[asselstine]

Summary

• Canonicalize VM image registry and repository names to lowercase while preserving tag casing for job create/update and image verification.
• Return field-specific image validation errors, including guidance when a URL scheme is supplied.
• Keep browser verification state stable across casing-only edits and add backend/browser coverage.

Validation

• npm test (full backend, PostgreSQL, browser and contract suite)

[linear]

GEN-2729