[03/03] DeepSec approvals: ETH-flow Safe bundle and TWAP entrypoints

[fairlighteth]

What changed

• Route ETH-flow approval through the shared approval gate and handle both transaction and Safe approval responses.
• Ignore stale ETH-flow partial approval amounts when the stored amount belongs to a different token.
• Gate both Safe bundle approval implementations before constructing or submitting approval transactions.
• Make TWAP creation wait until the zero-approval requirement is resolved.

Why

• ETH-flow and Safe bundle entrypoints constructed approvals outside the classic approval path, so they could bypass the widget host's approval-specific policy.
• Flow-specific readiness state must be resolved before transaction construction so the reviewed approval operation matches the submitted one.

DeepSec findings addressed

• Source: DeepSec vulnerability scan report dated 2026-05-05. This waterfall supersedes the closed aggregate PR fix: align approval hooks and permit spender checks #7620.
• MEDIUM - ETH-flow approvals bypass injected widget approval hooks: wrapped-native approval used the raw approval callback and could prompt the wallet even when the widget host rejected approval policy. ETH-flow now uses the shared gate before approval.
• MEDIUM - Safe limit-order approval bundle bypasses widget approval hook: a Safe batch could include an ERC-20 approval without invoking the approval-specific host callback. Both Safe bundle implementations now gate the actual token, amount, wallet, and spender before building or sending the approval.
• Review follow-up: TWAP creation waits for zero-approval readiness, and ETH-flow ignores stale partial approval state belonging to another currency.

Review guide

• This is PR 3 of 3: develop <- #7837 <- #7838 <- #7839.
• Review focus:
  1. ETH-flow approval entrypoint and response handling.
  2. Safe bundle approval entrypoints.
  3. TWAP zero-approval readiness.
  4. Stale partial-approval currency handling.
• Base branch is deepsec/approval-permit-02-shared-gate; review this diff against [02/03] DeepSec approvals: shared gate and classic permit paths #7838, not develop.

QA Testing

Developer verification on 11d3f3862:

• Targeted approval, permit, and ETH-flow hooks: 6 suites, 43 tests passed.
• cowswap-frontend, permit-utils, and common-utils TypeScript checks passed.

CI status on the amended head:

• Passing as of this update: Typecheck, Agent Harness, Setup, i18n extraction, Socket Security, CLA, and completed Vercel deployments.
• Test, Lint, Cypress, and the remaining preview deployments were still incomplete; use the Checks tab for their live result.

Known QA gaps

• No fresh manual real-wallet signing pass for ERC-20 approval, EIP-2612 permit, or DAI-like permit signing on the latest stacked head.
• No manual Safe bundle approve/presign pass on the latest stacked head.
• No manual TWAP creation pass with a token that requires zero approval; coverage here is unit and typecheck only.

Preview URLs

Surface	URL
swap-dev - branch preview URL	https://swap-dev-git-deepsec-approval-permit-03-flow-f90d54-cowswap-dev.vercel.app
explorer-dev - branch preview URL	https://explorer-dev-git-deepsec-approval-permit-03-1a966c-cowswap-dev.vercel.app
cowfi - branch preview URL	https://cowfi-git-deepsec-approval-permit-03-flow-entrypoints-cowswap.vercel.app
storybook - branch preview URL	https://storybook-git-deepsec-approval-permit-03-flo-4dad8a-cowswap-dev.vercel.app
widget-configurator - branch preview URL	https://widget-configurator-git-deepsec-approval-per-72f172-cowswap-dev.vercel.app
sdk-tools - branch preview URL	https://sdk-tools-git-deepsec-approval-permit-03-flo-dfa8f4-cowswap-dev.vercel.app

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
cowfi	Ready	Preview	Jul 10, 2026 12:18pm
explorer-dev	Ready	Preview	Jul 10, 2026 12:18pm
storybook	Ready	Preview	Jul 10, 2026 12:18pm
swap-dev	Ready	Preview	Jul 10, 2026 12:18pm
widget-configurator	Ready	Preview	Jul 10, 2026 12:18pm

2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
cosmos	Ignored		Jul 10, 2026 12:18pm
sdk-tools	Ignored	Preview	Jul 10, 2026 12:18pm

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Deploying explorer-dev with    Cloudflare Pages

Latest commit:	3fa697b
Status:	✅  Deploy successful!
Preview URL:	https://001f5420.explorer-dev-dxz.pages.dev
Branch Preview URL:	https://deepsec-approval-permit-03-f.explorer-dev-dxz.pages.dev

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Status:	✅  Deploy successful!
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[fairlighteth]

Cross-PR coordination heads-up: this PR inherits the shared approval-gate work from #7838, which directly overlaps #7697's permit-signing fix. #7697 also adds limit-order and lower-level swapFlow coverage.

The review on #7697 identified a cached-permit ordering issue that also applies to the shared gate in #7838. There is no direct file overlap in this PR, but flagging it here because the completed stack will carry that behavior.