fix: cp-8.0.0 require EIP-7702 for sponsored gas transactions

[matthewwalsh0]

Description

Sponsored and gas-included transaction publishing depends on the EIP-7702 delegation relay path. Previously, when atomic EIP-7702 support was unavailable for the selected chain, the delegation publish hook returned an empty result, which allowed the publish pipeline to continue to later publication paths.

This PR makes that path fail closed for sponsored and gas-included transactions by throwing a clear error when the chain does not support EIP-7702 atomic batching. Non-sponsored transactions keep the existing empty-result behavior when EIP-7702 is unavailable.

Changelog

CHANGELOG entry: Fixed sponsored and gas-included transactions falling back when EIP-7702 support is unavailable

Related issues

Refs: MetaMask/core#9240

Manual testing steps

N/A - covered by unit tests for the transaction publish hook.

Screenshots/Recordings

N/A

Before

N/A

After

N/A

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Performance checks (if applicable)

• I've tested on Android
  • Ideally on a mid-range device; emulator is acceptable
• I've tested with a power user scenario
  • Use these power-user SRPs to import wallets with many accounts and tokens
• I've instrumented key operations with Sentry traces for production performance metrics
  • See trace() for usage and addToken for an example

For performance guidelines and tooling, see the Performance Guide.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

---

Note

Medium Risk
Changes transaction publish behavior for gas-sponsored and gas-included flows on chains without EIP-7702, blocking unsafe fallbacks instead of silently continuing.

Overview
Sponsored and gas-included publishes must use the EIP-7702 delegation relay. When atomic batch support is missing for the chain, Delegation7702PublishHook used to return an empty result so later publish hooks could run.

This change throws for isGasFeeSponsored or isGasFeeIncluded when the chain is not EIP-7702-capable, with a clear error (prefixed as Gas Station 7702:). Regular transactions still get the empty result and can fall through.

Gas flags are normalized earlier (Boolean on isGasFeeIncluded / isGasFeeSponsored) and includeTransfer now keys off the same isSponsored flag. Unit tests cover sponsored and gas-included cases when atomic batch is unsupported.

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[mm-token-exchange-service]

PR template — items to address before "Ready for review"

Warnings — informational, address before merging:

• Pre-merge author checklist has unchecked items (e.g. "I've tested on Android"). Every box must be consciously checked — see docs/readme/ready-for-review.md.

See docs/readme/ready-for-review.md for the full Definition of Ready for Review.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: SmokeConfirmations
• Selected Performance tags: None (no tests recommended)
• Risk Level: medium
• AI Confidence: 88%

click to see 🤖 AI reasoning details

E2E Test Selection:
The PR modifies delegation-7702-publish.ts and its test file. The changes:

1. Move isGaslessBridge and isSponsored variable declarations earlier in the function (before the chain support check).
2. Add a new error throw when the chain doesn't support EIP-7702 but the transaction is sponsored (isGasFeeSponsored) or gas-included (isGasFeeIncluded).
3. Refactor includeTransfer to use the already-computed isSponsored variable instead of re-reading transactionMeta.isGasFeeSponsored.

These changes affect the EIP-7702 advanced account abstraction transaction flow — specifically sponsored/gasless bridge transactions. SmokeConfirmations covers EIP-7702 account abstraction features including batch transactions and gas fee token payments, making it the directly relevant tag. No other areas (swaps, staking, accounts, browser, snaps, etc.) are affected. No performance-sensitive code paths are changed.

Performance Test Selection:
The changes are limited to EIP-7702 delegation publish hook logic — specifically error handling for unsupported chains with sponsored/gas-included transactions. No rendering, loading, or performance-sensitive code paths are modified. No performance tests are warranted.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud