When Russian Abbreviations Break Your UI: A Cascade Debug Story

I was debugging the Cascade trend analysis frontend when a Slack message came in: “The translated labels look wrong.” One glance at the API response confirmed it—“Финансирование инвестиций в ИИ” (AI Investment Financing) had arrived pristine from Claude, but somewhere between the backend and the DOM, “ИИ” had collapsed into “ии”. Classic case of right data, wrong rendering.

The culprit was formatClassName(), a utility function that handles label capitalization for display. It was applying strict sentence-case logic—uppercase first character, lowercase everything else—indiscriminately to both English and Russian text. For English, this works fine because we maintain an ABBREVIATIONS set that preserves known acronyms like “LLM” and “API”. But Russian abbreviations like “ИИ” (AI), “США” (USA), and “ЕС” (EU) had no such protection. The lowercase transformation was eating them alive.

The decision point came down to this: should I add a massive Russian abbreviations dictionary to the frontend, or should I detect when we’re dealing with non-ASCII text and skip the aggressive sentence-casing altogether? The latter felt smarter. The backend’s Claude LLM was already returning perfectly capitalized Russian text via _enforce_sentence_case(). I wasn’t fixing translation quality—I was preventing the frontend from breaking it.

The fix was surgical: check if the input contains Cyrillic characters. If it does, preserve case entirely and only guarantee the first letter is uppercase. If it’s pure ASCII (English), apply the original sentence-case logic with ABBREVIATIONS protection. A simple includes() check against the Unicode range for Cyrillic (U+0400 to U+04FF) solved it without bloating the codebase.

Here’s a fun fact: Cyrillic script actually predates Latin in Byzantine tradition—it was designed in the 9th century by Saint Cyril specifically to preserve proper capitalization rules for Old Church Slavonic. Centuries later, and we’re still fighting the same battle: respecting case sensitivity in non-Latin alphabets.

The labels render correctly now. “ИИ” stays “ИИ”. The branch (fix/crawler-source-type) is clean, the build passes, and Monday’s code should behave exactly like Friday’s—which is all we can ask for 😄