Creating a topic failed intermittently — "a topic with that slug already
exists" — and worked when the author retried with a different name. The rule
was never intermittent, only invisible: the slug kept `[a-z0-9]` and dropped
everything else, so a Korean name contributed nothing. Whatever Latin word or
number happened to be in it became the entire slug.
Two ways that goes wrong, and the author hit both. `인증` reduced to an empty
string, which the form refused before a request was ever sent. `Redis 캐시` and
`Redis 클러스터` both reduced to `redis`, so the second one collided with the
first — a real conflict, reported honestly, about a slug the author never chose
and could not see.
Hangul is now romanized rather than discarded. Syllables decompose
arithmetically into initial, medial and final jamo, so this needs no table and
is deterministic: `백엔드 아키텍처` becomes `baekendeu-akitekcheo`. Only the
jamo mapping from Revised Romanization is applied — the sound-change rules are
deliberately left out, because a slug is read, not pronounced, and those rules
would make one name produce different slugs in different contexts.
The output keeps the shape document slugs already use
(`^[a-z0-9]+(?:-[a-z0-9]+)*$`), so the repository has one slug rule rather than
two, and the tests assert exactly that.
