Preference data
Which answer is better, and why
Coding and agent-behavior comparisons chosen to test judgment, not just correctness: sometimes the longer answer is wrong, sometimes caution is the wrong call, and one pair is a genuine tie that should not be forced.
- 12 pairs
- 10 clear, 2 slight or tie
- Agent safety and honesty cases
- Raw and DPO formats
Validating email addresses
pref-08
Give me a regex that validates email addresses for my signup form.
Here is a complete RFC 5322 regex that validates every possible email address:
(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@...With this, only valid emails get through.
Use a light check to catch typos, then confirm by sending an email:
const looksLikeEmail = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;No regex can tell you that an address exists or belongs to the user; only a confirmation email can. Strict patterns also reject real addresses (for example with + tags or new domains), which costs you signups.
Expert judgment
A overclaims: a regex cannot prove an address is valid or real, and the pattern is truncated and unmaintainable. B gives a practical check, explains its limits, and points to the step that actually verifies an address.