Enables proper alpha and beta release channels for QA and customer testing. This PR adds the prerelease flag to GitHub releases for alpha/beta versions and prevents the auto-updater from offering downgrades as "updates" to users running development builds.

Root Cause Analysis

The Problem

Two issues prevented effective alpha channel usage:

1. GitHub releases not marked as prerelease: When creating releases with tags like 4.12.0-alpha.1, the GitHub release was not marked as "Pre-release", causing it to appear as the "Latest Release" to all visitors.

2. False update notifications: Users running PR/development builds (e.g., 4.11.0) were being offered "updates" to older stable versions (e.g., 4.10.0). This occurred because generateUpdatesFilesForAllChannels: true in electron-builder automatically enables allowDowngrade: true.

Five Whys

Issue 1: Alpha releases showing as "Latest Release"

1. Why did alpha releases appear as latest? → GitHub wasn't told they were prereleases
2. Why wasn't GitHub told? → The prerelease flag wasn't set in the release API call
3. Why wasn't it set? → getTaggedRelease() didn't check for prerelease version components

Issue 2: Downgrade offered as update

1. Why was 4.10.0 offered as update to 4.11.0? → electron-updater's update-available event fired
2. Why did it fire for an older version? → allowDowngrade was enabled
3. Why was allowDowngrade enabled? → generateUpdatesFilesForAllChannels: true automatically enables it
4. Why is that setting enabled? → Required for multi-channel (alpha/beta/stable) support

Root Cause

1. Missing prerelease: true flag in GitHub release creation for versions with prerelease components
2. No version comparison before showing update notifications to users

The Fix

Approach

For prerelease flag: Detect prerelease versions using semver's prerelease array and pass the flag to GitHub's release API.

For downgrade prevention: Compare versions using semver before dispatching UPDATES_NEW_VERSION_AVAILABLE. If the "update" version is not greater than current, silently ignore it.

Implementation

1. GitHub Release Prerelease Flag

workspaces/desktop-release-action/src/github.ts:112-148

export const getTaggedRelease = async (version: SemVer, commitSha: string) => {
  const body = await getChangelog();
  const isPrerelease = version.prerelease.length > 0;  // NEW

  // ... in both PATCH and POST requests:
  prerelease: isPrerelease,  // NEW

The semver library's SemVer type has a prerelease array that contains components like ['alpha', 1] for version 4.12.0-alpha.1. An empty array means stable release.

2. Version Comparison Before Update Notification

src/updates/main.ts:249-263

autoUpdater.addListener('update-available', ({ version }) => {
  // ... existing skip logic ...

  // Prevent showing "updates" that are actually downgrades
  const currentVersion = app.getVersion();
  try {
    if (!semverGt(version as string, currentVersion)) {
      dispatch({ type: UPDATES_NEW_VERSION_NOT_AVAILABLE });
      return;
    }
  } catch {
    // If version comparison fails, proceed with the update
  }

  dispatch({ type: UPDATES_NEW_VERSION_AVAILABLE, payload: version });
});

Files Changed

Architecture

Release Channel Flow

Version Tag                    electron-builder              GitHub Release
─────────────────────────────────────────────────────────────────────────────
4.12.0          ──────────►   latest.yml        ──────────►  Latest Release
4.12.0-beta.1   ──────────►   beta.yml          ──────────►  Pre-release ✓
4.12.0-alpha.1  ──────────►   alpha.yml         ──────────►  Pre-release ✓

Update Check Flow

User App                    electron-updater                 Action
─────────────────────────────────────────────────────────────────────────────
channel=latest  ──────────►  checks latest.yml  ──────────►  Only stable
channel=beta    ──────────►  checks beta.yml    ──────────►  Beta + stable
channel=alpha   ──────────►  checks alpha.yml   ──────────►  Alpha + beta + stable

Downgrade Prevention Flow

                    update-available event
                            │
                            ▼
                ┌───────────────────────┐
                │ Is offered version >  │
                │ current version?      │
                └───────────────────────┘
                     │           │
                    YES          NO
                     │           │
                     ▼           ▼
              Show update    Silently ignore
              dialog         (no notification)

Verification

Testing the Prerelease Flag

After merging, create an alpha release:

# Update package.json to "4.12.0-alpha.1"
git tag 4.12.0-alpha.1
git push origin 4.12.0-alpha.1

Verify:

1. GitHub release shows "Pre-release" badge
2. Release does NOT show as "Latest Release"
3. alpha.yml exists in release assets

Testing Downgrade Prevention

yarn build
yarn start

1. Run a development build with version higher than published stable
2. Open About dialog → Check for Updates
3. Should show "No updates available" (not offer downgrade)

Testing Alpha Channel Opt-in

1. Enable Developer Mode in Settings
2. Open About dialog
3. Select "Alpha (Experimental)" from dropdown
4. Click "Check for Updates"
5. Alpha release should be offered

Considerations

What This Doesn't Change

• Existing stable release flow unchanged
• Users on stable channel unaffected
• No changes to build process or artifacts

Potential Risks

• Version parsing edge cases: If semver parsing fails, update proceeds (fail-safe)
• Channel selector still behind dev mode: Intentional - prevents accidental alpha opt-in

References

• electron-builder channels: https://www.electron.build/tutorials/release-using-channels.html
• electron-updater allowDowngrade: Clarification on allowPrerelease, pre-releases, and auto-updates with channels electron-userland/electron-builder#4988
• GitHub Release API: https://docs.github.com/en/rest/releases/releases

Summary by CodeRabbit

• New Features

  • Added ARM64 support for Windows builds and tooling to create & publish prerelease tags/releases.

• Bug Fixes

  • Update checks now only notify users when a newer app version is available.

• Documentation

  • Added comprehensive Alpha release process and troubleshooting guidance.

• Chores

  • Bumped package to an alpha version, adjusted release metadata to honor prereleases, updated CI branch triggers, and expanded lint ignore paths.

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