fix(calver): skeleton major bumps no longer cascade to hydrogen packages

[kdaviduik]

WHY are these changes introduced?

Relates to #3451

The [ci] release 2026.1.0 PR incorrectly bumps @shopify/hydrogen and @shopify/hydrogen-react to major version 2026.1.0. The only major changeset is 'skeleton': major in api-version-2025-10.md — hydrogen only has a patch changeset and hydrogen-react has none at all. The skeleton template's major bump should not force the library packages to advance to the next quarter.

WHAT is this pull request doing?

Introduces a CALVER_SYNC_PACKAGES constant to separate two concerns that were conflated:

• "Which packages use CalVer versioning?" → CALVER_PACKAGES (hydrogen, hydrogen-react, skeleton)
• "Which packages' major bumps trigger cross-package quarter advancement?" → CALVER_SYNC_PACKAGES (hydrogen, hydrogen-react only)

The root cause was that detectBumpType() and hasMajorChangesets() treated all three CalVer packages identically for major detection. A skeleton: major changeset would set the global hasMajor flag, which then forced ALL CalVer packages to getNextVersion(baseline, 'major') — advancing them to the next quarter even when they had no major changeset.

Files changed:

File	Change
.changeset/calver-shared.js	Add CALVER_SYNC_PACKAGES, update hasMajorChangesets() to use it
.changeset/detect-calver-bump-type.js	Gate hasMajor detection to sync-eligible packages only
.changeset/calver-bump-type.test.js	Add 14 new assertions covering skeleton-major scenarios

The fix is minimal: only 2 files needed code changes. The 4 other consumption points (enforce-calver-ci.js lines 137 and 165-167, enforce-calver-local.js lines 159 and 184) inherit the fix transitively because they call into the corrected functions.

HOW to test your changes?

1. Run the test suite:

   node .changeset/calver-bump-type.test.js
   

   All 32 tests should pass (18 existing + 14 new).

2. Verify the CLI command with current changesets:

   node .changeset/calver-shared.js has-major-changesets
   

   Should return false (current changesets include skeleton: major but no hydrogen/hydrogen-react major).

3. Key test scenarios to verify:

   • skeleton: major alone → detectBumpType() returns 'patch', hasMajorChangesets() returns false
   • @shopify/hydrogen: major alone → returns 'major' and true (no regression)
   • skeleton: major + @shopify/hydrogen: patch → returns 'patch' and false (the exact PR [ci] release 2025.10.1 #3451 scenario)
   • Single changeset file with both skeleton: major and @shopify/hydrogen: patch in the same frontmatter → returns 'patch' and false

Post-merge steps

After merging, the [ci] release PR (#3451) should be regenerated. The changeset workflow will re-run detect-calver-bump-type.js and produce correct versions (skeleton advances to next quarter independently, hydrogen gets a patch bump, hydrogen-react stays unchanged).

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your changeset-bug branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	February 6, 2026 7:13 PM

Learn more about Hydrogen's GitHub integration.

[fredericoo]

lgtm