@metamask/smart-transactions-controller

@metamask/smart-transactions-controller

Improves success rates for swaps by trialing transactions privately and finding minimum fees.

Installation

yarn add @metamask/smart-transactions-controller

or

npm install @metamask/smart-transactions-controller

Contributing

Setup

• Install the current LTS version of Node.js
  • If you are using nvm (recommended) running nvm install will install the latest suitable version and running nvm use will automatically choose the right node version for you.
• Install Yarn v3
• Run yarn install to install dependencies and run any required post-install scripts

Testing and Linting

Run yarn test to run the tests once. To run tests on file changes, run yarn test:watch.

Run yarn lint to run the linter, or run yarn lint:fix to run the linter and fix any automatically fixable issues.

Feature Flags

Smart transactions feature flags are managed via RemoteFeatureFlagController (LaunchDarkly). The configuration uses a default remote object for global settings and chain-specific overrides keyed by hex chain ID.

The flag in LaunchDarkly is named smartTransactionsNetworks.

Adding a New Flag

• Add the field to the schema in src/utils/validators.ts:

  export const SmartTransactionsNetworkConfigSchema = type({
    // ... existing fields
    myNewFlag: optional(boolean()),
  });
  

  The SmartTransactionsNetworkConfig type is automatically inferred from this schema.

• Add default value in src/constants.ts under DEFAULT_DISABLED_SMART_TRANSACTIONS_FEATURE_FLAGS:

  These values should be defensive. They are applied when the remote config is invalid or does not exist for a network. It disables smart transaction.

  export const DEFAULT_DISABLED_SMART_TRANSACTIONS_FEATURE_FLAGS = {
    default: {
      // ... existing defaults
      myNewFlag: false,
    },
  };
  

• Use in clients via the exported selectors:

  import { selectSmartTransactionsFeatureFlagsForChain } from '@metamask/smart-transactions-controller';
  
  const chainConfig = selectSmartTransactionsFeatureFlagsForChain(
    state,
    '0x1',
  );
  if (chainConfig.myNewFlag) {
    // Feature is enabled
  }
  

Release & Publishing

The project follows the same release process as the other libraries in the MetaMask organization. The GitHub Actions action-create-release-pr and action-publish-release are used to automate the release process; see those repositories for more information about how they work.

• Choose a release version.

  • The release version should be chosen according to SemVer. Analyze the changes to see whether they include any breaking changes, new features, or deprecations, then choose the appropriate SemVer version. See the SemVer specification for more information.

• If this release is backporting changes onto a previous release, then ensure there is a major version branch for that version (e.g. 1.x for a v1 backport release).

  • The major version branch should be set to the most recent release with that major version. For example, when backporting a v1.0.2 release, you'd want to ensure there was a 1.x branch that was set to the v1.0.1 tag.

• Trigger the workflow_dispatch event manually for the Create Release Pull Request action to create the release PR.

  • For a backport release, the base branch should be the major version branch that you ensured existed in step 2. For a normal release, the base branch should be the main branch for that repository (which should be the default value).
  • This should trigger the action-create-release-pr workflow to create the release PR.

• Update the changelog to move each change entry into the appropriate change category (See here for the full list of change categories, and the correct ordering), and edit them to be more easily understood by users of the package.

  • Generally any changes that don't affect consumers of the package (e.g. lockfile changes or development environment changes) are omitted. Exceptions may be made for changes that might be of interest despite not having an effect upon the published package (e.g. major test improvements, security improvements, improved documentation, etc.).
  • Try to explain each change in terms that users of the package would understand (e.g. avoid referencing internal variables/concepts).
  • Consolidate related changes into one change entry if it makes it easier to explain.
  • Run yarn auto-changelog validate --rc to check that the changelog is correctly formatted.

• Review and QA the release.

  • If changes are made to the base branch, the release branch will need to be updated with these changes and review/QA will need to restart again. As such, it's probably best to avoid merging other PRs into the base branch while review is underway.

• Squash & Merge the release.

  • This should trigger the action-publish-release workflow to tag the final release commit and publish the release on GitHub.

• Publish the release on npm.

  • Wait for the publish-release GitHub Action workflow to finish. This should trigger a second job (publish-npm), which will wait for a run approval by the npm publishers team.
  • Approve the publish-npm job (or ask somebody on the npm publishers team to approve it for you).
  • Once the publish-npm job has finished, check npm to verify that it has been published.

Testing changes in other projects using preview builds

If you are working on a pull request and want to test changes in another project before you publish them, you can create a preview build and then configure your project to use it.

Creating a preview build

• Within your pull request, post a comment with the text @metamaskbot publish-preview. This starts the publish-preview GitHub action, which will create a preview build and publish it to NPM.
• After a few minutes, the action should complete and you will see a new comment. Note two things:
  • The name is scoped to @metamask-previews instead of @metamask.
  • The ID of the last commit in the branch is appended to the version, e.g. 1.2.3-preview-e2df9b4 instead of 1.2.3.

Using a preview build

To use a preview build within a project, you need to override the resolution logic for your package manager so that the "production" version of that package is replaced with the preview version. Here's how you do that:

• Open package.json in the project and locate the entry for this package in dependencies.
• Locate the section responsible for resolution overrides (or create it if it doesn't exist). If you're using Yarn, this is resolutions; if you're using NPM or any other package manager, this is overrides.
• Add a line to this section that mirrors the dependency entry on the left-hand side and points to the preview version on the right-hand side. Note the exact format of the left-hand side will differ based on which version of Yarn or NPM you are using. For example:
  • For Yarn Modern, you will add something like this to resolutions:

    "@metamask/smart-transactions-controller@^1.2.3": "npm:@metamask-previews/smart-transactions-controller@1.2.3-preview-abcdefg"
    

  • For Yarn Classic, you will add something like this to resolutions:

    "@metamask/smart-transactions-controller": "npm:@metamask-previews/smart-transactions-controller@1.2.3-preview-abcdefg"
    

  • For NPM, you will add something like this to overrides:

    "@metamask/smart-transactions-controller": "npm:@metamask-previews/smart-transactions-controller@1.2.3-preview-abcdefg"
    

• Run yarn install.

Updating a preview build

If you make more changes to your pull request and want to create a new preview build:

• Post another @metamaskbot comment on the pull request and wait for the response.
• Update the version of the preview build in your project's package.json. Make sure to re-run yarn install!