chore(ci): derive RC slack notification changelog from git ancestry

[joaoloureirop]

Description

RC Slack notifications previously parsed CHANGELOG.md with @metamask/auto-changelog. It wasn't working because the release changelog is on a different branch and do not follow the format we want for the slack notification. This change builds the “What’s in this RC” section from git instead:

• A = git merge-base HEAD <base> (default origin/main, overridable via CHANGELOG_MERGE_BASE_REF)
• B = HEAD
• List commits with git log --ancestry-path A..B so only commits on the path between the fork point and the RC tip are included.

The reusable Slack workflow checkout is updated from fetch-depth: 1 to fetch-depth: 0 so merge-base has enough history on the runner.

Changelog

CHANGELOG entry: null

Related issues

Fixes:
https://consensyssoftware.atlassian.net/browse/INFRA-3482
https://consensyssoftware.atlassian.net/browse/MCWP-442

Manual testing steps

Feature: RC Slack notification changelog

  Scenario: Verify git-based commit list on a release branch
    Given a clone with full history and a remote tracking branch (e.g. origin/main)
    When CHANGELOG_MERGE_BASE_REF is unset or set to origin/main and the script runs with SLACK_BOT_TOKEN and TEST_CHANNEL
    Then the Slack message lists commits from git log --ancestry-path $(git merge-base HEAD origin/main)..HEAD and respects the entry cap

  Scenario: GitHub Actions reusable workflow
    Given the slack-rc-notification workflow runs after an RC build
    When the checkout uses fetch-depth 0
    Then merge-base and ancestry-path succeed and the notification posts without shallow-clone errors

Screenshots/Recordings

Before

After

Message preview link

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[github-actions]

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: None (no tests recommended)
• Selected Performance tags: None (no tests recommended)
• Risk Level: low
• AI Confidence: 97%

click to see 🤖 AI reasoning details

E2E Test Selection:
The two changed files are purely CI/notification infrastructure:

1. .github/workflows/slack-rc-notification.yml: Only change is fetch-depth: 1 → fetch-depth: 0 to enable full git history fetching for the new git-based commit listing approach.

2. scripts/slack-rc-notification.mjs: Refactored from CHANGELOG.md parsing to git history-based commit listing using git merge-base + git log --ancestry-path. Added dry-run mode, improved fail-open behavior, and updated Slack message formatting.

Neither file touches any app source code, test infrastructure, controllers, navigation, UI components, or any user-facing functionality. These changes only affect how the Slack RC notification message is generated and sent — a purely operational/DevOps concern. No E2E tests are needed to validate these changes, and there is no performance impact on the app.

Performance Test Selection:
No app code was changed. The modifications are limited to a GitHub Actions workflow (fetch-depth setting) and a Node.js script for generating Slack RC notifications. There is zero impact on app rendering, data loading, startup, or any other performance-sensitive area.

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