chore: INFRA-3188: automate release branch sync

[XxdpavelxX]

Description

Ticket: https://consensyssoftware.atlassian.net/browse/INFRA-3188
Test stable sync branch: https://github.com/consensys-test/metamask-mobile-test-workflow/actions/runs/20148777729/job/57923961348, consensys-test#174

Adds a composite GitHub Action and script to auto-open PRs syncing stable into active release/* branches after a release is merged.

• CI/GitHub Actions
  • New composite action /.github/actions/release-branch-sync/action.yml:
    • Inputs: merged-release-branch, github-token, optional github-tools-repository and github-tools-ref.
    • Checks out repo and tools, configures git, runs sync script.
  • New script /.github/scripts/release-branch-sync.sh:
    • Detects active release branches via open PR titles matching release: X.Y.Z.
    • Creates stable-sync-release-X.Y.Z branches from origin/stable, pushes, and opens PRs into corresponding release/X.Y.Z branches.
    • Skips invalid/older-than-merged branches, the just-merged branch, non-existent branches, already up-to-date branches, or if a sync PR already exists.
    • Emits a summary of created/skipped/failed operations.

Changelog

CHANGELOG entry: None

Related issues

Fixes:

Manual testing steps

Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]

Screenshots/Recordings

Before

After

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.

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

Adds a GitHub Actions workflow to validate merged release branch names and sync stable into open release/* branches.

• CI/GitHub Actions:
  • New workflow /.github/workflows/release-branch-sync.yml triggered on closed PRs to stable.
    • validate-branch job: Ensures merged head branch matches release/X.Y.Z.
    • sync-release-branches job: If valid, runs metamask/github-tools/.github/actions/[email protected] to sync stable into open release/* branches using STABLE_SYNC_TOKEN.

^{Written by Cursor Bugbot for commit 5492723. This will update automatically on new commits. Configure here.}

[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.

[sethkfman]

LGTM

[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: None (no tests recommended)
• Risk Level: low
• AI Confidence: 95%

click to see 🤖 AI reasoning details

This PR adds a new GitHub Actions workflow file (.github/workflows/release-branch-sync.yml) that automates the synchronization of release branches with the stable branch.

Key observations:

1. This is a brand new CI/CD workflow file (not modifying existing workflows)
2. The workflow only triggers on pull_request events when PRs are merged to the 'stable' branch
3. It validates release branch naming format and syncs release branches using an external GitHub action
4. This workflow has no relationship to the application code, E2E test infrastructure, or any test execution
5. It's purely a release management automation workflow

Since this change:

• Does not modify any application code
• Does not affect E2E test infrastructure (e2e/, wdio/, appwright/ directories)
• Does not modify any critical files (package.json, controllers, Engine, app/core/)
• Is isolated to release branch management automation
• Has no CI relationships with test execution workflows

No E2E tests need to be run to validate this change.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud