Sphere Layout Sync

A generated go-sphere project keeps receiving upstream layout changes. This skill performs that merge without destroying project code, and without silently reverting layout fixes.

Inputs

Do not modify any file until all three are established:

1. .sphere/layout.lock.json exists and its schema_version is one you understand.
2. The target upstream revision is resolved to a concrete commit SHA.
3. The working tree is clean, or the user explicitly accepted syncing over local changes.

If schema_version is unknown to you, stop and report it. Never guess the lock format.

If there is no lock file at all, this is a legacy adoption. Read references/legacy-adoption.md and do not start a normal sync.