fix(recurring): bind batch schedule key to signed terms

[LeoSlrRf]

Decouple schedule key from EIP-712 digest to prevent replay via re-signing

The bitmap tracking which payment indices have been triggered was previously keyed on the EIP-712 digest, which includes nonce and deadline. This meant a subscriber could re-sign the same economic terms with a fresh nonce or deadline and reset the paid-index tracking, allowing already-settled payments to be triggered again.

The schedule key is now derived exclusively from the fields that define the economic terms of the schedule (subscriber, token, recipient, amounts, period, etc.), deliberately excluding nonce and deadline. This ensures that re-signing with updated metadata does not produce a new key and cannot unlock previously paid indices.

Changes

• Introduces _scheduleKeyFromPermit and _scheduleKeyFromBatch (with public wrappers) to compute a stable, content-addressed key for each schedule.
• triggeredPaymentsBitmap and lastPaymentIndex are now keyed on the schedule key rather than the EIP-712 digest.
• Adds ERC20RecurringPaymentProxy__ZeroScheduleId error, reverted when a batch permit carries a zero scheduleId, which would make distinct schedules collide.
• Extracts _assertUnpaid, _assertOrder, and _markPaid helpers to centralise bitmap and ordering logic.
• Moves _markPaid to after the transfer calls so a failed transfer never marks an index as paid.
• Adds an explicit rejection of index 0 before the existing upper-bound check.
• Updates tests to use scheduleKeyFromPermit / scheduleKeyFromBatch and adds a dedicated Schedule key replay suite covering re-sign stability, zero-index rejection, key sensitivity to term changes, and zero scheduleId rejection.

[LeoSlrRf]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• refactor(recurring): pack schedule state into one mapping #1762
• fix(recurring): grant and revoke relayer as separate calls #1761
• feat(recurring): emit schedule and admin events #1760
• test(recurring): accept and reject EIP-1271 batch signatures #1759
• feat(recurring): add revokeCycles for admitted bits #1758
• docs(recurring): warn cancel does not drop allowance #1757
• fix(recurring): reject zero-amount legs #1756
• fix(recurring): guard rescueTokens with nonReentrant #1755
• fix(recurring): bind batch schedule key to signed terms #1754 👈 (View in Graphite)
• fix(recurring): revert on a failed or short subscriber pull #1753
• feat(recurring): accept EIP-1271 smart-account signatures #1752
• fix(recurring): emit 8-byte payment references #1751
• master

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[greptile-apps]

Greptile Summary

This PR makes recurring-payment replay state independent of signature nonce and deadline, preventing re-signing from resetting paid indices.

• Derives stable schedule keys from signed payment terms.
• Uses the stable key for order checks, replay checks, and paid-state updates.
• Rejects payment index zero and zero batch schedule identifiers.
• Adds tests for failed-transfer state rollback and stable schedule-key behavior.

Confidence Score: 5/5

The PR appears safe to merge with no concrete changed-code failure identified.

The executed recurring-payment path consistently derives one nonce-independent key for order checking, replay checking, and state updates, while reverted transfers leave payment state unmarked.

Important Files Changed

Filename	Overview
packages/smart-contracts/src/contracts/ERC20RecurringPaymentProxy.sol	Introduces stable term-derived schedule keys and consistently applies the single-permit key to replay and ordering state.
packages/smart-contracts/test/contracts/ERC20RecurringPaymentProxy.test.ts	Updates state assertions to use schedule keys and adds coverage for re-signing, index zero, batch key stability, term changes, and zero schedule identifiers.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Signed schedule permit] --> B[Verify EIP-712 signature]
  A --> C[Derive stable schedule key]
  C --> D[Check order and paid bitmap]
  D --> E[Execute token transfers]
  E --> F[Mark index paid under schedule key]
  G[Re-sign with new nonce or deadline] --> C

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