and is measured at zero, because the resolver reads only top-level to/data/value. Enforcement here is therefore vacuous for the shape mppx actually emits.
signTypedData → Voucher	EIP-712 Voucher{channelId, cumulativeAmount}	Fresh credential + revocation re-check (halts in-flight sessions on revocation); cumulative monotonicity; cumulative ≤ the linked escrow cap. Defense-in-depth above the on-chain escrow bound.
signTypedData → non-voucher	any other typed data	Allowed unconditionally on the default config, with no mandate evaluation. The claim that it cannot move escrowed funds is true and beside the point: an EIP-3009 TransferWithAuthorization moves the wallet's token balance directly, and mppx's own x402 client emits exactly that shape. Treat this surface as ungated. Fix tracked.
signMessage	raw message	Denied by default (opaque content could authorize a payment). Opt in with allowSignMessage only for non-payment flows.

Channel-id derivation (shipped)

The open call does not carry the channelId in calldata; it is computed on-chain via computeChannelId(payer, payee, token, salt, authorizedSigner, escrowContract, chainId). The adapter derives the same id offline at signTransaction (all inputs are in the open calldata + config + signer address), using the identical keccak256(abi.encode(...)) path the SDK uses. This links each open to its channel, so the voucher cap guard and top-up counterparty binding hold without any on-chain read.

The velocity counter (Option A)

• Scope: (subject-DID, UTC-day), in raw token units, per asset.
• Counts: escrow open + topUp deposits; trues up on close/settle (refund of unused deposit), so the counter tracks real committed spend, not just gross deposits.
• Recovery: rebuilt at startup by replaying the shared append-only JSONL audit log for the subject DID (opens add, settles refund). Cheap, bounded by events/day.
• Soundness condition: complete recovery requires all processes for the key to share one audit-log path. If the path is process-private, recovery is process-local.
• Fail-closed: if the counter cannot be established (audit log unreadable), a mandate carrying any velocity cap is denied — never silently allowed.
• Monthly caps are enforced deny-side as a lower bound using the daily figure (vendored core behavior); allow-side monthly accounting needs a stateful evaluator.

Per-voucher amount bound

A voucher's cumulativeAmount is bounded on-chain by the escrow deposit (the contract rejects a voucher above the channel deposit and pays only the registered payee), and the adapter additionally enforces cumulative ≤ linked escrow cap, monotonicity, and a fresh revocation check on every voucher. The escrow open that set the deposit is fully mandate-enforced. For MPP sessions the mandate per_transaction_ceiling / maxNotionalPerOrder bounds the session escrow (the max the whole session can spend), matching MPP's model where the escrow is the funding commitment.

Provenance / confirmation

Escrow contract addresses, selectors, ABI offsets, the computeChannelId formula, and voucher field names are confirmed against mppx@0.7.0 (dist/tempo/legacy/session/ escrow.abi.js, Channel.js, Voucher.js, internal/defaults) and exercised by harness/live-fire.mjs using the real ABI + derived channel id + a real viem signer. The vendored enforcement core is byte-identical to ows-op-verify (npm run check:core-sync). 28 conformance cases + 8 live-fire checks pass.