Add method to decode permission to GatorPermissionsController

[jeffsmale90]

Explanation

• Why change?
  When signing a permission, MetaMask must present the permission in a way that is easily comprehensible to the user. Based on the design shared here, the permission must be decoded from the eth_signTypedData_v4 request.

This PR adds that functionality to the GatorPermissionsController.

• What’s the solution?

Introduce decodePermissionFromPermissionContextForOrigin to GatorPermissionsController and register a new action handler. It:

• Validates the caller origin matches permissionsProviderSnapId (throws OriginNotAllowedError otherwise).

• Resolves enforcer contract addresses per chain via @metamask/delegation-deployments. Throws if contracts are missing for the chain.

• Identifies the permission type from caveats via identifyPermissionByEnforcers, extracts expiry and permission-specific data via getPermissionDataAndExpiry, and builds a DecodedPermission via reconstructDecodedPermission.

• Non-obvious pieces:

  • Added @metamask/delegation-core for terms helpers like createTimestampTerms and createNativeTokenStreamingTerms, and ROOT_AUTHORITY.
  • Added @metamask/delegation-deployments to source enforcer addresses and CHAIN_ID.
  • Moved the decoding logic into a subfolder, to make it easier to export internal functionality from utils.ts to facilitate low level unit testing, without polluting the interface that is exposed to the GatorPermissionsController with these functions.

References

Architecture design https://www.notion.so/metamask-consensys/SignTypedData-with-Metadata-Specification-22bf86d67d688023be67e2ee06e3a56a#22bf86d67d688023be67e2ee06e3a56a

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​metamask/​delegation-core@​0.2.0
	@​metamask/​delegation-deployments@​0.12.0

View full report

[V00D00-child]

I'm not seeing a strong justification for exposing decodePermissionFromPermissionContextForOrigin() via the GatorPermissionsController.

As mentioned in the inline comment, we should consider decoupling it entirely and exposing it as a utility function directly from @metamask/gator-permissions-controller.