AI GitHub Issue-to-PR Builder

Fix GitHub issue #142: Users can submit the registration form with an invalid email address.

Please inspect the repository first. Identify the relevant validation code and existing tests, determine the smallest safe fix, implement it, add or update regression tests, run the appropriate verification commands, inspect the final diff for unrelated changes, and prepare a review-ready PR summary.

Do not refactor unrelated code or add new dependencies.

Task Interpretation

Fix the registration email validation issue reported in #142 without changing unrelated registration behavior.

Repository Findings

• Located the registration validation logic in src/....
• Found existing registration tests in tests/....
• Confirmed the repository's existing test and lint commands from its project configuration.
• No new dependency is required.

Acceptance Criteria

• [x] Invalid email addresses are rejected.
• [x] Valid email addresses continue to be accepted.
• [x] A regression test covers the reported invalid input.
• [x] No unrelated registration behavior is changed.

Implementation

Updated the existing validation boundary and added a focused regression test using the project's existing testing conventions.

Verification

• Targeted registration tests: PASS
• Relevant lint/check: PASS
• Final diff inspection: PASS
• No unrelated files or temporary artifacts introduced.

PR Title

Fix registration email validation

PR Summary

Changes

• Tightened email validation at the existing registration validation boundary.
• Added regression coverage for invalid email input.

Risk

Low. The change is limited to the reported validation behavior and preserves valid email handling.

Rollback

Revert the two changed files if the validation behavior causes an unexpected compatibility issue.

Reviewer Notes

The implementation uses the repository's existing validation and testing patterns and avoids introducing a new dependency.